Pedal boxes
Moderator: martauto
yeah just wanted to add that the graph I posted is from the screw tye vlave, you beat me. I am undecided about screw type or level and also missed a brand new AP valve on ebay for £75!Theo325 wrote:I'll try and get hold of the wilwood graph, but this AP one is going to be very similar:
Theo just to clarify could you post up the following info;
front and rear disc sizes?
front and rear caliper piston diameter (no of pistons in each caliper?)
pad height and width for front and rear calipers?
pedal box you chosen?
m/c you have chosen for front and rear?
tyre make and size?
If yourself and Geoffbob don't mind me comparing with my own calculations?
front and rear disc sizes?
front and rear caliper piston diameter (no of pistons in each caliper?)
pad height and width for front and rear calipers?
pedal box you chosen?
m/c you have chosen for front and rear?
tyre make and size?
If yourself and Geoffbob don't mind me comparing with my own calculations?
Shakey, you'll find most of the info you're looking for (and my calculations so that you can make a comparison to your own) here. The calculations are based on a guestimated threshold braking deceleration of 1.15g. That assumption will be updated when Theo obtains the required traction data for his tyres.
ShakeyC wrote:Theo just to clarify could you post up the following info;
Hi Shakey, your input and findings are of course most welcome, and of interest.
front and rear disc sizes?
front and rear caliper piston diameter (no of pistons in each caliper?)
pad height and width for front and rear calipers?
pedal box you chosen?
m/c you have chosen for front and rear?
tyre make and size?
If yourself and Geoffbob don't mind me comparing with my own calculations?
front and rear disc sizes? 280mm front and rear
front and rear caliper piston diameter (no of pistons in each caliper?) 4 x 35mm per front caliper 1 x 36mm per rear caliper
pad height and width for front and rear calipers? Front = 100mm wide and 40mm high. Rear = 75mm wide and 40mm high
pedal box you chosen? Wilwood with 6.25 pedal ratio
m/c you have chosen for front and rear? provisionally looking like .625 rear and .875 front
tyre make and size? Toyo R888 in 205/50/15 (I also have them in 195/50/15, 195/55/15 and 215/50/15 and Michelin Pilot Cup Sports in 205/50/15 - what impact do the various sizes have?
Toyo have got back to me, but are unable to provide tyre traction data. 
Whilst browsing the Tilton site I noticed they had a form you can fill out and email to them, in turn they provide a recommedation on cylinder sizes. They got back to me and also recommeded a .625 front cylinder but a .750 rear cylinder. I exchanged emails with Mike from Tilton regarding pad friction and tyre grip and he said Tilton use .5 for pad friction and 1.1 for tyre grip, which have apparently been working well in their predictions.
Whilst browsing the Tilton site I noticed they had a form you can fill out and email to them, in turn they provide a recommedation on cylinder sizes. They got back to me and also recommeded a .625 front cylinder but a .750 rear cylinder. I exchanged emails with Mike from Tilton regarding pad friction and tyre grip and he said Tilton use .5 for pad friction and 1.1 for tyre grip, which have apparently been working well in their predictions.
I don't know how accurate my datalogger is but I have seen hardly anything above 1G of braking when going round the Ring.GeoffBob wrote:Shakey, you'll find most of the info you're looking for (and my calculations so that you can make a comparison to your own) here. The calculations are based on a guestimated threshold braking deceleration of 1.15g. That assumption will be updated when Theo obtains the required traction data for his tyres.
Even on sticky rubber and occasional wheel lock up.
Don't know if this info is of any value.
Maybe I am not breaking hard enough
PS acceleration G's is even worse....
That's a real bummer Theo! You can bet that data exists but that they just don't want to share it else they risk being compared to other tyre manufacturers based upon objective data, rather than subjective analysis (which can always be refuted as "just opinion").Theo325 wrote:Toyo have got back to me, but are unable to provide tyre traction data.
All depends at how many g's he did his calculation Theo. If you plug 1g into that excel spreadsheet I posted up for you, you get 0.75" for the rear master cylinder (try this for yourself). As you progressively increase the number of g's of your threshold braking manoeuvre you will see the size of your rear M/C will get bigger and bigger. This is why knowing the limits of your tyre traction is so important.Theo325 wrote:Whilst browsing the Tilton site I noticed they had a form you can fill out and email to them, in turn they provide a recommendation on cylinder sizes. They got back to me and also recommended a .625 front cylinder but a .750 rear cylinder.
Personally, it does not surprise me that he would run his numbers at 1g. Most people are unable to set their brakes and tyres up (especially tyres) to go beyond this. Depending on the time and effort you put in, and in particular the time you spend assessing tyre performance, you should be able to get up to around 1.3, maybe 1.4g on a set of hot slicks with your low weight and improved weight distribution working to your advantage.
Purely out of interest, Formula-1's and Indy-cars are capable of around 3g's of deceleration!
But please don't forget, the number one factor that enables you to both accelerate and brake at greater g's is weight loss! Braking torque on the wheel accounts for a linear force between the road and tyre. It is, however, by Newton's second law that this force is equated to acceleration (F=m*a), and thus the less the mass the greater the acceleration (under power) or deceleration (under braking). So here's a hot tip for you, if you want to improve both your acceleration and your deceleration, replace as much of the glass in you car with polycarbonate as you can.
If you are aiming for only 1g deceleration then I would say go for the 0.75" M/C. But on the right set of slicks and your calipers and discs, I'd suggest you keep a 0.875" tucked away for a dry hot day. You'll be pleasantly surprised at the result
If your logger indicates that you cannot exceed 1g of braking without losing traction then your braking threshold is 1g. This is actually very good for a car like the E30 on a course like the NÃarburgring.UweM3 wrote:I don't know how accurate my datalogger is but I have seen hardly anything above 1G of braking when going round the Ring.
Even on sticky rubber and occasional wheel lock up.
Typically braking calculations are performed assuming equal weight distribution from one side to the other (left to right). In other words, braking on a straightaway. You'll likely find that your 1g on the 'Ring will be a bit higher if you did a simple straight-line braking test. The other two hugely influential factors, as I mentioned above, are weight and traction. To further increase your deceleration you would have to consider reducing the weight of your car or increasing your traction. The only other factor over which you have some immediate control is your brake bias. For example, when your front wheels are approaching the limits of their traction you dont want your rears at only half their traction potential. But I am sure I am preaching to the converted in this regard?
I thought I'd just get a .75 and try it out, it wa available off the shelf and I wanted to have a set of cylinders so I could fully assemble the pedals and make sure I hadn't overlooked anything with regard to their fitment/pedal position.
As you suggested before, i'll try and buy a couple more cylinders once everything is up and running and I'm in a position to fine tune. I'll have to give full slicks a try sometime, I know when I went from road tyres to R-rated tyres I was amazed at the increase in grip.
I'm all for a bit more weight loss, polycarbonate windows and a heated front windscreen are on the wishlist, but i'm pretty much out of funds. I need to get the car repainted which is another £500 I hadn't budgeted for.
I got a picture of the pedal box in it's current state (apologies for the poor quality, you need a serious dose of diazepam to hold this camera phone steady enough to get a focused shot). The weld on the frame isn't too pretty but it's hard welding box section to a contoured bit of bodywork where the edges aren't flush. It's welded to the body shell in four different places and there isn't the slightest hint of unwanted movement no matter what you try.
Here's my penny saving fluid resevoir solution - it's a RHD E30 clutch fluid resevoir with an e30 brake resevoir cap/float fitted.
As you suggested before, i'll try and buy a couple more cylinders once everything is up and running and I'm in a position to fine tune. I'll have to give full slicks a try sometime, I know when I went from road tyres to R-rated tyres I was amazed at the increase in grip.
I'm all for a bit more weight loss, polycarbonate windows and a heated front windscreen are on the wishlist, but i'm pretty much out of funds. I need to get the car repainted which is another £500 I hadn't budgeted for.
I got a picture of the pedal box in it's current state (apologies for the poor quality, you need a serious dose of diazepam to hold this camera phone steady enough to get a focused shot). The weld on the frame isn't too pretty but it's hard welding box section to a contoured bit of bodywork where the edges aren't flush. It's welded to the body shell in four different places and there isn't the slightest hint of unwanted movement no matter what you try.
Here's my penny saving fluid resevoir solution - it's a RHD E30 clutch fluid resevoir with an e30 brake resevoir cap/float fitted.
I don't think you'll have any problems running a 0.75" M/C on the rear hydraulic line whatsoever. In fact I think it will work brilliantly with your R888's.Theo325 wrote:I thought I'd just get a .75 and try it out, it wa available off the shelf and I wanted to have a set of cylinders so I could fully assemble the pedals and make sure I hadn't overlooked anything with regard to their fitment/pedal position.
Theo325 wrote:As you suggested before, i'll try and buy a couple more cylinders once everything is up and running and I'm in a position to fine tune. I'll have to give full slicks a try sometime, I know when I went from road tyres to R-rated tyres I was amazed at the increase in grip.
Anything you can do to shed weight in future will be to your advantage - GRP in place of mildsteel panels, polycarb windows, lighter battery - every little bit counts. Sadly, if you're anything like me, it takes a lot of time to save up the money for those bits.Theo325 wrote:I'm all for a bit more weight loss, polycarbonate windows and a heated front windscreen are on the wishlist, but i'm pretty much out of funds. I need to get the car repainted which is another £500 I hadn't budgeted for.
Looks fantastic Theo! Well done. I think what you have done here will become the model for someone else attempting a similar engined conversion on an E30 track car. It's a pity the righthand mounted exhaust manifold is such an obstruction (and source of heat) on RHD E30's, else I think we'd see many more BMW engined tracksters doing the same. I look forward to hearing how she brakes.Theo325 wrote:I got a picture of the pedal box in it's current state (apologies for the poor quality, you need a serious dose of diazepam to hold this camera phone steady enough to get a focused shot). The weld on the frame isn't too pretty but it's hard welding box section to a contoured bit of bodywork where the edges aren't flush. It's welded to the body shell in four different places and there isn't the slightest hint of unwanted movement no matter what you try.
Cheers Geoff, your input has been brilliant throughout - I can't thank you enough.
Still got to sort out the accelerator bracket/mechanism and throttle cable, fit a clutch pedal stop and some return springs. I also need to make a bracket to hold the remote resevoir pots, make the front brake pipes up and then get braided hoses made up for the clutch and the rear brake line, though I'm still undecided where to route this. Almost forgot, need to either incorporate the orininal e30 brake switch with yet another bracket, or use a hydraulic type, which would propbly be the easier option.
As an aside, I asked Tilton for their take on Balance bar vs Proportioning valve and they replied with;
Still got to sort out the accelerator bracket/mechanism and throttle cable, fit a clutch pedal stop and some return springs. I also need to make a bracket to hold the remote resevoir pots, make the front brake pipes up and then get braided hoses made up for the clutch and the rear brake line, though I'm still undecided where to route this. Almost forgot, need to either incorporate the orininal e30 brake switch with yet another bracket, or use a hydraulic type, which would propbly be the easier option.
As an aside, I asked Tilton for their take on Balance bar vs Proportioning valve and they replied with;
Tilton Brakes wrote:Lose the proportioning valve. You do not need it since you have a balance bar. Proportioning valves are not as consistent in operation and keeping it adds another inconsistency to the system, which you do not want in brakes. Proportioning valves are used mainly when one has a stock single master cylinder and has no other way to adjust bias. The balance bar is superior.
Master cylinder sizing is coarse tuning. Balance bar adjustment is fine tuning. If you cannot get the balance that you need out of the balance bar adjustment, then you need to change master cylinder sizes.
Theo, I read that link you posted to one of the other ongoing 'zone threads the other day with some interest. I initially responded quite violently to Demlotcrew's comment with regard to keeping a proportioning valve with reasons similar to those presented by Tilton above. I then deleted my post for fear of starting an argument.
As I think both Uwe said here, and Demlotcrew said there, a bias bar sets you up to achieve balanced braking (optimum braking traction at each wheel) at only one pedal pressure. Of course I argue that if you want to win races that is exactly where you damn well should be braking each an every time! And if the track conditions change, your weight distribution changes (due to fuel burn-off), or your front tyres wear differently to your rears; well then, that's why you have a remote bias adjuster on the dash!
This is pretty much how I worded my initial response and partly why I deleted it. I could only imagine the rain of annoyed responses it would have attracted.
Having thought it through, however, and as I said in an earlier post, I believe that there is a place for a proportioning valve in the rear brake line since it works to maintain the optimum brake bias regardless of how hard you are braking at the time. This is one thing that sets it aside from the operation of a bias bar - namely a bias bar cannot cap the pressure to your rear calipers like a proportioning valve will. A proportioning valve can, however, like a bias bar, adjust your brake bias.
Thus, if you get into trouble going too fast into a corner, you still have some mechanism to brake safely. Of course, you don't win races this way. I therefore consider fitting a proportioning valve with a dual master cylinder brake setup to be a bit like running with training wheels.
The major disadvantage that they present, in my opinion, is in that they add one more variable to the brake system that must be taken into account in the calculation of the M/C sizes. It is, therefore, more difficult to setup a dual master cylinder brake system with a proportioning valve such that your brakes actually work better than before you fitted one. But done properly it can be a valuable tool. Of course, if you are serious about braking at your traction threshold before each and every corner then I really don't see the point to fitting one. The only value that it adds is in its ability to cap the rear caliper pressure.
I still plan to post up a comparison of brake performance with and without a proportioning valve for you. I won't present all the maths as with the valve it does start to get a bit hairy, but I'll at least present the graphs so that you can see the effect upon stopping distance at say about three or four different pedal forces. With my current workload I'm afraid I just haven't had a chance to do this yet.
As I think both Uwe said here, and Demlotcrew said there, a bias bar sets you up to achieve balanced braking (optimum braking traction at each wheel) at only one pedal pressure. Of course I argue that if you want to win races that is exactly where you damn well should be braking each an every time! And if the track conditions change, your weight distribution changes (due to fuel burn-off), or your front tyres wear differently to your rears; well then, that's why you have a remote bias adjuster on the dash!
This is pretty much how I worded my initial response and partly why I deleted it. I could only imagine the rain of annoyed responses it would have attracted.
Having thought it through, however, and as I said in an earlier post, I believe that there is a place for a proportioning valve in the rear brake line since it works to maintain the optimum brake bias regardless of how hard you are braking at the time. This is one thing that sets it aside from the operation of a bias bar - namely a bias bar cannot cap the pressure to your rear calipers like a proportioning valve will. A proportioning valve can, however, like a bias bar, adjust your brake bias.
Thus, if you get into trouble going too fast into a corner, you still have some mechanism to brake safely. Of course, you don't win races this way. I therefore consider fitting a proportioning valve with a dual master cylinder brake setup to be a bit like running with training wheels.
The major disadvantage that they present, in my opinion, is in that they add one more variable to the brake system that must be taken into account in the calculation of the M/C sizes. It is, therefore, more difficult to setup a dual master cylinder brake system with a proportioning valve such that your brakes actually work better than before you fitted one. But done properly it can be a valuable tool. Of course, if you are serious about braking at your traction threshold before each and every corner then I really don't see the point to fitting one. The only value that it adds is in its ability to cap the rear caliper pressure.
I still plan to post up a comparison of brake performance with and without a proportioning valve for you. I won't present all the maths as with the valve it does start to get a bit hairy, but I'll at least present the graphs so that you can see the effect upon stopping distance at say about three or four different pedal forces. With my current workload I'm afraid I just haven't had a chance to do this yet.
Well in the end it's all trial and error and personal taste IMHO. You start off with your calculations to get the best head start possible and the rest is field experience.
I believe whatever the recommendations are (regarding the prop valve AND a balance bar), in the end of the day is counts how fast YOU get round a track. If it makes you faster and it's working for you then why not add one. (prop valve I mean)
I know from past experience that some fast drivers have sometimes some wierd setups nobody else can use, but hey as long as you are going faster than anybody else who cares!
I also believe that on the level we drive that it doesn't matter if things are not 101% optimum.
Let's face it, we're not pushing it to the limit.
If I would give my car to an expert racer they might just laugh at the piece of junk (setup etc) but it doesn't matter to me, I like it as it is and i have fun round the track. If I have to slow down a little here and there because my hardware doesn't allow me to go fast, so be it. I don't earn money with racing, it's just for fun.
And in my opinion it's the skill of a good driver not to drive over the limits of the given hardware. You have to finish first to finish first.
I believe whatever the recommendations are (regarding the prop valve AND a balance bar), in the end of the day is counts how fast YOU get round a track. If it makes you faster and it's working for you then why not add one. (prop valve I mean)
I know from past experience that some fast drivers have sometimes some wierd setups nobody else can use, but hey as long as you are going faster than anybody else who cares!
I also believe that on the level we drive that it doesn't matter if things are not 101% optimum.
Let's face it, we're not pushing it to the limit.
If I would give my car to an expert racer they might just laugh at the piece of junk (setup etc) but it doesn't matter to me, I like it as it is and i have fun round the track. If I have to slow down a little here and there because my hardware doesn't allow me to go fast, so be it. I don't earn money with racing, it's just for fun.
And in my opinion it's the skill of a good driver not to drive over the limits of the given hardware. You have to finish first to finish first.
On an internet forum? Surely not.This is pretty much how I worded my initial response and partly why I deleted it. I could only imagine the rain of annoyed responses it would have attracted.
From what you're saying Geoff a proportioning valve does have it's place in my setup. Ultimately the car is a road legal track car, not a race car - so I will have limited opportunities to drive at 10/10ths and brake at the threshold of traction. The valve/no valve comparisison would make for interesting reason, but please don't sacrafice too much of your lunch break/free time!
Uwe, I'm in agreement with you. The greatest limitation to my car will be my driving. But knowing that you've got a setup which theoretically is close to optimal is reassuring. It's also a topic I find rather interesting, so learing about the subject and gaining more of an understanding is another benefit to threads such as this.
Theo, I know you are keen on Toyo R888's, but out of interest, have a look at Dunlop's semi slicks here. The Dunlop DZ03G range are very popular down here.
So far as I am aware, Dunlop are running some sort of special in the UK at the moment under the heading of "Tyre-Testers" where they are looking for drivers to compare their products to others. Not sure if this is of any interest to you or whether you can get a discount out of them based on this?
So far as I am aware, Dunlop are running some sort of special in the UK at the moment under the heading of "Tyre-Testers" where they are looking for drivers to compare their products to others. Not sure if this is of any interest to you or whether you can get a discount out of them based on this?
Theo,
As promised, I have compared the braking performance of a number of dual master cylinder braking setups, both with and without a proportioning valve in the rear hydraulic line.
In order to undertake this comparison I constructed a mathematical model using MATLAB. The model is a simple point-mass type model with semi rigid connections. The height and separation of the masses are specified in order to define the cars COG and wheelbase. Lateral symmetry is assumed (2D), so the model is only good for straight line braking simulations, which is as required for the purposes of this comparison. Unless stated explicitly below, all brake components, running gear etc. are as defined by yourself. These results therefore apply specifically to your car. The traction limits of the front and rear tyres were calculated using a standard linear-exponential model for a semi-slick tyre. I can provide the details of this model if you want me to, but won't go into it unnecessarily.
Please click on the graphs to enlarge them as they may otherwise be unclear.
Figure 1 shows the predicted braking deceleration, and front and rear wheel traction fraction as a function of the force applied by the driver to the brake pedal for Setup-A. Setup-A is a 5/8”a front master cylinder, a 3/4”a rear master cylinder, with the pedal bias-bar adjusted to 50%, and no proportioning valve.
In case you are unaware, traction fraction is defined as the fraction of a tyres available traction consumed by the braking force. The reason this is important (and thus worth showing in the graphs) is because we would like the front and rear traction fractions to be as similar as possible in the interests of maintaining vehicle stability while braking. For example, if the front traction fraction is significantly greater than the rear, we would expect the rear to concertina into the front when braking hard. Fortunately, unless the car is made from papier-mache, this doesn’t happen. However, when entering a corner, or in the presence of a strong crosswind, the rear may start to overtake the front since the net force will cause it to pivot around its moment of inertia in the vertical. I have had this unfortunate experience on more than one occasion.
The traction fraction is also important because, at a value of 1.0, all the traction of that wheel has been consumed by the braking force. Any additional braking force therefore results in a loss of traction at that wheel. Thus, in order to achieve the best deceleration possible, we require that all wheels reach their traction limit simultaneously. If the front wheels, for example, reach a traction fraction of 1.0 while the rear wheels are only at, say, 0.73, then our threshold deceleration will be unnecessarily low.
This is exactly as shown in Figure 1, which indicates a deceleration threshold of exactly 1.00g as a result of a loss of traction at the front wheels. At the deceleration threshold the rear wheels still have roughly 27% of their traction in reserve. Figure 1 also indicates that the front traction fraction is significantly greater than the rear traction fraction across the full range of pedal force. We thus conclude that this problem might be corrected by adjusting the pedal bias-bar.
Figure 1:
Figure 2 shows how the situation is improved by implementing Setup-B, where the pedal bias-bar has been adjusted to 57%, increasing the rear brake force. Figure 2 indicates a greatly improved threshold deceleration of 1.19g, purely by adjusting the brake bias towards the rear. Nonetheless, the front traction fraction is still significantly greater than the rear traction fraction across most of the range of pedal force. That is, up until around 34kg of pedal force, at which point the front and rear traction fractions crossover at a value of around 0.87. As a result of this cross-over, when the threshold of deceleration is reached, a loss in rear wheel traction is experienced, as opposed to a loss of front wheel traction, as in the case of Setup-A. For reasons that I am sure you are aware of, a loss of front wheel traction is preferable to a loss of rear wheel traction.
Figure 2:
Increasing the pedal bias-bar setting to 64%, as one might expect, only makes the situation worse, as shown in Figure 3 for Setup-C. Here, despite the similarity in the front and rear traction fractions below a pedal force of 20kg, above 20kg they rapidly depart from each other. When the rear finally lets go at a threshold deceleration of 1.08g the front wheels still have 28% of their traction in reserve. It could be argued that this a good thing since this additional front wheel traction can be used to help steer out of the ensuing over-steer. This is fine, indeed desired, for drifting. But for racing I’d rather have brakes that work properly, where the rear doesn’t lock-up unnecessarily.
Figure 3:
We therefore conclude that, although not ideal, of the above three setups, Setup-B is optimal under the presented conditions.
Figure 4 shows what happens if we take Setup-C and simply insert a Tilton brake proportioning valve with the knee-pressure (the point at which the output pressure reduces by 1/3 of the input pressure) set to 500psi, in order to counteract the way in which the rear traction fraction gets ahead of the front traction fraction after 25kg pedal force. Figure 4 clearly indicates that this tactic is successful since the front and rear traction fractions are now very similar over the full range of the pedal force, and, at the limit of traction, a threshold deceleration of 1.22g is achieved. There is, however, a price to pay for this improvement. Some mechanical advantage has been lost as a result in the reduction in the rear hydraulic pressure and, consequently, it now takes a full 47kg of pedal force to achieve the threshold deceleration.
Figure 4:
There are two ways that we can deal with the increased pedal force required to achieve threshold braking in Setup-D. We can accept this penalty and simply press the pedal harder, taking full benefit of the improved distribution of traction between the front and rear, or we could consider reducing the size of the rear master cylinder in order to regain some of the lost mechanical advantage.
Figure 5 shows the effect of reducing the diameter of the rear master cylinder from 3/4" down to a 5/8”a, which is, coincidentally, the same diameter as the front brake master cylinder. Due to the change in brake bias, the pedal bias bar is adjusted to 52%. The knee pressure of the brake proportioning valve is kept at a value of 500psi. Despite its similarity to Figure 4, Setup-E demonstrates two significant advantages when compared to Setup-D, namely, the pedal force required to bring about the threshold of deceleration is reduced to 37kg (10kg lighter than before) and at no point does the rear traction fraction exceed the front traction fraction. This means that, at the limit of deceleration the front wheels will brake traction slightly ahead of the rear wheels. This is as desired in a race-car. Compared to Figure 4, however, Figure 5 indicates a threshold deceleration of 1.18g, slightly less than for Setup-D, but still in excess of Setup-A and Setup-B. This is a small price to pay for a lower pedal force with well balanced traction.
Figure 5:
Figure 6 shows the resultant deceleration as a function of the force applied to the brake pedal for all five setups under consideration. Figure 6 indicates that Setup-A, Setup-B and Setup-C produce virtually identical deceleration, the only difference being the magnitude of the threshold deceleration. What we gleam from this is that, adjusting the pedal bias-bar has little or no effect upon the amount of straight line deceleration the car can achieve as a function of pedal force. Only the absolute maximum (the threshold) is effected. However, since adjusting the bias has a significant effect upon the front and rear traction fractions (as shown in Figures 1 through 3), we can expect adjusting the pedal bias-bar to have a significant effect upon the stability of the car, particularly noticeable while simultaneously braking and cornering. Figure 6 further indicates that Setup D provides similar deceleration to the previous three setups up until around 25kg of pedal force, beyond which the brake proportioning valve reduces the rear brake force, which thus reduces the overall deceleration at any pedal force thereafter.
Of the five setups, however, Figure 6 clearly indicates that Setup-E is superior since it delivers the best deceleration across the range of pedal force, while maintaining the optimum traction fraction. Unless you are specifically looking to achieve the maximum deceleration possible, this is definitely the setup to choose for your car.
Figure 6:
Finally, Figure 7 shows the straight-line braking distances as a function of time for the five setups. During each simulation the brake pedal force was increased linearly at a rate of 1000N/s from zero pedal force up to the pedal force commensurate with the threshold of traction for that setup. Thus, for Setup-A, Setup-B, Setup-C and Setup-E, roughly 35kg of force was progressively applied to the brake pedal over a period of 0.35s, and sustained at 35kg thereafter. This is quite within human capabilities. For Setup-E, 47kg was progressively applied over 0.47s. Each car had an initial velocity of 50mph (22.35m/s). While the initial velocity has a significant effect upon the absolute outcome of each simulation, it has no effect upon the relative comparison between the different setups.
Figure 7:
Figure 7 indicates that the setup with the worst stopping time and distance is setup A, with a stopping distance of 27.4m in a time of 2.36s. Setup-C produced the second worst result with a stopping distance of 25.5m in a time of 2.19s. The remaining three all produced a very similar result of roughly 23.5m in 2.0s.
It is clear, therefore, that by all measures of performance, Setup-E (with two 5/8”a brake master cylinders, a brake proportioning valve set to 500psi, and a rearwards pedal bias of 52%) is superior to the other four cases considered.
As promised, I have compared the braking performance of a number of dual master cylinder braking setups, both with and without a proportioning valve in the rear hydraulic line.
In order to undertake this comparison I constructed a mathematical model using MATLAB. The model is a simple point-mass type model with semi rigid connections. The height and separation of the masses are specified in order to define the cars COG and wheelbase. Lateral symmetry is assumed (2D), so the model is only good for straight line braking simulations, which is as required for the purposes of this comparison. Unless stated explicitly below, all brake components, running gear etc. are as defined by yourself. These results therefore apply specifically to your car. The traction limits of the front and rear tyres were calculated using a standard linear-exponential model for a semi-slick tyre. I can provide the details of this model if you want me to, but won't go into it unnecessarily.
Please click on the graphs to enlarge them as they may otherwise be unclear.
Figure 1 shows the predicted braking deceleration, and front and rear wheel traction fraction as a function of the force applied by the driver to the brake pedal for Setup-A. Setup-A is a 5/8”a front master cylinder, a 3/4”a rear master cylinder, with the pedal bias-bar adjusted to 50%, and no proportioning valve.
In case you are unaware, traction fraction is defined as the fraction of a tyres available traction consumed by the braking force. The reason this is important (and thus worth showing in the graphs) is because we would like the front and rear traction fractions to be as similar as possible in the interests of maintaining vehicle stability while braking. For example, if the front traction fraction is significantly greater than the rear, we would expect the rear to concertina into the front when braking hard. Fortunately, unless the car is made from papier-mache, this doesn’t happen. However, when entering a corner, or in the presence of a strong crosswind, the rear may start to overtake the front since the net force will cause it to pivot around its moment of inertia in the vertical. I have had this unfortunate experience on more than one occasion.
The traction fraction is also important because, at a value of 1.0, all the traction of that wheel has been consumed by the braking force. Any additional braking force therefore results in a loss of traction at that wheel. Thus, in order to achieve the best deceleration possible, we require that all wheels reach their traction limit simultaneously. If the front wheels, for example, reach a traction fraction of 1.0 while the rear wheels are only at, say, 0.73, then our threshold deceleration will be unnecessarily low.
This is exactly as shown in Figure 1, which indicates a deceleration threshold of exactly 1.00g as a result of a loss of traction at the front wheels. At the deceleration threshold the rear wheels still have roughly 27% of their traction in reserve. Figure 1 also indicates that the front traction fraction is significantly greater than the rear traction fraction across the full range of pedal force. We thus conclude that this problem might be corrected by adjusting the pedal bias-bar.
Figure 1:
Figure 2 shows how the situation is improved by implementing Setup-B, where the pedal bias-bar has been adjusted to 57%, increasing the rear brake force. Figure 2 indicates a greatly improved threshold deceleration of 1.19g, purely by adjusting the brake bias towards the rear. Nonetheless, the front traction fraction is still significantly greater than the rear traction fraction across most of the range of pedal force. That is, up until around 34kg of pedal force, at which point the front and rear traction fractions crossover at a value of around 0.87. As a result of this cross-over, when the threshold of deceleration is reached, a loss in rear wheel traction is experienced, as opposed to a loss of front wheel traction, as in the case of Setup-A. For reasons that I am sure you are aware of, a loss of front wheel traction is preferable to a loss of rear wheel traction.
Figure 2:
Increasing the pedal bias-bar setting to 64%, as one might expect, only makes the situation worse, as shown in Figure 3 for Setup-C. Here, despite the similarity in the front and rear traction fractions below a pedal force of 20kg, above 20kg they rapidly depart from each other. When the rear finally lets go at a threshold deceleration of 1.08g the front wheels still have 28% of their traction in reserve. It could be argued that this a good thing since this additional front wheel traction can be used to help steer out of the ensuing over-steer. This is fine, indeed desired, for drifting. But for racing I’d rather have brakes that work properly, where the rear doesn’t lock-up unnecessarily.
Figure 3:
We therefore conclude that, although not ideal, of the above three setups, Setup-B is optimal under the presented conditions.
Figure 4 shows what happens if we take Setup-C and simply insert a Tilton brake proportioning valve with the knee-pressure (the point at which the output pressure reduces by 1/3 of the input pressure) set to 500psi, in order to counteract the way in which the rear traction fraction gets ahead of the front traction fraction after 25kg pedal force. Figure 4 clearly indicates that this tactic is successful since the front and rear traction fractions are now very similar over the full range of the pedal force, and, at the limit of traction, a threshold deceleration of 1.22g is achieved. There is, however, a price to pay for this improvement. Some mechanical advantage has been lost as a result in the reduction in the rear hydraulic pressure and, consequently, it now takes a full 47kg of pedal force to achieve the threshold deceleration.
Figure 4:
There are two ways that we can deal with the increased pedal force required to achieve threshold braking in Setup-D. We can accept this penalty and simply press the pedal harder, taking full benefit of the improved distribution of traction between the front and rear, or we could consider reducing the size of the rear master cylinder in order to regain some of the lost mechanical advantage.
Figure 5 shows the effect of reducing the diameter of the rear master cylinder from 3/4" down to a 5/8”a, which is, coincidentally, the same diameter as the front brake master cylinder. Due to the change in brake bias, the pedal bias bar is adjusted to 52%. The knee pressure of the brake proportioning valve is kept at a value of 500psi. Despite its similarity to Figure 4, Setup-E demonstrates two significant advantages when compared to Setup-D, namely, the pedal force required to bring about the threshold of deceleration is reduced to 37kg (10kg lighter than before) and at no point does the rear traction fraction exceed the front traction fraction. This means that, at the limit of deceleration the front wheels will brake traction slightly ahead of the rear wheels. This is as desired in a race-car. Compared to Figure 4, however, Figure 5 indicates a threshold deceleration of 1.18g, slightly less than for Setup-D, but still in excess of Setup-A and Setup-B. This is a small price to pay for a lower pedal force with well balanced traction.
Figure 5:
Figure 6 shows the resultant deceleration as a function of the force applied to the brake pedal for all five setups under consideration. Figure 6 indicates that Setup-A, Setup-B and Setup-C produce virtually identical deceleration, the only difference being the magnitude of the threshold deceleration. What we gleam from this is that, adjusting the pedal bias-bar has little or no effect upon the amount of straight line deceleration the car can achieve as a function of pedal force. Only the absolute maximum (the threshold) is effected. However, since adjusting the bias has a significant effect upon the front and rear traction fractions (as shown in Figures 1 through 3), we can expect adjusting the pedal bias-bar to have a significant effect upon the stability of the car, particularly noticeable while simultaneously braking and cornering. Figure 6 further indicates that Setup D provides similar deceleration to the previous three setups up until around 25kg of pedal force, beyond which the brake proportioning valve reduces the rear brake force, which thus reduces the overall deceleration at any pedal force thereafter.
Of the five setups, however, Figure 6 clearly indicates that Setup-E is superior since it delivers the best deceleration across the range of pedal force, while maintaining the optimum traction fraction. Unless you are specifically looking to achieve the maximum deceleration possible, this is definitely the setup to choose for your car.
Figure 6:
Finally, Figure 7 shows the straight-line braking distances as a function of time for the five setups. During each simulation the brake pedal force was increased linearly at a rate of 1000N/s from zero pedal force up to the pedal force commensurate with the threshold of traction for that setup. Thus, for Setup-A, Setup-B, Setup-C and Setup-E, roughly 35kg of force was progressively applied to the brake pedal over a period of 0.35s, and sustained at 35kg thereafter. This is quite within human capabilities. For Setup-E, 47kg was progressively applied over 0.47s. Each car had an initial velocity of 50mph (22.35m/s). While the initial velocity has a significant effect upon the absolute outcome of each simulation, it has no effect upon the relative comparison between the different setups.
Figure 7:
Figure 7 indicates that the setup with the worst stopping time and distance is setup A, with a stopping distance of 27.4m in a time of 2.36s. Setup-C produced the second worst result with a stopping distance of 25.5m in a time of 2.19s. The remaining three all produced a very similar result of roughly 23.5m in 2.0s.
It is clear, therefore, that by all measures of performance, Setup-E (with two 5/8”a brake master cylinders, a brake proportioning valve set to 500psi, and a rearwards pedal bias of 52%) is superior to the other four cases considered.
Sorry been away last week and totally forgot about this, I punched in the same base figures as Geoffbob and simulated the same scenarios, then I tweaked some of the figures and re-simulated. Overall Theo I agree with what you have will work very well.
1/3 brake pedal travel (normal road braking) 53% Front 47% Rear brake force distribution at 0.1G (Hydraulic bias 23% Forward 77% Rear)
2/3 brake pedal travel (hard but not full braking) 66% Front 34% Rear brake force distribution at 0.68G (in wet limit of tyres, pressing any hard will lock both front and rears together) (Hydraulic bias 47% Forward 53% Rear)
Full brake pedal travel 77% Front 23% Rear brake force distribution at 1.24 G which will lock all wheels in dry (Hydraulic bias 34% Forward 66% Rear)
Theo regarding your questions about different tyres, sizes and profiles, I concentrated my afternoon here. Out of all those sizes 205/50/15 I would consider the best all around profile, interestingly the other sizes (195/50/15 - 215/50/15) there is not enough difference to warrant changing m/c sizes or pedal ratios and just slight tweak of balance bar is most that would be required therefore you have plenty of flexibility as long as you run same profiles on all tyres.
1/3 brake pedal travel (normal road braking) 53% Front 47% Rear brake force distribution at 0.1G (Hydraulic bias 23% Forward 77% Rear)
2/3 brake pedal travel (hard but not full braking) 66% Front 34% Rear brake force distribution at 0.68G (in wet limit of tyres, pressing any hard will lock both front and rears together) (Hydraulic bias 47% Forward 53% Rear)
Full brake pedal travel 77% Front 23% Rear brake force distribution at 1.24 G which will lock all wheels in dry (Hydraulic bias 34% Forward 66% Rear)
Theo regarding your questions about different tyres, sizes and profiles, I concentrated my afternoon here. Out of all those sizes 205/50/15 I would consider the best all around profile, interestingly the other sizes (195/50/15 - 215/50/15) there is not enough difference to warrant changing m/c sizes or pedal ratios and just slight tweak of balance bar is most that would be required therefore you have plenty of flexibility as long as you run same profiles on all tyres.
Once again Geoff you've gone way beyond what I could reasonably have expected you to have done to help me out here. I can't help feel I'll probably get myself confused when I attempt to adjust the setup if it starts raining while on track, would this be best done on the balance bar or proportioning valve?
I like the braking distance comparison chart , 50mph-0 in 23.5 metres sounds very useful.
Shakey, thanks too for your input. Were your findings based on Geoff's recommendation of a .875 cylinder or with the .750 cylinder which I purchased through impatience!?
I would ask what impact there would be on the optimal setup when running staggered tyres, eg 195/50 fronts and 215/50 rears, but I think the best thing to do would simply not to do this.
I like the braking distance comparison chart , 50mph-0 in 23.5 metres sounds very useful.
Shakey, thanks too for your input. Were your findings based on Geoff's recommendation of a .875 cylinder or with the .750 cylinder which I purchased through impatience!?
I would ask what impact there would be on the optimal setup when running staggered tyres, eg 195/50 fronts and 215/50 rears, but I think the best thing to do would simply not to do this.
You're welcome.Theo325 wrote:Once again Geoff you've gone way beyond what I could reasonably have expected you to have done to help me out here.
Theo, have a look at figures 4 and 5 again. Pay close attention to the green and red curves that show the front and rear traction fractions. See how similar they are to each other? So long as those two curves are the same your brake bias will be correct regardless of how hard you push the brake pedal. This means that you don't need to adjust a thing when it starts raining! That's the beauty of a setup like this. You have almost perfect bias at all times (because your front and rear traction fractions are equal at all times). In other words, if you find yourself in trouble because you entered a corner a bit too fast you still have the ability to brake (within reason, obviously) without the cars arse overtaking its nose, or understeering towards the outside edge of the track.Theo325 wrote:I can't help feel I'll probably get myself confused when I attempt to adjust the setup if it starts raining while on track, would this be best done on the balance bar or proportioning valve?.
Now have a look at Figure 1 again. Look at how high the front traction fraction is compared to the rear. This car would oversteer (as the rear pushed on the front) if you braked while cornering with that setup. Similarly, a car whose rear traction fraction was markedly higher than the front would tend to understeer while braking in a corner (as the rear tried to hold back the front).
The only time you will need to adjust the bias-bar is as a result of weight redistribution due to fuel burn-off at the rear or if your front and rear tyres wear differently. Once your proportioning valve is setup you can leave it well alone (and for this reason I would recommend the knob type over the lever). If you do need to adjust your bias for any reason, do it with the remote bias-bar adjuster.
Oh, and I forgot to mention, that's for warmed up 195 semi-slicks all round on dry tarmac. I can do the calculations for any speed you like if you want. The point, however, is how the different setups compare. Not much difference between them actually. The important difference, at least, is in the way the last two setups give you balanced braking across the range of pedal force. I would thoroughly recommend you fit the components from Setup-E.Theo325 wrote:I like the braking distance comparison chart , 50mph-0 in 23.5 metres sounds very useful.
Theo either is suitable, i recommend the .875 with 205/50/15 on basis the balance bar can be left in the middle straight out the box and you have a very good base setup. This leaves you plenty of margin to tweek the bias via balance bar to suit your taste. If you use the .750 you need 1 1/2 turns via balance bar towards rear to achieve same balance.
The way i set up cars is find a large roundabout (when not busy and safe obviously) go round and apply the brakes if the car understeers and you seem to be travelling a wider circle you have too much rear bias. For the front if it feels like the nose is going into a tighter circle you have too much front bias. Its a very usefull way of balancing the brake bias other than straight line braking which to be honest is more difficult to tell whats going on.
Regarding staggered tyres its not a good idea unless your confident in what your doing as you will have less front end traction and steering which I find usefull on some corners it evens out the balance for all 4 wheel drifts rather than just under/oversteering at the limit to get better lap times as you can get on the power well much earlier even before reaching the apex .
The way i set up cars is find a large roundabout (when not busy and safe obviously) go round and apply the brakes if the car understeers and you seem to be travelling a wider circle you have too much rear bias. For the front if it feels like the nose is going into a tighter circle you have too much front bias. Its a very usefull way of balancing the brake bias other than straight line braking which to be honest is more difficult to tell whats going on.
Regarding staggered tyres its not a good idea unless your confident in what your doing as you will have less front end traction and steering which I find usefull on some corners it evens out the balance for all 4 wheel drifts rather than just under/oversteering at the limit to get better lap times as you can get on the power well much earlier even before reaching the apex
.Thanks for clarifying Geoff, I understand now that with such well matched/setup brakes road conditions shouldn't impact upon balance because both axles are effected to the same extent by reduced grip.
Shakey, sounds like a good way of setting a car up so as to take into account trail braking. Just need to find a big roundabout in Kent without numerous potholes and changes in surface...
The reason I wanted to know about staggered tyres is that I have four good 215/50s which I want to get my moneys worth from, but I'm pretty sure they will be too wide to go on the front. I'll try running a staggered setup on a trackday and see how it goes.
Cool, just for fun could you post up the 124mph-0 stopping time and distance with setup-E. The new Pagani Zonda Cinque will do it in 4.3seconds, I want to see how my car stacks up!Oh, and I forgot to mention, that's for warmed up 195 semi-slicks all round on dry tarmac. I can do the calculations for any speed you like if you want.
Shakey, sounds like a good way of setting a car up so as to take into account trail braking. Just need to find a big roundabout in Kent without numerous potholes and changes in surface...
The reason I wanted to know about staggered tyres is that I have four good 215/50s which I want to get my moneys worth from, but I'm pretty sure they will be too wide to go on the front. I'll try running a staggered setup on a trackday and see how it goes.
Theo, what you have to keep in mind is that without a proportioning valve you will only have balanced braking at one pedal force. For example, you might set your M/C's and pedal up so that you can pull a 1.1g braking manoeuvre on dry tarmac with a pedal force of say 35kg. And that's fine, so long as you always apply 35kg of pedal force before every corner in order to always brake at 1.1g of deceleration.Theo325 wrote:Thanks for clarifying Geoff, I understand now that with such well matched/setup brakes road conditions shouldn't impact upon balance because both axles are effected to the same extent by reduced grip.
But what about if you want to brake at say only 0.4g? Well then, in that case your bias will be wrong (because the weight of the car will be distributed differently at 0.4g) and thus you won't have the correct distribution of traction between the front and rear wheels, and that will effect your stability if you are cornering at the time. That's basically what Demlotcrew was trying to explain to you the other day.
Ideally, you want the amount of traction consumed by your front and rear brakes to be the same regardless of how hard you push down on the brake pedal at any time. Just in case it's unclear, the horizontal axis of the first six graphs I posted is how hard you are pushing the brake pedal.
Although a proportioning valve doesn't do a perfect job, you can see by comparing the traction fractions in those graphs that for Setup-D and Setup-E it's about as good as it's going to get.
Sorry if I am labouring this point unnecessarily, but it's important you understand exactly how a proportioning valve effects your setup.
I'll post that graph you asked for in a moment.
"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
I understand this Geoff, Setup E appears to offer a good balance throughout the full scale of pedal force. As this car is going to be road legal and driven to trackdays and the 'Ring it's nice to know that the brakes will offer a decent balance for a variety of braking situations. I think it's fantastic that you are able to calculate all this, and even better that you can explain to me so I understand. My only concern is that these calculations are all dependent on a series of assumptions such as vehicle mass etc. Fancy doing it all over again once I have concrete figures for all necessary fields!? 
As requested, from 200km/h to 0 in 4.8 seconds. However, to get this time you'd have to maintain the car on the threshold of losing traction (with perfectly biased brakes) for the duration (no brake modulation), across all irregularities and fluff that might be in the road. I think you'b be looking at around 5.5 seconds more realistically with Setup-E.
"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
You're on the money there Theo! I do this for a living and you'd be surprised how easy it is to produce a physically realistic model (using some of the latest simulation software on the market) that produces some of the most useless results because I input some crappy values based on poor assumptions. It's a case of garbage in, garbage out - quite rightly spotted!Theo325 wrote:IMy only concern is that these calculations are all dependent on a series of assumptions such as vehicle mass etc. Fancy doing it all over again once I have concrete figures for all necessary fields!?
No problem running it all again. I have the models all written up already (that's 99% of the effort) so all I have to do is change a few of the input parameters and just hit enter.
And if any of the above doesn't make any sense to you don't hesitate to ask. It's not rocket science, but I know from experience that it takes a bit of effort to get your head around it first time. At least I know it was that way for me.
"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
Thanks for the extra graph, I can't see myself performing any 200km/h-0 stops, nice to know how it stacks up against some serious machinery though.
As soon as I have the necessary figures I'll pass them on so you can do the clever stuff!
As soon as I have the necessary figures I'll pass them on so you can do the clever stuff!
I do find myself having to read through some of the posts before I can make sense of them, but it's all making sense to me at the moment.And if any of the above doesn't make any sense to you don't hesitate to ask. It's not rocket science, but I know from experience that it takes a bit of effort to get your head around it first time. At least I know it was that way for me.
To save yourselves some effort the result i got with Geoffbobs base figures and assumptions and the simulations i ran again with my own data from previous experience there isn't a major difference and was without a brake bias prop type valve of any sort.
1/3 brake pedal travel (normal road braking) 53% Front 47% Rear brake force distribution at 0.1G (Hydraulic bias 23% Forward 77% Rear)
2/3 brake pedal travel (hard but not full braking) 66% Front 34% Rear brake force distribution at 0.68G (in wet limit of tyres, pressing any harder will lock both front and rears together) (Hydraulic bias 47% Forward 53% Rear)
Full brake pedal travel 77% Front 23% Rear brake force distribution at 1.24 G which will lock all wheels in dry (Hydraulic bias 34% Forward 66% Rear)
ps motorway slip road type roundabouts usually big enough to safely get upto reasonable speed so when your trail braking its easy to tell if the circle your travelling is getting bigger or smaller. Tyre combos you could use your 215's on rear with 205 front, or 205 rear with 195 fronts
Geoffbob models are excellent getting a head start but unfortunately it can't take into account how a driver drives, many times I set up racing cars of all sorts and it just does not work the same with 2 or more different drivers
1/3 brake pedal travel (normal road braking) 53% Front 47% Rear brake force distribution at 0.1G (Hydraulic bias 23% Forward 77% Rear)
2/3 brake pedal travel (hard but not full braking) 66% Front 34% Rear brake force distribution at 0.68G (in wet limit of tyres, pressing any harder will lock both front and rears together) (Hydraulic bias 47% Forward 53% Rear)
Full brake pedal travel 77% Front 23% Rear brake force distribution at 1.24 G which will lock all wheels in dry (Hydraulic bias 34% Forward 66% Rear)
ps motorway slip road type roundabouts usually big enough to safely get upto reasonable speed so when your trail braking its easy to tell if the circle your travelling is getting bigger or smaller. Tyre combos you could use your 215's on rear with 205 front, or 205 rear with 195 fronts
Geoffbob models are excellent getting a head start but unfortunately it can't take into account how a driver drives, many times I set up racing cars of all sorts and it just does not work the same with 2 or more different drivers
Going to resurrect this post as I'm in the process of junking the servo and want to fit a Pedal box.
A few questions to throw up.....feel free to flame as required!
Floor or Bulkhead? floor means I can put the seat further back but anything I should look out for?
Optimum balance products. anyone used them? any good?
GeoffBob. Do you offer your technical knowledge to any one?? PM if so I can Paypal the price of a beer if you need incentive 
A few questions to throw up.....feel free to flame as required!
Floor or Bulkhead? floor means I can put the seat further back but anything I should look out for?
Optimum balance products. anyone used them? any good?
GeoffBob. Do you offer your technical knowledge to any one?? PM if so
I can Paypal the price of a beer if you need incentive See us in www.racingsaloons.co.uk helped by,
alloyproducts for alloy fabrications
www.motorsportoils.co.uk for Lucas oil
www.zeroexhausts.co.uk for the noise
MTech 07831831846 for an engine!
alloyproducts for alloy fabrications
www.motorsportoils.co.uk for Lucas oil
www.zeroexhausts.co.uk for the noise
MTech 07831831846 for an engine!
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Dan318-is
- Married to the E30 Zone
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Mate i'm working for an OEM bike company and we have contacted four tyre manufacturers, none of them will give us even a sniff of data. I think the only people they give it out to are the big boys/f1 teams.Theo325 wrote:Toyo have got back to me, but are unable to provide tyre traction data.
No worries about the beer mate (but thanks for the offershorty73 wrote:GeoffBob. Do you offer your technical knowledge to any one?? PM if so
) - ask away and I'll help you if I can. I've only ever once worked with a set of floor mounted pedals. 'Probably your best option if you are serious about racing. You'll need to pull your seat right back and down so that your legs are angled correctly (almost straight out) to operate them, else they can be damn uncomfortable. You'll then need to look at an E36 (or longer) steering column to push your steering wheel further back, as well as modify the mounting for the column so as to drop the wheel down. The lower seating position will lower the cars COG slightly (since you are sitting lower) but is only any good for racing. If your car doubles as a daily driver you'll battle to park or negotiate traffic (although I'm a short-arse, so maybe my experience isn't the best to go by).shorty73 wrote:Floor or Bulkhead? floor means I can put the seat further back but anything I should look out for?
In all other respects their setup (M/C's, balance bar etc) is much like any other set of racing pedals. Some modificaions will be required to the floor and/or base of the firewall to fit floor mounted pedals and M/C's.
"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
The cars track/race only so no worries about car parks etc.
I think if I modify the steering etc too much I could fall foul of a few regs and make myself ineligible for anything I would be competitive in.
The set up I have seen have the M/C towards the driver under an ali foot plate so I don't think I'd need too much in the way of a bulkhead mod. Columns already dropped a shade and a deep dish wheel might give a bit of extra reach.
Could be another can of worms that doesn't need opening
If I post some specific stats could you come up with a base line (M/C's and pedal ratio etc)for me to aim for?
I think if I modify the steering etc too much I could fall foul of a few regs and make myself ineligible for anything I would be competitive in.
The set up I have seen have the M/C towards the driver under an ali foot plate so I don't think I'd need too much in the way of a bulkhead mod. Columns already dropped a shade and a deep dish wheel might give a bit of extra reach.
Could be another can of worms that doesn't need opening
If I post some specific stats could you come up with a base line (M/C's and pedal ratio etc)for me to aim for?
See us in www.racingsaloons.co.uk helped by,
alloyproducts for alloy fabrications
www.motorsportoils.co.uk for Lucas oil
www.zeroexhausts.co.uk for the noise
MTech 07831831846 for an engine!
alloyproducts for alloy fabrications
www.motorsportoils.co.uk for Lucas oil
www.zeroexhausts.co.uk for the noise
MTech 07831831846 for an engine!
Craig, here are a couple more photos of my setup - I chopped up the original pedalbox and modified the throttle linkage to suit. Theres and adjustable clutch pedal stop as well, I've not got pedal return springs on the clutch and brake pedals - not sure if they're really needed.
Sure, I'll help where I can.shorty73 wrote:If I post some specific stats could you come up with a base line (M/C's and pedal ratio etc)for me to aim for?
Maybe start a separate thread though, so that we can keep your data, graphs etc separate from Theo's. Lengthy threads with a lot of information can be confusing for other zoners using the search tool while looking for similar info at a later date.
To help you, I'll need your cars weight and weight distribution (corner weights would be useful if you have) not to mention the details of your full brake setup (calipers, discs and pads, front and rear) and what tyres you are running on.
Before we go any further, however, have a good look at what Theo and other zoners have done on their cars. If you are going to fall foul of your regs it might be a good idea to consider if some other solution on the zone may work for you. I also suspect that if you opt for floor mounted pedals you'll need to drop your column even further than is. A deep dish wheel with a quick release adaptor and steering boss can do wonders to increase the length of the column, but without lowering the angle of the column the wheel also climbs higher and can become impractical and/or silly. But I am sure we can find something that will work for you.
"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti