E30 with SR20DET

[Theo]

The pedal box is made by Wilwood, in hindsight I should have gone for the Tilton assembly which you have but I have a local supplier of Wilwood who had the pedal box on the shelf - that's a deciding factor for someone as impatient as me.

I'll tweak the pedal height and report back with the results. My master cylinders are horizontal, but a pedal return spring is something I've always meant to add anyway.

[winx]

I have spoken to race technologies today and they will give me a 10% discount on any spend over £200, or for a group buy of 5 or more units they will give 20%
Not sure if you are on any other forums where people might be interested in joining a group buy?
Let me know if you are interested...

[Theo]

20% off is pretty damn good. I'm tempted, I really am. One thing that appeals is you can use the original fuel level sender whereas other dashes need you to have a different level sender which is a pain on the E30 where the sender is mounted to the in-tank lift pump.

I wonder if the E30 speedo sensor can be used? Any ideas?

[winx]

[Theo]

Cool, thanks for posting that.

I don't think I know anyone else who might be interested and to be honest, I'm by no means a certainty either.

[GeoffBob]

Hi Theo,

Well, as I suspected, with your current setup (M/C's = 5/8" both front and rear, bias bar = 52% and prop valve set to 500psi) then 300mm discs and 45mm two-pot callipers on the rear WILL cause your rear wheels to lock-up at just under 20kg of pedal force. At this point your front brakes will be around halfway to their threshold, which means that your braking times and distances will suffer badly.



However, if you replace your rear M/C with a 3/4" unit AND set your prop valve down to 300psi (typically around setting 2 or 3) then you'll reduce your rear hydraulic pressure sufficient to prevent your rears from locking up ahead of the fronts.



If this is what it takes for you to run the same brake compound on both the front and rear than I see no reason not to fit this combination, although the idea of having larger discs on the rear (300mm) than on the front (280mm) seems somewhat odd to me. I suspect that your rear discs will outlive the rest of your car, that’s just how little you’ll actually be using them. Your rear pads will probably last 2 -3 times as longs as your front pads.

Your stopping distance and time from 50mph on a flat surface work out the same with the M3 callipers. The only difference between the two is that your M3 callipers are operated at greater pressure.



Theo, understand this, fitting these brakes will do nothing for your braking times or stopping distances. As with all cars, your traction is limited by your tyres, and fitting bigger brakes won’t do anything to overcome this. If it means, however, that you get to pay less for your pads and can buy pads (front and rear) of identical compound, then it makes sense to fit them.

[GeoffBob]

Theo, one other thing,

Take a close look at the first graph I posted above. Take note that, even though the rears lock up at just under 20kg pedal force, they do so at just under 1G of deceleration. That's 1G of deceleration at 18kg of pedal force!

Now look at the second graph. See how 18kg of pedal force only gets you around 0.7G of deceleration.

Now, which brake setup do you think would feel better if you were driving the car. The first, obviously!! The brakes would literally feel sharper because you get more G's for less pedal force. The second setup WILL, however, deliver superior braking performance because with the second setup you can pull more G's in total before one or other set off wheels break traction. The price you have to pay for these extra G's, however, is that you have to press the pedal harder.

Take note EVERYONE reading this. Think twice before saying "Hmmmm, these upgraded brakes feel so much better". It's not about how hard you press the damn pedal, it's about which brake setup slows the car the fastest. Of course minimal pedal force is nice to have, but we can’t always have this.

[billgatese30]

Take note EVERYONE reading this. Think twice before saying "Hmmmm, these upgraded brakes feel so much better". It's not about how hard you press the damn pedal, it's about which brake setup slows the car the fastest. Of course minimal pedal force is nice to have, but we can’t always have this.

Just thinking out loud here Geoff, could Theo not adjust his pedal ratio to lower the pedal force on the more effective setup, assuming that it doesn't have a major detriment on increasing the pedal travel too much?

[Theo]

Fascinating post Geoff, thanks a lot for taking time to run the calculations and post up the results.

I should mention that running larger rear brakes will be a temporary measure, a larger front setup will follow in the new year. That said, a combination of these results coupled with the performance of my current brakes (now that the front pads/discs are changed) makes me further question my logic in using this proposed 300mm rear setup. Would using the 2 pot caliper with the smaller 35.1mm pistons negate the requirement of changing the master cylinder, or did you not get a chance to check this?

For those not in the know, a set of PF01 pads for the e30 m3 rear calipers is £170 or so. A set of pads for the 2 pot aluminium calipers which are to be used on the 300mm setup is £35! My current EBC yellow rears didn't last too long (or perform particularly well), but perhaps pad lift would be much longer with the Performance Frictions. I suspect it would.

Hmmm

[billgatese30]

Out of curiosity Theo, are you going for Alcon's on the rear?

[Theo]

No Chris, it's a WMS caliper. Original plan was to fit the caliper to my 280x10 Z1 disc, but that wasn't possible.

[billgatese30]

Shame, I have a set or two of discs those kicking around in the garage somewhere.

I may see how the standard M3 setup performs first and then sort a pedalbox before I start changing calipers. After all, I am keeping mine mainly as a road car rather than purely track orientated.

What pad shape will Keri's new caliper be?

[GeoffBob]

[GeoffBob]

I should mention that running larger rear brakes will be a temporary measure, a larger front setup will follow in the new year. That said, a combination of these results coupled with the performance of my current brakes (now that the front pads/discs are changed) makes me further question my logic in using this proposed 300mm rear setup.

Fitting larger front brakes ASAP makes sense Theo. Keep in mind, however, that neither addition will reduce your stopping time/distance (but will, however, reduce brake fade and increase pad life). Having both larger front and rear brakes/callipers will also require less pedal force to achieve threshold braking. If, however, you really want a shorter stopping distance then you need to increase your tyre traction (or move your engine to the mid-mount position ).

Would using the 2 pot caliper with the smaller 35.1mm pistons negate the requirement of changing the master cylinder, or did you not get a chance to check this?

I didn’t even bother to check TBH as you seemed keen on the 20mm ventilated discs. I stand corrected (Keri will be able to tell us) but I don’t think the 35mm callipers will fit over a 20mm ventilated disc. At least that’s how it is with Alcon callipers. If they do fit over a 20mm thick disc then the answer is likely to be yes.

Theo, do WMS not do a smaller 2-pot calliper similar to the Alcon’s I used? If they do, why not use them with the Z1 260mm x 10mm discs?

[GeoffBob]

I may see how the standard M3 setup performs first and then sort a pedalbox before I start changing calipers. After all, I am keeping mine mainly as a road car rather than purely track orientated.

A pedal box provides the freedom to adjust your brake bias by adjusting the position of the clevis pin. Then, if the bias is drastically out, you can change the size of the front or rear M/C's. The disadvantage (for a road car at least) is the loss of the brake servo. That loss (on a track car) is more than outweighed by the ability to adjust the brake bias, in order to achieve identical brake traction at the front and rear, thus bringing the car to a halt in the shortest time. It honestly doesn't matter how big your brakes are, if your bias isn't correct your stopping times will suffer.

[billgatese30]

Well, when I say I'll be fitting a pedal box, the main reason for it is so I can ditch the servo in favour of dual cylinders, this is partially so I can adjust to get the optimum settings regardless of what calipers/discs are there, but also to gain more space in the engine bay as I'm fitting the S50, which is very close to the servo. I'll possibly also look into ditching the ABS at the same time, so re doing all the brakes lines around there are already going to be out, fitting a pedal box and prop valve isn't any extra work. Initially it'll be set to match the stock calipers/discs and then as I upgrade front and rear discs/calipers, its merely a case of updating one or both of the M/C's and adjusting prop valve & bais at the pedal box.

[Theo]

Fitting larger front brakes ASAP makes sense Theo. Keep in mind, however, that neither addition will reduce your stopping time/distance (but will, however, reduce brake fade and increase pad life). Having both larger front and rear brakes/callipers will also require less pedal force to achieve threshold braking. If, however, you really want a shorter stopping distance then you need to increase your tyre traction (or move your engine to the mid-mount position ).

I'm on the look out for 15" slicks but they're rather hard to get hold of, shame I don't have 17" wheels as you can get sets of lightly used BTCC and WTCC slicks for peanuts.

I didn’t even bother to check TBH as you seemed keen on the 20mm ventilated discs. I stand corrected (Keri will be able to tell us) but I don’t think the 35mm callipers will fit over a 20mm ventilated disc. At least that’s how it is with Alcon callipers. If they do fit over a 20mm thick disc then the answer is likely to be yes.

I should have explained the situation regarding pistons size and disc width on these calipers. They are two piece calipers with a series of bolts holding the two halves together. Sandwiched between the two halves is a spacer matched to the disc width - so you can definitely use a caliper with the smaller pistons on a vented disc.

Theo, do WMS not do a smaller 2-pot calliper similar to the Alcon’s I used? If they do, why not use them with the Z1 260mm x 10mm discs?

Sadly not, the 2 pot caliper is lug mounted and can't be made to work with the e30 trailing arm mounting points. There's no radial mount alternative, if there was that would be the logical choice. Saying that, pads aren't too expensive for you Alcon R Types - same can't be said of the calipers though.

Shame, I have a set or two of discs those kicking around in the garage somewhere.

I may see how the standard M3 setup performs first and then sort a pedalbox before I start changing calipers. After all, I am keeping mine mainly as a road car rather than purely track orientated.

What pad shape will Keri's new caliper be?

For what it's worth, love the standard brakes on an m3, they feel great. Whether they are quite as good on a right hand drive car with the dreaded floppy linkage bar, I don't know.

This is the pad shape - http://www.wilwood.com/BrakePads/BrakeP ... dtype=7012

[billgatese30]

Theo, I have a good LHD host for the S50 now (link in my sig) after the last one ended up in the barriers so no linkage bar to worry about. Nice to know for future reference that 'Dynalite single' pads work out cheap. I'll have to draw it up so that I can use it in future size trials. I already have over 900 disc shape/models to use and about half a dozen calipers to choose from. although most of the caliper's I have drawn are fronts.

Nice to hear that the M3 setup is quite nice to start with.

Oh, and sorry for hijacking.

[Theo]

Oooh, very nice! If you were to fit a pedal box to that it would be much easier than on RHD models because of the flat bulkhead you have to play with. Whether or not I'd do this to an M3 which is primarily a road car, I'm not sure.

[billgatese30]

I'm not sure either yet, but the thought of making my own box to fit to the standard position still seems like a good plan. although I feel that time may dictate otherwise.

[GeoffBob]

Well, when I say I'll be fitting a pedal box, the main reason for it is so I can ditch the servo in favour of dual cylinders, this is partially so I can adjust to get the optimum settings regardless of what calipers/discs are there, but also to gain more space in the engine bay as I'm fitting the S50, which is very close to the servo. I'll possibly also look into ditching the ABS at the same time, so re doing all the brakes lines around there are already going to be out, fitting a pedal box and prop valve isn't any extra work.

Chris, your reasons for wanting a pedal box are spot on. Adjustable bias is worth its weight in gold! Also, in the event that your bias is badly out (such as ater changing callipers) its no big deal to change a single M/C. I keep a range of different size M/C's in my fridge for all occasions.

Initially it'll be set to match the stock calipers/discs and then as I upgrade front and rear discs/calipers, its merely a case of updating one or both of the M/C's and adjusting prop valve & bias at the pedal box.

This is where you need to be cautious Chris. With stock E30 callipers fitted, a 6:1 ratio pedal set will not retun the mechanical advantage lost when the servo is removed. This is the reason why you should consider fitting bigger callipers at the same time as you fit your pedal box. With the stock cailipers you'll have improved brake feel, but you'll need the legs of a Greek God to push the pedal.

EDIT: Chris, PM me the details of your callipers and your proposed pedal set and I'll do the same brake calculations for you.

Soapbox time:
It burns my bum something chronic that bigger callipers are fitted to stock cars under the asumption that this results in improved braking performance. Anyone who believes this is just plain bonkers Callipers with bigger and/or more pistons require less fluid pressure to achieve the same brake force as stock calipers. In other words, it takes less leg effort to lock the wheels. The point is, however, the the point at which the tyres start to skid has nought to do with the size of the brakes - its about tyre size, tyre compound, tyre temp and the dynamic weight upon the tyre (oh, and of course road surface).

Bigger callipers are fitted to race cars because a) they generally have tyres with more traction (and can thus tolerate harder braking without skidding) and b) the bigger pistons offset the mechanical advantage lost when the servo was removed. That, and of course bigger brakes last longer and have a larger surface area for cooling.

Sorry, I'm not ranting at anyone in specific (and I am certainly not out to offend Keri, not by any measure). The point is, bigger brakes have their place, but understanding their place is the key to better braking.

[GeoffBob]

Oooh, very nice! If you were to fit a pedal box to that it would be much easier than on RHD models because of the flat bulkhead you have to play with. Whether or not I'd do this to an M3 which is primarily a road car, I'm not sure.

I wouldn't hesitate, not for one second. I'd give my left nut for a S50'd LHD M3 with a pedalbox and bigger calipers.

[Theo]

I must say it's very eye opening having your input on upgraded brakes - I find myself looking at CSLs and 911s with 6 pot calipers and massive discs and wondering whether they are actually any good.

[GeoffBob]

I must say it's very eye opening having your input on upgraded brakes - I find myself looking at CSLs and 911s with 6 pot calipers and massive discs and wondering whether they are actually any good.

While I have no doubt that those brakes are selected to complement the cars overall weight, weight distribution and specified tyres, I also have no doubt that the bigger brakes give the customer a warm and secure feeling while driving at speed. Not to mention that bigger brakes are probably cheaper than having penoplasty.

It also depends just how much heavy braking the car is designed for. Heavy and relentsless braking (such as on track) puts a lot of heat into the brakes, and dissipating that heat is easier the larger the surface area of the disc. And here we find the usefullness of ceramic compound discs. In other words, bigger discs and brakes might not improve your stopping times or distance, but you will be able to brake for longer with them before they overheat.

Theo, If you were planning on entering an endurance race or doing multiple laps of the NÃarburgring, then I'd say fit the biggest brakes you can get under your rims. But at the same time, understand that it is to make your brakes last longer, and not to shorten your stopping distances. If you want that, fit better tyres (and stay out of the kitty litter )

[keri-WMS]

I thought I'd bung in a few comments:

- I'm not easy to offend so don't worry about that!
- The WMS T10 caliper is similar to the Alcon and takes the same dinky pad as the Dynalite single.
- I would love to do a smaller rear kit with it, but the caliper touches the lugs at anything less than about 295mm.
- The 300x20 rear kit does fit in the 15" BBS though!
- Something bigger for the front inside the 15" BBS is also planned...

[GeoffBob]

I'm not easy to offend so don't worry about that!

Oh, I don't care how easy you are to offend keri, I just wanted it publicly known that I wasn't deliberately trying to

The WMS T10 caliper is similar to the Alcon and takes the same dinky pad as the Dynalite single. I would love to do a smaller rear kit with it, but the caliper touches the lugs at anything less than about 295mm.

Is there nothing we can do about this Keri? Alcon do their 2-pot caliper with either lugs or radial mount. I know that the lugs are without mounting holes and designed to be machined and drilled to suit the application. I wonder if it wouldn't be possible to machine the lugs back on the WMS-T10's to fit? Of course, if the lugs totally collide with the mounting ears on the back of the E30 hub then there would be a problem. Even with the Alcon radial mounts, BTW, I had to fettle with a dremel around the hub.

[keri-WMS]

I'm not easy to offend so don't worry about that!

Oh, I don't care how easy you are to offend keri, I just wanted it publicly known that I wasn't deliberately trying to

Ha!

The WMS T10 caliper is similar to the Alcon and takes the same dinky pad as the Dynalite single. I would love to do a smaller rear kit with it, but the caliper touches the lugs at anything less than about 295mm.

Is there nothing we can do about this Keri? Alcon do their 2-pot caliper with either lugs or radial mount. I know that the lugs are without mounting holes and designed to be machined and drilled to suit the application. I wonder if it wouldn't be possible to machine the lugs back on the WMS-T10's to fit? Of course, if the lugs totally collide with the mounting ears on the back of the E30 hub then there would be a problem. Even with the Alcon radial mounts, BTW, I had to fettle with a dremel around the hub.

It's a real pain, but basically not without a one-off version of the caliper. I might be able to do something clever with it in the future, but that's speculation - the lugs hit really badly..!

[keri-WMS]

Hot off the press - we're back to 294mm rear, the 300mm disc has just been abandoned as the "drum" conflicts with the E30 shoes in a place that isn't safe to machine!!!

[billgatese30]

Keri, PM me with what the what disc specs you need and I may be able to help you source an alternative. I have a good database of disc dimensions (and them all linked into SolidWorks too)

[keri-WMS]

I think I'm ok, but ta for the offer! I've got the details of 1,200 discs to play with, the trouble here is WMS caliper lugs vs BMW strut/hub lugs (same as the E30 M3 and E36 but not as bad).

I think I have a final plan for the "ultimate" 15" BBS kits - 290mm front and rear, 2 pot T10 caliper rear, new (huge) 4 pot T30x caliper front.

It just happens that 290mm is the very biggest possible at the front in the BBS, and 290mm is the smallest possible on the E30 rear hub.....handy I suppose!

[e21Jason]

I have an obp cockpit mount box in my RDH m3 if you want some pic's, and the e24 calipers bolt up to the m3 struts but have a larger front piston if that helps.

I use this brake setup on the rear of the e21, basiclly alloy disk bell with an inner steel ring wich is used for the hand brake,




but i did also think about these

http://www.rallydesign.co.uk/product_in ... s_id=11370

[keri-WMS]

It's quite a neat solution that, something we plan to look at but a bit fiddly. Did you locate the steel ring off the bell directly (not just the bolts) to make sure it's concentric?

[UweM3]

. I have a good database of disc dimensions (and them all linked into SolidWorks too)

is that available online?
I own a solidworks seat BTW

[billgatese30]

Whats your Email Uwe. I'll send it over, I set it up as an excel spread sheet and then used that as a design table to create several (900+) configurations from.

Also, are you on 2011 yet?

[GeoffBob]

I use this brake setup on the rear of the e21, basiclly alloy disk bell with an inner steel ring wich is used for the hand brake

Nice! What a great idea