My E30/R5Turbo track car - Gearbox MkIII

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GeoffBob
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Sun Nov 08, 2009 7:31 am

Thank's Theo for your comment! Gunni, that's high praise indeed from yourself and I am quite taken aback - thank you sincerely.

Keri, yes, you are quite right about the Celica 3SGTE engine being transverse.

My original plan of action with this project was to put a R5Turbo body (which is mostly GRP and aluminium) over an E30 sub-frame/floorpan/monocoque (whatever you call all the bottom bits) with a turbocharged M42 engine (no S14's locally I'm afraid, and a 6-pot would be just too big for an R5). However, with the R5 being such a small car I quickly realised that I would run into problems with the exhaust manifold colliding with the steering and brakes on a RHD car. I therefore opted to substitute a Japanese engine with the exhaust on the left.

Unfortunately, very few of the top-spec Jap cars are imported to South Africa. In fact, our Toyotas and Nissans are all locally made, so we have very little to choose from. I therefore opted to pickup a "Jap-Scrap" Toyota S3GTE engine. Jap-Scrap are what we call 2nd-hand engines and gearboxes imported to keep some local cars alive. For the most part these engines are picked up and thrown (unmodified) into all sorts of unroadworthy vehicles (No MOT in SA) just to keep them going for a few extra years. However, if you look carefully through these imported engines (shipped in by the container load) you can find some real gems that just don't belong in a burned out pick-up truck. When the Jap’s load the containers full of old engines they don't care whether they throw in an old NA 4AGE Corolla engine, or an ST205 3SGTE. Although the 3SGTE's are rare, if you look hard you can find them. There are also some very nice Subaru and Mitsubishi engines to be had. Of course, if these engines are to be used in any kind of performance application they have to be rebuilt and every component measured for tolerances. These engines can easily have done anything from 30,000km to 300,000km.

If I had considered the transverse AWD as an option I would not be able to obtain the AWD drive-train from a Celica locally, but in which case I would not have been able to use the suspension, sub-frames and drive-train from an E30, of which there are an abundance locally.

So yes, RWD it is, and 245 semi-slicks on the rear to try and keep some of that wheel-slip at bay.

Sorry Gunni, but I don't have any videos. To answer your question, I am a physicist - my speciality is combustion and detonation physics (which is occasionally why I go a bit overboard on this topic :o: ) However, prior to studying physics I qualified as an engineer. I work here for the Landwards Science group where we develop new technology for military vehicles. I work mostly on the electronics side now as mechanical work seems to becoming less and less these days. Pity.
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Gunni
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Sun Nov 08, 2009 10:03 am

I myself will be digging deeper into combustion events when I do my masters as well as overall engine design.

It´s real interesting stuff.

Can´t wait for a video of this thing. Should be a crazy missile
With great challenges comes great engineering.

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GeoffBob
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Mon Nov 09, 2009 9:00 am

Gunni, good for you that you want to study an MSc. The book "Internal Combustion Engines: Applied Thermosciences" by Feguson and Kirkpatrick (see here) was one of my text books and I can thoroughly recommend it if combustion events are of great interest to you. It deals in detail with the different heat cycles, and in particular the evolution of the combustion chamber pressure for both NA and FI engines.

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I'll have to get someone to take a video of the car for me once I get her back on the road.

Regards.
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Gunni
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Mon Nov 09, 2009 11:02 am

Thanks, I´ll definetelly pick that one up.
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GeoffBob
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Tue Nov 10, 2009 7:59 am

'Am feeling well chuffed today! Fitted the custom PAS pump hoses last night and I now have power steering on the car. The Toyota pump works really well with the E46 rack. Took it for a little test drive this morning (before work) and found the level of assistance to be about just right. Not too much to take away the feedback from the road, but not so little as to not be worth the effort. I was initially concerned that there would be compatability issues between the Toyota pump and BMW PAS rack - not so (my pure good fortune). Installing the PAS hoses and rack was also made easier by the fact that the Toyota PAS pump is on the right of the engine directly above the rack fluid connections. :cool:

'Have fitted the fluid bottle inside the front right wing (for lack of anywhere else to fit it).

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Wed Nov 11, 2009 8:55 pm

Having not been on the zone for a while sat back and read through your project, most definately the most thoughtout one iv ever seen! Almost get an impression you built your car as an excuse to do more maths (guilty myself :cry: )
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Fri Nov 13, 2009 9:01 am

Ta Shakey.

Can't say I look for an excuse to use maths though. I treat maths same as any other tool in my tool box - I haul it out and use it when I have to. I think I know enough to know that maths can be a really useful tool that can make the outcome of a project that much more successful, but ultimately it's the hands on cutting, grinding and welding that floats my boat. Like most builders/modders I get a great thrill out holding something in my hands that I made myself.

Took me just on six months to design my cars frame. Did all the calculations working out the placement of the suspension components in order to get the caster, camber, toe, travel etc exactly right. And at the end of it all I was just bursting to pick up a tool and get on with the damn thing. Had I just rushed straight in with an idea and a hammer she probably wouldn't have worked quite as she has. Brings to mind that old saying about "fail to plan - plan to fail". Thus endeth my sermon, now where's my hammer got to? :D
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GeoffBob
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Sat Nov 21, 2009 8:22 pm

Lights now all connected up and working.

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Sun Nov 22, 2009 10:17 am

Looking good buddy :D

I really can't wait to see this one finished and in action, you really are going to need Jedi reactions to catch the back end on this one!

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GeoffBob
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Sun Dec 13, 2009 1:42 pm

Cheers Mark :thumb:

'Nother pic showing a little more progress. Couldn't resist fitting the spots, afterall, the R5T was a Group-4 and Group-B rally car, even if this one won't make it any futher than the track.

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Wed Dec 23, 2009 6:50 am

Further work on bonnet. All paint, no stickers. Done using vinyl stencils cut on an XY-table.

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billgatese30
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Wed Dec 23, 2009 1:19 pm

Looking good Geoff

How much is left to do before it is ready for the track?
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Mon Jan 25, 2010 4:39 pm

Hi All! Back from my summer holiday 8O. While you lot up north were suffering snow blindness I was getting a tan (and probably skin cancer). One of the perks of living in the Southern Hemisphere. But no worries, I'll be laughing on the other side of my face in six months time :D
billgatese30 wrote:Looking good Geoff

How much is left to do before it is ready for the track?
Thanks Bill. A whole list of things to get her finished I am afraid. Black pin-stripes down the sides to separate the colours, fit and paint the sills below the doors, paint and fit the louvered vents, lots of colour-sanding between additional coats of paint, and finally three coats of gloss with final sanding and polishing. And all of this to be done before I refit the windows, door catches/locks etc, the rubber door and window seals, and all the other fiddly bits. I'd say at least another six months given that I only work weekends on her and need to wait for the rainy season to pass before I can continue painting.

This is how she looked at the end of last year before I went on holiday.

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GeoffBob
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Wed Feb 03, 2010 4:40 pm

Too much humidity in the air to continue with the paint work so have opted to focus upon mechanicals till the weather dries up. Have thus pulled apart my spare W55 gearbox in preparation for having a set of my own gears cut.

As many will attest to, a gearbox from a standard road going car has ratios ill suited to racing. When making use of a typical 5-speed box 1st gear will find application only in the pits and paddock, and 5th will only find itself gainfully employed along lengthy straightaways ”“ thus leaving 2nd, 3rd and 4th to do all the work (and a 3-speed box is no fun).

While some limited success may be had in returning 5th to active duty by increasing the ratio of the final drive, it often results in having to take tight corners in 3rd (with limited torque at lower rpm), or at a slower speed in 2nd.

The ultimate solution, as has been practiced for many years, is to fit a true close-ratio gearbox with the 1st ratio sufficiently low to make it useful in slow/tight corners, but with the 5th ratio high enough to still be of use along the straightaways. Granted, this limits off-line acceleration in 1st gear due to the lower ratio (usually around 2.5:1 compared to the 3.5:1 of a typical road going car), but any disadvantage is quickly regained.

I have thus designed a set of spur (straight-cut) gears to replace the helical gears in my spare W55 box (shown below) to meet the above requirements. I don’t nearly have the skill required to manufacture these myself, so will have them cut and hardened by a local gear-maker. The entire secondary (intermediate) shaft with gears will have to be remanufactured.

The ratios that I have selected (as dictated by the number of teeth on the new spur gear pairs) are:
1st: 2.53:1
2nd: 1.81:1
3rd: 1.34:1
4th: 1:1
5th: 0.75:1

Although at this point in time I may still opt to change 5th. 4th is fixed at 1:1 by the way the gearbox works (when 4th is selected the input shaft directly engages the output shaft). I have designed the gear-set such that dropping one gear at 7000rpm results in the revs falling to 5250rpm, regardless of which gear the box is in at the time.

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Theo
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Wed Feb 03, 2010 5:15 pm

Bespoke gears is serious stuff indeed -very cool.
I have designed the gear-set such that dropping one gear at 7000rpm results in the revs falling to 5250rpm, regardless of which gear the box is in at the time.
No money shifts then!? How does this work?

Welcome back by the way :)
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Wed Feb 03, 2010 6:50 pm

this is serious stuff! :D
watching with interest :cool:
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GeoffBob
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Thu Feb 04, 2010 8:02 am

Theo325 wrote:Bespoke gears is serious stuff indeed -very cool.
I have designed the gear-set such that dropping one gear at 7000rpm results in the revs falling to 5250rpm, regardless of which gear the box is in at the time.
No money shifts then!? How does this work?

Welcome back by the way :)
Ta, I knew it was time to get back to work when the rains arrived :(

The way it works:
A typical road-going box starts with around a 35 to 40% jump in ratio between 1st to 2nd gear. This gap drops down to around 30 to 35% between 2nd to 3rd, and progressively drops further as you climb up through the gears.

What this means is that if you want to land on exactly 4000rpm, say, after avery shift your revs would have to be higher before the shift in first gear than in fourth gear. I don't know about you, but I can barely remember what gear I am in, yet alone what revs I need to be at (for each individual gear) to land up on the money after each shift!

Thus, by making the shift in ratio between the gears the same (in my case roughly 25%), the engine revs will be the same coming out of every shift, provided you commence each shift at the same revs.

For example, if the spacing between all gears is fixed at 25%, then shifting up at 6000rpm in any gear will see you coming out of the shift at exactly 4500rpm. Likewise, shifting down at 4500rpm in any gear will see your revs climb to 6000rpm. Obviously all of this assumes no change in vehicle speed while shifting.

I have opted to set my ratio steps to around 25% on my 5-speed box in order that I still maintain some off-the-line acceleration. However, if I had a 6-speed box I would keep my first gear where it is (as above) and follow this with 20% steps up to 6th. What a magnificent gearbox that would be!
gareth wrote:this is serious stuff! :D
watching with interest :cool:
Ta, I'm off tomorrow for a tour of the factory where the gear-maker makes his gears. I'll post up some pics if he lets me take some.
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Theo
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Thu Feb 04, 2010 9:18 am

Ah right, I think I misunderstood what you meant by dropping a gear at 7000rpm!
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Thu Feb 04, 2010 12:14 pm

Theo325 wrote:Ah right, I think I misunderstood what you meant by dropping a gear at 7000rpm!
Sorry, I should have said "shifting up a gear" instead of "dropping a gear". I realise how that reads now. Likewise, I think I misunderstood what you meant by "money shift". :D
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Theo
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Thu Feb 04, 2010 6:23 pm

The money shift:

[youtube][/youtube]
GeoffBob
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Thu Feb 04, 2010 9:13 pm

Ah, I see. Not so much a case of "on the money" as costing money. That's what comes of shifting down when you should go up!
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Thu Feb 04, 2010 10:11 pm

That video made me laugh lol!

Very cool stuff Geoff, I'm looking forward to hearing those whining gears :D
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Fri Feb 05, 2010 2:28 pm

rix313 wrote:Very cool stuff Geoff, I'm looking forward to hearing those whining gears :D
Oooh, don't mention the noise! Already making me regret my decision. I mean, I know its the right thing to do - just like getting married. But still doesn't mean you want to put up with the whining. :)

Well, this morning I visited ARMA gear cutters (see here) in Germiston, South East of Johannesburg, South Africa. And what a fascinating time I had learning how gears are cut.

Three types of machine (and derivatives thereof) are employed to cut gears, namely:

The Hobb cutter, which rotates a Hobb cutting tool adjacent to a slowly rotating workpiece in order to cut the gear teeth into the blank workpiece. If the axis of the cutter is 90' to the work piece then the result is a spur gear. However, by varying the angle of the cutter to the workpiece, helical gears are cut, as shown below:

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The Fellows cutter, which literally chisels away with a cutter using an up down motion, similar to an old fashioned shaping machine. The cutter is slowly rotated clockwise as the workpiece slowly turns anti-clockwise (or vice-versa), progressively munching away on the gear. This machine is often used where there is no room to use a Hobbs cutter.

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And finally you have the good old Sunderland gear cutter (made in England), which works similarly to a Fellows cutter (left to right on this machine), but without the cutter rotating.

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These are three of the basic machines that Veron Pappas (the owner ARMA gears) operates and the most easy to photograph. He also operates a number of much newer CNC gear cutting machines, but these are much less interesting to look at as they resemble big cream coloured boxes from the outside with the workpiece embedded somewhere behind a closed door. The principle of operation, he assured me, is however the same, except that it is computer (as opposed to artisan) controlled.

What impressed me greatly about Veron Pappas and his machine shop staff is their ability to manufacture crownwheels and pinions for final drives. I can't speak personally for the UK, but down here there are very few people with the know-how to do this sort of work.

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Shown below are the spigot shafts for local heavy-duty mine vehicles.

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Aside for doing work for the local mining industry (mine vehicles, heavy trucks etc), Veron also does a huge amount of work for the small and empoverished local motorsport community. He cuts the gears (for example) for the very popular Wesbank V8 CanAm style supercar series (see here) and also manufactures all mechanical components for the locally manufactured and exported Speads RM07 F1 style and RS07 LeMans style single seaters, see here. Now, I don't wan't to start sounding like an advertisment for ARMA, but this really is impressive stuff IMO.

Fairly safe to say that manufacturing the gears for my little box will be a walk in the park.
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Fri Feb 05, 2010 3:32 pm

Geoff

Did you now that in the uk you can get a ford type9 to 4age bellhousign which opens up a mass of options from alloy gearbox casings, custom gear ratio's sequential conversions and several after market qualife, trans-x, elite, denrith boxes

Might be cheaper than a custom gear set

Jason
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Fri Feb 05, 2010 3:47 pm

GeoffBob wrote:I mean, I know its the right thing to do - just like getting married. But still doesn't mean you want to put up with the whining. :)
I will always treasure that statement :lol:
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Fri Feb 05, 2010 4:03 pm

e21Jason wrote:Geoff

Did you now that in the uk you can get a ford type9 to 4age bellhousign which opens up a mass of options from alloy gearbox casings, custom gear ratio's sequential conversions and several after market qualife, trans-x, elite, denrith boxes

Might be cheaper than a custom gear set

Jason
Hi Jason,

The Quaife aftermarket box I had my eye on sells for £6400. Mating it to my 3SGTE engine is not a major issue for me, finding £6400 on the other hand is. The reason I have a Toyota W55 box with my engine is not because it bolts right up (it doesn't, I had to build the bellhousing) - but because it is one of the best deisgned and most reliable gearboxes ever manufactured. Toyota have used this box in modified form on everything from TRD built race cars to Landcruisers. A version of it is still used today on the V8 powered RWD Lexus cars. As much as I would love to fit the Quiafe box I had my eye on, I can have near enough the same for a fraction of the cost due to the fact that labour and raw materials are fairly cheap down here.

Thanks anyway for the suggestion.

Geoff
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Fri Feb 05, 2010 4:47 pm

If the deals that good you give me the detials as I would not mind some getrag265 group A gear ratios do they do rings as well

Jason
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Fri Feb 05, 2010 7:07 pm

e21Jason wrote:If the deals that good you give me the detials as I would not mind some getrag265 group A gear ratios do they do rings as well

Jason
Follow the linky in my above post to ARMA gear cutters. Keep in mind that they are a gear specialists, not gearbox specialists. You will need to provide them with reasonably detailed drawings of exactly what you want. They will take care of the tooth profile and engagement angle for you in order to make sure the gears mesh correctly.

They don't do synchro rings, but can make dog-rings to replace the standard engagement teeth so long as you provide engineering drawings (I would expect that most of the competition gears they manufacture use either dog rings or full-on dog gears to facilitate gear engagement as a synchro shifted box is not ideally suited to competition use).

I guess part of the reason this is a reasonably cost effective option for me is that I can provide them with detailed engineering drawings of exactly what I require. I'm really only paying for the manufacturing of the requested items. If you are not fluent in "gearbox design" you are basically at the mercy of the after-market manufacturers who already have the required design specs and dimensions to hand.
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Sun Feb 07, 2010 10:46 am

I am no expert with gearboxes so excuse my simple question.
you are spacing your gear ratios evenly, but will this not be counter productive as higher as your speed gets? (wind resistance)
I can only talk about motorbike gearboxes and we used to have a tall first, reasonably even "mid" section (2 and 3) and 4th, 5th and 6th progressively closer together.

On the other hand, the few turbo charged cars I have driven (with big bhp) didn't bother what gear you selected. Foot down and off they went :mad:
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Sun Feb 07, 2010 12:14 pm

Hi Uwe, I trust that you are keeping well.

Not a simple question at all. You are quite correct. Fortunately, the engine will run out of revs at about 220km/h (due to the final drive ratio), a tad before wind resistance becomes a notable obstacle to the engines reasonably healthy HP. I am therefore gearing the box to keep the engine revs within the engines fairly narrow power band (from around 4500 to 6500 rpm). Wind resistance is, however, the reason that I may still opt to change the ratio of the 5th gear in favour of a lower top speed, but with improved acceleration. For example, I'd rather get from 175km/h to 210km/h in say 4 seconds, than take 6 seconds to get from 175km/h to 220km/h (these aren't real numbers BTW, just making a point)

BTW, the reason I am opting for such a slow top speed in 5th, but such a high top speed in 1st, is due to the nature of the two nearby racetracks (Kyalami and Zwartkops) which both have fairly short straightaways and reasonably tight bends/corners. It is my plan to take the tightest corners in 1st gear, but still be able to use 5th on the fairly short straightaways. Despite the engines fairly healthy HP and ability to propel the car to speeds well in excess of 200km/h out on a lengthy straight (with the correct gearing), I doubt that I will ever have the distance (or courage) to exceed 200km/h at either Kyalami or Zwartkops.
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Sun Feb 07, 2010 2:31 pm

karimMSalama wrote:that car is awesome
Thank you Karim :D

Assalamu alaikum, and welcome to the Zone.
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Sun Feb 07, 2010 3:32 pm

After a fair bit of calculation using MATLAB, and simulation using GTR2 (around both Kyalami and the Nurburgring) I have arrived at the following gears: 29, 32, 31, 31, 32 and 29 teeth on the gear clusters (1st through 5th) and 19, 27, 33, 42 and 45 teeth on the intermediate shaft (also 1st through 5th). These gears define the ratios:

1st = 2.00:1
2nd = 1.55:1
3rd = 1.23:1
4th = 1.00:1
5th = 0.85:1

Since I first posted my chosen ratios you will see that I have reduced my 1st, 2nd and 3rd ratios, closing up the gaps between the gears. This will reduce my off-the-line acceleration in 1st gear even more than before, but makes it a perfect gear for negotiating tight corners once I am up to speed. I have also raised the ratio of my 5th gear, as discussed earlier.

While deciding these ratios I have managed to work the gear teeth numbers such that the 4th and 5th gear pairs can be cut with a Metric Modulus-2 cutting tool, without any necessity for the tooth profile to be corrected. The 3rd, 4th and 5th gear pairs will be cut with Modulus 2.25, 2.5 and 3.0 cutters, but will, unfortunately, require some correction to the tooth profile. Luckily for me this is the gear-cutters problem, not mine. I have, however, managed to determine the teeth numbers such that the profile correction is absolutely minimal, which means I have the strongest gears possible. The gears, as I stated earlier, will be spur gears (straight cut) as opposed to helical gears. Spur gears are significantly noisier than helical gears, but are also substantially more efficient, and thus result in substantially reduced transmission losses. The fact that I am using spur gears also removes the axial forces placed on the various shafts, and thus alleviates the need for tapered bearings.

The percentage change in ratio between the respective gears are:

1st to 2nd : 22.2%
2nd to 3rd : 20.7%
3rd to 4th : 18.9%
4th to 5th : 15.4%.

So the percentage change between gears does marginally decrease, but by nowhere near as much as one would expect from a road-going gear-box.

Interestingly (and I am afraid you will just have to take my word that this is purely coincidental) my 1st through to 5th ratios correspond fairly closely to the 2nd through to 6th ratios of the Quaife 60G 6-speed box. My 5-speed box will, therefore, effectively function as a 6-speed box with 1st gear removed, as was the case with the older 5-speed LeMans cars. If I had this ”aextra”a gear in my box it would effectively function as a ”acrawler”a gear to make negotiating the pits and paddock easier. One thing is for sure though, with a 1st gear ratio of 2.00:1, my problems with wheel-spin in 1st gear will surely be eradicated.

Shown below is a graph of engine revs (rpm) as a function of speed (km/h) while shifting up through the gears. The shift is executed each time at exactly 6000rpm. The final drive has a ratio of 41:10, and the rear wheels are shod with 245/17/40’s.

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"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
UweM3
E30 Zone Squatter
E30 Zone Squatter
Posts: 1657
Joined: Sun Jul 03, 2005 11:00 pm

Sun Feb 07, 2010 4:21 pm

GeoffBob I am sure you know how to do the math, allow me a question just out of curiosity.
You know what speeds you want to achieve on your choosen tracks. So working the gear ratios out ect ect is simple. But how you take into account of how fast/good your engine will build up the revs given that this is acompletley new car you haven't driven before and have no data to compare/base on?
Do you know what I mean? Where do the bhp come into the calculation? Or do you just use a known/similar configuration of a car you know and take an eduacted guess?
It could well be that the car handles much better (hopefully not worse) than you think and you manage a higher speed out of bend X as anticipated and therefore the top speed on the following straight will be much higher and you run out of revs.
Or is this just a matter of playing with the final drive ratio?
GeoffBob
Forced Induction Specialist
Posts: 1843
Joined: Tue Apr 28, 2009 11:00 pm

Sun Feb 07, 2010 5:16 pm

Fortunately, I have a torque curve for my engine, and I have a reasonable estimate of the cars final mass and mass-distribution. Newton’s laws are fairly strict about how fast an object can take a corner, with the only tricky variable to pin down being the tractive force provided by the tyres. If the cornering forces exceed the tractive forces, then the car over-steers or under-steers, depending upon which end lets go first.

Fortunately, GTR2 uses a fairly realistic tyre model (mathematical simulation) based on the work of Pacejka, a gentleman who has essentially characterised the tractive capabilities of tyres as a function of rubber compound, contact patch area, tread pattern (if any), temperature, pressure, slip-angle, and of course the corner-weight pushing down on each tyre. This combined with a mathematical model that takes into account the mechanics of the suspension (type, dynamic camber, caster, toe, damping and spring rates etc) makes for a fairly realistic (and fun) simulation tool. Well, it is at least sufficient to enable the selection of my gear ratios) but is of course no substitute for the real thing.

You are of course quite right that if the car does in fact handle faster out of a corner then it could run out of revs along the next straight. However, I honestly cannot see myself ever exceeding 200km/h and I have more than sufficient revs (and torque) to get there. My concern, therefore, is primarily for acceleration. And regardless of the dynamics of the car through a corner, a higher gear ratio will get me to the rev-limited top speed quicker.

While improving the cars rev-limited top speed may be a simple matter of changing the final drive ratio, this doesn't necessarily improve lap times since due to the commensurate reduction in wheel-torque in all gears. In other words, the cars acceleration will suffer. On a reasonably fast LeMans type circuit (with minimal tight corners) this might not be much of a penalty to pay. However, on a track that has both tight corners and long fast straightaways, the performance of this car will undoubtedly be limited. I'm not one for going over 200km/h though. I've been there a few times before (legally) in small scary glass-fibre canoes-on-wheels and it scared poo out of me.
Last edited by GeoffBob on Sun Feb 07, 2010 5:29 pm, edited 1 time in total.
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"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
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