Ultimate transmission rebuild?

[techspy]

I am considering purchasing a spent transmission (Renault for 94 S4) and rebuilding it with any higher performace parts that may be available. I am not having probs with my current one, but I would like to have another one to install later with as much of a reliability/performance increase as possible. Any suggestions or recommendations on what parts are available and/or where to buy the trans?

John
94 S4
http://hometown.aol.com/oneshotcop/myhomepage/profile.html

[rob.e]

Try a renault forum e.g. renault 21 turbo is same unit, or a GT40 forum - some of these guys use the renault box in their replicas.

cheers
Rob

[moriarty]

Have a look at the following site

www.bell-performance.co.uk

[feffman]

John:

The link to Derek Bell's web site for the Renault tranny shows one of the weak points on the transmission as the main shaft. The Rapier Racing Esprit is putting a lot of horsepower(550-600HP) through the stock tranny with no problems other then the bolts which hold the bell housing to the tranny twisted. Already rectified with aircraft grade bolts.

The best upgrade available, in my humble opinion, to the tranny is a Quaife limited slip differential. I did this for my 1999 V8 and it makes a world of difference with drivability. Call Mike Fridman of Michael's Motorsports at [phone] for the Quaife unit.

Mark Pfeffer

[rob.e]

feffman said:

The Rapier Racing Esprit is putting a lot of horsepower(550-600HP) through the stock tranny with no problems

Mark - is the Rapier tranny totally stock? Ie syncros still in place etc? If so that is very impressive.

[feffman]

Rob:

They installed the Quaife limited slip from Michael's Motorsports (www.MichaelsMotorsports.com) and the rest is stock. Well they changed the bell housing mounting bolts to aircraft grade to prevent twisiting from the torque.

Mark Pfeffer

[karlfranz]

feffman said:

Rob: They installed the Quaife limited slip from Michael's Motorsports (www.MichaelsMotorsports.com) and the rest is stock. Well they changed the bell housing mounting bolts to aircraft grade to prevent twisiting from the torque. Mark Pfeffer

I saw the damage done to the bellhousing holes by the increase in torque. What I'm puzzled by is that we always hear how the second gear or the halfshafts are the weakest links and are more likely to snap on these gearboxes when we have too much power. However, in this case they seem to be holding up fine. Any ideas?

[techspy]

Thanks for all the info guys. I will definatly be doing some research on this. As for the stock trans holding up in that racing environment, the only thing I can think of is that it is rebuilt often. Otherwise it just makes no sense that a stock car destoys these things as they do when a race car with 500 hp doesn't. Maybe its all about quality control. Meaning, that if you go through your trans, as a racing team would, and make sure that all the parts are within the specs they are designed to be in, it will work as it should.

John
94 S4
http://hometown.aol.com/oneshotcop/myhomepage/profile.html

[feffman]

Karl:

My understanding that it's usually the second gear synchros that go. Fortuantely I've never had to deal with this (knock on wood).

Mark

[dr.hess]

Ya know, it seems like it is the 2nd gear syncro that goes out on _all_ trannies. Europa, MR2 (all manuals: C50, C52, E's), T50's, etc. I think it is just that no matter how tough you build a transmisssion, that 1-2 shift is going to get nailed on the street. I also bet that race car doesn't do too many hole shots or even 1-2 shifts.

Kinda like my Harley. After I busted up the first belt drive, I stopped doing hole shot wheelies on it. I don't think 900 lb full dressers were designed to pull the front wheel up in a hole shot.

The ultimate transmission would probably be that dog box some big race team designed. Never have to worry about that 2nd gear syncro with that one. It don't have one. Costs was in five figures, pounds or dollars, if I recall. Seems like they were saying 600 horse was no problem with it.

Dr.Hess

[rlearp]

We've got a ton of info on the site about transaxles. Check it out under Engines and Transaxles at www.gt40s.com

A ZF unit would be great in the Esprit, able to handle the power and it is very strong. Kennedy Engineering could make an adapter for the Esprit engine I'm sure. Next to that would be a good Porsche G50/50 box with a good LSD. The Renaults can be built fairly strong as there are many in racing GT40s that are putting out 500+hp, no joke. But, building the Renaults can be costly.

But, even so, everyone fears drag racing with the transaxles, seems they can easily go boom with high power and stress.

[kevin-84turbo]

I have a in car video of a racing V8 Esprit( Team Lotus) and it does not have a standard box, the noise is so High it must have straight cut gears and the change is so quick it is likely its sequential!?

Dont know what box theyd use tho, many racing Porsches use a Gemini Racing box so with somechangeover it may be possible to use that, for racing that is.

Kevin

[rob.e]

This topic has come up a few times.. check out:


www.pistonheads.com/gassing/topic.asp?t=40247&f=17&h=0

www.pistonheads.com/gassing/topic.asp?f=17&h=0&t=30473

www.pistonheads.com/gassing/topic.asp?f=17&h=&t=41814

www.pistonheads.com/gassing/topic.asp?t=68081

www.pistonheads.com/gassing/topic.asp?t=49953&f=17&h=0&

[rlearp]

Only thing with the Porsche boxes is you have to flip them over since, in OEM, they are at the front of the engine. Remember - Porsche 911s are a rear engine car.

Flipping is no problem however, you just have to plug the vent tube and create a new one on top of the box. We've got a lot of the GT40 guys that run the G50 and G50/50s flipped to great effect.

R

[rob.e]

rlearp said:

Only thing with the Porsche boxes is you have to flip them over since, in OEM, they are at the front of the engine. Remember - Porsche 911s are a rear engine car. Flipping is no problem however, you just have to plug the vent tube and create a new one on top of the box. We've got a lot of the GT40 guys that run the G50 and G50/50s flipped to great effect. R

John Hazzard races a v8 in the uk with a g50 box. Lots of modification required to get the drive shafts in the right place apparently, plus you lose the rear luggage area.

[hazzardv8]

realistically forget the g50/50 route for a road car,it just isn't practical,
good for a racer though!!!give it big welly off the line and you know it won't break!!

[Squelch]

I personally feel that the bad reputation of the Renault gearbox in the Esprit is due to poor drivers.
Look at this in reality, how many first owners of Esprits drive another car on a daily basis that has a manual trans ?
How many drivers of a manual trans incorrectly think that to drive fast, you have to shift fast ?

Proper shifting, and proper clutch work can add tens of thousands of miles to the life of a trans, and good racing drivers know this.

[igreenrover]

In the UK – a large proportion will have manuals as second cars. I have three cars with manual transmissions and no Autos... It would be interesting to see if the Renault boxes are more of a problem in the US, as it would point towards your theory?

It seams that the only place where people complain about the box is in the Esprit, other people using it with far more HP and torque are often happy with it.

Gareth

[rlearp]

I drive a manual everyday. I agree that proper use will help the tranny, but, that just isn't it. The transmission has a number of issues that the GT40 crowd know well and address because they were never meant to live behind 350hp Esprit motors, much less 500hp motors in the 40s. I know one issue in the box is the lack of a single input shaft - the piece actually is two parts. They make a single part with larger bearing surfaces to replace the original that seems to help the box a lot, along with some other bits.

[Dr.Hess]

Hey John,
How's about a quick refresher on the proper way to shift a R'boxed Esprit to promote long life?

Dr.Hess