gearbox for GT40 mk1 ?
- Thread starter NickGT40
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I very much am interested in this answer as well. I am planning on building a RCR MkI that will get some track time. I have been wanting to know what is the best ZF variant for a GT40. Also values/prices. Quaife give you a starting list price. Any help greatly appreciated.
Thanks Nick. Is the UN1 the first series ZF 5DS-25? If so what are you going to run?
Ian Anderson
Lifetime Supporter
Good morning
There is a lot of information on this site already.
When you say track use is it for an occasional track day, only track time or full out racing?
Mainly road the UN1 which is Renault manufactured transaxle will cope well up to about 350 hp and once built with some more beefed up bits about 400 hp so for the occasional track day on road tures
The ZF was manufactured in the 1960’s for the GT40 program and in the day they ran about 450hp..so one of these could work to this sort of power …… remember in the 60’s they kept on the black and off the kerbs. They also ran metalastic joints that took some shock.
Full out race type driving with today’s sticky slicks and running on kerbs etc will break most transaxle
Quoted on this site is expect to pay twice the price for a transaxle that you pay for the engine.
My guess and I am sure others will disagree that transaxle would be
VW beatle aircooled
Renault UN5
Renault UN1
Numerous Audi
Porsche G52
Porsche 4 speed from 930
ZF and ZFQ
Lamborghini type…..read up on SLC builds but too long to fit in GT40
Then SADEV etc which are megabucks
Guess what……. The price of the transaxle will go up in price multiple times more than the HP increases
Ian
There is a lot of information on this site already.
When you say track use is it for an occasional track day, only track time or full out racing?
Mainly road the UN1 which is Renault manufactured transaxle will cope well up to about 350 hp and once built with some more beefed up bits about 400 hp so for the occasional track day on road tures
The ZF was manufactured in the 1960’s for the GT40 program and in the day they ran about 450hp..so one of these could work to this sort of power …… remember in the 60’s they kept on the black and off the kerbs. They also ran metalastic joints that took some shock.
Full out race type driving with today’s sticky slicks and running on kerbs etc will break most transaxle
Quoted on this site is expect to pay twice the price for a transaxle that you pay for the engine.
My guess and I am sure others will disagree that transaxle would be
VW beatle aircooled
Renault UN5
Renault UN1
Numerous Audi
Porsche G52
Porsche 4 speed from 930
ZF and ZFQ
Lamborghini type…..read up on SLC builds but too long to fit in GT40
Then SADEV etc which are megabucks
Guess what……. The price of the transaxle will go up in price multiple times more than the HP increases
Ian
Well said Ian !!
Regards Brian
Regards Brian
Howard Jones
Supporter
Wow! I could write several pages about this. But I won't......however, I will try to respond succinctly. You want to use your car for "track usage". Here's what I have learned. Heres is the example,
SLC approx weight = 2650ish.
Engine power = 530hp with torque output no less than 400ft/lbs and maxing out at 530 ft/lp from 2700-6500 rpms.
Tires= Toyo RR dot slicks 10.5 inches wide on the front and 13 inches wide at the rear.
Aprox downforce= several hundred at 130-160 mph
Brakes= I can outbreak everything except open wheel or full-on prototype real deal racecars. All the streetcars on street tires every time.
The performance envelope is in line with a modern GT3 driven by a competent mature but amateur driver with equal tire performance. I can stay with the older guys like me but the young simi pro drivers are always going to be faster.
The previous 355 ci engine had 425HP and 200-400isn ft/lbs of torque. I had a Porsche G50/Quaife TBD with every high-strength part upgrade available and it lived a good reliable life for several years of track work and approx 2500 miles total. I built a much more powerful 400 ci motor and purposely held power to 525HP and 500 ft/lbs of torque. It took approx 10, 30-minute sessions to eat the pinion gear. It cost me $12.000 to completely overhaul and replace every worn part with the highest grade of available replacement part when I had it repaired. The weak link was the 7.5 inch diameter R&P in the G50 series. I have commissioned a 996 turbo 6 speed with all the strongest pieces including a TBD and a spray bar. The R&P in this series of Porsche transaxle is a 9-inch. It will cost approx $25,000.
What does all this mean? There is a real limit to how much hp/tq you can run through a street-derived transaxle. Period!!!! Especially if used in a track car AND YOU WANT TO DRIVE IT QUICKLY on slicks. My best advice is the gearbox MUST have a R&P diameter of 9 inch or better. The engine should be held to 500hp or less and I would advise more like 350-400hp.
Note: my horsepower figures come from a professional racing engine builder's dyno that is certified for SCCA TRANSAM-mandated engine power limits. These are known REAL horsepower numbers, not bench-racing dreamer figures.
So if you want to know $$$$$'s. The 400 ci motor is a +$25,000 SBC built around a Dart block with 41/8 inch bore,11 to 1 CR, a very expensive rotating assembly, custom roller cam, and the best AFR heads they make. Along with the $25K GRBX I'm building I am at 50 fucking K for the power train....................plus the $900 stub shafts and $1000 drive shafts.
BTW the race GRBX's are AT LEAST double the cost of what I have. Call them $50K plus
600-700HP engine and slicks????? Forget about it..............buy a used racecar and have a race shop maintain it for you. There is a reason a new Porsche GT3 costs approx $300K.
Be very careful what you wish for when you say "track car"
SLC approx weight = 2650ish.
Engine power = 530hp with torque output no less than 400ft/lbs and maxing out at 530 ft/lp from 2700-6500 rpms.
Tires= Toyo RR dot slicks 10.5 inches wide on the front and 13 inches wide at the rear.
Aprox downforce= several hundred at 130-160 mph
Brakes= I can outbreak everything except open wheel or full-on prototype real deal racecars. All the streetcars on street tires every time.
The performance envelope is in line with a modern GT3 driven by a competent mature but amateur driver with equal tire performance. I can stay with the older guys like me but the young simi pro drivers are always going to be faster.
The previous 355 ci engine had 425HP and 200-400isn ft/lbs of torque. I had a Porsche G50/Quaife TBD with every high-strength part upgrade available and it lived a good reliable life for several years of track work and approx 2500 miles total. I built a much more powerful 400 ci motor and purposely held power to 525HP and 500 ft/lbs of torque. It took approx 10, 30-minute sessions to eat the pinion gear. It cost me $12.000 to completely overhaul and replace every worn part with the highest grade of available replacement part when I had it repaired. The weak link was the 7.5 inch diameter R&P in the G50 series. I have commissioned a 996 turbo 6 speed with all the strongest pieces including a TBD and a spray bar. The R&P in this series of Porsche transaxle is a 9-inch. It will cost approx $25,000.
What does all this mean? There is a real limit to how much hp/tq you can run through a street-derived transaxle. Period!!!! Especially if used in a track car AND YOU WANT TO DRIVE IT QUICKLY on slicks. My best advice is the gearbox MUST have a R&P diameter of 9 inch or better. The engine should be held to 500hp or less and I would advise more like 350-400hp.
Note: my horsepower figures come from a professional racing engine builder's dyno that is certified for SCCA TRANSAM-mandated engine power limits. These are known REAL horsepower numbers, not bench-racing dreamer figures.
So if you want to know $$$$$'s. The 400 ci motor is a +$25,000 SBC built around a Dart block with 41/8 inch bore,11 to 1 CR, a very expensive rotating assembly, custom roller cam, and the best AFR heads they make. Along with the $25K GRBX I'm building I am at 50 fucking K for the power train....................plus the $900 stub shafts and $1000 drive shafts.
BTW the race GRBX's are AT LEAST double the cost of what I have. Call them $50K plus
600-700HP engine and slicks????? Forget about it..............buy a used racecar and have a race shop maintain it for you. There is a reason a new Porsche GT3 costs approx $300K.
Be very careful what you wish for when you say "track car"
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Hi Nick, I run a Audi 01E on my car with a Coyote crate engine and while I realise it diverts a little from the authenticity of the car it is a very strong and very reliable gearbox. Still quite a few available on your favorite auction site and parts are readily available, it's a very cost effective solution for the GT40. I have a Quaife lsd in mine and the ratios for certain codes are perfect when mated to a V8, most of the codes you might want are six speed but you can forget about first as just for pulling out of your driveway. I'm sure you'll find all the information you need on here if that's the route you choose but I have lots of useful stuff if it helps. Good luck whichever way you go.
Andy Sheldon
Tornado Sports Cars
Nick
I would fit the SADEV if you are going to give it some real stick on a track
It always amazes me how many people confuse a ZFQ with a genuine ZF
They are nothing like the same
Forget the ZFQ
Thanks
Andy
I would fit the SADEV if you are going to give it some real stick on a track
It always amazes me how many people confuse a ZFQ with a genuine ZF
They are nothing like the same
Forget the ZFQ
Thanks
Andy
