A Few GTD GT40 Questions

With my recent purchase of a GTD I have a few questions I'm hoping some of you could give me some feedback on.

1. I have the Renault Turbo Transaxle: What fluid do you use - 90 wt?

2. The air cools pretty well until you get into stop and go traffic. I noticed the condensor is back by the engine. Anyone running it up front somewhere?

3. First GT40 I've ever had. Noticed slight viberation that is not wheels/tires, is that common with rear-engine transaxles vehicles or should I be searching for a problem ie; engine balancer, clutch etc.

4. Rear transaxle ratio seems pretty low which I thought would be the opposite for higher top end speeds. Get up and goes quick what rearend ratios are most of you running?

Thanks for your feedback, I love the car just need to sort out a few things! /ubbthreads/images/graemlins/smile.gif

Hi Gary,

I'm local. Call me when you have time. I will be available in the AM. 214-914-2446. Also, please look at www.scatracks.org. The Shelby meet is at TMS on 10/28-30. You should join/attend if at all possible.

Regarding your specific questions....

Use synthetic transaxle fluid if you can. Something like Amsoil will be fine.

You can run the condensor up front if you like, not an easy job to relocate. May want to look for air leaks, and make sure it has been properly serviced. e.g., new receiver/dryer, proper evacuation, and proper charge (R-12 or CF-134A)
Vibration may be loose halfshaft bolts. They should be safetywired and loctited. May also be a warped or out of balance rotor. Is the transaxle properly mounted & snugged down?

The transaxles most folks use are geared that way... Mostly high HP 4 or 6 cylinders is what they came on from OEM use. Unless you go with a custom ZF ratio'ed box, ya just have to live with this one...

I use Castrol TFX in my box without bad side effects. Used it now for 12 years.

The rear diff ratios can vary but the best to have is the tallest gearing at 3.44. Even a standard 302 can drive that very nicely. The crown and pinion gears should be interchangeable if you are happy splitting a box apart.

One source of vibration could be engine. The factory used to supply marine engines and then used a non standard flywheel. This flywheel needs balancing to suit the engine. I fell foul of this many years ago but a flywheel balance to match the damper fixed it.

Only problem is how to tell what is what on your car when you don't know the full history of its build in massive detail. If you know the gear ratios in the box you could work out your diff ratio by pushing the car along the ground one revolution of the flywheel and counting how many times the wheels rotate.

The condenser is sometimes placed in front of the radiator with good effect. Also consider upgrading your compressor hanging off the engine. If it is a 505 it can be upgraded I beleive to a 705. I am not 100% on this myself having no air con on my car at all.

Tom and Malcolm,

Thanks for your suggestions!

Tom I'll try to give you a call in the next day or so. I have a bunch of friends in SCAT and have been a memeber in the past with my Cobras. Like to take the car out to the event but I don't plan to do much with it until I get this vibration fixed. Be interested in hearing about your CVA is it solid blue?

You can get some noise and vibration when the pilot bushing in the end of the crank is tight, loose or trying to seize. I think most people have gone to a roller bearing type rather than the bronze originally supplied by GTD. If your car is pre 1991 manufacture it probably has the 3:89 ring and pinion rather than the better cruising 3:44 gear set.

You can also add a larger AC condenser from Vintage Air. It cools better than my production car.

Here they are side by side

The car number is: GTD4030592 and was supposely built here in the the US in 1997 but I really don't no for sure. I sent some pics of the transaxle to Frank in UK and he says it is the R30 with the 3:89 ring and pinion. I had 3:73s in my Cobras with 5 speeds and not really concerned about that. The Vintage Air Condensor looks like the one to have. This car still has the R12 system with the 505 compression. going to get it checked out soon but my 1st priority is the vibration. Think I'll put a new fluid dampner on it first and see if that fixes it. If not I'll pull the motor and transaxle over the next few months and then upgrade it. A nice 331 stroker with the webers ought to be neat!

GTD30592 would indicate that the chassis and bits are from 1992 vintage even though it may have been built later .