Inverting/lowering the Renault G'box

[Julian West]

In the new GTD club mag there is an interesting article on inverting a renault gearbox. The writer also wrote a similar article in the Spring 1999 issue.

Has anyone here done the same mods, or got any info/experiences/opinions? The objective would be to lower the C of G. Apparently the Diff can be flipped to 'reverse' drive. Is there any machining necessary to do this?

The main difficulty in lowering the engine/g'box on the GTD chassis is the cross member that runs between the rear lower wishbone pickup points on either side.

The said member cannot (?) really be lowered as it would then be lower than the rest of the chassis. It's a 40 X 40 mm square section & I understand it takes alot of suspension loading & is a critical area.

So if the cross memeber can't be moved, an alternative is to somehow take a chunk out of the G'box! inverting it would have the same effect....

Also, driveshaft angles are an important consideration.....

What is the general consensus?

Hi Julian

The cross member you refer can be altered to allow a normal way up box to be lowered. I think Kevin is the only chap to have inverted the box to date. Have a look at Roy and Julian's cars next time you see them. Andrew has just gone through the engine lowering process with success. He did things slightly differently as he also widened the gap between the two longitudinal chassis rails so the box could be lowered even better. This involved new suspension arms being made. He has not complained about poorer handling as a result. In fact this year he has gone quicker and this may be because either he really does have a 9600 rpm engine (!) or the lower centre of gravity is of real benefit. Maybe he does what it says on Ray Christophers car, he gets better with age! [img]images/icons/tongue.gif[/img]

If you lower your engine, which I think is an excellent thing for you to be doing, you will need to get new exhausts as clearly the old system you now have, will foul chassis members. It has been said by some owners that the GTD has the engine a bit high in the chassis so lowering it is good.

I am trying to persuade Brian to do this work to his car before he gets too far with his build.

The drive shaft angles have not been a problem to Roy or Julian as far as I am aware. Andrew bust a shaft this year but that quite likley had nothing to do with angles, just repeated abuse from swift launches. I bust one a couple of years back and my gearbox/engine has not been lowered. Dave Parker is in a separate category ( the MEGA category!) for busting CV joints and shafts but his GTD has a slightly different set up in the engine bay to your GTD.

Best thing you could do is go look at the cars that have done this work and see which way you like best. You do not have to reinvent the wheel here.

Malcolm

[ October 11, 2002: Message edited by: Malcolm M ]

[Bill Musarra]

Those of us in the U.S. would love to see some pics of the altered chassis/gearbox setups that you guys have done. An Article would be of great help also. Is there one in the mag. or would it have to be published here on the forum? It is obvious that the state of the art is more advanced in the UK.,,,,, or are the models being put out today making allowances for the work you guys are "having to do" to improve handling.

I personally would like to have a great handling car. Just wondering if these are the things I might have to consider. What about the other trans setups out there. What do you manufacturers have to say obout this [img]images/icons/shocked.gif[/img] [img]images/icons/rolleyes.gif[/img]
I have heard that having "0" angles on the half shafts is not desirable (vibration I believe).
I also have heard that a coulpe of you blokes have also moved your engines forward a few inches. What is the story on that???
Bill

[Neal]

Does anyone have some reference measurements for engine/trans location? I'm interested in optimal height and fore to aft position.

Oil pan rail to ground and trans driveshaft centerline to rear hub centerline (X,Y)?

[Frank Catt]

You guys in the states might like to talk to Fran Hall in Detroit, who is working through me to copy the chassis modifications that I did to Andrews car. The centre of gravity was vastly improved by lowering the engine 75mm (3 inches). On the yellow car (Robin Batts car)I lowered the power unit 100mm (4 inches)Frank

[ October 11, 2002: Message edited by: F CATT ]

[Paul Thompson 'Hooligan']

Hi all,
Lowering the gearbox from the std GTD location certainly improves stability / handling.

Robin Batt's installation (not too clear I'm afraid)


and Andrew Fordyce's part way through conversion


best regards

Paul Thompson
(co conspirator at 'Smart-Tech' aka Roy Smart)

[Julian West]

Obviousley there are a few others interested in this modification,would anyone have a picture they could post here?

[Julian West]

Paul,

thanks for posting the pictures. In the picutre of andrews car, you can clearly see just how low the engine is.

I'll have to crawl under a few cars with a camera to see what has been done to thetransverse chassis member, right under the bellhousing.

[Frank Catt]

I am going to be visiting Fran Hall in Detroit from 1st November to 5th November, so if anyone stateside wants to talk 40s------------ Frank