Cable Gearchange, HELP!!!!!!!

Simon H · 07-25-06, 03:51 AM

Hi All

I have finally come up against what may be the worst part of building a GT40 replica, the gearchange set up. I have been patiently working away on my KVA for over a year now and it is finally complete. Complete that is apart from the parts required to change gear. I have finished the all the wiring, set up the suspension, painted the bodywork and had a trial run of the engine (the 4.5L Rover V8 sounds great!!). However I am really having a hard time sorting out the gear change mechanism. I have already made an abortive attempt at a rod change but it just would not adjust correctly. This has now been taken out and I need to think again.

After doing much searching on the forum I am looking at a cable change as a potential. I assume that many GTD's had this set up that works quite well (if the cables are protectled from the exhaust heat). Please, please, please could anyone send me pictures of how this set up is made, positions, brackets etc. Take pity on a guy who after a year of hard work is just one step away from having his first drive!.

I have a Renault 21 turbo gearbox in my car if that helps. I have made a very good job of the clutch, brakes and it would be a shame not to have a good gearchange system. After all this effort my brain is just all thought out and I would really appreciate some help. When I have got the bodywork back on I must take some pictures and post them on the forum so you can see what it did look like and its transformation. Its amazing what a coat of paint and set of wheels can do!.

Many thanks

Simon

Julian West · 07-25-06, 05:15 AM

Simon,

Here are some pictures of a standard GTD cable change. You sometimes see these advertised for sale in the club mags, or you may be able to fabricate something similar.

I'm sure you can 'suss' how it works from the pictures, Hope these help!!

Regds,

sibbat2 · 07-25-06, 05:35 AM

I have a CAV GT with a Right hand rod gear change designed by Frank Catt of Wealden Engineering. I too have a Renault 21t gearbox.

Malcolm · 07-25-06, 05:41 AM

If you are going cables, then seriously consider using a rose joints and not the knuckle joints as in Julian's pictures. The knuckles suffer and put play into the system after a while. A well set up cable system can work very well. It just takes time to align it all up correctly.

jpc_bate · 07-25-06, 06:13 AM

I too have a frank catt rod gear change done by the cars previous owner - its spot on.

Simon H · 07-25-06, 06:16 AM

Once again you have given me the information I need. Julian, Sibbat2 and Malcolm thank you all very much. The pictures are just what I was after Julian and I think I have a much better idea of what is required. I have some rose joints spare Malcolm so I will base the set up around them. I have just been down the local marine chandlers and obtained the two cables. Nice and heavy duty so they should do the job ok.

Once again a big thank you to all, without the assistance of the forum over the last year I could not have turned my dream into a reality. I pushed the car outside my factory for the first time on Saturday and over just half an hour I had three different people pull into our car park and drool over the car. Perhaps this confirms that a GT40 is a rare and welcome sight on the Isle of Wight!!.

Regards

Simon

Frank Catt · 07-25-06, 08:31 AM

Simon, if you want a gtd cable system I will give you one FOC, Frank

Ken Mason · 07-25-06, 10:08 AM

Frank,

I have a GTD cable change already - can I have a free GTD to go with it?

andys · 07-25-06, 12:11 PM

To express an opinion, I offer that the GTD cable mechanism design holds a distinct advantage that many others do not. With this system, both selector and gate articulation loads are spread across both cables, as each function employs both cables simultaneously. This allows for reduced cable sizing, and eases routing issues. When comparing this to a typical cable system that employs one cable for each function, the latter requires significantly larger and more robust cables. The larger cables are less flexlible and of course larger in diameter. The only down side I can think of would be the additional friction created by activating two cables simultaneously, but that might be offset by the smaller cable size. Still, I think the GTD is a very clever design. That said, is there a GTD owner that is unhappy with this system? Perhaps it harbors some flaws?

Andy

Frank Catt · 07-25-06, 01:31 PM

Ken, yes, as long as you take it used bits, one bit at a time ,Frank

Jonathan S · 07-25-06, 02:46 PM

The GTD set up looks easier to fabricate as well.

Larry · 07-25-06, 05:01 PM

I have recently posted pictures of my cable shifter set up under "Pictures if my newly finished BEC GT40" in the Media section (sorry I don't know how to link to it)...take a look. I have a 01E Getrag 6-speed connected to a SBF and it is rose jointed.

David Tickle · 07-26-06, 03:36 AM

Simon. I have a KVA with exactly this type of cable change. Mine connects to a Renault 30 box. It works fine, but maybe a little stiff.
Malcolms comment above is most important. Change the knuckle joints for rose joints. While testing, before the car was on the road, at least two of the knuckle joints broke. They have a weak point where the thread joins the ball.
Dave

JohnC · 07-26-06, 07:06 AM

As a general question - (not just for the GTA setup) has anyone managed to fit a reverse lockout to their shifter? Would it be worthwhile to have?

TIA,

John

Simon H · 07-26-06, 07:28 AM

Thanks you all for the replies and the information you have given. I was rather worried on how to proceed with my gear shift set up. Now I am more than confident on what I need to do.

A BIG BIG BIG thank you to Frank Catt at Wealden Engineering for helping me with the parts required. I have spoken to Frank a couple of times now and apart from knowing GT40's inside out, he is more than happy to offer friendly advice. I have never undertaken such a job as building a car before and without this sort of help it would have been impossible for me.

Regards

Simon

Frank Catt · 07-26-06, 04:49 PM

Simon, please E mail me your postal address for large parcel ! Frank

David Tickle · 07-27-06, 01:44 AM

Simon. One other thing I have just remembered. The large black fabricated bracket which bolts to the gearbox, you can see on the gearbox photo's above. Check the welding on this. On mine, although it was finally painted as a finished item, one of the fabricated welds had only been tack welded. As a result, it broke after a few hundred miles on the road. Fortunately, I wasn't too far from home and after manually selecting third gear at the gearbox end I was able to get back

Simon H · 07-27-06, 02:59 AM

I have sent you an E-mail Frank, many thanks.

Hi David, thanks for the warning regarding the brackets. I am suppose I am fortunate living on the Isle of Wight as I could not drive so far from home!!.

Tony Hunt · 07-27-06, 06:11 AM

Before we all get carried away by the merits of the GTD cable gearchange, may I explain why I scrapped mine.
The simple reason, and I'm surprised no-one has mentioned this yet, is that the gate is reversed. When I started driving my car, the previous owner had stuck little numbers on the gate to remind himself which was which, and I never got over having to look down to check. Taking a quick downchange from 5th to 2nd at 80-something on a quick approach to a roundabout (in a land far, far away) doesn't bear thinking about! So, at the end of the first season, out it came.
Frank is very generous to give a cableset away, but have you worked out why he can do it? He's up to his ankles in them! Most people who have stuff done to personalise their car opt for the rod change pretty early on.
A good rod change is every bit as positive as the GTD cables, the gate is the right way up and the rod and rose joints, IMHO, look aesthetically better. Also it's a simple matter to incorporate a simple lift-up reverse lockout on the gate when doing the job.
OK, my car is a GTD, but most KVAs came with a rod change, so if you can't make one work, you ain't trying.
No, Frank didn't do my rod change, though I'm certain he would have made his usual beautiful job of it. I can give you the details of who did if you e-mail me.
My 2p.

Jonathan S · 07-27-06, 10:30 AM

I did notice the gate being reversed. It would seem that there are a number of ways to fix that with the same basic design. For example you could connect the cables above the pivot point on the stick rather than below it. Another would be to connect the cables in front instead of behind the stick. Obviously these would all require fabrication.