Gearbox linkage : from rods to cables

[Yon]

Hello everyone, new member here from Biarritz, France !

I am a junior motorsport engineer/mechanic currently helping my dad during my free time in his workshop dedicated to classic cars.
He owns a Ford GT 40 since years (MkI from 1969, right hand drive, gear lever on the right) but doesn't have so much time to take care of it, so I decided to give it a try.

The main problem here is that he would like to change the gearbox (Renault UN1) linkage swaping the rods system to a cables one, because with the current system the gears are in the wrong way (1st gear on the right).

I saw some informations on other forums about adapting linkages from other cars like Mazda mx5, Toyota e90, etc, but didn't find anything specific or detailed.
He already bought a linkage system from a Toyota e90 (cables are too short but lever positions are matching), I don't know what could be the better option, adapting the Toyota system with longer cables and making my own shift system on the gearbox's nose, or going a total different way with your ideas if any of you already made this kind of modifications.

Thank you in advance for your answers !

 

[Ian Anderson]

Welcome to the Forum.

UN1 with right hand drive and right hand shift is perfect for a rod change and it is fairly easy to do and you end up with a H pattern shift.

left and back is reverse
half left and forward is first
half left and back is second
forward is third
back is fourth
and right and forward is fifth

I will track down some photographs and post them

Ian

 

[Jean-Marc]

Bonjour, et bienvenu, j'habite dans le Jura, j'ai une GT40 RCR équipée avec un changement par câbles mais sur une boite ZF.
Les câbles et le levier viennent de chez Cableshift

Cable-Shift - Home

 

[JP Verweij]

You don't want to change to cables!

 

[Mike Pass]

It should be relatively easy to change the pattern. If you can post pics of your linkage at the gearlever and at the gearbox end the forum members will be able to assist.
Cheers
Mike

 

[Yon]

Welcome to the Forum.

UN1 with right hand drive and right hand shift is perfect for a rod change and it is fairly easy to do and you end up with a H pattern shift.

left and back is reverse
half left and forward is first
half left and back is second
forward is third
back is fourth
and right and forward is fifth

I will track down some photographs and post them

Ian

Thank you for your answer ! Can't wait to have a look at the photos !

 

[Yon]

Bonjour, et bienvenu, j'habite dans le Jura, j'ai une GT40 RCR équipée avec un changement par câbles mais sur une boite ZF.
Les câbles et le levier viennent de chez Cableshift

Cable-Shift - Home

Merci beaucoup je vais y jeter un oeil !

 

[Yon]

You don't want to change to cables!

If I could avoid it I would, the problem here is that the gears pattern is reversed. I prefer to change for cables than to change the gearbox because the driver caused an over rev putting the wrong gear

 

[Frank Catt]

Yon, repeat - You do not want to change to cables !
fitting rod change correctly is a very simple job, perhaps you should send some pictures of your existing system for us to see.

 

[Yon]

Yon, repeat - You do not want to change to cables !
fitting rod change correctly is a very simple job, perhaps you should send some pictures of your existing system for us to see.

It may be an option, didn’t find a solution with rods adaptation during my researches but some of you may know one. Here are some photos of the whole linkage system :

 

[Frank Catt]

Yon, Well, I think it is fair to say that I am not surprised it not working, what a mess ! But without doubt you can make a rod change that will transform it. Frank

 

[Richard Milner]

Yon, repeat - You do not want to change to cables !
fitting rod change correctly is a very simple job, perhaps you should send some pictures of your existing system for us to see.

Here’s a photo of the rod change on my GTD GT40 designed, made and fitted by Frank Catt. No stirring a wooden spoon in a bowl of custard for me but clean crisp changes up and down, especially 3rd to 2nd. Beats cables anytime.

 

[Ian Anderson]

Here are some pictures of the DAX gear change when being set up

The rod end was moved closer to the chassis rail mounting the gearstick further to the right than shown in the photo

The rod then runs straight back along side the fuel tank and through the firewall, where it attaches to a universal joint and the rod moves inboard to the front of the gearbox and a second universal joint where the rod then runs direct fore aft.

Lastly everything connected and standard H gearshift

Ian

 

[Ian Anderson]

Some pictures of the sort of thing people do at the gearbox end

 

[Ian Anderson]

A pic of my rear gear hang mechanism

 

[Ian Anderson]

Now I heard of someone in Australia who made a rod gear change and instead of the rod end and pivoting at the front did that in the same way a rifle bolt works.

This could also be done for the Renault box but you would have to work out the movement at the rear….. I believe the first arm on the gearbox instead of being mounted downwards would need to be mounted upwards to retain the standard H change

Ian

 

[Neil]

Transaxle shift linkages in a mid-engine car can be difficult. Here is how I did it with a Porsche G50 5-speed transaxle (not a GT40, though). I used Thompson ball bushings and Case 60 shaft. This geometry preserves the conventional 5-speed shift pattern.

 

[Yon]

Thank you all for your answers ! I'm gonna have a look at the different photos that have been sent, the good new is that apparently I can keep a rods linkage system. I'm gonna take some measures and draw some plans before to decide what could be the better option !

 

[Yon]

Hi everyone ! Some updates from my work on the linkage upgrade.

I tried to imagine a new system thanks to your ideas. One problem I didn’t see is that there is apparently less room in the bay to fit straight rods like in your examples, which could explain why the final rod mounted is bent to reach the gearbox end.

I don’t want to cut or drill through the engine bay walls, so I thinked about a quite easy solution that sounds good (at least in my opinion).

The actual system is quite messy as Frank said, but it’s working perfectly. The original problem is that the gears pattern is reversed (right and forward is first). With the actual system (similar to a rifle bolt as Ian explained) I could just need to put the anchor point of the side link upside down to reverse the movement of the system and get a H pattern with the first gear left and forward. I can also decide to keep the first arm is this position or also put it upside down to get the first gear left and backward like a ZF gearbox.

The system will be less messy as I plan to clean, repaint and probably remake the last rod with fewer and clean welds.

Let me know what you think about this solution !

 

[Frank Catt]

Go back to the drawing board Yon, start again, but first change the selector rod into the gearbox so that it is on the right hand side of the caseing.