Gordini Project - Fitting the HA1 5 Speed Gearbox

First step is to change the bellhousing and input (clutch) shaft for the R4 parts which are 10mm shorter.

The additional length appears to have been added to the 5 speed gearbox to make it easier to fit the fan belt, rather than to make room for a bigger clutch, so changing the bellhousing shouldn't restrict clutch choice (though fan belts will be as fiddly to swap as they are in the R4).

The Renault 4 parts are on the left in the photo.

Here the gearbox has been attached to an engine, and positioned so the mountings for the driveshafts are central in the car. (The front crossmember is missing.)

The front of the gearbox sits to the left side of the car, and with the rubber mounting attached (I used the R5 TX mount, and cut the top and bottom off) the gearbox extends about 20mm forwards of the original 4 speed gearbox.

The TX gearbox mount is angled which makes the design of the mounting face a little more fiddly.

Here's the modified front crossmember compared to an original GTL crossmember. The new one is a lot thinner. I didn't take as many photos as I should during the modifications.

I cut out the front skin of an original crossmember and knocked over the flange in the center to clear the gearbox. With the gearbox being offset to one side this didn't provide enough clearance, so I let in a new 30mm section into the middle of the crossmember. This meant I had to cut and shut the outer parts of the crossmember by 15mm so the outer wing and bonnet mountings would end up in the right place.

From there a 2mm reinforcement was added to the inside of the front skin to regain a little stiffness. After adding some spacers for the mounting bolts that panel was boxed in with a 1.5mm panel which needed a 5mm joggle to allow for the angled mounting (visible if you enlarge the photo by clicking on it).

THe mounting holes in the TX mount were in totally the wrong place for the Renault 4, so new ones were drilled in the bottom and sides of the mounting.

A couple of further box sections (1.2mm) were required to extend the rear face of the crossmember back to the chassis members.

I welded the modified crossmember back in about 5mm forward of where the original crossmember would have been. This shouldn't create a problem for inner or outer wing mountings (the outer parts of the crossmember are bendy) but I will have to modify the lower flange on my GTL style bonnet to fit.

Here's a poor quality photo of everything in place including the spare (seized) Gordini engine I'm using for positioning.

Next step will be to fit the body and steering and then wonder why the steering column fouls the carburettor manifold.

The 5 speed gearbox still needed to be adapted to take the Renault 4 umbrella style gearchange rather than the original floor mounted change. This is easily done by swapping the top covers over and adding some gear selector parts from the 5 speed gearbox to the 4 speed box top cover (the part that needs to be swapped over is circled in the photo. It's shorter than the R4 part).

Reverse gear shares the same plane as 5th, and the inhibitor spring feels too firm for the R4 brolley change, though it feels no firmer than the R5 spring. I'll probably fit another spring later on.