I have an electric fan on the oil cooler that I can switch on when the car is stopped in traffic. It's enough.

Since the BMW 1100/1150/1200 R-series motorbikes relies on air rather than a fan, no probs.

A very interesting thread Joolz. Your ingenuity is amazing.

Modifying the gearbox mounting, the blocks of wood are screwed together and to the axle to form a simple jig. The smallest yellow piece was added after the mount was cut off, and is 1" thick, weld the mount back on and it's 1" further back.



And back in the car, with the mountings bolted in place. The rubbers are infact intended for exhaust mounting, and it occurred to me recently that they are not designed to cope with high tensile forces. I'm now slightly worried that a bit of heavy braking will see my gear linkage disappearing through the dashboard, closely followed by a gearbox shaped lump being formed in the bonnet. I could probably attach a piece of chain across the rubber to prevent the worst happening, but I'm thinking I may have to redesign the mounting anyway.



Note the precisely recessed bulkhead.

Once the car was up and running I discovered that the gearbox I've fitted has a horribly crunchy syncro on 3rd. And with a bit more use I'm thinking that maybe it wouldn't do any harm to have slightly longer gearing, preferably with 5 speeds. The trouble is that the back of the g'box looks like this:


There's not a lot of room for a longer box and even less room for a GSA type engine mount, it would want to sit exactly where the inner ends of the steering rods are. I really don't want to lift the box over the axle as some people do, I'm wondering whether if I cut the mounting off a GSA box and cut the bracket off the front axle, and fabricate something different, it might just work. Also if I use a GSA box I'll have to do the whole driveshaft adaptors thing. Plus a fair amount of time/money went into making this 'box setup work, so it seems a shame to bin it so soon.

There's this 5speed for sale on Leboncoin for 120euros including the brakes, not the bargain of the month, but a fair price? Anyone able to offer me one cheaper?



Notice the bigger rear cover with rubber mounting bush underneath.

<thinks> The LN box is a G box - so the output shafts could be swapped over. I don't think it's quite as straightforward as on a 2cv box, but I doubt it's that much worse. I'll be over at the lockup today, so I'll have a look at the spare G 4spd I think I've got in there.

Thanks Adrian, I've no idea how hard it is to change output shafts, but like most people I'm scared of gearboxes, in theory I'm quite happy to go mixing and matching different bits, but I really don't fancy doing that setting the crown wheel and pinion backlash thing, with the shims or however it goes.

I had a bit of a drive today and it could quite happily cope with a much higher 1st gear, pulling away in 2nd rarely presents a problem, so it could be an option just to change the final drive ratio. The main problem is that in top it'll do 70mph on half throttle, but at 5000rpm, which isn't great for the fuel economy.

I've been having a play with the tuning calculations on Cats site, it tell me that the engine should give a theoretical maximum of 104mph, but with the current LNA box will only do 98, which is exactly what testing has shown.

It doesn't think that a GSA 5sp is ideal for top speed, as 4th is too short and 5th is too tall.

It likes the idea of the LNA box with the final drive ratio from an Axel, and it so happens that I have an incomplete Axel 4sp box at home from an unfinished motorbike project, not mine, one of the output flages is missing and I think the dif's been welded up, but if the crown wheel unbolts from the dif then there's a 50% chance of it being the right ratio. This combination would allow it to reach it's potential top speed, and has the benefits of keeping the existing brakes and g'box mounts. But on the downside I'd need to set up the crown wheel and pinion and I'd still not have an overdrive gear for cruising.

Apparently the ideal box is an Axel 5sp, with 4th being perfect for top speed and having a 5th for cruising, but on the downside, It'll have a long rear casing and the wrong output flanges, and where am I going to find one.

ARRRGH! remind me why I'm doing this again... oh yes I remember

I have this engine / gearbox combination. I bought it many years ago.
(It should have been in the Orange)

The gearbox housing should come from an LNA, and the rear would come from the GSA, but the bracket is cut off. which is after two bent piece of iron which fit in the original 2CV rubber fittings.

Is this a solution??

As far as I know it is possible to cut off the original mountingpoint og a GS(A) box, I even believe it is neccesary to make is fit in a A-type. and just as Lars says, it is possible to use the cover bolts for mounting a bracket to it.

Even when a 5 spd box has got a to long ratio it would be nice to have a higher ratio just for cruising (and you aren't allowed to drive faster than .. miles/h anyway but it is possble then t mount SMART tyres, those have a smaller diameter (10 km/h difference in top speed with normal 2cv) and probbably those are better resistant to higher speeds as well!

suc6 with this project!

greetzzzzzzzzzz

Rusty

The rear mount on a G box is part of the rear cover - so should be straightforward to just swap an LN rear cover onto a G box - although swapping to a 5spd wouldn't work.

Thanks for the suggestions, but I don't think any of them would allow me to move the box any further back than it already is, I wouldn't bother changing to a GS box unless it was a 5speed, and at the moment I can't think of any way of fitting in a 5sp without lifting it over the axle. I might be able to move the engine forward 10mm and might be able to machine a bit more off the bellhousing if I thin the flywheel to match. To be honest I'm probably pushing my luck trying to get a 5sp under a standard 2cv bonnet.

As the gearbox mounting is at the moment, the distance between the bracket on the axle and the rear casing is; 2mm of bracket, about 6mm of bolt head, and about 3mm of clearance. And that's with the bracket on the axle moved back 25mm, so I've already got every spare millimetre I can find. Plus there is no spare room between the steering rod ends and the back of the casing, so I would have to lift the back of the box.

Does anyone know exactly how much longer a 5speed is over a 4sp?

Should I move the front axle back 2 or 3cm? I don't see why I can't.

Should I go and buy that 5sp off leboncoin? Do they come up for sale very often?