Hello,

This is my first post here, although I've been reading some posts here from time to time. As I don't see a forum for introduction, let me just start by telling that I'm building a GKD legend 6. Started out over a year ago and have been making slow progress. The car is on its own wheels now and the engine / transmission are in for a trial fit (they'll need to come out to install a clutch later on).

As I am using a transmission which has not been fitted to this chassis before I'll need to get a propshaft sorted. I got the UJ standard one, but besides being the wrong length for this box (obviously) the UJ will also not fit the box.

Quite a while ago I took a picture of the issue there:
My Blog

Seeing the more modern propshaft on cars not being using U-joints but different sorts of CV joint and seeing that a driveshaft is much lighter while carrying less torque, I think it should be possible to use a modern variety prop shaft with 'modern' joints and a lighter shaft which would also fit underneath the shifting mechanism.

Here are some examples of the line I was thinking along: GKN prop shafts


Are there companies providing this? Would it be possible to get one from a breaker and shorten it ?

[Edited on 13/7/12 by MarcV]

Welcome

Firstly an idea of your location might help, this can be put on in your 'control panel / optiions' top right of the screen.

As for your propshaft issues, if you contact firms like Bailey Morris Ltd linky (there are others) all you will need to do is give them a few detail ( Gearbox you are using, Diff and size of flange, Distance between the two) and they will make a new prop for you with the u/j's of your choice.

Thanks, location has been added.

I think the propshaft I have laying around comes from dunning and fairbank. Bailey and Morris also sounds familiar indeed.
The issue at hand is that I doubt that any U-joint will fit. Furthermore I think a lower weight shaft with CV joints will be a better option, maybe along the lines of the Porsche Cayenne front prop shaft....

Hi Marc :-) What's the advantage of using CV joints over UJs? I can't see NVH improvements being the big motivator on our cars?

Hello mr. Rodgling ;-)

No, it would mainly be size and weight. I think it is weird that the prop shaft is about twice as heavy (didn't measure it, but just the 'feel' as the driveshafts.

But the most important would be size. There is such a small space left underneath the SMG actuator that the joint used needs to be shorts and not too large in diameter. I think the pictures on my blog (see link in start post) show this nicely.

Also, I can't help but wonder why modern cars tend to head towards CV jointed prop shafts (porsche, audi, VW...)

Could you have the UJ or CV joint spaced back from the transmission by enough to clear the actuator? It doesn't have to be right at the end of the prop?

If weight is a concern, I found a company who make carbon fibre props... they don't list prices though so it might be more than the rest of the car.

It would need to be quite a bit, looks as if I would need to space it back at least some 15cm. Not too sure on the bearing loads it will cause (not sure as in I have no idea whether this could even be an issue ;-))

Ofcourse weight is a concern, but more in the sense that I don't understand why one would use such a heavy thick shaft for this purpose. As mentioned, a drive shaft is a lot lighter while carrying more torque.

I understand the reason the BMW prop shafts are thick, they are a lot longer than the one I need (at least 3 times as long), so the torsional deflection is much more of an issue there than it is in these kits.

But hey, any ideas are more than welcome, thanks so far!

I would expect a CV joint to be larger in diamater than a UJ for a given power handling capability.