U_joint on wheel side cv joint on diff/gearbox side

Paul Hendrickx

Supporter
Hello all,
question for the brave... if i have a drive shaft with on the wheel side an u_joint and on the gearbox side an cv joint ,would it work?
How can the cv joint pick up the rotation variance from the u_joint while this one works on an angle?

On the genuine gt40 you had u_joint wheel side and gumbo rubber on the gearbox side..... and the cars did 4500km in 24hours...
just try to understand it....
so if anyone knows......
Thx Paul
 

Bill Kearley

Supporter
Much better to have 2 CV joints. Depending on the angle you may have extra wear and possible vibration. In any case, make sure that the axle is short enough as to not bottom out in the drive flange. disconnect shock and sway bar and move upright up and down and make sure it doesn't. The use of rubber in that situation made it possible.
 
Paul,

I have the U_joint - CV joint combination on my GT40. The U_joints are on the wheel side. My advice is that you have CV joints all arount as I think I pick up significant vibration with the mixed combination.

John
 

Ian Anderson

Lifetime Supporter
Supporter
Hi Paul

I also believe the vibration increases exponentially with the angle of the driveshaft
Originals had little angle on the driveshaft in standard (rest) .position so little vibration and any vibration was taken up by the rubber.

A replica with a UN! / Audi box has a lot of angle in the driveshaft and so a mix of CV and UJ is not desirable.

Of course you could do UJ at both ends with a splined shaft in the middle.

Ian
 
It's even worse than just two U-joints because you can't put them out of phase to cancel each others vibrations out somewhat.
 
Just run a couple of 930 CV's with the chromoly race cages and stars designed for the offroaders, I'd be amazed if you're running more angle than they will take:

 
You wouldn't put two U joints out of phase with each other - that would double the amplitude of the velocity variation end to end. Keeping them in phase means the output shaft and the stub axle remain at constant velocity, while the intermediated shaft has velocity variation. Which is somewhat acceptable since the output shaft and stub axle are roughly parallel to each other. Def wouldn't work well on a steering axle. But yeah, just use two CVs.
 
You should also bear in mind the height of sidewall of rear tires, if your using 15" rims with taller sidewall that will absorb some of the inner/outer speed differences. Also the position of output flanges of driveshafts can be critical and some transaxles like Audi & Renault do not work well with regard to this and require the engine to be fitted in a nose down attitude which can introduce further problems like coolant flow, air locks etc..
 
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