Question for you CAV boys

[Frank Catt]

Can I just inquire from guys running ZF transmissioned CAV cars on any problems / solutions with driveshaft CVJs. We have a car , built by the factory, that runs the joints at 12 degrees deflection, this overheats the outer units and fries the grease in short order on the track. Do you have any stronger units that will run at a greater angle than the factory fitted units ?? Thanks in advance, Frank

 

[Cliff Beer]

Frank, 12 degrees should not be a problem for the CV's. In fact, that's just about optimal as far as a good running angle. There's going to be some healthy angle changes on the track due to lateral loads, but if 12 degrees is the static position and the car isn't bouncing around too much on its suspension during the track day it should be OK.

My suspicion is that the quality of the CV's being used is not that great. Here's one important thing I've learned about CV's over the years: "rebuilt" CVs tend to have very little rebuilt about them. The clearances are checked and so long as there's no major groove in the running contact patch the CV housing is re-used, often with a few different (but still used) balls to replace any obviously bad ones. This results in a "rebuilt" CV which has uneven tolerances and bearing surfaces which have been pounded pretty good. CV's should always be newly manufactured when replacing old ones. New is typically not that much more expensive than rebuilt for off-the-shelf stuff. Just my experience.

Here in the US we have a lot of 4X4/offroad shops who typically do a very good job of custom building CV axles for higher hp/tq applications. After installing "rebuilt" CVs in my CAV some years ago and having those fail within 2,000 miles I spent the money on some good quality axles from a 4X4 shop with a very good reputation - much, much better.

Just my $.02.

 

[Bob Putnam]

Also, make sure that the axles are not too long, making the joints bottom out under certain circumstances.

 

[johann hamm]

4x GKN Porsche 930 CVs, handle angles of 25 degree with high hp. Packed with Swepco Moly 101 grease.

Custom made side-shafts and wheel spigot shafts supplied at the time by CAV to replace the chronically failing Audi setup.
CV joints spaced on transaxle flange and custom teflon inserts to take up side-shaft playto 3mm with suspension compressed to shortest distance between outter and inner cv.

CAV 106 565hp 560ftlb. RBT CWP 3,2.
Tested on track, high speed runs beyond 300kph, and general use. No problems.

 

[Frank Catt]

Thanks Johann, I spoke to Jean at Autofutura today, and he confirms that CAV no 100, the car I was running this weekend at Ascari, is in fact the first car they built, and was used as a demonstration car that Stirling Moss drove at Le Mans in 2007 as a pace car. This car has the unmodified earlier Audi joints you describe, and Jean confirms that 12 degrees is in fact the absolute maximum deflection, and that this set up is not strong enough for track use. He is sending to me details of all of the modification upgrades you have also fitted, which I am sure will be sufficient for our use. Frank

 

[johann hamm]

Its a pleasure Frank. Greetings to Jean and when its sorted im sure you will enjoy the ride.