axle angles

[ali grey]

Hi Guys,
i am wondering what your opinion of my axle angles are ,i am a bit worried about max up down looks fine.do you just have to accept these angles with audi box.
cheers for your thoughts,Ali

[Terry]

Some consideration should be made to what the "donor" CVs come from. A 930 CV will have a larger misalignment than the smaller joints. Looking at your photos, if you have the 930 joints, then the upright-side joint is marginal, and the tranaxle-side joint is well beyond it designed working range. Of course, you must consider speed and torque as applied to these angles, which I think for the GT crowd, is a given that it's going to be a lot...and a lot, and this will further limit the useable range of angles.

The attached link is one of the best I've found for analyzing CV joints.

http://www.blindchickenracing.com/Ho...joints_101.htm

Just curious, is this a common control arm geometry for a GT? Just looking I see a pretty high roll center and wondered if this was normal?

[Cliff Beer]

Ali, it looks to me like you're past the max upward angle in the pics. Have you looked at your spring lengths and rates? Maximum travel is modest in most GT40s, typically because the car isn't that heavy and has relatively high spring rates comparatively (and most have reasonably good sized roll bars in the rear as well which tends to lessen travel).

One other consideration here is that a new CV with proper tolerances will bear an offset load much better than a worn or inferior CV with greater tolerances. The "rebuilt" CVs generally are not so good - the "rebuilding" process is minimal, so, go with new high quality CVs straight from the manufacturer (Lobro for example).

[The New Roaring Forties]

Ali, looking at the angle of the top arm, I doubt you would ever see that much movement - the CV manufacturer advises 8 dgerees working angle per CV will limit you to around 280km/hr constant speed, that is the speed of that balls racing through (greater distance) of the cage at that angle is the limiting factor.

Interestingly speedway in Aus use the same unis at much greater angles but replace and/or service them regularly so it seems it limits durability (number of cycles) rather than just leading to failure

Regards Paul

[Fred W B]

I've read somewhere that you can get away with up to 10 degrees at the normal ride height, which pretty much agrees.

As above I don't think you have to worry too much about the angle at full bump

Cheers

Fred W B