930 CVs and Double Plunge

[Kyle]

I’m fitting C5 outer CVs to 930 inners. This puts them in a double plunge configuration. The axles are quite long and only have a clip on the outer most edge of the axles.

I can easily install another clip on the inner CV, (lateral/outermost) to the inner race. That way the inner CV is completely clipped in.

Does the outer CV need a clip at the outer most portion? And inner?

Read though lots of information and it seems as though these axles can float. In addition it seems that it’s sort of impossible for the inner cvs to go lateral too much.

I think I will go ahead and make sure the clips are on the inner CVs on both sides of the race. The outer will be challenging as these are usually done with the compression type of clips that compress when slid over.

Thread 'Axles - floating or not?'

Apr 6, 2010

Hi All,

I'm in an unfortunate situation with the firm who made me some custom axles. I am using Porsche 930 box with 930 CVs on both the inner and outer ends, so nothing unusual.

I have some porsche race car axles of a different length, and the CV inner section is a nice engineering fit on the splines of these original axles, and will slide smoothly on the splined section at just a light hand touch. I supplied both as a sample.

The new axles arrived and the CV inner is a light to medium interference fit on the spline - i.e. needs to be hammered on.

I want the CVs to be centred...

• andrewrobertson
• Replies: 27
• Forum: GT40 Tech - Powertrain/Transaxles

 

[Kyle]

As I research more one think I need find is if the outer C5 joint is plunging or fixed. I believe it is fixed. In addition the 930 or series 15 joints have side to them I believe on which way they should face in relation to the outers.

 

[Brian Kissel]

I’m interested in your research. Please continue to update.
Thanks

 

[Kyle]

More research, these guys are running dual plunging with circlips on only the outside of the axles. They have an install video here, a lot more angle than any GT is going to see as well.

 

[Jerry Irwin]

do not allow the splines to slide.....full stop.
Jerry

 

[Kyle]

Kyle,
If your Axle is sized properly, the clips on either end of the axle hold it in both directions. This is part of a larger conversation, but the short of it is, on an offroad vehicle (prerunners, race cars), you axle should have somewhere around 3/8"-1/2" of float when installed in the vehicle, at full droop (Suspension and drive train assembled, suspension is hanging on the limit straps you should be able to slide the axles left to right between the hub and transaxle 3/8-1.2). And less than that and your axle may be too long, which could result in your axle crashing into your transaxle CV output flange at full bump. Any more than that and it may be possible for the star on your CV to fall off the splines of your axle - towards the center of the axle. From experience, I can say that both results suck.
But to be clear, in these race/pre-run applications, you 100% want the axle to be able to float, to accommodate the change in distance between the hub and the transaxle during the suspension stroke.
There is a lot more to this, but that is super basics. Hope that answers your question.

 

[Kyle]

The C5 outers are not actually plunge CVs. They’re straight cut which allow a large angle but no shaft movement when clipped.

I’ll only clip both ends of the inner race transaxle side. Maybe outer CV inner once I take measurements and confirm full droop and compression.