Strength of DOJ vs SFJ's and Max Axle Angles

[DBCooper]

We have several Porsche 914's with WRX engines and transmissions and have seen several unusual failures of the inner CV's (DOJ's and SFJ's).  What's odd is that they seem to just come apart, without being hammered into a failure, just kind of disassemble while being driven normally.  Nothing broken, not even any sign of damage.  These are custom Sway-A-Way axles that have been re-splined to connect the outer CV's and stub axles of a Porsche 914 with inner DOJ's and SFJ's to fit a Subaru 5MT transmission.  Typically they're the 2000-2004 WRX transmissions with male output stubs.

 

The CV's and DOJ/SFJ's don't seem to be damaged, they just come apart, and it doesn't happen often, really only a few times among quite a few cars.  Still it's not good and I'd like to find the cause and then a solution.  I suspect we have too much angle in the axle, because the Subaru transmission axle outputs are offset from where the 0914 stub axles are located, giving us an axle angle of maybe 10-15 degrees.  So the question, does anyone know the maximum design angle permitted for those inner CV's?  And if you know that maybe you'll know if those max. angles different for DOJ's and the SFJ's?  If it's not the angle is there anything else it might be, that should be checked?

 

And lastly, if you have enough knowledge and expertise to know max axle angles would you alsoknow the relative strengths of those two, the DOJ's and the SFJ's?  We're two wheel drive, so we're putting all the power through those two wheels instead of spreading it out among four, meaning we do break things.  Which joint would be the better choice for strength, the DOJ's or the SFJ's?

 

Thanks

 

[904svo]

DB what you will find is that when the wheel axles swing thru their arc the shafts become to short allowing the cv joint to come apart as you have too

much angle on the cv joints allready.