Mach 5

Based on a lot of the positive feedback I've read, about a month ago we installed new Empi Vanagon axle assemblies in our lightly modded '86 951. This AM, I gave it full throttle/boost in first and it blew out the drivers inner CV joint. I thought that maybe I had not greased them well enough when I installed them. However, when I removed the failed CV joint, the inner race shows signs of deforming at the edges, which allowed the ***** to escape (see pic). There were no signs of excessive heat, burnt or blueish marks, which I would expect to see if it was lack of lubrication that caused he failure. If it was just lack of grease, I would consider getting another Empi axle and greasing the hell out of it. But if it is structural weakness, obviously I shouldn't get another one. If that's the case, I should probably replace the other axle with something stronger. I'd welcome any opinions.

Thanks.
Roger

Mach 5

I think I answered my own question. I compared the inner race/carrier on the Empi Vanagon axle with one of the OE ones it replaced. The OE is clearly larger (2mm larger in outside diameter, on the right below). I get the feeling I should probably bite the bullet and get OE type axles/joints.

refresh951

How are you bracing the tranny?

arthropraxis

I run vanagon axles with around 350 RW FT/LBS of torque, IIRC. I have blown a transaxle but not a CV, yet.
The transaxle mount is filled with urethane.

bw993

Same thing happen to the EMPI CV axles that I used on my track car. The CVs lasted two events, with a solid tranny mount. Switched back to OEM and all is good again.

Mach 5

Stock. When we replaced the axles, I bought the window sealant to fill the tranny mount. However, when I tried pushing on the tranny, it didn't move much, so I decided to skip it. I'm guessing you think I should do this?

Roger

refresh951

Yes, a must really if your car is modded for more power. The failure is caused by the tranny swinging. My EMPI's have held up to drag racing at very high power levels.

Mach 5

OK. I'll order another Empi axle (heck, they're only $61 at partsgeek.com). I think I'll use the CVs off the new axle to replace both inner CVs. I'm assuming the twisting of the tranny affects the inner joints more than the outer.

Roger

JET951

Cheap J--K , thats why its so cheap

jasonlp

Same but track, no issues.

V2Rocket

somebody needs to do a C4 Corvette style u-joint axle conversion...

odonnell

Check out Nadella axles... the early 911s some 912s used them. Probably equally as much work as C4 axles to fit though, while being way more expensive.

Mach 5

Another Empi is on it's way. I'd like to think if these can hold up to the kind of power that Shawn is putting through them, they certainly should be able to withstand what we're putting through them. With a 2.5L at 15lbs boost, I suspect we aren't any more than 260 lb/ft at the wheels. I'll pull the tranny mount off tonight and fill it with 3M window weld. hopefully that will solve the problem.

First AutoX is the end of April. Wish me luck!

Roger

Tom M'Guinn

Do you happen to know the CV joint part number of the one that just broke? Mine are going strong with plenty more power than your car, though I don't have very many miles on them yet and installed a semi-solid transaxle mount at the same time.

Mach 5

I bought the Empi axle assemblies, 90-6805. It seems like the "semisolid" tranny mount is the key here. As I mentioned above, I bought the urethane to do this with the axles when I replaced them last month, but decided not to. Oh well, live and learn.

Roger