bgiere

I saw a TBI for the 997 cups that recommends a large reduction in torque values for the center bolt or stub axle...50 ft lbs was recommended. Is this applicable to the 996 cup as well? Was this TBI put out because there were failures? I haven't gotten a clear answer yet.

fstockcarrera

[QUOTE=bgiere;11819151]I saw a TBI for the 997 cups that recommends a large reduction in torque values for the center bolt or stub axle...50 ft lbs was recommended. Is this applicable to the 996 cup as well? Was this TBI put out because there were failures? I haven't gotten a clear answer yet.[/QUOTE
According to Dan Jacobs, this does not apply to the 6cups. The axels fail at the center bolt flange and so I replace the axels at 40 hours. The CV's don't seem to be the weak link. Don't bother with changing the grease as the axels will time out before the cv is an issue. Imo the CV bolts are a single use item. Cheap. Or use grade 8 (manufacturer) bolts that can not loosen.

Bob

fstockcarrera

correction Stage 8 locking bolts is what we are now using after a cv bolt failure this year.
http://www.stage8.com/gm.html

Viperbob1

Just ordered a set...

amso3

I think this was covered 6 months ago on another RL thread. I spoke with PMNA engineer at that time and this reduced torque ONLY applies to the newer cars. They have different parts and there was an issue, which does not apply to 996.

bgiere

Thank you for the tips! Ordered some Stage 8 too!

John@DSM

We have sold a lot of replacement center lock stub axles. We have examined many of the removed parts, some from our own cars, and found almost all have been over torqued, with the threads leaning outside. We are attributing that over torqueing to tightening of the centerlock nut while hot, which can raise the effective torque significantly. Check your stub axles and nuts regularly.

chrcook

I'd have to agree with Bob on the failure point, it was not the CV joints for me, it was the prop-shaft portion of the axle assembly. In case you are wondering, when this fails, and you are running center locks, the wheel comes off and does a TON of damage (wheel, all suspension arms in the corner, brake caliper, bent frame rail, crushed muffler, ripped rear bumper and the axle). And a three wheeled car designed for four wheels is a bit of a handfull.



I'm now on the replace every 40hrs max sort of guy. Too much risk to push.

I've been running 350ft*lbs on the center lock bolt. What are others running?

fstockcarrera

350ftlbs here but I don't think that is related to axel failure. I have not heard of a center bolt failure but many axel failures. We change the center bolts annually, at $100 each why not.

bgiere

I replaced mine last winter with the center bolt stub axle from Demon Speed, seemed to be very high quality.

fstockcarrera

Yep broke the LR axel in the downhill @ Lime Rock. Kept it off the wall, lost most of the corner suspension and the wheel, The track hook bent the left rear quarter because They don't have a flat bed? !! Always liked those car control clinics on three wheels at 100mph