Hey all,

I picked up a used lightweight flywheel and had it resurfaced. On 2 separate occasions, the bolts retaining the flywheel to the crank broke. The first time this happened, I replaced the 2 originals with some grade 8 bolts. This 2nd time around getting the flywheel off the new bolts seemed to hold better (harder to get off) than the originals I had left. BTW, it was original bolts that broke the 1st and the 2nd time. The 1st time, the thread locker did not hold but think that was from overheating the flywheel (clutch slip). The 2nd time (and better clutch), the thread locker held better but not as well on the original bolts. All bolt holes and bolts were cleaned thoroughly before reinstall.

It looks as if the bolt holes on the flywheel are VERY slightly ovaled. This 2nd instance, there was probably only 8 hours of run time on it but most of that was road racing.


Need advice: Change all bolts and change the flywheel OR just change all the bolts?

 

I had a very similar problem a while back. I used ARP bolts torque to 75ft lbs w/ thread locker. Let set up for a day, finished the install and no problems since. The bolt holes in my flywheel were a little questionable looking also, but like I said no problems. I had 3 that broke off in the crank and the other three were loose, (had someone else do a clutch install a couple years ago). Not an easy task to get broken bolts out of the crank laying underneath a car on jack stands. Hope this helps.

 

ARP's would help like 95blkbird said. If the holes are no longer round I would have them drilled and bushed. You may be getting some out-of-balance/vibration due to the holes.

 

Definitely going ARP then for my next set of bolts. Good advice to drill and bush and may very well do that.

Flywheel/PP assy was balanced together before being put in last time so I know that is not an issue.