drwhosc

Here is my rear pinch bolt, obviously not normal. Looks like I have some thread issues.

What can cause this.

Can I replace the bolt, re-tap the treads and be good, or do I need to pull the sleeve. the TT grove alignment appears to be correct.

Once again, thanks for all the help, I always appreciate the knowledge on this board.

Dave928S

That damage would normally be attributed to the drive shaft sliding towards the front of the TT, however, the thread damage would be also usually be also on the rest of the thread, as a consequence of winding the bolt out to remove it. You need to be absolutely sure that the groove is correctly aligned at the back and that it doesn't just appear to be correctly aligned, because the spline has worn, which effectively widens the groove. Checking that the front is projecting the correct dimension forward from the front of the TT flange, will ensure the drive shaft is located correctly within the tube.

That bolt is also not a standard factory pinch bolt, and may or may not be the correct stress grade. Here is a pic of two standard bolts, with the top one showing clear evidence of spline imprint, and flattening of the thread when it was wound out, without releasing the pressure from the slipped forward shaft first. The bottom bolt is brand new correct grade and dimension.

I doubt you would need to retap the thread in the clamp, as the damage is outside the area of its engagement with the thread. If the new bolt won't easily wind in by hand, however, then you should clean out the thread.

drwhosc

Thanks for the info. The bolt is not the right one, and I bet it is an 8.8 grade, not a 12.9. It is thought to see into the access hole to check the alignment. the position looks like it is where the lower part of the clamp meets the threaded part. I saw a thread by mrmerlin on how to slide the drive shaft. the front splines look good.

The front was definitely looser then it should have been. there was a pklamp on the front, and I think it saved me...

Mrmerlin

when you get a new bolt test fit before you final tighten it .

NOTE start at the rear pinch bolt first.

NOTE a helper is good here so you pry the drive shaft as needed to make the shaft cutout fir the collar and the input shaft.
add some blue loctite to the threads then tighten to 61 ft/lbs
you might consider replacing all of the bolts

drwhosc

yes going to replace all the bolts, I saw an earlier pic of Dave928s rear spline where the grove was widened. I hope I am not there yet. If so, I think I am going to have to rotate the shaft and find a spline position that is in better shape. I think I will reassemble and recheck for wear in a few months.

I think I am Ok since the wear is concentric and not a spot like a misaligned shaft will be. Something killed the treads though... Hopefully it is just a weak bolt grade.

Hopefully I can lock this puppy down, I really dogged a bullet here. I am going to add this job to my yearly maintenance when I do my grounds.

thanks for the help...