Please help lower clamp bolt problem

[goldman15]

I was reinstalling my forks after a steering bearing grease job and the lower fork clamp bolt just will not torque to 18 ft lbs. I did the one side of the clamp without any problem and the top of the other side without any problem. However, when I went to torque the lower clamp bolts to specified torque they just kept turning and turning. I suspected I was tightening them past the 18lbs but my torque wrench did indicate so. I just kept tightening, waiting for my torque wrench to say stop, but the clamp bolt snapped. Has anyone had this problem were the clamp bolt just keeps turning and won't reqister torque? Also is it possible I did any damage to the fork or is the metal on the fork hard enough that it is likely I did not do any damage to the fork? It doesn't look like there is any indentation in the fork metal. I am now afraid to use the torque wrench on this bolt again. How critical is the right torque on the lower clamp bolts? This is not a problem with my torque wrench, I tried another torque wrench I had and it did the same thing (wouldn't stop). The pattern I was using to torque the bolts was tightening the top bolt first then the bottom bolt. Is this correct? Anyone know what the size of the clamp bolt is because I will be hunting one tommorrow? Sorry for the long post and thanks for the feedback.

 

[BRush]

Somethiing does not track. The bolt would not stop turning, yet it snapped? There are four lower bolts (two per side) did all of them show this problem or just one? Unless your torque wrench is fubar, I suspect you have thread damage. I'd recommend cleaning and inspecting the threads for damage. Use a tap to chase out the threads.

 

[goldman15]

thanks for the reply brush. My torque wrench is fine. Only the lower left clamp bolts would not torque. Doesn't appear to be any thread damage. How hard is it to pinch the fork tube? It seems like these clamp bolts are designed to fail before any damage would be casued to the tube. I noticed the bolts have a very noticeable thin spot where the threads begin.

 

[23jayhawk]

I would second BR on chasing the threads, even if they 'look' fine. If you've broke a couple steel bolts in aluminum clamps, at a minimum you'll want to dress up the threads. Careful with the tap & use some fluid.

If I read your post correctly, you were torking first the top, then bottom bolt of each clamp pair. If so, I would suggest you bring them up to torque in parallel. Snug both, then run up to 75% of final torque, then final torque.

 

[canyncarvr]

This isn't going to help...but I've had pretty much the same thing happen.

I didn't snap anything. I could tell I was past the selected torque. I didn't keep turning till something broke. Brand new wrench.

Loosened everything up and took another go at it. Ended up losing the torque wrench and doing it by 'hand'.

After I did it by hand, I checked it with my new wrench (not a $15 schmuck's special!). I got different responses from the wrench tightening from 6-9 o'clock than 12-3.

Point of this is to say I've had the exact same response. I have no idea why. Probably a screwed up wrench. Don't know.

Chase the threads. Don't JUST listen for the wrench click! 'Listen' to your elbow, too!