I had 2 bolts stretch on me, and one of them snapped. I'm curious to know why this would happen.

The bolts are from the outside cam holders (on the flywheel side). They are the 10mm ones that only get torqued to 7.2 ft/lbs. I tried to torque them down, but they felt like they would not stop spinning. Almost like it was stripping the threads, but it wasn't. One of them finally snapped, and I just stopped tightening the other when I felt it doing the same thing.

I know the bolts were not bottoming out. Could my brand new torque wrench be wrong? It starts at 120 in/lbs (10 ft/lbs). Could the wrench be inaccurate under 10 ft/lbs?

I got as many pics as I could. The left bolt is the one that snapped. The middle one got streched (in the same exact place as the left one), and the one on the right is normal.

 

Torque spec are 108 in/lbs. around 9 ft/lbs..
Did you use a 1/4 torque wrench?

i use Snap-On QD1R200 1/4 torque wrench with range of 40-200 in/lb.. with Redline Assembly lube.. never got a problem..

I think you have torque wrench inaccurate.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by brainwo &raquo;</TD></TR><TR><TD CLASS="quote">Torque spec are 108 in/lbs. around 9 ft/lbs..
Did you use a 1/4 torque wrench?

i use Snap-On QD1R200 1/4 torque wrench with range of 40-200 in/lb.. with Redline Assembly lube.. never got a problem..

I think you have torque wrench inaccurate. </TD></TR></TABLE>

Thanks for the info. I'm using a 3/8 drive TW. I guess I should get a 1/4, and new bolts while i'm at it.

 

What is the range of your torque wrench?

Did you use an extension? If so how long?

Length of socket used?

Did you use any lube on the bolt before installing it?

These factors do affect the the torque applied, but the torque wrench does feel like it is being torqued that much. Also torque wrench should come precalibrated from the factory, but most calibrations only have 3 checks:20% of full range, 60% of full range, and 100% or full range! So that would mean that below 20% of full range isnt calibrated!

Example: If you have a 0-10ft-lb torque wrench, only 2lbs., 6lbs., and 10lbs. is checked. Anything below 2lbs. is uncalibrated or considered inaccurate. But this usually has no effect until start using bigger torque wrenches!(0-100lbs, 50-250lbs, etc)