U-bolt torque and thread length (3 Viewers)

[georgebj60]

Some RTH needed. How critical is the exposed thread length at the front u-bolts? The service manual says to tighten to 90 ft lbs, ensuring the exposed length of the u-bolts is consistent. I understand mine will likely be longer at the back as I have caster shims installed, but they’re longer at back vs the front by more than the shim thickness. Is there some rocket science here, or is it snug to 90lbs and call it a day?

At least it looks like my exposed threads are even left to right.

 

[georgebj60]

Actually on second look, the difference in thread length is pretty close to the shim thickness. I’m going to carry on.

 

[Godwin]

After you run them a few days, couple hundred miles or so, recheck the torque. You may need to do this 2-3 times before you reach the point where re-torquing remains tight.

 

[georgebj60]

It seems like I’ll never get to 90lbs torque. I stopped at about 80. Feels like they’ll just keep turning.

 

[duncanrm]

It seems like I’ll never get to 90lbs torque. I stopped at about 80. Feels like they’ll just keep turning.

Hahaha.. I hate that sensation of second guessing the torque... "am I about to break it or does it really need to be this tight???"

 

[georgebj60]

Hahaha.. I hate that sensation of second guessing the torque... "am I about to break it or does it really need to be this tight???"

Exactly! Plus I’m not sure I trust my torque wrench. It maxes out at 100lbs so I’m near the limit. I need a bigger one anyway so I might grab one and double check the bolts.

 

[1911]

Exactly! Plus I’m not sure I trust my torque wrench. It maxes out at 100lbs so I’m near the limit. I need a bigger one anyway so I might grab one and double check the bolts.

Good thinking; not many torque wrenches are accurate near either end of their ranges. Ideally you want a selection of quality wrenches with different spreads/ranges, including an inch-pounds one.

 

[bj70bc]

the bolts do keep stretching for sure, even waiting an hour or two they will take another half or full turn to hit 90 again,

 

[OSS]

90ft lbs is only relevant for the original leaf spring pack and original u bolts. That torque ensures the nut will bottom out due to no more threads on the u bolt - and click off the wrench.

Trying to torque the u bolt nuts on any other thickness of spring pack or different u bolts to 90 ft lbs will spell disaster — way too high of torque setting. You’ll never get there.

 

[yotadude520]

Here’s what happens when you keep on trying to torque at 90 ft lbs with aftermarket u bolts.

 

[bj70bc]

cool, well the ubolt flip kit i have got torqued to 90, looks good....

 

[georgebj60]

Hmm. I wonder if I should back off the bolts then. i never did reach 90lbs, but gave them a bit of a pull with my breaker bar. And glad I didn't keep trying to get them to 90lbs. I guess to move forward I'll just make them tight, and re-check often.