U-bolt torque and thread length (1 Viewer)

[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.

 

[DrRock]

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

Yes, I’m running a flip kit too and was able to get to 90 ft/lbs. Prior I had them at 70 ft/lbs and was getting creaking so went up to 90. The flip kit supports the U Bolts really well.

 

[CruiserTrash]

I'll third the 4Plus u-bolt flip kit torque here. Running 90ft-lb with no problem getting there or maintaining that level. For stock the torque spec has several factors, including the metal channel that holds the rubber isolator. Once you go to aftermarket spring packs and remove the isolator stuff, all of the factors that went into informing that torque value choice are out the window.

 

[OSS]

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

EXACTLY!

 

[MDH33]

And for the difference in length, i usually just cut them off. They'll get mangled on rocks if you do anything off the pavement.

 

[toy_tek]

I’m perplexed. The spec for the 62 is 105 and I didn’t have any issue getting that with the Dobinsons u bolts or the 4+ flip kit. Dobinsons said “use the factory torque”, so I did.

 

[georgebj60]

I’m perplexed. The spec for the 62 is 105 and I didn’t have any issue getting that with the Dobinsons u bolts or the 4+ flip kit. Dobinsons said “use the factory torque”, so I did.

From what I can gather, it works with the 4+ flip kit, but not the factory spring seats. I definitely felt like things were not going well when I was tightening my u-bolts. I hope I didn't go too tight, but since nothing is bent and I never got to 90 lbs I'm thinking things are okay.

But I will say this, there are no instructions with the Dobinsons kit, other than to say "get a professional to install this". But the MUD community prides itself on and promotes people learning and doing things themselves. So I'm a bit surprised that I didn't come across this issue in all the threads I researched on the install.

I had so many questions. Which way is the steering stabilizer supposed to sit (above or below the drag link)? How tight should the lower shock bolt be (the stated torque in the manual again seemed way too high)? And why aren't my original lower shock bolts long enough for the Dobinsons shocks? Should the grease zirk on the shackle point toward the inside or outside of the truck? Does it matter?

Anyway, I did eventually figure things out, it just took a lot longer than if I didn't have to google things a bunch of times.