Mrmatt2009

I added a leaf and 1' spacer in the rear... tightened U-bolts to an amount i do not remember and am going to retighten (3 weeks later), whats a good amount to torque the U-bolts at?

8sec-z

I just did the OME HD leaf swap. The repair manual says 102ft lbs for the leaf bushing bolts and 52ft lbs for the leaf u-bolts.

Mrmatt2009

Thank you!!!

dukie564

two grunts and a GRRRRRR

it's very scientific

TheJerm

just make it tight enough to not come loose, it isnt that critical.

ericfx1984

getting it too tight can effect ride and flex...

TheJerm

How so?

5-90

By binding up the bushings and articulation.

Torque specs for years I have FSMs for are on my site - in the Tech section.

NB: When torquing any suspension fasteners, you want to leave them fairly loose until you have the vehicle sitting on the ground in its natural resting position. Bounce the bumper a couple of times, let it settle, then torque everything.

Why? Because that way the bushings and such will be set in the position where they spend the most time. Torquing everything while up in the air means that the bushings won't be sitting static (when parked) in their natural resting position, which means you'll accelerate wear and failure of the bushings.

TheJerm

I dont see how it would bind the bushings, it doesn't even interact with them. The spring pack is already bolted together with a center pin and that doesn't let anything move in the pack. Then you bolt the axle it so the axle wont move in relation to the leaf packs. Articulation comes from the shackle travel and the twisting of the pack.

jth877

They are also a one time use stretch bolt, technically. I would use them twice, then toss.

TheJerm

idk how many time ive had them off but i just reuse them. 100 ft/lbs is no where near the yield strength of u-bolts, let alone the tensile strength. And I tighten them more than 100 ft/lbs ( a assume, usually break a sweat doing it) and never had problems.

I think its a ploy to make you buy more ubolts

dukie564

It has nothing to do with the ultimate or yield strength of the bolts. It has everything to do with the cyclic fatigue, particularly in the threads. Ubolts rely on clamping force from the threads to keep the assembly rigid. Reusing the bolts, even though the same amount of torque is reached, increases the friction between the threads and the nut, and decreases the clamping force by over 55%.

Overtightening will also cause the threads to elongate, so that's a bad idea as well.

Trust the structural engineer - it's a bad idea on such a critical area.

ericfx1984

My mistake... I thought we were talking about the i bolts... oooops

Mrmatt2009

a big reason to why i was asking was that my new U-bolts came with lock washers and once I got to 50 lbs or so i squeezed two of the lockwashers out.

Kvogden

Sorry to revive an old thread, but how do you even get a torque wrench on the u-bolt nuts? The bolts on my RE lift stick up like 4"