changing U bolts only

I too am curious about this. When I did mine I just made them tight and made sure they were even on both sides. But then I got my gears changed out and the guy said he used an air wrench on them and they tightened up much more then I was able to get them with just using hand tools.

 

I'm guessing that the guy was just lazy when he used the impact wrench. When I had work done the guy used a hand wrench and then finished it off with a torque wrench. Kind of used an x pattern to kind of keep them even.

 

Assembly Manual say 35-45 ft. lbs.

IMO that's only good if you can get the shock plate to make contact with the spring perch. With new rubber pads and especially with poly pads getting the two together is difficult with "only" ~40 ft. lbs.
Also, most u-bolt kits do not include lock washers and I believe they didn't come from the factory either. Under load the u-bolts will stretch and the nuts will loosen up a bit. You will want to re-torque after a few hundred miles.

 

I never use those U-bolts that come from the auto parts stores. I go to our local spring shop and they make me the bigger diameter a set that will fit through the holes in the housing and plate. I tighten them with the impact till they won't turn anymore. Then tighten them again after running the vehicle on the road again every other day for a week or so till they don't move again. Haven't had a rear end fall out of a vehicle yet.

But that's me, Mr. Gorilla fist.

 

A couple of years ago there was a thread about torque specs for the U-bolts. someone posted a link to a site (TRW maybe? ) with torque specs for various diameters of the U-bolts. As the diameter increased, the torque spec got higher. In my case, I have 1/2" U-bolts (made by a local spring shop) and the torque spec I used was 75 lb ft. I also used a criss cross pattern to keep them pretty even. good luck.

 

Absolutely true. Just like retorqueing the lug nuts on new rims after they are driven a few miles. Boring story but that's where I got my name.

 

I don't like the auto parts store u bolts because they aren't flattened on the ends like stock - so you are driving a small surface area into your axle housing. Seems like you could indent it if you tried hard enough (like running the nuts on with an impact? Yikes.)

 

U-bolt torque values

Here's a link for the recommended torque settings.

http://www.eatonsprings.com/ubolttorques.htm

Also, read the entire post about re-using U-bolts (don't).
Gary