Check your U-bolts!!

[K85 Octane]

I had ORD cut some ZeroRates with a 5 degree edge. So they ARE my shims and all bolted together. The rear ZeroRates are straight across.

Yes, a couple of big C clamps is good. You'll need the clamps when assembling also. Re-use an old bolt to align the center holes, then put the new ones in. This way you're not pounding on new pins.

 

[1-ton]

I have done a few lifts, and I re-tighten new U-Bolts about 4-times after an install. After installing, and torquing down new set of U-Bolts...

1. I literally roll the truck a few feet in the drive way, and re-tighten them.

2. I drive the truck around the block, and re-tighten them again.

3. I then drive the truck approximately 10-Miles, and re-tighten them again.

4. I then drive the truck for 100-Miles, and then re-tighten them again.

this usually does it for the rest of the U-Bolts life, unless you wheel real hard.

 

[mrk5]

Ouch, I use a torque wrench and set them to appropriate torque in a cross pattern. Then I re-torque them after ever run until they stop moving (usually takes 3 or 4 runs until they stop stretching).

This has been exactly my experience as well.

I've used 150 ft-lbs for a setting. I think that number came from a lift kit install.

We had the cross pattern torque sequence drilled into our heads in the navy so I pretty much do that with everything now.

 

[evolve991]

Checked mine a few days ago. Sure enough they had loosened up. Since then I drove over 100 miles a day for 3 days so I'll be back under there tomorrow just to be sure.

 

[Mastiff]

Well, I got the passenger side mostly done. Turns out the leaves were all shifted like crazy, so the center pin holes were nowhere near lining up, like 6" off in some cases. I tried tapping them into place, but ended up removing the clamp bolts and completely unloading the pack to get everything lined up again.

The most painful part of this job is getting the axle out of the way far enough to allow the center pin to go up through. The ORD springs arch so much, and the pack is so thick, the only way I can find to do it is to drop the axle until it is limited by the parking brake (shocks already disconnected), then bottle jack on the spring itself to push it up. That or fully remove the axle on both sides and roll it out. I dread that because disconnecting the parking brake is a major job on a 14bff.

One more side to go. Then I need to decide if my driveshaft is reusable, in particular the section that mates into the 208, which was flopping around and dragging.

 

[Mastiff]

One of the center pins was still partially in place.

 

[Blue85]

The most painful part of this job is getting the axle out of the way far enough to allow the center pin to go up through. The ORD springs arch so much, and the pack is so thick, the only way I can find to do it is to drop the axle until it is limited by the parking brake (shocks already disconnected), then bottle jack on the spring itself to push it up. That or fully remove the axle on both sides and roll it out. I dread that because disconnecting the parking brake is a major job on a 14bff.

Normally to get the bolt through I'll put two jacks on the leaf spring, one in front and one behind the axle. Then between dropping the axle and raising the spring you can get enough clearance. Of course the holes have to be lined of first, but you can put a bolt or something through from the top first before compressing the spring and then push it out from the bottom later.

When the pack is bolted together I use ratchet straps to pull the axle around and line up the bolt head with the perch hole.

 

[scottystills]

One more side to go. Then I need to decide if my driveshaft is reusable, in particular the section that mates into the 208, which was flopping around and dragging.

Is it damaged or just loose? CV right?

As long as the flange is ok at the H is in tact, just replace the ujoints.

 

[sheepdog_tx]

So is it the ubolts themselves or how they were tightened? I'm about to do new springs, concerned now this happening to me.

 

[Mastiff]

So is it the ubolts themselves or how they were tightened? I'm about to do new springs, concerned now this happening to me.

I'm pretty sure they loosened up. The U-bolts themselves didn't fail. I torqued them to 150 two times, but I guess you need to keep checking them like crazy for a while, until they stop taking more turns. I honestly don't know what I really did wrong, but I probably only had 25 miles on them before hitting the bumpy washboard that caused the problem.

 

[Mastiff]

I have done a few lifts, and I re-tighten new U-Bolts about 4-times after an install. After installing, and torquing down new set of U-Bolts...

1. I literally roll the truck a few feet in the drive way, and re-tighten them.

2. I drive the truck around the block, and re-tighten them again.

3. I then drive the truck approximately 10-Miles, and re-tighten them again.

4. I then drive the truck for 100-Miles, and then re-tighten them again.

this usually does it for the rest of the U-Bolts life, unless you wheel real hard.

I'm being super diligent about this. They have not stopped moving yet. First I went in a circle around the cul-del-sac and retightened. Then around the block. Then a short drive. Now a longer drive. Every time I've gotten at least a quarter turn from one bolt or another on all four corners. The fronts are the originals that were on when I had "the incident", so they've been shaken quite a bit. I'm using 150 ft-lbs.

It really makes me wonder about lift kit installs done at shops. People just take off and go, and I don't think they all end up with their axles falling off. Is it more paractical to just blast them with an impact until they stop? Those half inch U-bolts are probably indestructible, and I doubt you could crush a 14-bolt axle tube.

 

[diesel4me]

The usual torque for a 9/16" u-bolt is in the neighborhood of 125 ft/lbs..
Once they are seated and stretched after a few miles ,and re-torqued ,they shouldn't loosen up again...going ballistic on them with an impact or cheater bar will only buckle the spring plates ,the stock ones aren't even 1/4" thick..

Cheap U-bolts that come with some lift kits are rather stretchy and I've seen a few snap off too,like they were not properly hardened,they were either soft or too brittle..

 

[campfire]

I'm being super diligent about this. They have not stopped moving yet. First I went in a circle around the cul-del-sac and retightened. Then around the block. Then a short drive. Now a longer drive. Every time I've gotten at least a quarter turn from one bolt or another on all four corners. The fronts are the originals that were on when I had "the incident", so they've been shaken quite a bit. I'm using 150 ft-lbs.

It really makes me wonder about lift kit installs done at shops. People just take off and go, and I don't think they all end up with their axles falling off. Is it more paractical to just blast them with an impact until they stop? Those half inch U-bolts are probably indestructible, and I doubt you could crush a 14-bolt axle tube.

What U-bolts are you using?

 

[Mastiff]

What U-bolts are you using?

DIY4x ones, new. Well, the fronts are ORD, the rear are DIY4x.

 

[Stomis]

Its funny this came back up. I was driving the work truck the other day and started hearing an odd rattle. Got the the shop and found my driver side ubolt loose by 1/4in of play! I put them on there tight as I could crank buy hands with an 18in wrench but it just goes to show when you put them on, you need to go to drive to the store and buy a cup of coffee or what ever excuse to go drive for 10 miles and come back and torque them again.

I dont think they'll ever break unless the nut locks up from rust. Theres just way to much bolt to stretch, especially with the U at the bottom.

 

[Blue85]

Is it more paractical to just blast them with an impact until they stop? Those half inch U-bolts are probably indestructible, and I doubt you could crush a 14-bolt axle tube.

You could probably use the thread pitch and some math to figure out how many lbs of tension is in the bolt at 150lb-ft on the nut (if you have a good guestimate for friction). My guess is that the threads would strip before you could deform the 1/4" wall axle tube. The front cast spring plates are probably even stronger.

Some people say that U-bolts have to be re-tightened because they stretch and threads deform, but I don't think it's true. This same phenomenon would apply to all fasteners, maybe just based on their length. After tightening them a few times, you can take them off and the nut spins fine along all of the thread (i.e. thread is not deformed). I think its all due to the U-shape. It's shaped in such a way to fit easily over the tube, but as you tighten it, the shape deforms a little. So the distance from where the bolt touches the bottom of the axle tube to where the nut is decreases slightly, loosening the fastener. When you put the new U-bolt on, it fits fine in the spring plate, but when you take it off, the "U" shape is wider and the outside of the threads hangs up in the plate.

I bet the amount of tightening needed depends partially on how springy the bolt is, especially if you use an impact wrench. The bolt will bounce back in torsion eating up some of your lb-ft. So the longer the bolt the worse this will be, but all else being equal a longer bolt also tends to clamp better with the same load through it.

 

[campfire]

You could probably use the thread pitch and some math to figure out how many lbs of tension is in the bolt at 150lb-ft on the nut (if you have a good guestimate for friction). My guess is that the threads would strip before you could deform the 1/4" wall axle tube. The front cast spring plates are probably even stronger.

Some people say that U-bolts have to be re-tightened because they stretch and threads deform, but I don't think it's true. This same phenomenon would apply to all fasteners, maybe just based on their length. After tightening them a few times, you can take them off and the nut spins fine along all of the thread (i.e. thread is not deformed). I think its all due to the U-shape. It's shaped in such a way to fit easily over the tube, but as you tighten it, the shape deforms a little. So the distance from where the bolt touches the bottom of the axle tube to where the nut is decreases slightly, loosening the fastener. When you put the new U-bolt on, it fits fine in the spring plate, but when you take it off, the "U" shape is wider and the outside of the threads hangs up in the plate.

I bet the amount of tightening needed depends partially on how springy the bolt is, especially if you use an impact wrench. The bolt will bounce back in torsion eating up some of your lb-ft. So the longer the bolt the worse this will be, but all else being equal a longer bolt also tends to clamp better with the same load through it.

Aren't U-bolts often torque-to-yield fasteners (like most cheap head bolts)? TTY bolts would indeed be stretching out during loading.

 

[kennyw]

Aren't U-bolts often torque-to-yield fasteners (like most cheap head bolts)? TTY bolts would indeed be stretching out during loading.

I don't think so. I talked myself out of that theory earlier in this thread.

 

[campfire]

Aren't U-bolts often torque-to-yield fasteners (like most cheap head bolts)? TTY bolts would indeed be stretching out during loading.

I don't think so. I talked myself out of that theory earlier in this thread.

Oops. I had completely forgotten about that piece of the conversation. And I was even part of it.

 

[rdn2blazer]

This happened to a buddy in his company supplied work truck driving down the freeway at 70mph . Didn't crash thank god. Truck was just two months old. Loose from the factory.