Front Spring U-bolts Loose

[Tow4]

I pressure washed the Deuce today and afterwards did an inspection front to back. I look at everything from suspension to drive train, brakes, oil drain plugs , etc

When I was checking the front axle springs and u-bolts I noticed the lock washers on the spring u-bolts did not look fully compressed. I'd looked at them before and thought they were OK. Today I put a wrench on the nuts and was able to turn them. That's not good I'm thinking. Granted, it's a big end wrench for a 1-1/16" nut, but still...

My previous experience with spring u-bolts is you put a 3 or 4 foot pipe on your breaker bar and tighten that puppy down. Then go back after driving the truck a few days and do it again. There's no way I should be able to move it with an end wrench. Anyway, I go and check the TM and I find the torque spec is 170 to 180 FT-LBS. I'm kind of surprised it's that low, so I go put the pipe away and get out the torque wrench and tighten them all up.

All 4 u-bolts on the front axle took about one revolution of each nut to tighten. I have never seen spring u-bolts come loose before so I guess at some point the front axle or springs were changed and not properly torqued.

 

[DieselBob]

My previous experience with spring u-bolts is you put a 3 or 4 foot pipe on your breaker bar and tighten that puppy down. Then go back after driving the truck a few days and do it again. There's no way I should be able to move it with an end wrench. Anyway, I go and check the TM and I find the torque spec is 170 to 180 FT-LBS.

That's the way we always did them also. Kind of a surprise that the torque is that low.

 

[Flyingvan911]

I'm glad you found it before it caused an accident. A great example of doing a thorough check of your vehicle to find ptential problems before they become a wreck.

 

[spicergear]

You may wanna find out how much torque you're 4' pipe wrench dealie can actually apply. I was in a class that dealt with metal fatigue and there was quite a windfall doled out to a person who had a truck tire come through their car and do some real damage because the lugs were over-torqued to the point they yielded and broke while at speed. The trucking company hired the instructor of the class (because of his accreditations in metalurgy and inspection) and found it was the mechanic at the tire shop so the blame fell onto that place instead of the trucking company.

Torque and re-torque. Don't get jammed up because of a tradition.

 

[joshs1ofakindxj]

No joke! I found the same thing on my truck last weekend when changing the differential and transmission fluid. Mine was only the driver side 2 u-bolts though. They needed a complete revolution or more to tighten up but the passenger side was tight.

Is anyone else tempted to cut off that excess, low hanging u-bolt material? That just looks ready to catch something off road. I'm going to buzz those off with a cut off wheel this weekend before I go out in the woods.

 

[Tow4]

You may wanna find out how much torque you're 4' pipe wrench dealie can actually apply.

I did. It's pounds of force x length of arm. If you put 75 lbs of force on a 4 foot lever you get 300 FT-LBS. I figured 300 FT-LBS was minimum. The old timer at the spring shop I got the u-bolts from said to use a 4 foot pipe and not to worry about breaking them. That was a long time ago, so I don't remember the size of the bolts.

It is much better to use a torque wrench and torque specs; but, you can get pretty close calculating the arm and force.

 

[joshs1ofakindxj]

Well just how do you figure how much force you're putting on the end of that pipe?

 

[porkysplace]

I would scrap the lock washers and replace with locknuts .

 

[spicergear]

I did. It's pounds of force x length of arm. If you put 75 lbs of force on a 4 foot lever you get 300 FT-LBS. I figured 300 FT-LBS was minimum. The old timer at the spring shop I got the u-bolts from said to use a 4 foot pipe and not to worry about breaking them. That was a long time ago, so I don't remember the size of the bolts.

It is much better to use a torque wrench and torque specs; but, you can get pretty close calculating the arm and force.

I get that but you still need to know how much force YOU'RE pulling with and you also just stated that you're 130lbs over-torqued.

I'm not trying to stir anything just make people aware that there is liability EVERYWHERE.

 

[Tow4]

I would scrap the lock washers and replace with locknuts .

I don't know if I've ever seen lock nuts for spring u-bolts. Spring u-bolt nuts are longer for a larger thread contact area.

I get that but you still need to know how much force YOU'RE pulling with and you also just stated that you're 130lbs over-torqued.

I didn't over-torque them. I used a torque wrench. Please reread the first post; last sentence in 2nd to last paragraph. My example in post #6 was just that, an example from the past.

Well just how do you figure how much force you're putting on the end of that pipe?

I use this.

 

[Floridianson]

The only thing I ever put a torque wrench on is rods, mains and intake manifold. I always get new U bolts and new nuts for the truck I am working on and use a 14" box end wrench and pull will all I got. You are correct about the nut being larger.

 

[ICAT]

Replace the lock washers. They are wore out

 

[spicergear]

Missed a couple words in that sentence, sorry Tow4-

 

[Tow4]

No problem spicergear, it's easy to miss things.

I'll keep an eye on them ICAT; if they loosen up again, I'll replace them.

I hear you James, my rule is if the spring pack comes out (usually with broken leaves), it gets new u-bolts going back in.