Rear U Bolt - Correct Torque?

[Ol'Blue]

Hey all, what is the proper torque on the rear axle u bolts for the stock 1/2" bolts?

Thanks!

 

[broncnaz]

45-60 ft lbs according to ford. I would also suggest rechecking the torque after the first 100 miles.

 

[Ol'Blue]

45-60 ft lbs according to ford. I would also suggest rechecking the torque after the first 100 miles.

Thanks, exactly what I was doing. PO did the lift and was just checking everything.

 

[baddad457]

If they lifted it, then it no longer has the stock U bolts. 40-60 ft/lbs is nowhere near tight if you ask me, not for 1/2 bolts. Torque would also depend on what thread count it is too.

 

[Ol'Blue]

If they lifted it, then it no longer has the stock U bolts. 40-60 ft/lbs is nowhere near tight if you ask me, not for 1/2 bolts. Torque would also depend on what thread count it is too.

Oh good catch baddad457. I should have been more spacific. I have a WH 3.5" lift but dont know where the u bolts came from. Just checked the thread count and its 1/2" x 20. Thanks,

 

[74strokerbronco]

well by torque charts if there a grade 5 u bolt 85-90# if grade 8 type then 110-120#

 

[broncnaz]

WH includes ubolts with there kits. 1/2" x20 definetly can use a little more than 1/2"x13 as was said grade 5 about 85 ft lbs dry torque.

 

[DirtDonk]

All those recommendations are legit based on some bolt values. But we typically use a little less, more in line with Ford and Rancho specs.
Here's our instructions:
http://cdn.wildhorses4x4.com/downloads/WH/1195 0311-13.pdf

Paul

 

[baddad457]

I've never used a torque wrench on U bolts, I get em as tight as I can pull with a 1/2 breaker bar. Never had any break or come loose.

 

[broncnaz]

I've never used a torque wrench on U bolts, I get em as tight as I can pull with a 1/2 breaker bar. Never had any break or come loose.

While probably not a overly critical torque. The whole point is getting the correct info out there. Over torqued bolts tend to be overstreched and thus weaker than if they were torqued correctly. You may not have had any failures and thats fine.
I dont torque every bolt that has torque specs either but I do know the general torque rating of the fastner and try not to go above it.

Throwing info out there that is not the best can lead to problems for some people. For all we know this guy is 6'8" and strong as a ox. His tight as he can get it could be way tighter than your tight as you can get it.

 

[Ol'Blue]

Thanks all for the input. Although not 6'-8" and strong as an ox, I do tend to overtighten. Based on the size and thread count and the strong possibility that they are WH, I went with 70 lbs.

 

[baddad457]

While probably not a overly critical torque. The whole point is getting the correct info out there. Over torqued bolts tend to be overstreched and thus weaker than if they were torqued correctly. You may not have had any failures and thats fine.
I dont torque every bolt that has torque specs either but I do know the general torque rating of the fastner and try not to go above it.

Throwing info out there that is not the best can lead to problems for some people. For all we know this guy is 6'8" and strong as a ox. His tight as he can get it could be way tighter than your tight as you can get it.

1/2" head bolts are torqued to 105 ft/lbs, I doubt I'm overtorquing the U bolts with a 1/2" breaker bar. With that said, under torquing them can be more dangerous in my opinion, resulting in the axle coming loose at the wrong time. U bolts are made from fairly stretchy material, I've never seen one separate from any reason. Seen plenty of broken springs though in my nearly 40 years of driving professionally

 

[broncnaz]

Ive broken ubolts by overtightening more so on purpose but they do break. Point is overtightening you've already over stressed the bolt. they only strech so far. It can go at anytime. Yes under tightening is almost as bad but your more likely to feel the issue and still be able to tighten the loose bolt. Your over stressed/streched bolt may tighten up more your on the verge of breaking. As its way weaker due to the over torque.
Head bolts are a different story for a lot of reasons. Apples and oranges comparison. Unless you use your 1/2 breaker bar on them to and just guess your torques. Most head bolts are grade 8 or better which will take more torque than your standard grade 5 ubolt which is what most people will have. Off hand I dont know of any ubolts for broncos that are grade 8. Im pretty certain that WH's are grade 5.
Again its all about the correct info for the OP or anyone else that needs the info. If it was a trail fix with no torque wrench availible sure tighten it best you can.

 

[70_Steve]

Here's a chart I found on-line, along with all the associated text.

 

[baddad457]

Ive broken ubolts by overtightening more so on purpose but they do break. Point is overtightening you've already over stressed the bolt. they only strech so far. It can go at anytime. Yes under tightening is almost as bad but your more likely to feel the issue and still be able to tighten the loose bolt. Your over stressed/streched bolt may tighten up more your on the verge of breaking. As its way weaker due to the over torque.
Head bolts are a different story for a lot of reasons. Apples and oranges comparison. Unless you use your 1/2 breaker bar on them to and just guess your torques. Most head bolts are grade 8 or better which will take more torque than your standard grade 5 ubolt which is what most people will have. Off hand I dont know of any ubolts for broncos that are grade 8. Im pretty certain that WH's are grade 5.
Again its all about the correct info for the OP or anyone else that needs the info. If it was a trail fix with no torque wrench availible sure tighten it best you can.

I've seen some of the factory U bolts that were hardened, the universal replacements are the softer variety, I bought a pair at a local spring shop that were bent to spec while I waited, with ones like these, you'll strip the threads long before you'll overstress and break them.

 

[broncnaz]

Yes some application do have grade 8 ubolts from the factory they also tend to be 9/16 in or larger in those cases. They also have torques in the 150 ft lb or higher range.
The whole point is correct info for the OP.
While you may believe that you will strip the threads of lower grade stuff before you overstress them you are mistaken anything over the max torque rating will result in over stress. Once over the max torque rating then its just a matter of how well the fastner was actually made wether it will strip out or break. The only cut and dry correct answer is use the torque tables for fastner size and type you are using or the recommended torques for the parts you are installing. All kinds of things work but that doesnt mean they are right or will work for everyone.