U-Bolts - Reuse or replace?

[sam dupont]

Chrysler recommends only 45 pounds. Wouldn't torque to yield be far greater than that? Does I/H use the same type of nut?

90 lbs on 1/2" bolts. They use a Crown type lock nut, but they don't have dimples. The Service manual recommends retorquing a number of times. Apparently, there's a engineered spring effect. I only recently learned of the term torque to yield while I was messing with some U-bolts. I knew there were "one use" head and mains bolts, but didn't know the proper term.

 

[LowBikeMike]

Ive got a new set or two for 69 8 3/4. If anyone wants them they can have them for the price of shipping.

 

[eldubb440]

Ive got a new set or two for 69 8 3/4. If anyone wants them they can have them for the price of shipping.

I'll take a set....... I cut all mine

 

[YY1]

The threads are exposed to all the nastyness the rest of the underbody is exposed to.....but are bare metal with cut threads. Do the math.

I generally use a nut splitter, rather than try to back the nuts over those threads.
Once removed, I clean and inspect them and run a new, non-lock nut up them.
If they pass those tests, I reuse them.
I don't remember ever using lock nuts to put them back together, either.
Never had one come off.
I have used lock washers, but rarely.

 

[RemCharger]

The threads are exposed to all the nastyness the rest of the underbody is exposed to.....but are bare metal with cut threads. Do the math.

 

[YY1]

Interesting.
Never noticed.
Still have done several and never had one come off, or even loosen up.

 

[Photon440]

90 lbs on 1/2" bolts. They use a Crown type lock nut, but they don't have dimples. The Service manual recommends retorquing a number of times. Apparently, there's a engineered spring effect. I only recently learned of the term torque to yield while I was messing with some U-bolts. I knew there were "one use" head and mains bolts, but didn't know the proper term.

Were the IH bolts fine or coarse?

 

[RemCharger]

Interesting.
Never noticed.
Still have done several and never had one come off, or even loosen up.

I've always reused when possible. The problem up here was they get gravel beat and rounded off.
I'd prefer the flattened and knurled factory ones all day long. The round ones don't inspire me due to lack of grip. They probably instigate bending the tube as well.

 

[sam dupont]

Were the IH bolts fine or coarse?

1/2x24 threads on dana 44 axles

 

[QuickBpBp]

When I swapped my 8 3/4 from a 68 GTX to my '64 Dodge to get rid of the tapered spline set-up. I used the same U bolts off of the GTX. Decades of racing and street driven miles those U-Bolts still remain tight with the original nuts from Ma mopar... If they look good use them. I am sure there are plenty of other areas that money could be spent like in the gas tank driving it around when finished.

 

[Photon440]

1/2x24 threads on dana 44 axles

I can't say I'm even familiar with a 1/2 X 24 thread. It's not in the listing of Unified Thread Standards.

 

[BSB67]

View attachment 1983275

Internet info is so terrible.

They may, or may not be rolled. They may be grade 8, or grade 5.
Of course, a rolled thread is the best possible, and can be reused without issue not withstanding other damage.

A grade 5 cut thread is rated to 85-90 ft-lbs. Factory torque spec for the u-bolt is 45 ft.lbs. No where near yield.

Nobody for the factory was retorqueing them. No one for the service garage is re-torqueing them.

Check the threads and make you decision.

 

[BSB67]

I can't say I'm even familiar with a 1/2 X 24 thread. It's not in the listing of Unified Thread Standards.

more mis-information

 

[sam dupont]

1/2"-24 Hex Nut (plated)

 

[sam dupont]

more mis-information

you shouldn't brag about it

 

[RemCharger]

Internet info is so terrible.

They may, or may not be rolled. They may be grade 8, or grade 5.
Of course, a rolled thread is the best possible, and can be reused without issue not withstanding other damage.

A grade 5 cut thread is rated to 85-90 ft-lbs. Factory spec is 45 ft.lbs. Nobody for the factory was retorqueing them. No one for the service is re-torqueing them.

Check the threads and make you decision.

All I did was post the information straight from Eaton spring. ( that someone had brought up earlier.) I agree it does not necessarily apply to other manufacturers. I also agree that standard machining and metallurgy principles do apply.
Reinstalling U-Bolts - EATON Detroit Spring Reinstalling U-Bolts - EATON Detroit Spring