U-Bolts: To re-use or not?

-
BigBlockMopar28

BigBlockMopar28

Well-Known Member
Joined
Jul 11, 2016
Messages
382
Reaction score
85
Location
Corbin, KY
I want to hear some opinions on this. I get the concept of why it (may) not be a good idea to, but at the same time im curious to see what you guys think. Also if thread locker or double nutting it plays any part?

In my particular case, there's a very good chance that the bolts im taking off (swapping springs) have been on since the factory.
 
I say yes. That is IF the nuts come off easily. Usually, they do not. If they are very difficult to remove, it stresses the metal and I will not reuse them at that point.

Of course, if they are as old as you say, I would chunk them anyway. New ones are inexpensive.

Are you really that cheap that you want to risk the damage that can incur if they break?
 
i have , I did , I run them , I will continue to. in fact , I've never seen or heard anyone ever talk bad about it until someone invented the internet. same **** with air shocks and long tube headers. of course if they are stripped or rusted out then yes it can be bad
 
If they were twisting while you were loosening the bolts like mine were at outrageous angles, it's better to get new ones. Almost thought mine were going to snap when I was wrenching on them with a jack handle taped to a ratchet.
 
The factory long nuts are very severe lock nuts. As said before, rust, dirt, and wear from the road elements make it just about impossible to remove them without stressing the U bolt. Buy new correct ones with the flattened arch and the crosshatch from AMK, Not cheap.
 
lemondana said:
Buy new correct ones with the flattened arch and the crosshatch from AMK, Not cheap.
Click to expand...

Thanks, wasn't aware of AMK...perfect!!

I've downloaded their U Bolt catalog and have found what I need....do you happen to know whether the bolts come with nuts? It's not specified.
 
lemondana said:
The factory long nuts are very severe lock nuts. As said before, rust, dirt, and wear from the road elements make it just about impossible to remove them without stressing the U bolt. Buy new correct ones with the flattened arch and the crosshatch from AMK, Not cheap.
Click to expand...


I have worked on a LOT and I mean a LOT of Mopars through the years and not one single one of them ever had the flattened U bolts you speak of. Not ONE. So I will disagree those type are "correct" as you say for old Mopars. Now, they "might" be a good upgrade, that I will go along with. However, totally not necessary.
 
The factory u bolts were designed to distort the threads when it was torqued the first time. That made a positive locking effect. Some will distort better than others, but they are still a one time use bolt by design. Will a used u bolt re-torque and be good a second and third time....its happened. Some of the ones that had to be torched off may have done a better job doing what they were designed to do.

Just for safety, I do not re-use U bolts for street duty. I have several used ones on my cars for the sake of mock up builds or yard cars that only get driven around the yard, however I mark used U-bolts with a splash of chebby orange paint and they get replaced when the car gets approved for regular to heavy street use.

Not saying U bolts were the cause but......why take a chance with bolts when new ones are available and designed to work like the factory ones.

 
"U-bolts are not to be reused" was printed on paper in books like service manuals. That never stopped people from reusing them. There's a torque spec too that is often ignored.
Critical? Dangerous? Who knows? My opinion... We aint talking head bolts.
I'll bet my quarter that the originals are destroyed in removing anyway. Good luck
 
Heat the nuts before removing them. Buy new lock nuts and use loc-tite. Never had an issue. Watched dad do it many many times in the late 70s thru the 80s on a fleet of chrysler taxi cabs - talk about an abuse fleet of vehicles.... they were running early 70s Newports and Furys when he start that side job. Went thru the Volare' and Aspen era and then the Diplomat/Gran Fury used police cars. Never seen a broken U-bolt. We replaced a ****-ton of rear ends in those 18 years.
Admittingly, that was all severe street duty. Depending what you are doing with your build, you may or may not want to replace yours......
 
The old ones were made out of the correct material and correctly heat treated. You don't know what the new ones are made of (Chinesium, perhaps?)

Something to think about.
 
69_340_GTS said:
The old ones were made out of the correct material and correctly heat treated. You don't know what the new ones are made of (Chinesium, perhaps?)

Something to think about.
Click to expand...
I have never had a problem w/ used ones, but I soak them w/ wd 40 or a rust penetrant before removal. I have (slightly) rebent some to go on a slightly larger dana 60 from an 8 3/4 and ran them on a 750 h.p. hemi superstocker w/ no problem used nuts and all. Just take care of them taking them off, and make sure their not bad to start with. Have never experienced any twisting , If I did I`d replace them .
 
Don't forget the proper torque. 45 ft/lb. Drive a few hundred miles and re-check. They might be fatigued if they came off a race car but the torque is low enough there shouldn't be any stretching. Like the guys said, heat and penetrating oil so they come off clean and don't damage the threads.
 
as above...properly torqued to 45 lbs would not distort the metal to a fatique or damaging level.
...now if they are not the original installed pieces,who knows what the last guy did? Just look at
your removed parts and if the threads are messed up or rusted badly, replace them.
Check them after a few miles if you re-use them.
 
U-bolts are torqued on both of their ends, hence the seemingly low torque number.
Combine the numbers and you'll end up at the number where a 1/2" thread should be torqued.
Just like wheel-nuts, except the studs are way shorter and can stand a little more torque.

All my Mopars I've bought over the years have the factory flattened U-bolts that grip the axlehousing.


dcc-4120611_w.jpg
 
heat the nuts some, do not get the u bolts very hot. sometimes the nuts are very tight and the bolts get twisted-throw them in the scrap bin. look at the moparperf bolts - they are flattened and knurled at bend-like stock. and the nuts are long with a locktite type feature. with slicks I found that the torque is better at what Calvert racing suggests-65
 
I have reused them religiously for 30 years, when they are in decent shape...if your brave enough to reuse your lug nuts, then reusing u bolts is no big deal.
 
Got a new set with my hotchkis springs will be using those in my 67.

Got a used set with a 2001 ford explorer rear going in my other car. Oiled up the threads, the nuts came off pretty easily once i got past the initial torque. Truck was in a dry environment its whole life. Everything came apart easily. I will beadblast, prime, paint, and reuse them.

I have reused U bolts on plenty of projects as long as they were not rust pitted, or the nuts had a hard time coming off. Never had any issues.
 
AMK has the correct long lock nuts also. Just spend the money and get one of their big catalogs. A lot of neat bolts and other stuff needed on our cars.
EVERY Mopar that I have worked on in the last 45 years has had the flattened rear end U bolts.. I've seen other makes of cars that don't or didn't use the flattend bolts and the rearend housing would actually be pinched down under the round stock of the U bolt. I think the original Mopar ones are still available also. They used to sell I think 3 different lengths also. I'll look the part numbers up and see if they're available yet
 
Geez, General spring sells U bolts in sets for like $6.95. Rani is dead right about how the threads are designed. I've reused them before......but that doesn't make it right. It makes it dangerous. Be dangerous if you want to. Just remember, the torque on them is only 45 LB FT. So if they have been used, they may not stay tight.
 
hope i don't jinx myself, i re-used a pair on my current 8 3/4,
but i have never even heard of one failing.
 
I run a wire brush around the thread to clean them before I remove the nuts.
Also apply penetrate and anti sneeze.
The nuts come right off.
My mild drivers are not race cars and nothing has failed yet.
That's about all I know.

71K8iTy9yIL._SY463_.jpg
 
I replaced mine for no other reason than it was quicker and easier to cut them off with a cutting wheel.
 
You must log in or register to reply here.
-

Back
Top