A body 8 3/4" u bolt question

[1968 Dart 270]

These are the u bolts and shock plates i got with my factory a body 8 3/4" rear end. I just put them all side by side the other day and noticed one is slightly longer than the others. They have the flattened inner area to prevent crushing the axle tube. Supposedly these were factory original to the car. They fit over the tube fine. Just wanted to be know which one is the actually factory length? Could the factory have put one that was slightly longer on?

 

[RustyRatRod]

Somebody probably just grabbed the wrong length goin down the assembly line or threw a different one in the pile. No big deal. That said, those are "technically" aren't supposed to be used again once they are removed. Either way, don't forget, the nuts only torque to 45 FT LB.

 

[Dana67Dart]

This is the thing that MIGHT bite you in the butt is the distance from the inside of the U to the start of the threads.

My springs are 6 full leaf HD OEM springs for 67 and they measure ABOUT 5" from the inside of the U to the shock plate. If you take your U bolts and put them over your 7 1/4 you will have a good idea if they will work.

As for Nuts, the OEM crushed in nuts are typically a one time use part. The nuts supplied with my repo U bolts from Mancini racing are a long standard nut with a split lock washer.

 

[TrailBeast]

Somebody probably just grabbed the wrong length goin down the assembly line or threw a different one in the pile. No big deal. That said, those are "technically" aren't supposed to be used again once they are removed. Either way, don't forget, the nuts only torque to 45 FT LB.

And supposedly with the weight of the vehicle on the springs.

 

[A56]

That's not really unusual and probably the manufacturer cut and bent one that was a smidge longer. There were two different lengths for 8 3/4 and Dana 60's depending on year and model. Longer ones were on B and E bodies, but that "long" one you have there isn't one of them..

 

[RustyRatRod]

And supposedly with the weight of the vehicle on the springs.

Correctamundo.

 

[toolmanmike]

Are those even the original U bolts. The oem ones were flattened under the radius with a knurl on that area.

 

[1968 Dart 270]

Are those even the original U bolts. The oem ones were flattened under the radius with a knurl on that area. View attachment 1716338309

Yes they are all flattened and knurled. See photos

 

[1968 Dart 270]

Somebody probably just grabbed the wrong length goin down the assembly line or threw a different one in the pile. No big deal. That said, those are "technically" aren't supposed to be used again once they are removed. Either way, don't forget, the nuts only torque to 45 FT LB.

Why are U bolts not supposed to be reused? I've been reading through old threads and others have said they just reused them. I know the crush nuts are one time use,but why would there be a problem using old u bolts?

 

[Dana67Dart]

This is what I used on my 67 Dart 8 3/4 conversion, I have stock 6 leaf read springs and they fit perfect. If I had 5 Leaf they still would have fit, just had more thread exposure below the shock plate

U bolt on left is (nominal) 6-5/8 (A Body)
U bolt on the right is (nominal) 7-1/2 (I and an 8 foot cheater bar removed them from an E Body rear)

Note that the threads all start at about the same distance from the inside of the U

 

[A56]

New ones aren't cheap but for what is required of those U bolts and being 50 years old. I'd replace them.

 

[Big.J.007]

Used U-bolts would not be my 1st second or third choice to reuse..

 

[Dana67Dart]

I know the crush nuts are one time use,but why would there be a problem using old u bolts?

(I and an 8 foot cheater bar removed them from an E Body rear)

There ^^^ is your answer. I most likely twisted the bolts and I know I heated them up just by turning the nuts! I had sprayed them in the weeks leading up to removal. Buying used you don't know what was done to them.

ALL THAT BEING SAID...

Wire wheel the threads, look for obvious damage, check the log one that the nuts will be able to torque without bottoming on the bolt shank and you will be (MOST LIKELY) fine. I was going to use used U bolts AND nuts till a friend talked me out of it. Infract I had the bolts in the photo in post 10 on the left installed and drove on them for a week while the replacements came in. Sometimes ignorance is bliss and I MOST LIKELY would have been just fine.

 

[RustyRatRod]

Why are U bolts not supposed to be reused? I've been reading through old threads and others have said they just reused them. I know the crush nuts are one time use,but why would there be a problem using old u bolts?

Because they stretch and get weak and can break. Also, the threads themselves are cut differently as to lock in place a lot of times. A big percentage of the time they will lock down and break when you try to remove the nuts. Reuse them all you want. They are cheap. Not something I will reuse.

 

[RustyRatRod]

New ones aren't cheap but for what is required of those U bolts and being 50 years old. I'd replace them.

If they aren't cheap, you're buying them from the wrong place.

 

[RustyRatRod]

This is what I used on my 67 Dart 8 3/4 conversion, I have stock 6 leaf read springs and they fit perfect. If I had 5 Leaf they still would have fit, just had more thread exposure below the shock plate

View attachment 1716338322

U bolt on left is (nominal) 6-5/8 (A Body)
U bolt on the right is (nominal) 7-1/2 (I and an 8 foot cheater bar removed them from an E Body rear)

Note that the threads all start at about the same distance from the inside of the U

View attachment 1716338323

Crap, if you pay that for U bolts, will you adopt me?

 

[A56]

If they aren't cheap, you're buying them from the wrong place.

What do you interpret as cheap? $50. ?

 

[RustyRatRod]

What do you interpret as cheap? $50. ?

General Spring has them for 10 bucks each.

 

[1968 Dart 270]

If they aren't cheap, you're buying them from the wrong place.

Where are you buying them from?

 

[RustyRatRod]

Where are you buying them from?

See above. Cool avatar.

 

[Dana67Dart]

Crap, if you pay that for U bolts, will you adopt me?

Are you wealthy?

 

[RustyRatRod]

Are you wealthy?

What's that?

 

[RustyRatRod]

Are these the 7260 u joints? Should be. Photo of factory dart 8 3/4" driveshaft.

View attachment 1716338340

If the ID of that yoke is 2.125" then yes.

 

[A56]

If they aren't cheap, you're buying them from the wrong place.

Well they have them but they are not the OE style in post #7.

 

[RustyRatRod]

Well they have them but they are not the OE style in post #7.

I knew that was coming. Who cares? How is the rear end gonna go anywhere? As long as somebody ain't STUPID and doesn't over torque the nuts, there's no way in hades to crush the rear end housing at 45 foot pounds. Ain't happenin. I don't know why people make such a big deal about the flats on the u bolts. I've seen factory cars without them. They used both. If it was so danged important, that's the only style anybody wouldda ever made.