8-3/4 Pinion Nut Torque???

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70DusterBob

70DusterBob

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I had a shop put my diff in. Problem is it makes noise at 30mph. Only around 30mph. But it is loud enough to hear over my engine, which is pretty loud.

I went by another garage to day, he said the pinion nut is supposed to be torqued not impacted on. I saw the first garage impact it on. So I'm fairly certain that's what it is.

1 What is the torque supposed to be on the pinion nut of a 8-3/4 with a crush sleeve?

2 How much trouble, or how involved is it to replace the crush sleeve
 
Then it has shims and not a crush sleeve so you are better off but if it has bad bearings then it still needs pulled. 741 or 742 both have shims.

Pinion nut torque 240 ft-lbs
 
inertia said:
8.75" Rear End Torque Specs

All specs are lbs-ft, unless noted

Bearing Cap Bolts 90
Ring Gear Bolts 55
Pinion Flange Nut:. Min torque
Small Pinion. 120

Tapered Pinion. 170

Large.Pinion. 240

Chrysler Differential Info
Click to expand...

Man you guys are the greatest...

So is it possible to obtain a correct 240 ft lbs of torque with an impact?

I'm guessing that it's loose. Not 240ft lbs. What kind of noise would that make?

Is it safe to drive 10 miles to the new garage?
 
You can far exceed that torque with an impact. But as a general rule, I avoid using impacts with mechanical element bearings, except for disassembling something that is going to have the bearings changed. But the torque is usually high enough to be a concern with how the car is supported and what you foul the pinion flange against when tightening it. It's easier than most realize it is to lever a car off of jack stands.
 
You have got to be sure which diff you got.
If it DOES not have a crush sleeve, and uses shims, it would not be unusual to see a shimmed pinion run in with an impact, then some may do a final torque.
If it DOES have a crush sleeve, that could be started with impact, then final tighten with torque wrench.
The original shop may not have been incorrect dependant on the diff.
You may just have a bad bearing all along
 
inertia said:
You have got to be sure which diff you got.
If it DOES not have a crush sleeve, and uses shims, it would not be unusual to see a shimmed pinion run in with an impact, then some may do a final torque.
If it DOES have a crush sleeve, that could be started with impact, then final tighten with torque wrench.
The original shop may not have been incorrect dependant on the diff.
You may just have a bad bearing all along
Click to expand...

Hey,

It am pretty sure it is the 742.

I don't know if it has a crush sleeve but he said it did. Several times. It is a fresh rebuild. I got 400 ft from home and heard a sound like two swords running against each other without the "ing" if you know what I mean. The schhhhh without the ing.

I took it back, drove it 40 miles back with no noise. He impacted the old yoke off and lightly impacted the 1350 on to measure for the drive shaft, then impacted the new one on.

It makes noise at 30 mph when there's no acceleration or deceleration. As soon as I give it a touch of gas it stops. It made the noise 5 times on the way home.

Please advise.
 
I’m leaning towards a bad bearing, too, but I would check the brakes out on the back. I’ve heard similar noise from a broken anchor pin before.
 
I can't think of anything that makes the noise you describe, except maybe the dust deflector on the yoke, ( the saucer shaped thing behind the u-joint) if out of position can cause a scuffing sound, rubbing on the case, at driveshaft speed.
If I had done the job, I would like to know about, diagnose, and have the opportunity to remedy the issue.
 
Well, here's the deal now. When I removed the drums, the shoes were half cooked, a bit shiny, and half gone. They were brand new when he installed the brakes with the diff. I fixed the Schhhhhh noise by releasing the ER Brake and adjusting the shoes all the way in. I backed up and hit the brakes in reverse about 4 times, until the pedal came back up. The Schhhhh noise was gone. Someone told me the ER brake cable gets tight when you go from 9" to 10" brakes. Which I did go from 9 to 10 inch brakes. Then, without a peep from the rear end or brakes or anything, I took it back to the shop that assembled the diff to get the drive shaft measured so I could buy a new one. The shop owner's friend had put the diff in.

When I got there the shop owner impacted the stock pinion nut off. His buddy put the stock one on because I didn't have the 1350 U-joint shaft to replace the stock drive shaft with a 1350 shaft. So the owner removed it with an impact because we needed to measure for the new 1350 shaft. He then impacted the 1350 pinion yoke on, measured it to be 49", which I doubt it is, then he impacted the 1350 yoke off, and impacted the stock yoke back on. The shop is 40 miles from my house. On the way home, the diff made a different noise, like a grinding, reminded me of when my wheel bearings on my bicycle had come out of the race and was like popping or grinding. It made this noise 5 times on the way home when no or little acceleration or deceleration was present.

I believe he was not supposed to impact the stock or the 1350 yoke on. There are torque specs for it, because you never know what an impact will torque a nut/bolt to.

What's the word?
 
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