Rear diff issue

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Apr 3, 2026 | 07:32 AM

#16

CBW3

Thread Starter

8th Gear

Joined: Apr 2026

Posts: 8

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Quote:

Originally Posted by Mudsport96

By transmission side I assume you mean the pinion. Which is where I am lost. If the diff is damaged, it should be difficult to turn from anywhere. Do the axles turn when you spin the pinion?

My apologies...I was referring to being able to spin the transmission while in neutral and the drive shaft disconnected.
I have not tried to spin the pinion with the axles disconnected yet...I will do that today just to see what happens.

Apr 3, 2026 | 07:42 AM

#17

CBW3

Thread Starter

8th Gear

Joined: Apr 2026

Posts: 8

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Quote:

Originally Posted by manicmechanic007

Normal operation it sounds like to me
You JUST found out how hard it is to turn a limited slip around by the wheels
Drive line is not much easier
Those 10.25's are tough
Go easy on those wheel bearing hub seals, and if mine, I'd verify there is a slinger kit installed
Those leaked gear oil for years before we added slinger kits to every 10.25 Sterling axle out there
Numerous bulletins and updated seals came out before somebody figured it out that the slinger was the fix

Thank to everyone for the input. This is where I am getting stuck trying to figure out if I actually have an issue or not. My assumption was that something was wrong only because I could not spin the wheels in order to adjust the brakes. I have zero experience with LS.
I was not familiar with a slinger kit, but now that I looked it up, both sides do have them installed.
I think at some point the driver's side seal was leaking and they tried to put a new seal in but did nothing to clean up the sealing surface which is completely rusted over. I plan to clean it up the best I can then look for recommendations on silicon or other to help with any minor imperfections when reinstalling the seal.

Apr 3, 2026 | 10:35 AM

#18

90project5.0

Fleet Mechanic

Joined: Oct 2025

Posts: 1,840

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You should be able to turn it by hand. If you cannot, then something is off. If you have to put all the force you have or a breaker bar almost to get rotation, your truck is going to have to do the same thing. That will affect mpg at the least! My wife can turn mine by hand and she’s a small woman. She grunts at first, but gets it moving. I’ve had to have her help before. That was with axles and driveshaft still attached.

Apr 4, 2026 | 11:09 AM

#19

1Butcher

Cargo Master

Joined: Mar 2007

Posts: 2,848

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I have a 95 F250 with a limited slip. With the differential fully assembled, you are not going to spin one wheel easily. The clutches in the differential prevent that. With enough force, you will break the clutches loose. If you unbolt the axle, then the hub will turn easily. It's just a wheel bearing so it should.

If you don't have limited slip differential, with the differential fully assembly, the wheel should spin freely.

I'm not going to read all the comments again, but don't think you have a problem at all.

Apr 4, 2026 | 11:48 AM

#20

KULTULZ

Cargo Master

Joined: Mar 2002

Posts: 3,132

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From: W (BY GOD) V

Quote:

Originally Posted by 1Butcher

WHAT HE SAID, BUT ...
The clutch adjustment (and service check) is performed by measuring break-away torque.

The clutch pack may have been adjusted incorrectly, no limited slip additive added at assembly or service or possible internal damage.

Try running the shoes fully out to contact drums. Releasing the self-adjuster arm, back-off say three-four clicks and see if the pedal raises and it stops better.

If the shoes are new and were not arc-ground to the drum, it may take a few thousand miles for then to fully seat. The self-adjuster feature will not be able to function correctly during this period. They will have to be readjusted manually again and then the self-adjusting feature will take over if operating correctly.