Is this normal for a rear diff

Dustin Jackson · Jul 14, 2024

Chasing down a shake above 75mph and so I figured I’d take a look at the rear diff. I’ve never inspected it before so I’m not sure if this is normal or not

Thoughts?

Doubeleive · Jul 14, 2024

Dustin Jackson said:
Chasing down a shake above 75mph and so I figured I’d take a look at the rear diff. I’ve never inspected it before so I’m not sure if this is normal or not

Thoughts?

that's not necessarily what you want to check, you want to check the pinion, u-joints, driveline, slip yoke.
if you want a good idea of what condition the differential is in then pull the cover and check the magnet, visually inspect.
normal wear will just have a fine silt like material on the magnet, anything chunky or excessive metal is not a good sign.
you will need diff gear oil and preferably a new gasket if you crack it open, use a bucket to catch the fluid it makes a big mess otherwise and has a smell.

Dustin Jackson · Jul 14, 2024

Doubeleive said:
that's not necessarily what you want to check, you want to check the pinion, u-joints, driveline, slip yoke.
if you want a good idea of what condition the differential is in then pull the cover and check the magnet, visually inspect.
normal wear will just have a fine silt like material on the magnet, anything chunky or excessive metal is not a good sign.
you will need diff gear oil and preferably a new gasket if you crack it open, use a bucket to catch the fluid it makes a big mess otherwise and has a smell.

@Doubeleive I had it jacked up so I could check for loose ujoints and pinion. So everything in the video is to be expected?

Doubeleive · Jul 14, 2024

Dustin Jackson said:
@Doubeleive I had it jacked up so I could check for loose ujoints and pinion. So everything in the video is to be expected?

turning the wheel like that yes there is some normal play between everything, generally if you see a leak around the pinion then that is a potential sign of wear happening the seal can "seep" but it's probably 50/50 on if it is just the seal or there is enough wear that it causes a leak. The best way to check is the magnet inside the cover.
if the u-joints are questionable you can pull the drive line and check them by hand, see if they move by hand easily or are stiff, hard to twist, or feel rough.
checking the driveline it's self takes a balancing machine at a drive line shop

donjetman · Jul 14, 2024

Dustin Jackson said:
@Doubeleive I had it jacked up so I could check for loose ujoints and pinion. So everything in the video is to be expected?

yes, its normal.

A lot of slop in our high mileage ole drive train.

Dustin Jackson · Jul 14, 2024

Thanks gentlemen for the second set of eyes

j91z28d1 · Jul 14, 2024

as for the shake, what kinda shake?

slow frequency or more of a hum

Dustin Jackson · Jul 14, 2024

@j91z28d1 Its hard to describe. Kind of like a bit of a wiggle? I think it’s tires. At 75mph it comes and goes

Charlie207 · Jul 15, 2024

It's almost always tires.

Your drivetrain "slop" looks normal, at least close to mine, which was checked by a mechanic. He put a pry-bar in the rear diff. u-joint to hold it steady, and rotated each rear wheel. Remember, we get like 25-30% drivetrain loss in these 4wd GMT900s.

tom3 · Jul 15, 2024

Might rotate tires from front to back and see if there's a difference.

Is this normal for a rear diff

Dustin Jackson

Full Access Member

Doubeleive

Wes

Dustin Jackson

Full Access Member

Doubeleive

Wes

donjetman

Full Access Member

Dustin Jackson

Full Access Member

j91z28d1

Full Access Member

Dustin Jackson

Full Access Member

Charlie207

Full Access Member

tom3

Full Access Member

Similar threads

Forum statistics

Latest posts