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TR6 TR6 Differential Followup, and inspection questions. How do you know it's good?


Senior Member
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Hey all:

Back with more qs. Dropped the exhaust, removed the differential. Tried rotating the output shafts as well as the input--felt kinda 'notchy', like there were gears in there or something ;)

Pulled the r and l output shafts and bearings--bearings felt good, spun nice, no funny spots.

Put them back in the casing, pulled the back of the casing off and took a peak inside: If you hold the input and one of the outputs, and try to spin the other, there's what seems to be a lot of play in the planet (?) gears--you can wiggle it quite a bit. How much is too much? I mean, there's enough slop that you can 'click' the gears while you wiggle them. This is the 'gear lash' right?

Also, those gears (except the crown and pinion) all seem to have a notch in them about 1/2 way up the tooth: Normal? Looks machined.
(EDIT TO ADD: pix on the internet imply it's normal)

And, FWIW, the oil looked like mud when I drained it--didn't see anything shiny though.

So: Is there an inspection procedure for a differential that I can perform? Or do I just get the rest of the oil out of it and send it off to be rebuilt$$$?

Edit to add: any reason that a local transmission shop *couldn't* rebuild it?
Last edited:


Great Pumpkin - R.I.P
A small amount of play is normal, enough to cause a 'click'. But that "notchy" feeling is cause for concern; it should turn perfectly smoothly as long as you keep going in the same direction. Unfortunately, the bearing most likely to fail is also the hardest to get to. This is what I found in my newly purchased "rebuilt" Stag diff:

So I'd say send it off (if you can't do it yourself).

There's nothing particularly magical about the TR6 diff IMO, but based on a recent experience with having a Buick differential rebuilt; I'd say it's worth the extra hassle and expense to ship it to someone you trust. The first rebuild went sour in less than 1000 miles, and the things my local (trusted) shop found showed clearly that the first shop had no clue (and apparently had a gorilla on staff).


Senior Member
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Pulled the diff, local shop said they'd look at it--supposed to go in tomorrow. Figured I'd take one last look at all the bits and pieces before then. Took checked the drive shaft ujoints for play--again. (The way I normally check for play is to grab either side and twist in opposite directions). Felt tight. Really tight.

Lay down the one end of the drive shaft, noticed that the ujoint didn't move/pivot. At all.

U joint seized. Guess I haven't seen that before.

Cancelled appt for diff rebuild, off to napa for u-joints.

Thanks again, guys.
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