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TR6 TR6 differential leak fix - what to do?

MTribe

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Hey guys,

I just finished rebuilding my TR6 engine and swapping in an HVDA W58 transmission. Believe it or not, the garage floor is now dry beneath the motor! It doesn't leak! The key was using Right Stuff--I actually sealed everything with Hylomar and Permatex first, it leaked, took everything apart and resealed with Right Stuff, no leaks.

Anyhow, now I'm motivated to fix the rear differential leak so I won't need any drip pans beneath the car.

<span style="font-weight: bold">Anyone have any advice about what to do to fix a rear differential leak?</span>

Is it as easy as replacing some seals, or is it prudent to just rebuild the whole thing? If so, how much work is that? Should I just pull the whole thing out and replace the diff mount bushings too while I'm at it?

Any thoughts on how much work the above options are, and what should be done, is appreciated.
 

Andrew Mace

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MTribe said:
Anyhow, now I'm motivated to fix the rear differential leak so I won't need any drip pans beneath the car....
Before you do anything else, make sure the vent is clear. It's nothing more than a cotter pin that is (or should be) free to move up and down in a hole atop the cover (if I'm reading the workshop manual correctly). When the vent plugs up with road grime, pressure inside can force gear oil past even good seals.

That's a five-minute job worth trying before you do anything more drastic. Beyond that, I yield to others for their advice, but I wouldn't rebuild a quiet, "tight" differential simply because of a slight leak! :wink:
 

poolboy

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Can you tell where the leak is coming from ? Next to Andrew's scenario the next best thing that that it could be is a leak at the pinion seal. If it's at the inner axle shafts, that's another story..
Any time you have the differential down, it's a good opportunity to inspect the mounts and I'd go so far as to say to reiforce at least the right front regardless of what you find.
Mounting bushings, yes, I'd take the opportunity to evaluate them if they have any age on them.
If you have the rubber bushings in the rear, be sure that the metal inner sleeve is still bonded to the rubber.
And like Andrew, I wouldn't rebuild a differential just because it leaked.
 

Opa

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I agree with all above,but were it mine i'd have a peek inside,or have it peeked at by a shop.If the diff.is oem to the car, after thirty plus years there is gonna be some wear.
 

KVH

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If it's not the vent or the drive shaft seal leaking, but rather the rear differential cover seal, you'll hear lots of opinions, but after listening to folks on this Forum I used black hi temp Permatex Silicone.

The differential doesn't get that hot anyway, but after using silicone, mine is sealed very tight and clean, with no leaks. The correct torque was important because on my first try I left the bolts too loose (of course, you don't want to overtighten or strip threads either).

I followed the instructions carefully. I believe I let the gasket/cover side dry first overnight, then put the cover on. After torqueing the bolts, I let that sit for a few hours then checked the torque again.

Good luck.
 
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MTribe

MTribe

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Unfortunately I can't tell where it's leaking from... there is oil and grime ALL OVER that area, and thick, too.

Is there a good, easy way to check for wear? E.g., holding the input and one of the outputs, and seeing how much play there is when rotating the other output?

If I were to open it up, what would I look for?
 

TR3driver

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MTribe said:
Is there a good, easy way to check for wear? E.g., holding the input and one of the outputs, and seeing how much play there is when rotating the other output?
That's one indication. Basically checks the thrust washers.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]If I were to open it up, what would I look for? [/QUOTE]Look at the mating surfaces of the gear teeth. They should be shiny with no visible wear or pits. A matte appearance, or any discoloration in the mating area indicates serious trouble.

My vote for most likely source of the leak (given the above) would be the input shaft seal. If it was a stub axle, I think you'd see more oil on that side.

I don't know how practical it is to replace it with the diff still installed in a TR6, but I've done it on a TR3. You'll need to make a lever that you can bolt to the flange to hold it, but that can be just a chunk of flat iron from Home Depot with a couple of holes in it.

The attached photo shows a stub axle, but you get the idea.
 

TR3driver

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Forgot to mention, the diff on my late TR3A had at least 200,000 miles on it while I owned the car, plus who knows how many in it's former life. The thrust washers were pretty loose when I got the car, they are still pretty loose, but it worked just fine. With input and one wheel locked, I can turn the other wheel roughly 1/4 turn ...
 

TR3driver

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Also, rebuilding a diff is a fairly major undertaking.

At least for me, the new bearings were quite a bit different than the old ones, so it took many cycles of [install the bearings, do a trial assembly, remove the bearings, fiddle with the shims] to get the clearances and tooth pattern just right. So IMO a press and suitable bearing separator are absolute essentials.

However, I found the case spreader to not be essential; as some determined prying will move the carrier through the case without it's being spread. Here's a shot of it coming out. Note the strap bolted to the diff housing and held in the vise; very handy for freeing both hands.
 

TR3driver

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Here's a shot of the little bracket I made, to hold the dial indicator for checking carrier bearing clearance. The final assembly has no clearance of course, in fact it's a slight pre-load. But to set the pre-load, you remove all the shims, do a trial assembly and measure the clearance. Then choose a shim pack that is slightly thicker than the measured clearance (I forget how much thicker offhand).
 

poolboy

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I think you should get a degreaser and clean it. Top it up and drive it until you can determine where the leak is coming from.
You're not going to want to handle a greasy differential anyway, if you do end up having to remove it.
 
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MTribe

MTribe

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Randall--belated thanks for the pics and details, much appreciated.

Well it's been months and I haven't had a chance to take a look at it. I'm sure it varies on what needs to be done, but anyone have recent data on what a typical rebuild should run at a shop?
 
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