If a limited-slip differential is successfully accomplishing the tasks set before it, that is to say it applies power to both wheels while under acceleration, yet still allows those wheels to turn at slightly different speeds from each other while turning a corner... then is there anything else to know or test, before I simply pronounce that it's in good condition?

For example, I realize with other friction surfaces, like brake linings or clutch disks, that a certain amount of wear takes place within the functional lifespan. A road test is not sufficient to verify, since brakes with 20% pad thickness remaining will usually work just as effectively as brakes with 90% remaining. But to determine remaining life expectancy, a visual examination of the lining thickness will tell me in a few moments, as long as I have the experience to know what to look for.

But for differentials, I don't have years of experience knowing what the insides are supposed to look like, so I'm looking for any other clues I can get my hands on. I know there are some sort of clutch packs in a limited-slip differential that do wear out. Diagrams show them pressed together with springs or shims, but since there doesn't seem to be any adjuster mechanism, I assume the clamping force gets diminished over time as the (linings?) wear down. And, just like with a clutch, eventually there would not be sufficient clamping pressure to transmit power.

If I'm right, and this clamping force is in fact diminishing, is there a way to measure it with a torque wrench on one of the axles, or something like that? I have not come across any such techniques in any manuals anywhere. Does that mean a visual inspection, perhaps with a micrometer, is the only reliable method?

Thanks!

- Erik

PS. The car has 228k mostly gentle miles on it, lots of them highway. On rare occasions when I chirp the tires in first gear, both sides leave little black patches on the road. Going around corners is done without noise or chattering, unless on loose pavement in which case I can hear the inside tire scrabbling for traction. To me, even though I'm about to go exploring for new pinion bearings and seals, the differential itself is working fine and I ought to leave well enough alone...

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Lots of early Valiants and Barracudas have crossed my path.
Also a handful of other toys for variety now and then.

burn rubber on pavement, if you get two perfectly even stripes, then the SG is in good shape

Justin

I jack up one rear wheel and see how hard it is to turn. With a good sure grip, you can barely turn the wheel that's off the ground. This will not tell how much life is left in it, only a visual check of the clutches can do that. With the cone style (non clutch) unit, this may not be possible.
At least new sure grips, or equvilent, are available for the 8 1/4 and 8 3/4 rears, finding one for a 7 1/4 is harder than hitting the Lotto.

Cecil

in my dakota with a 8 1/4 SG i can break the lugs loose with one wheel off the ground.
Frank

the clutch pack type can be spec'd out by measuring pack thickness and preloaded spring pressure. the clutch pack plates should be within thicknes and warpage limits of manufacturer. the spring pressure is measured like valve springs, ie. at loaded height measure the force in pounds. the place to get these specifications? maybe one of the rear end builders offering reman units of the type you have. cone models just have the spring measure to deal with, again info from a reputable reman shop.
JUST BURN'EM DUDE

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D-100 sl6 all mopar when they still sold the good stuff!!

FWIW - Mine is 6 years old, and has been put through a lot of abuse. I can now just barely turn one wheel by hand with the other on the ground.
I also can remove the lugnuts with one wheel off the ground.

-S/6

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The "Silver Bullet"
87 Ram D150