Rear End servicing?

patrickt · #1 (**permalink**) 12-23-2021, 03:14 PM

Here is the pertinent part of the service bulletin.

patrickt · #2 (**permalink**) 12-23-2021, 03:24 PM

And less pertinent, but still interesting is Coventry West's discussion of Jag rear fluid changes. Here:
https://www.coventrywest.com/dealing-with-differentials

w-lewis · #3 (**permalink**) 12-23-2021, 04:55 PM

Thanks!

NROTOXIN · #4 (**permalink**) 12-23-2021, 05:14 PM

Quote:

Originally Posted by patrickt

Here is the pertinent part of the service bulletin.

This bulletin is only about draining the Initial (special) oil. Are you suggesting that W-Lewis has this Initial fill oil as noted in the 1963 bulletin?

patrickt · #5 (**permalink**) 12-23-2021, 05:23 PM

Quote:

Originally Posted by NROTOXIN

This bulletin is only about draining the Initial (special) oil. Are you suggesting that W-Lewis has this Initial fill oil as noted in the 1963 bulletin?

In the Jag service docs, they call for initial changes for Powr-Lok diffs, but not for non Powr-Lok diffs, around the five to seven thousand mark. For non Powr-Lok diffs, they call for a change out at the 500 mile mark. GM would also call for the same change out at the 5 to 7.5 mark for LSD rears and then never again. But if you did not have the LSD in it, then you never had to change it at all. If he has a Powr-Lok in there, now's the perfect time to change it out and then probably never change it again in his lifetime. If it's a non-Powr-Lok, then just leave it as is. Or, if he does manage to put 30k miles on it, then change it as per CW's recommendation. But if he's only put 5k in 20 years then I doubt he'll hit that mark. The easiest way for him to check whether he has a PL in there is to just nail the throttle and look at the marks. That's easier than jacking the car up and manually turning a wheel. Make sense?

patrickt · #6 (**permalink**) 12-23-2021, 06:07 PM

Here, I happened to have these handy...

NROTOXIN · #7 (**permalink**) 12-23-2021, 06:33 PM

So your service bulletin was completely out of scope of his situation.....got it. Now, if it is just a GOOD time as any (not mandatory) to change the fluid, that is much more in scope and makes sense.

Signed 2021 not 1963.

patrickt · #8 (**permalink**) 12-23-2021, 06:48 PM

Quote:

Originally Posted by NROTOXIN

So your service bulletin was completely out of scope of his situation.....got it. Now, if it is just a GOOD time as any (not mandatory) to change the fluid, that is much more in scope and makes sense.

Signed 2021 not 1963.

The point of the service bulletin is to highlight that Powr-Lok LSDs have a break-in period of five to seven thousand miles. Back in 1963 that was news to the Jaguar folks. Non-LSDs don't have a break-in period. Most of the guys around here with Jag rears don't know that and don't realize that they should probably change out their rear fluid at the five to seven thousand mark if they have a Powr-Lok. Grubby's post above is a perfect example of simply not knowing that requirement for a one-time change out on LSDs like the Powr-Lok, whether you have an XKE or a Camaro. He's likely surprised to see that GM specifically called for a fluid change out on an LSD at 7,500 miles and then never again. Chances are, you are too. You just won't admit it.