'90 IRS Removal/Rebuild

So the rear calipers on my '90 XJS decided to start leaking very badly, I’m sad to say, quite a while ago. This being an all original car, I’ve decided to drop the whole IRS to rebuild the calipers, rear shocks, and see what else I can find while I’m in there.

I’ve seen a few videos of dropping the IRS, and it doesn’t look “terribly” difficult other than being under the car, removing brake lines, handbrake, a couple pieces of exhaust, and the rear speedo sensor, plus 8 bolts (from what I can see) holding the IRS to the body.

My Question is this: Those that have done this job, besides rebuilding the calipers and replacing the shocks, what else should I do “while I’m in there”? The car only has 45k on it, was not noisy, but…

Thinking:

  1. Pinion Seal
  2. Output Seals?
  3. Diff Cover Seal

Thoughts? Experience? Thank you!

If the Pinion Seal is not leaking I would leave it alone. You can always do it in situ, it’s very easy.
Mine was not leaking, I changed it anyway only to discover that the new seal was leaking… had to change it again, thankfully it worked. Even bought a Speedy Sleeve, but it was not needed in the end.

Definitely change the Output Seals, plus the output bearings bearings with a new crash sleeve.
I also changed the wheel bearings and seals at the hub and all U-joints.

I did not touch the Diff Cover Seal in mine.
Only if it’s leaking or if you want to have a peak inside the diff.

You should also check the condition of the wishbone bearings and replace the felt seals with lip seals at the outer pivot bearings.

And of course change your brake rotors and pads, unless they are new.

It might look like an extensive list, but you don’t want to have to take that cage out again any time soon.

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How about rubber components such as mounts and bushings?

All rubber bushings in mine were fine so they went back in.
Very easy to assess their condition once the IRS is out.

PS
I didn’t even undo the big (forward) radius arm bushings, they were in perfect shape and are known to cause trouble, but instead left them in place and separated them in the small end (rear).

I agree with Aristides here, this is not a job that warrants wholesale replacement of rubber parts just because. If you find any are in sorry shape, yes, by all means replace, but not willy-nilly.

If you find you need to replace the four subframe mounts in the wheel wells, you might want to read through some of the past discussions. I think they can be summarized as: Buy the genuine parts, not the aftermarket garbage. When those things fail, your entire rear suspension can fall out the bottom of the car.

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