Decided to change the differential lube in our 87 XJS, Dana unit, no drain plug. Got the lower plate off, got the cover loose but it does not appear you can remove the cover without removing one of the inner lower control arm brackets. Am I missing something or does the suspension have to come apart?

 

Couldnt you use suction from fill plug?

 

Possibly but the fill plug isn't very accessible. I also wanted to get the cover off so I could clean out the chips when i drill the bottom of the casting for a drain plug.

 

I think there are covers you can buy that have a drain. Check Summit. Better option than drilling it.

 

FYI the bottom of the DANA diff is not very thick. I think it would be hard to tap a reliable leak free hole. When I rebuilt my DANA, that is the reason I did not make a drain plug for it.

 

I agree it's not very thick but I was only going to drill and tap it 1/8 NPT. It's only a 9mm hole so it won't drain very fast but it will drain. Definitely not thick enough for a 1/2 npt plug.

 

Well I drilled the bottom of the diff for a drain plug, plenty thick for a 1/8 NPT plug. The old oil was pretty gross, probably been in there since new, 140,000 km.
I had to remove the inner control arm pivot from the diff to get the cover out. One bolt was tight with a shim pack, the other one was loose but retained by the safety wire and no shims. Does anyone know if they are originally shimmed equally from the factory? I was considering putting the original thickness shim pack in both places.

 

The shims are unique for each rear end, they control the rear toe. So they will be placed on an "as needed" basis.

 

Thanks, I'll put it back as it was.

 

I hesitate to disagree with a member as knowledgeable as Jagboi, but my belief is that the shims are there to enable the fulcrum pin, on assembly, to be slid through the eyes of the cage and the eyes of the diff 'dog bone' castings with no binding.
ie: The ease of inserting the pin is what the shims are for, and it is a case of just adding to each end of the casting, between the casting and the diff, whatever thickness of shims is required to allow the pin to be inserted easily. The cage position of the pin eyes are what (unadjustably) sets the lower wishbone angluar position fore and aft.
You are lucky that one end is still tight with shims, so my suggestion would be to tighten up the bolt with the shims there, and then measure with a feeler guage the gap under the other end of the casting, and add shims to that so the gap is just filled. Then tighten up.
I strongly recommend using high sttrength Loctite on the bolts; they do work loose.

 

Here ya go, PITA but 100% required in MY opinion.

 

Grant, good article and it makes a lot of sense. It's going to be tricky with most of the suspension still attached but I'll try and report the results.

 

Just to be sure, we are talking about the shims C28428? That go between the inner fulcrum bracket C21977 and the differential?

I had a reread of the manual, and Greg is correct, they are to allow the centre to centre spacing of the inner fulcrum brackets to match that of the cage when bolted to the diff. I know a guy in England who is into racing and he also uses those shims to control toe, with suitable modifications to the cage.

 

Those are the shims. I got it back together after measuring the gap front and rear, ended up with .020" front and .018" rear. I made the shims with a hole in the middle, no slot so they can't come out in the future. I think that backs up the fact the original shims fell out of the rear location, thus the loose bolt. the bolts are installed with a generous dose of red loctite