My winter pet project will likely be to remove the rear subframe to fit Powerflex bushings, change the diff oil, replace the upper shock mounts with Baxtor's rear mounts, and replace the lower shock bushings.
I expect to keep the lowered springs and CATS shocks (only at 59,000 miles right now). I don't have a leak from the pinion seal, should I replace it anyway?

Looking at what others have done, I'm puzzled as to why people apparently release the struts at the upper ends and leave them attached to the control arms before lowering the assembly. Wouldn't it make sense to leave them attached to the car body instead to reduce the assembly weight, and remove them separately after the frame is out of the way? Or is there a concern that the mounting studs can't handle the bending moment when the lower strut ends are left unsupported?

 

If you are talking about the rears, the top of the stud is controlled by the same type of foam the front has, so most likely most of it will be dissolved to dust.
Be sure and pry the wire loom retainer on each side of the frame out of it's hole so as not to crush them when things go back.

 

As I recall (it was a while ago), leaving everything attached to the subframe just makes it quicker and easier, and disassembly is trivial once the subframe is out. The assembly is fairly heavy with the diff/half shafts/subframe, so you need to lower it on a jack anyway. Lowering it on a trolley jack is fine as long as it is balanced and your are not under it, but for installation I find it easier to line it up using a transmission jack with 360 degree castors, since it can roll in any direction (I use the harbor freight 450 lb low lift one), although I've also done it with a trolley jack. Exhaust hanger mounts are a pain, but everything else is simple (calipers, top mounts, top and bottom subframe mounts, prop shaft - mark the orientation for balance just in case, and whatever else I forgot....). Just raise or lower it bit by bit to check nothing is hanging up, and don't forget to disconnect the cats shocks once they are accessible as the subframe is lowered. Lube all the powerflex bushings well with the supplied stuff to avoid annoying squeaking. If you disassemble the spring assembly, try to get the top mount bolts aligned as accurately as possible before raising up the subframe to refit.

 

I found it very helpful to fashion a wooden trolley the width of the axle to support the wheel hubs and centre section, with different sized blocks to accommodate the various heights of the components when in the vehicle and then lower / lift the entire trolley with a trolley jack. Then with the entire axle on a trolley it can be easily moved out from under the car. This also helps with unbalance etc when lifting back in.

I also recommend you check the flex coupling on the driveshaft at the gearbox end while you are there. I am just about to replace my second perished coupling at 110,000 miles.

 

Thanks guys!
I have the car on jack stands now and crawled around a bit last night to scope it out a bit. The Projects in the Barn videos are a very helpful reference, as are of course the multiple threads here on the forum, as always.

My Adamesh stage 2 exhaust upgrade gives the car a lovely sound and a nice performance boost, but it is not making removal of the exhaust mounts any easier due to its larger cross section compared to the OEM over axle exhaust. I was able to get a ratchet wrench on the bolt heads on the passenger side with enough room to loosen them a bit, but the driver's side will be a major challenge. I could just barely get a 10mm nut driver on the heads, but had nothing that will fit to turn the driver with in that position. Ordered small 1/4 ratchet wrench, which I think will do the trick. If not, an articulated box wrench will be the next attempt.

 

Welcome to the tool-buyer's club. When I was a working mechanic, we often would make modified wrenches from ordinary box or combination wrenches using an acetylene torch and a bandsaw.

 

Took a while, but managed to get all four exhaust bracket bolts out. This configuration was my silver bullet:


I bet putting them back in will be interesting also, once I get to that point. Pre-locating them in the holes with electric tape may be the way to go?

 

The biggest help is a dolly to get the rear end out, move it around and get it back in place. I just made one out of 2x4's with some casters. I left everything attached and lowered it all in one piece.
I also had all of the pieces I could sand blasted and powder coated, to match the car. That was 11 years ago, and it still washed up like new.

 

Wow, that is a nice-looking finish!
And the dolly you made is a great idea too. I'm planning to use a motorcycle jack to lower the frame, and it may be wide enough that I can use it for maneuvering around too. If not, I may steal your idea.
Thanks!

 

LMG:
Please let us know how it goes for you and your process. Photos as you go are always welcome too!
IMO; all of us who are or become “long-term-owners” will likely be faced with this eventuality.

Cheers!
Brian W.

 

Ok, I think I just realized why it's preferred to not leave the struts attached at the top and then remove them separately. The spring is just compressed against a seat in the control arm, it's not a self-contained unit like it is in the front. Without the spring stabilizing the shock by applying force to a spring seat directly on it, the shock is only held in place (at an angle) by the nut on the shock center stud. That's not much resistance to the applied torque from gravity at all. Best to bring it down with the rest of the frame assembly then.

The motorcycle jack was just delivered, will grab a few pictures once it's assembled and in position under the frame.

 

My setup is shown below.
The car ended up sitting a touch higher on the jackstands than the motorcycle jack was willing to go, hence the piece of 2x12, which I considered bolting to the jack but found there was no need. Lowering the frame went smooth as butter until I realized that the exhaust clamp bolts would interfere with the wishhbone on both sides. Tried to rotate the clamps out of the way only to find that they had been tack welded to the pipe (thanks for that one, Adamesh!). However, it turned out that the assembly wanted to tilt backwards a little bit after it cleared the wishbone mounts, so it just barely cleared the bolts in the end. But this caused another scare: The wishbone bushing sleeve on the driver's side ended up leaning against one of the cable harnesses coming out of the trunk, see the second photo. Fortunately, there is a harness clamp right there that absorbed the load so I'm 95% sure no damage was done. If I'm wrong, I'm in a world of hurt...
The final challenge I ran into, one that caught me completely by surprise and remains unsolved, was the cable from the headlight self-leveling arm. I thought I had carefully looked the frame over to make sure there was nothing else attached to it, but the way this cable is tucked away, I didn't notice it until the frame was just almost on the ground. Another inch or two and there would have been a lot of tension in the cable, possibly enough to pull the wires out of the connector. This connector actually got the better of me last night, I groped that thing all over for at least 10 minutes without finding the tabs to release it. It's not obvious in the third photo, but access is very restricted, so I couldn't get a good look at it. I'll try to figure it out tonight. As a side-note, I actually disconnected the self-leveling system some time ago as it insisted on dropping the headlights to the extreme low position, even though both the front and rear sensor arms are properly attached to their joints. I never bothered to troubleshoot that one, just disconnected the system and set the height manually.
The fun continues!

 

It's amazing how much better a pair of rested eyes work. Figure out the connector's secret right away last night and there was no further drama in lowering the frame and sliding it out.
Now the real fun begins!


I have ordered new diff oil (will go with 75W-140 Mobil1) and the full suite of Powerflex bushings for the rear, but the the lower shock bushings seem surprisingly hard to source here in the US. Only came across very pricey options so far. Will do some more searches on this before I bite the bullet. Also need to grab new droplinks of course.

Two questions came up that I may also post in separate threads:

- I told an old-timer at work about what I'm doing and he recommended filling the diff with a 50/50 mix of diesel and engine oil and spinning it around a few times to loosen up the crud before filling with the new diff oil. I have not seen this discussed anywhere but sounds like a good idea with no risk of harm, anybody have thoughts on it?

- I'm not excited to strip the assembly any more than necessary, but I wonder if I should go ahead and replace the four bushings on the pendulum and the two on that bracket/plate that I can't find the name for, six bushings in all. It's a bit irritating that you can't inspect the condition of the bushings without a fair bit of disassembly, some of which can be not so fun as shown in Simon's terrific "Projects in the Barn" videos. Those of you that have worked on the rear subframe, did you also do those six? See screenshot below. What condition were they in?
Thanks!

 

Lars, these are the lower shock bushings for the rear that I used. It looks like they are talking about just one but they came in a package of two, so not too bad a deal.
They state DP but when you open them, they will be URO, made in Germany, but in this case they are not bad.

JAGUAR XJR XJ8 XK8 XJ12 XJ6 VANDEN PLAS LOWER REAR SHOCK BUSHING BUSHINGS | eBay


Be sure and install the shock into the hub carrier with caution, hitting the spring for the rubber will knock it out of the grove very easy.

 

Thanks for that find Wayne, much appreciated!
Yup, I'll try to ease them into the carrier very carefully!

 

Lars, I would recommend replacing the complete shock absorber. If the bushings are shot then the shocks aren't far behind, unless you know some definite history of their age.

Of course, if they are active dampening shocks then that is another story. When I redid mine, I did all of the consumables as they are much easier to get at now with the rear end out.

 

As far as the crud dissolver solution suggested above, I would be very reluctant to go that route.
A: Turning the diff by hand will do little to nothing to provide any velocity to the proposed solution or to push it into the recesses of the internal casting crevasses.
B: You may slightly loosen something but not get it out completely, thus making a bunch of debris that later finds its way into sensitive areas.
C: Street driven diffs should never get to the temps that would create the kind of sludge you are likely to be talking about. I can show you pics of my 55 Chevy pickup diff that came out after 150K miles. Nothing that would need a solvent bath. Regular gear oil changes will get the metal out, which is 99% an issue when they are new.

 

Thanks!
I've now read up a bit on it and am reaching the same conclusion.

 

Partially disassembled and partially cleaned, been smooth sail so far. Almost no rust, and what little there is, is only superficial.
Couldn't fit my large spring compressors to the struts so have small ones on order. Also looking at hydraulic presses, and judging from the experience of others, a 6T should be sufficient for this job. If I have ever have to replace balljoints, I'll need a bigger one for sure.

There was a bit of oily crud on the passenger side of the assembly, but almost none on the driver side, so I suspect the passenger side drive shaft seal is not entirely tight. Never had any drips, and if the amount of oil in there now is near the nominal amount, I don't think I'm going to worry about it.

 

You could also consider doing the wheel bearings - both my XKR and XK8 had one of the rears start to show some wear/movement at 60-70k miles.