IRS removal from a very badly rusted SIII / How to support safely the rear end?

IRS removal and Rear section Terminal rust…


this is my first post on the forum, but I’m reading and following regularly some discussions since I bought my first SIII back in 2008.

She passed away some years ago, killed - for me at least by extensive corrosion on the RH rear section, floorpan, outer and inner sills included up to the front toe board as am really not as skilled at hard body work than I am to mechanical, electricity and electronic maintenance being an industrial maintenance engineer since 1979… Had imported this car from Scotland (with a serious lack of knowledge of the weak points of the XJ body at this time, I learned it since ^^) this being I think the reason of these disastrous sand and salt damages.

But being felt in love with the fantastic behaviour of these cars I bought another SIII in very good condition, absolutely free from corrosion but not from mechanical damages to the differential caused by the two left hands of the PO, discovered after buying the car of course… The guy has changed an output shaft oil seal without any knowledge nor understanding of what can be bearing preload so the corresponding bearing is now turning into shiny metal dust giving a very nice tint to the diff oil and a light but annoying rumble noise at low speed…. Up now.

The rear brakes pads having to be replaced and callipers being in need of a rebuild I plan to salvage the whole IRS from the first car (the rotten one) whose differential is in VGC.

My problem / question is:

How you, experienced XJ owners, would you support the rear end of the rusted car, thus knowing that the RH rear jacking point has disappeared, the left one being very weak, the sills closing panels are fully rotten and I can clearly see that the lower end of inner sill is very damaged on all the length of the car….

Having made the right and very strong spacer to place under the tie plate without breaking anything I can jack the car up quite easily. The front end is already lifted and securely supported.

But where to place stands to support so safely the rear end to be able to remove the IRS???

Thanks by advance for your help

Thierry, S/W of France near Toulouse

imo, the car should only be lifted minimally off the ground, with the rear wheels left on

one should never get under a suspect IRS unless it is blocked from falling

are you going to cut the exhaust, or attempt to pry it apart ?

the most difficult part is separate the radius arm main bush from the post on the body
I made a simple tool to do this

Once apart, take of the wheels, and drag the IRS out the side

in that case, the vehicle only needs lifting less than 6"

Big pieces of timber on the jack stands would be my suggestion or cut the car away from the IRS if its that bad, what are you going to do with the rest of the body/

Using the tie plate as a jacking point is a standard and approved procedure to lift the rear end, Thierry…

To support the rear end; the under-car body itself should be strong enough - using suitable length of timber. Or timber long enough to reach across beyond jackpoint to jackpoint…

As Tony says; safety is paramount - stability is essential. As you have lifted the front end; stability there is just as important. It may be pertinent to remove the front wheels and drop the front end down on timber lying on the ground for minimum lift and maximum stability…

Some brute force may be required for dismantling, like for the radius arm. So ensure that the set-up is stable in all directions - and does allow required access…

xj6 85 Sov Europe (UK/NZ)

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…give the car a good shove in all directions before you do anything else. You can also remove the forward arms of the IRS and see if the mounts are more stable, but the long timbers are more promising. Use as much wood as you can and then drop the IRS out the side. Or lift it up higher, put the timbers under the car and then pull the IRS out with the jack? You will have to disconnect the brake lines and exhaust (mine comes apart easily), that’s why some height will be good.
Good luck,

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many thanks for your replies.

Of course my own safety is my main concern! I have never had any of my cars repaired by others than myself as I learned mechanic in my childhood so I am definitely aware of the dangers of such a work and of the required caution such as the “shake and bump” test :wink:

The car is already raised at a sufficient height to work on the exhausts, brake line, shaft, etc… about 15’’ between the ground and the bottom of the sills. As far as I can see it could be enough to remove the IRS from a side.

May be I had not given enough details… The RH bottom panel has completely disappeared, the radius arm mounting is definitely worn - that is the main reason why I ceased to drive the car, very dangerous it moved audibly while driving ^^ It would require at least to change the part named “rear chassis member repair section” in the parts catalogue and to repair the bottom 2’’ of the inner sill to withstand any weight.

LH is somewhat better but relatively frightening too…

Do you think that timbers around the driving shaft tunnel and other planks, used wheels and tyres, so on could stand the car?

Its a little hard to be sure exactly what you are asking here, but the car and IRS can and should be blocked with planks, and tyres…no precaution is too many, unless it gets in the way.

if you are asking whether rusted sills will support the weight, without pictures, only you can judge
…cant imagine they would be so bad the job cant be done safely

will say the IRS is surprisingly nose heavy…it will tilt or fall forward unless the pinion yoke is supported

I find it easiest to use several trolley jacks to have complete control over raise or lower IRS

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A heavy plank from side to side relying on the pan and center tunnel for support.

Aye, on a plank to span from the center of the IRS to the pinion nose. Cushions the nose heavy tendency.
Check Aristides neat support, casters included!!

As the body is that “hopeless”, I join in the idea of cutting the car away in chunks leaving the IRS!!! Makes disposal of the detritus easier…

Were that operation done in a “wrecking yard”, I suspect the car would be rolled on it’s side and the mounts cut with a torch and allow the IRS to fall away…
Torch guy standing aside, of course…

Caveat, I’ve not done this operation. But, , Te swaps I’ve done decades ago in Corvairs sure looks similar.


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Tony, thanks for your recall about the unbalance of the IRS and the necessity to support efficiently the nose of the differential. The idea of leavining the wheels in place seems sound too if the car is high enough to remove the whole thing by the rear.

Otherwise my idea is to use a trolley jack and a strong plank to support the thing with caution to the balancing. And yes the right hand outer part of the chassis is in incredibely poor condition. Will support the car by distributing the load from every other still sound parts of the floorpan, LH bottom side and center tunnel, and work under the car before the final part of the job by sypporting also with a 3 tons stand placed under the tie plate. The front end is supported by 2 stands under the front cross member

Carl I have checked Aristides post with much interest, thanks.

For a lot of reasons I will definitely forget the suggestion of cutting the rear of the car apart, unapplicable in the context, fire hazard, other…

Again thanks everybody for your remarks, comments and suggestions I will post infos and pictures of the work in progress, I plan to have it done before the winter to rebuild the IRS at the bad season and fit it in the “good” XJ next year, no emergency about this swap the calipers and differential should do it good for quite a moment yet.

… New 1983 XJ Sovereign which is really a great car, just completed the usual full service job on it, filters, draining all fluids, some electrical repairs, handbrake fix (ouch… fortunately I had alrerady done it on the first SIII so I got the training ^^), rear hubs greasing, anti-roll bar rubbers, etc.

Just 60k miles from new, runs as it should, great body, engine and gearbox, always kept dry and sleeped indoor, almost fully fonctionnal electrical systems. Will have to salvage also the AC compressor from the first car too.

For now I have to undergo myself some maintenance on my sometime obstructed coronary arteries… Coronarography and may be angioplasty this friday.

Hope to be back very soon.

Many thanks again for your help and support, great list!

But it is stable under for and aft and sideways loads, Thierry…?

xj6 85 Sov Europe (UK/NZ)