XJS Radius Arm Mounting

I have a 1992 4.0 XJS, I am in the process of doing some restoration work, I have noticed that the Radius arm mounting at the rear N/S needs to be replaced. I am looking for any advice before I tackle this job. I have already rebuilt the front end including all front panels and front suspension mountings. My main concern is how to ensure that I mount the radius arm mounting cup in the correct position (left right, up down, forward and back). Any help and advice will be appreciated.

Welcome Garreth.
I have no experience with this however I have seen a lot of discussion on this forum on that subject. Try using the search function and I think you find a lot of info that could very well answer your question.

Best regards,


I did look, I only found lots of discussions about issues with removing the arms and bushes. I will have another look as I suspect this is common with all Jags.

Hi Garreth-
Am I understanding correctly - the protrusion on the bottom of the body that fits into the large-end N/S (near side) radius arm bushing needs to be replaced? That sounds like some significant body damage or rust…?

If it was me… I would replace everything else - rear suspension subframe mounts, the bushings in the other radius arm, and the bushings in the N/S radius arm, put everything back together (including the O/S (off-side) arm) and get the car sitting on its wheels, roll it back and forth a bit to settle the rear suspension, bolt up the rear of the N/S arm, then use the newly-bushed front of the N/S arm to locate the mounting protrusion. There should not be any pushing or pulling or twisting to located the the arm on the mount, it should just fit over nicely.
As far as vertical location (you must be missing a bit of structure if vertical location is a concern?) I’d probably try to use other reference points to get the body level, and then measure the distance from the O/S mount to the floor, and replicate that on the N/S mount.

If the car has been wrecked and the unibody is twisted or damaged, then all bets are off, you’d need a frame rack to figure that out…Alternatively you might find a body shop with a frame rack and they may have some reference dimensions you could utilize.

Or maybe I am misunderstanding completely, wouldn’t be the first time.


Check out my YouTube channel Jag Mods.

Here’s how to rebuild the Radius arm
Don’t be alarmed by the fact you don’t see any the XJ-S’s. The XJ Saloons (XJ6 & XJ12) prior to either 1988 or 1992 (depending on what country you reside in) share pretty much all of the suspension components with the XJ-S. Oh, I also have 3 XJ-S’s

There’s a couple of key points about placement and how the bush goes in and out. I do have a 20ton press, but this can also be accomplished with a carefully placed socket or take you radius arm down the the local hardware store and start sifting through plumbing bits until you find one that works. this also covered in the video. I also have the dimensions for the official Jaguar tool radius arm tool.
If you feel so inclined.

1 Like


Thanks for the replies so far. The issue I have is with the body, Not the radius arms, or any part of the IRS (That’s a later project). I replaced the radius arms a couple of years ago with complete replacements from SNG, including the Bushes already inserted. I know I have to cut all the rust out (There’s a lot) and I am confident of my welding capabilities. I will try and load up a picture to show what I am up against.

Garreth (K6GTS)

It looks like it’s still there. Why don’t you just take some measurements from marked spots on the structure that won’t be going anywhere, and then locate your new boss using those measurements?