Radius Arm Cup Location

[Quelch]

I am restoring a 1967 series 1 E Type Jaguar OTS. The new
floor assemblies already had the radius arm cups attached.
Before work on the car commenced the body tub was placed in a full body rotisserie jig. The car was attached (pinned or bolted) to the jig in the following locations:-

The LH & RH ½ inch bolts at the front of the floor rails where the engine frames attach.

The LH & RH Radius arm cups.

The LH & RH aft independent rear suspension cage mounting bolts in the rear wheel well.

At this stage everything lined up perfectly in relation to the car fitting into the jig.
The old floor panels were removed / replaced one at a time. When the replacement floor panel assembly was located to the jig at the forward end of the rail (the 1/2” bolt where the engine frame attaches) I noticed that the new radius arm cup appeared to be too far forward in relation to where the original was located by about 5/32”.
The car has been removed from the jig and I have been taking measurements trying to find where the discrepancy lies. I have set the car level and dropped a plumb line down and recorded measurements “J” and “I” on the Jaguar diagram in the manual. These measurements are very difficult to get an accurate reading!
I have also temporary installed the IRS assembly and attempted to attach the radius arms to the cups. With the shock absorbers disconnected and the radius arms level the mis-match appears to be as follows:-

L/H radius arm cup 0.175” too far forward
R/H radius arm cup 0.155” too far forward

How much is too much? Would there be enough wiggle room to successfully build everything up with the IRS Assy pulled forward to accommodate the radius arm cups in these locations?
Everyone’s thoughts on this problem would be very much appreciated.

[abowie]

The bushes do not fit directly onto the cups when you put the IRS in. There is usually a bit of force/weight in the boot/jacking shennanigans etc required to get them in. Yours look to be pretty close and there is a surprising amount of give in both the radius arm bushes and the IRS mounts.

[christopher storey]

I agree with Andrew. Once you have got wheels on the car , you can push the car back and forward a few times and you will find that the IRS has lots of compliance which will affect the relationship between the radius arms and the cups on the body, so that with a bit of luck you can get the bolts in. One tip I would suggest is to coat both the cups and the recesses in the arms with copper slip or similar, which will make them easier to release in future

[Quelch]

Thanks for the information, I'll let you know how it goes.