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I have a 1968 Jag 420 which has been restored to a very good condition prior to my purchase. It is fitted with 5J 72 spoke wire wheels with Dunlop SP 185/15 tyres which appears to be correct. I cannot remove the rear wheels. The suspension does not appear to drop sufficiently to allow the wheel to clear the wheel arch - it's not even close. It has been suggested to me that the shock absorbers may be at the limit of their extension and are preventing further movement. I have tried jacking the car up at one side only and also centrally but without success. Has anyone come across anything like this? Any advice would be appreciated. In the light of nothing positive I think my next step will be to disconnect the rear shocks and see if the trailing arm drops sufficiently to allow the removal of the wheels and, if so, see if I can get the 'correct' ones. But, before that, I just wanted to see if I was missing something obvious. Thanks

Hi Keith,
Many moons ago I owned an S type which you will agree is about the same as the 420.
I fitted XJ rims and tyres (205/ 70 /15.) to the rear.

These where standard rims secured with nuts. Getting the wheel on and off was a work of art.
With the car jacked up, the part of the tyre sitting on the ground had to be pushed in towards the centre of the car, ie towards the diff to about 45 degrees. This then allowed the top of the tyre to pass between the partly closed off wheel arch, a feature of this model, and the hub. Then lift the wheel onto the studs in the normal manner.

The 185 tyre you refer to is the correct size.

The complication with yours is, you say you have wire wheels but you do not mention if they are mounted onto splined hubs or after market bolt on's.

Wire wheels were an option from new but has somebody done an un authorised mod introducing hubs from another model which may have increased the vehicle track

I have just read my S type manual and it says

Pressed steel - rim section - 5J
Wire spoke - rim section - 5K

I hope that helps a little - keep us up to date

Oldtimer

Hi, Thanks for taking the trouble to reply.

The wheels are splined, not bolt on, and there is insufficient room laterally to get the wheel off the spline and so I am unable tilt the wheel (in any direction) to clear the wheel arch.

Oh , There is something amiss I'll have another think tomorrow - paste my bedtime

You could try ringing Ken Jenkins (number in the front of the JEC magazine) what he doesn't know about these old cars isn't worth knowing.

The only thing that comes to mind is that the dampers (two per side??) are not correct and don't have sufficient droop. You could also ring the firm that rebuild your car, if they are good they will remember your car.

Brian

OK, I bit the bullet today and disconnected the shock absorbers at the bottom from the wishbone and ........the suspension dropped and I was able to remove the wheel. I tracked down the owner who had the wire wheels and hubs put on and he assured me he used to remove the wheels regularly for cleaning before attending shows, so I can only assume someone has replaced the shock absorbers with incorrect ones at a later date. However, the issue I have would have been readily apparent when they tried to put the wheels back on! Who knows. New shocks next which should, hopefully, cure the problem.

Hi Keith

A bit late I know, but I had the same problem with my 420 when I first got it although not as bad due to having bolt on wheels. Someone had fitted E-Type (I think) dampers, which restricted suspension travel. Actually, it was worse than that because they did it only on one side, which gave the car a lop sided look.

The good news is that damper replacement is one of the easier jobs on an IRS car. Fit good quality ones when you come to do the job. It will be beneficial.

Things like this only make me wonder what else has been likewise carelessly repaired.

Regards

Hi Stuart,

Thanks for replying. All indications that I am on track to the solution gratefully received! Your post reinforces my view that replacing the shocks should fix the problem.

Keith

Hi Keith,
Seems you have the answer to the problem but do let us know when the job is finished

OK, that euphoria was short lived. Just removed the shocks from one side and they are identical in length to the new ones. I am sure the new ones are correct as they have the same part number and are specified for the car across 2 different supplier web sites (Manners & SNG Barret). I need to consult a 420 guru I think. Not a happy bunny.

Hi Keith

Something you might want to check. Some wire wheels are laced to give more offset, looking from the back of the wheel when your trying to take the wheel off, how much distance do you reckon your short for the wheel hub to clear the splined hub!

Hello Keith,

just a shot in the dark as I don't know how you were jacking the car up. If you place your jack under the suspension does that give more clearance, i.e compress the suspension, not extend it?

Otherwise I suspect that new wheels are needed?

Alec

Are u close to me Keith ? Brands Hatch , ive got a few bits n bobs that might b helpful . Russ

Hi Keith,
It appears that an extraordinary amount of time is having to be invested into a simple problem.
I have given this subject some thought from time to time over the past couple of days and cannot come up with a sensible answer. However I have re-read all of this thread and you tell us that the car had been restored prior to your purchase.
You say that the previous owner took the wheels off on a regular basis for cleaning - OK - so did the car get sold on and then refurbished and then sold on to you. If this sequence of events is correct has any major surgery been carried out on the inside of the rear wheel arches reducing clearances.
The rear suspension sub frame is attached to the body via four V blocks, two each side. With the wheels in place visual examination will be difficult although a limited view can be seen from underneath inboard. The purpose of this is to check integrity and security- what I really mean is to see that no jiggery pokey has taken place.
I am really struggling with this one and cannot understand how on earth the wheels were fitted after unknown work was carried out
I have removed these IRS units in the past and never been confronted with this problem, my thoughts are that somebody is telling porkies and you will be left to unravel it.
Do keep in touch with your progress and we will have to see what the next stage is
Oldtimer

Thanks for all the replies. Russ, unfortunately, I couldn't be much further away - the north of Scotland near Inverness. Having removed the rear shocks on one side and compared them to the new ones, and having found them to be the same size, it occurs to me that if if this is the issue, it would have to be both shocks and coils springs that are wrong as they are effectively a unit. Once the rear shocks are undone, the wishbone does not have to move a huge amount to remove the wheels so I think new shocks and coil springs could be the answer but which ones? I don't understand how someone could have run this car and not addressed the issue as it is pretty fundamental to routine maintenance. I intend making some calls later today and will report back.