Steering wheel shimmy/vibration
 

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About 4 years ago I completely rebuilt the front suspension. Stub axles, bearings, callipers, discs, ball joints and steering ball joints. After about 6 months the steering was all over the place, and it transpired two ball joints had failed completely giving about 3mm of play in each. had to be the bottom ones of course, so a pain but done.
About 2 years later some drivetrain vibration seemed to appear so an new OEM propshaft (still available and surprisingly cheap) was fitted and all good, for a bit.
A year after that, as in a few months ago, a huge clonk from the rear end was diagnosed as loose bottom wishbone inner fulcrum casting bolts. Out with the cage and these were done too, together with new fulcrum bearings. All good, vastly better BUT...
It seemed the gearbox mounting was a bit solid, so that was renewed, again much better BUT
Although the drivetrain was now dead right, an annoying shimmy was coming through the steering wheel at between 80 and 90 KPH. Not a wheel imbalance, more like bump steer at about 4 beats a second. It reappeared at 140KPH as well. So I dropped the rack and looked at the rack mounts. These are the JaguarSport ones, which will never go sloppy, but the rubber parts had gone rock solid compared with new ones - which I had in stock. With huge difficulty they were changed. The JS bushes have a solid steel endpiece combined into the rubber bush itself, so they cannot be driven out with a threaded rod or a hydraulic press. I had to cut this steel end off, then burn out the rubber, then cut through the steel outer along its length where it fits into the rack eyes, then lever and chisel it out.
replacing was fine as they can be driven in with a press, or in my case a threaded rod system. try out car, MUCH better, BUT...
Some shimmy still there. Time for drastic action: Place international call to the WoOZ.
"What about the rear V mounts on the front subframe?" enquires the Master. I explain the no-expense-spared genuine items were fitted a mere 10,000 kilos ago, and that one sows a slight crack under tension when on a two post lift, but seems solid enough, and send a snap to Oz for the Great One to inspect. "That's the problem" The Mighty and Eternally Revered Great XJS Prophet instructs his awed disciple.
So two days ago FedEx pitches up to the place with two new Metalastic V mounts, and yesterday my mate Michel comes round to help.

• Beam on car to support engine by front lift eyes
• remove air boxes and undo engine mount top studs with 9/16ths ratchet spanner
• up goes the lift
• undo column/rack UJ
• undo shocks at the wishbone
• loosen front 6 shot huge bolts
• jack under subframe, undo V mount to subframe bolts
• Lever down the rear of the subframe enough to get at the front of the two V mount bolts, but not enough to stress the brake flexible
• replace V mounts, and jack up the rear to engage the engine mounting studs in the engine brackets

Now someone can no doubt explain this to me, but they were about 1cm away from the hole! So we have a tone of engine held up on chains to the beam, and a ton of subframe on a jack, and nothing much has moved, but they have, somehow. WE tried levering, waste of time. What to do? Followed by half an hour of trying hopeless ideas, followed by the hard work, which was as follows:
In the end we removed, one side at a time, the huge front subframe bolt, thus enabling the subframe to easily be levered so the engine mount stud could engage. On with the stud bolt but not tightened. The alignment problem has now transferred itself to the six shot bolt/bolt hole line-up. A big lever and it gets installed. Ditto the other side, but a bottle jack came to our rescue in this case.
4 hours work and it is done. Stop for a late lunch and with trepidation try it out in the afternoon.
ALL GOOD. A quite unbelievable difference, perfect factory-standard steering and ride. Also for some reason, quieter with a small but detectable reduction in cabin noise.
A pic attached of the mount that was failing - the pic shows it under tension, not in its normal position under compression when the wheels are on the ground. If on the gound or on a 4 post lift, this fault would be undetectable. Who would have thought it could cause all that trouble? And the other side was renewed too, and even though not split, it showed quite a bit of deterioration.
SO THANK YOU WoOZ!

Well done Greg, glad to help, and the phone calls are the usual riot.

SIMPLE cars, I say it over and over, and the problems are equally as SIMPLE, only compounded by human theorists thinking TOO damn hard, instead of just DOING IT.

Egg timer out of storage I suggest?????

British Non-Metalic components, OOPS.

As I refit my front subframe, I aligned the V mounts first and then used the front bolts to align the front. Worked easy. The same method used to refit the front subframe on the X300 and X308... Just that the huge bolts are at the rear instead of the front... :)

My problem, daim, was not aligning the V mount to subframe studs. It was aligning the engine mount stud on the engine mount bush to the engine bracket itself.

Hey Greg,

Do you have a "wider field" version of that photograph. Somehow my mind isn't telling me where to look.

Thanks,

John
1987 XJ-S V12

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John
I cannot find a long shot photo, but the above show a V mount in situ and also the chassis rail from where the old one has been removed. The exhaust downpipe is in the shot too. On your car if you look at each side of the rear of the front subframe, just ahead of the rack and slightly above it, you will see a rubber mount each side that attaches the subframe to the lower chassis rail. These rear mounts, plus the big "six shot" mounts each side of the front of the subframe, locate the entire front suspension to the monocoque. You cannot access the front bolt that hold the V mount to the chassis rail with the subframe in position, so the technique is to hinge it downwards on the front six shot mounts, the huge bolts in which are loosened for the purpose.
The subframe also carries the engine on two large round rubber mounts, which locate into a bracket each side of the engine. Aligning these with the engine, when the subframe needs to be swung up again is often hard to do; because of the give in the rubber six shot mountings of the subframe and the gearbox mount too. The difficulty I had was that the engine brackets did not align with the engine mount studs when I swung the subframe back up. Hence my being forced to remove the huge bolt from each side of the front six shot mounts (one side at a time, NOT both together!! as at this stage the rear V mounts are not attached to the subframe) so as to give me some play to align the engine mounts to the engine brackets. Then, of course I had to align the six shot bolts with their chassis holes to fit them again!