Notes on XJ6 front suspension isolator replacement

Just thought that I would make up some notes after changing out front suspension isolators on the '72 XJ6.

  1. The upper control arm units were completely flogged out - the rubber components had almost completely worn through. There are four halves and they tend to leave behind their inner metal cylinders on the mounting shafts - they responded well to some heat or in the worst instance the Dremel. The upper control arm splits into two halves around the upper ball joint. NOTE the position of the castor shims on reassembly. I suspect that this replacement provided the most significant improvement in the ride/handling outcome of the whole job. It’s also the easiest as there is no need to remove the front springs - a big job, I covered earlier. The new halves pushed in with some silicon lubricant. Don’t tension the isolator halves until the car is on the ground.
  2. My upper ball joints were sound - so just a grease!
  3. Removal of the lower control arms is a big job and springs must be removed. The curious thing being that, despite the flanged ends of the isolators looking a bit ratty, the internals were completely sound. I did replace them but, on balance especially given the spring task, probably could have got away with the originals if I had known. These have to be pressed out (and in) and I did it with my 4" vice. The troublesome task for the lower arm is (of course) removing the mounting shafts. The Good Book makes no notes about dropping down the steering rack or removing the exhaust down pipes - but this is a must! Fortunately my shafts were not rusted in place - the inner steel cylinders of the isolators can rust to the shafts. Tension the big shafts when the car is on the ground!
  4. Rear subframe mountings were also replaced. To do this I removed the front subframe mounting bolts - the big transverse units at the radiator end - and carefully lowered the engine about 1 1/2". I had to remove the oil filter to gain access on drivers side. Painstaking but not difficult!
  5. Sway bar droppers were removed and rubbers (8 off) were replaced. The droppers themselves were rusted under the rubbers and I built them with mild steel MIG wire. Shaped back by grinding and linishing. Had replaced the main sway bar rubbers recently and this work is routine per book.
  6. Lower ball joints were replaced - the old ones being the shim type. You must drift out the upper ball joint ring from the arm to fit the new “sealed for life” units. This part seems often to be damaged by ball joint removers so I think changing to the sealed units is a good move.

I still have to change the big rubber bushes mounting the front of the subframe to the body. I want to do this in situ and it will require lowering the whole subframe (further than per above) and some thought! As for the lower control arm the existing big isolators, as I inspect them, don’t look too bad. Any thoughts appreciated!

Worth noting that all isolators came from SNG and were “sourced in the UK” except for the big subrame units at the front (still to be replaced per above), which were sourced in India. I bought the bottom ball joints locally - made by TRW.

The car now points and rides wonderfully. I don’t expect any of these items had been previously replaced as we’ve had the car since 1987. Also note, for completeness that I replaced the tie rod ends about three years ago. Finally note that I went for standard “Metalastick style” replacements instead of poly to preserve ride quality.

Paul

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I replaced all my S1 front end bushes etc earlier this year - but chickened out when it came to the sub frame vee mounts. When you lowered the engine/sub frame assembly did you need to disconnect anything else?

What do you mean by the lower control arm big isolators?

Frankie

No, only came down a bit less than an inch - the whole subframe at the four mounting points. Dropping down evenly meant I was good for the engine fan as well. Transmission mount remained untouched. There is enough clearance around the carbs and enough slack in the wiring on the engine.

Should have said the big isolators at the front of the subframe - sorry for confusion!

Thanks - very helpful. Interesting that you didn’t need to disconnect the steering column at the bottom UJ.

Couldn’t you replace the front mounting bushes without dropping the subframe? Undo and drift out the main bolt, undo the bolt securing the clamp holding the isolator to the subframe and withdraw?

Frankie

Yes. Follow the ROM instructions. I did it pretty easily.

David

Frankie

Hi Frankie, I actually did disconnect the bottom UJ - you might be able to get away with not doing so if you are only doing the vee mounts - but you must do this job if you are removing the lower control arm shafts, which I did. Expect it’s better to always disconnect so as not to damage the collapsible steering column assembly. Paul

I had not realised the front subframe mounts were bolted to the subframe - per Frankie’ s drawing. Will have another look. Paul

I too had to disconnect the bottom UJ , the subframe wouldn’t come down quite far enough without doing so but after that it was easy. Awkward getting out the forward bolts up unto the chassis but can be accessed from above leaning over the wings. Certainly no need to remove the subframe.

Ian