Jacking to change front air strut

[PaulGover]

I need to replace my front air struts. Various things suggest I need to raise the front end, both sides. What with the limited clearance (the front is sitting on the bump stops or whatever), I suspect that will be hard. (Annoyingly, I have a lift in the garage, but it has part of an XJS on it... And I'm not sure I could get the XJ over the lift on its currently drooped suspension.)

Reading many forum items on replacing the struts, if I understood correctly Mike (J44EAG, once the forum's moderator but I think sadly no longer) said it's possible to change the struts just jacking one side at a time. Is that the case? I'll be a lot happier with 3 wheels on the floor than trying to balance the car on a couple of jacks until I can get axle stands under the chassis rails (or maybe some non-moving bit of the front suspension).

Suggestions on a postcard please.

Meanwhile I will gather strength for the assault on the TX60 lower spring bolts. Though I should be in luck - I had the front suspension bushes replaced a few years ago, and if I recall correctly, that involves removing said bolts, so they have been disturbed.

[iRS]

Hi Paul,
I replaced a front air strut a few weeks ago, admittedly I used my 4 poster lift which made it a lot easier but I don't see why you can't do what you suggest. My question would be how you're going to jack it up and then support it. Would that be under the sill? The key is to get enough ground clearance so that you can get the existing air stut removed and to do that you want to remove just as much as possible that's in front of you, so the brake disc, the calliper and every connection to the hub carrier - ARB, track rod end, upper wishbone etc. Be careful with the level sensor when you remove it and try not to touch the inner bolt of the lower arm as this will put out your camber setting. I’m happy to have a quick chat about it if that would help. My number used to be in the magazine – try an old copy – or PM me for a number. Cheers, Roger

IMG_0293 copy.jpg (20.19KiB)Viewed 3129 times

[PaulGover]

Thanks Roger. Having read some more, such as Mike's long write-up, and the sheet from Bilstein that comes with the air strut, I've decided the best thing to do is see if I can get my XJS back together and off my lift. This is my chickens coming home to roost - I should have fixed the XJS ages ago!

I'd considered raising the car using my home-made engine support bracket (a long piece of 2" square steel tube that's good for lifting several tons) under the car at the front jacking points, and resting on a couple of trolley jacks at first, axle stands later. But it turns out to be about 18" too short, and I'm not convinced I'd get the clearance.

As for trying one side at a time, I'd missed the bit in the manual that says "disconnect the anti-roll bar" (called something else), and I doubt that's possible with one wheel in the air, the twisting force would be significant.

Out of interest, was getting the lower mounting bolt out as hard as in Mike's case? I'm not looking forward to a day with a lump hammer. The last couple of times with that were removing my front brake disks on the X308, and the lower wishbone fulcrum shafts on the XJS. The neighbours probably still hate me for all the noise (and Anglo-Saxon oaths).

[iRS]

Well the first time, it simply didn't come out at all. I removed the air strut and lower arm together and used a combination of angle grinder, die grinder and drill and tap. And a new bolt. Ever since then, I haven't had a problem. I think a bit of grease on reassembly and removing them from time to time does the trick. I think there's an account of it on the forum.

[PaulGover]

Just when I'd started sleeping properly again ...

[PaulGover]

A belated update. I got my XJS to run, so it's off the lift and the XJ TDVi is now on it, sans front wheels. I've started dismantling to replace the air strut, following the very informative sheet Bilstein include with the strut.

The good news: I've been using WD40 penetrating spray - this isn't normal WD40, it's a (new?) different product from the same people, and it certainly seems to penetrate - and pushed a very thin screwdriver either side of the rubber bush around the lower strut mounting, so as to try to get some into the bush, as well, of course, as copious spray over all the nuts and bolts involved. End result, they all move, even the big T60-head bolt moved with only a reasonable heave on my breaker bar! Result.

Bad new (there's always bad news), the upper ball joint spins when I try to get the nut off. The workshop manual mentions not letting the upper ball joint hex spin, so I don't know if there are some flats for a super-thin spanner somewhere to stop it spinning. Alternatively, I keep reading on-line about a T30 socket involved, maybe on the end of the ball joint, I've not yet looked. Otherwise I'm a bit stymied as to how to get the damned nut off. Having read up on this, I realise I can't use brute force methods, or I'll be stuck with replacing the upper wishbone since the ball joint is an integral part thereof, and of course said wishbone is expensive.

[PaulGover]

I'll answer my own question.

The ball joints have a T30 socket embedded in the threaded portion of the ball component.

I read a few times that people had a problem with the retaining nut seizing on the last bit of the thread, despite using a T30 driver to hold everything still. I too encountered this - I wonder if someone was too enthusiastic with a ball joint splitter, and squashed the thread, or maybe is just corrosion. Whatever, after that, I now run a 12x1.75 (coarse) metric die down the thread to clean it first - no problems after that.

I noticed the boot on the track-rod end was split. A quick search on the Internet leads to GSF, who sell a suitable one for 95p.
Lots of rust on all the iron bits; I will at a later date give them a lick of paint. I'd be interested in any suggestions; I have a tin of Hamerite spray that's supposed to be good for this sort of application - if it's not dried up.

[PaulGover]

And a final update:

It's alive! (sorry, you have to skip through an advert before you get to the clip).

The hardest part of fitting the struts was just, erm, fitting them - getting the studs into the holes and a nut on one before I ran out of grip and the damned things slid down again. Oh, and tightening the big bolt with the car on the ground (it's one that has to be tightened with the suspension in normal position, not on a lift, or the bushes get preloaded). Despite the workshop manual saying "don't use a socket extension", I did just that, though with a wobble bar extension to get round the tyre. Not sure I achieved the full 175 Nm, but it was a lot...

I gave the compressor an overhaul with bagpipingandy's kit and replaced the dessicant - and had one of those "part leftover" moments having reassembled (there's a plastic retainer I forgot). (Warning: the high pressure air line from it screws into plastic, and the workshop manual says max torque 44 lb-inch, so there's a danger of stripping the thread if you're too enthusiastic).

Then a day trying to get the car to stand on its own feet. The Bilstein instructions go through a series of lowerings that, reading the dealer training info are to get the ECU out of "lifting mode" (which inhibits starting the compressor) and into "vehicle too low" mode, which starts the compressor even if the car isn't moving. I followed them to the letter, but nothing happened.

I noticed the unchanged rear struts were on full extension even with the lift way down. Reading the manual again, I realised that the ECU won't come out of lift mode unless all wheels move up a bit, and the back ones didn't. That leaves two ways to proceed; one is to drive at more than 2 kph (several Internet items report this working), but Bilstein say on no account move until the struts have lifted the car, and anyway I wouldn't have been able to get the car of the lift. That left letting some air out of the rear struts.

I got the spare wheel out of the boot, and loosened the blue and red air lines at the valve unit about a turn and a half, and lowered the rears to about 380mm. Retightened the connections, started the car and the compressor kicked in! 5 minutes later the car was sitting pretty. Then "just" tighten the suspension nuts now it's in normal mode, and drive off. First time back on the road in 4 months! No warning lights, and a nice smooth ride.

[ptjs1]

Paul,

Great to hear of your efforts, your ingenuity and your ultimate success! Well done! Great job!

Did you take any pics that you could share with us?

Cheers

Paul

[PaulGover]

No pics that add anything to those from Roger above. I've a bad one of the compressor, but it's too dark, and I think that's covered elsewhere too.

One further point, relative to my original question: I think it is possible to do it using axle stands, and care...
You have to be able to get the lower wishbone sufficiently down to allow the struts to clear it, so that's a limit, but I think realistic with axle stands in the approved spots. The danger point is probably getting the old large lower bolt out. Even a nicely oiled and clean bolt will need 175 Nm, which is a lot, and a rusty one could be lots more and there's a danger of toppling off the stands if everything isn't properly stable. Then if the compressor doesn't start after changing the struts, bleeding the rear struts might do the trick again, with no need to raise and lower the car.

It's very satisfying to keep the car on the road - I reckon it will see me out now, and that's far better than scrapping it for £750, which I seriously considered some months back. It took me about 5 days in total (the rest of the time was spent getting my other Jaguars starting and out of the way ...), and total cost about £1,900 for both front struts and odd tools (mostly sockets) - I suspect significantly cheaper than getting a Jaguar agent to do it.

[PaulGover]

Watching an old "Wheeler Dealers", I noted Ant Armistead replacing the piston ring on a Porche's air suspension compressor, looking exactly like the one the X350 uses. The suspension in question had been leaking overnight, so it was pumped up each time the driver started the car. In California, with dry air, it probably doesn't matter much, but a similar problem overhere would lead to the pump's air drier becoming saturated. Which reminded me that I meant to comment on this in this thread about fitting new air struts.

The point is, if you need to replace air struts, and if the problem will have meant the pump would have run significantly more often than usual, you really should overhaul the pump and drier as well. I've read that you can put the drier beads in the oven, or just purchase a bag of new beads and filters (as I did).

In normal conditions the pump hardly gets used - a bit of air if you put a heavy load in the boot or on the back seats, or as weather conditions change (ambient temperature affects the pressure of the stored air, and of course the lifting effect is proportional to the difference between the stored and atmospheric pressures), but both are relatively small and probably fulfilled from the reservoir. The workshop manual explains that the system regenerates the drier when there's excess air stored by venting the stored dry air back through the drier. Overall, this means the drier should only contain water equivalent to one filling of the entire system. However, if there's been a leak, the pump will have been (a) running a lot more often that usual, and (b) drawing wet air through the drier but losing the extra through the leak, leaving the drier getting ever wetter.