Part of me wonders what the big deal is about air suspension, but then again I am driving a 12 year old car with (I am pretty sure) original struts. I am getting an suspension fault message on the dash indicating suspension is low, and I don't always hear the compressor either. Also, sometimes when it is really cold in the winter time the suspension won't lift which I am thinking means the seals on the struts are getting worn out maybe? I wouldn't say the ride is as nice as I think it should be. Also, there seems to be a lot more road noise than my friends BMW 540 but someone said the aluminum cars are noisier. Not sure why though. But I digress....

I have been thinking about replacing the struts but I may spread the cost out by doing two now and the other two later one.

Question. Does it matter if I replace the front or rear first? Also, is it probably smart to also replace the air compressor at the same time?

I appreciate the help. Peter

 

Fronts seem to go first, from braking, shifting the weight forward.
Rears seem to last longer.
The compressors can often be refurbished.
The piston ring, head, as well as other parts, are available

 

If you have the money, buy four new air springs, a Bagpipping Andy compressor rebuild kit and check all the hoses with sprayed on soapy water to ensure no leaks. The ones in the boot (trunk) are easy to access. Check them first.

Compressor: If you rebuild, see Air Suspension Compressor Rebuild - Part 4 of 7 Owner: Don B about "cooking" the moisture out of the desiccant. If you determine the compressor is broken and not rebuildable, first a Warning: do not buy the compressor, nor the air springs from RMT in Florida. Buy a new Wabco brand compressor.

Air Springs: Most people say the Arnott air springs are reliable and come with lifetime warranty.

You can install all of the above yourself with basic tools. Just be careful not to break delicate bolts.

Suspension: At the same time, check all the suspension parts. Bushes (rubber bits) wear out, and best practice is to replace all of them, all the ball joints and other moving parts in both the front and rear suspension. A Jaguar should run like a magic carpet, smooth and quiet. If you are tight on money, only replace what needs to be replaced, but in my experience, if you do have the surplus cash replacing everything that tends to wear out makes the car ride like new. I do this with all my cars, not just Jag.

Road noise, check to ensure you have quiet tires.

Regarding aluminium bodies being noisier, have a read of this 2004 Car and Driver road test of the new XJR

Lighter the new car may be; noisier it is not. Quieter camshaft drive chains and tuned induction paths have helped reduce engine noise, and numerous procedures and material applications throughout the car have made the new XJR especially calm inside. Even the Eaton blower's noise is subdued until operating at high speed and full throttle. Like a singer in a chorus awaiting a cue, the blower saves its song for high-performance driving. Then, to confirm the contribution it's making to the car's greatly hastened progress, the whine suddenly rises above the mellow growl of the V-8.

Even wind noise is low in the new XJR, thanks to careful body sculpting and triple door seals. Enthusiasts might consider the new XJs too quiet, but Jaguar devotees will undoubtedly appreciate the levels of refinement. The suspension is a case in point. By using air springs, Jaguar engineers have provided automatic ride leveling and quite remarkable body-motion control without having to use particularly firm spring rates.

By eliminating the steel coils in conventional springs, the Jag people have also removed one of the paths that conduct vibration into the body. In this category of car, it seems air springs are becoming par for the course. Considering how well the XJR handles and corners, the ride is remarkably civil. Even here the sense of lightness prevails. The XJR glides over imperfections and only jogs a bit when confronting bad pavement breaks. Special plastic wheel-housing liners help reduce the sounds the tires make in their war with bumps, but the 19-inch 40-series Pirelli P Zeros on our car did relay the roar of rough road texture into the cabin when the surfaces got grainy. Just not loudly.

 

Replace the fronts only, to start with, the bill will be easier to swallow.
The rears usually last much much longer

 

Thanks Wingrider. Fronts it is! Peter

 

Thank you for the additional detail. The advice is very much appreciated.

Peter

 

It should be noted that the Arnott's only adjust for ride height. Unlike the factory air springs, they do not adjust for side sway nor front and rear pitch. Your original factory air springs can be rebuilt by Rebuild Master Tech. Some people have had to get a second set from RMT, but they make good on their work. I had RMT rebuild my factory air springs about a year ago and have had no trouble with them (2006 VDP).

 

Make sure your compressor is working first. It can cause your failure since it may not put out enough air in the time allotted before a fault is logged. It is the cheapest place to start.

 

Are you saying that the Arnott's don't work with the CATS system??

 

I'm glad to see a positive story from an RMT strut, however, buyer beware as both the ones sent to me failed. One out of the box and the other about 5 weeks down the track. See my post RMT Replacement and Hauntings. I not sure how common this is and I got a pair of decent battle clubs to be fair. Perhaps you could fill them with that emergency tyre stuff lol...

 

As I commented above, the international experience with RMT is not good, and a google search will find many unhappy customers.

It's a family business, but it seems to be more like the Bunkers than the Nelsons
RMT has quality control problems, sending out defective products, which may work if you are in the US and don't mind the shipping back and forth until you get a good set. But overseas it means long waits for defective parts where they ignore emails and only act when you ring them... and then are snarky about it. Return postage is more than the refund they will give, making RMT parts tuition in the school of hard knocks. Then again I've spent more on taking the family to town for a birthday dinner; it's mostly just annoying when spending money on luxury should be a pleasure.

There is an alternative. I found this company in Germany: https://www.air-suspension-shop.com/...front-BILSTEIN. 737,59 € includes VAT which I presume is German 19%, which means 619€ each or about US $730 each as opposed to RMT rebuild for about $285 each. Yes, $3,000 for a set of four is not cheap - about the price of a return ticket for the family to LHR back in the days when people took overseas holidays (sigh), but you bring the Jag performance back to new.

It really all depends on how long you intend to keep your X350. If it is a lifer car, meaning at least ten years, then it's just part of the fun. If you are shopping, best to find one good shape but needing new air shocks and then negotiate down on the suspension so you start with new. The air springs need to be understood as a consumable, like tyres and brakes. They will fail. If you pay $5,000 for the car, just put $3,000 in the bank to be sent to Germany when (not if) the air springs fail, and you will be fine.

There are many alternatives including Arnott that just do the air part, not the computer-controlled shocks, or you can bag the system entirely and using Arnott coil-over shocks. But then it's not the original brilliant Jaguar experience.

Your money, your choice.

 

Arnotts do not have the CATS system. They do not stiffen the ride on command the way the Bilsteins can.