Due to CATS system fault light I recently replaced rear struts with Arnott AS-2889 units and afterward found ride quality to be harsh. Experienced Jag mechanic diagnosed this as associated with the 2889 unit having an "emulator" (or simulator?) that apparently makes the computer think active suspension dampening is occurring and keeps the light off, but in the meantime active, real-time, suspension adjustments are not taking place. The mechanic discussed this with Arnott yesterday and I am getting ready to call them to see about a) a refund or b) if struts without emulator are available (other than from the dealer).

Has anyone seen this and have any comments? Thanks

 

Best if you'd come on here first before rushing out and buying the Arnott units; we'd have been able to tell you about the air suspension system.

The Jaguar X350 air suspension system uses Bilstein spring/damper units that alone have the ability to switch damper settings between Hard and Soft, (but note that there may be Far East copies). As far as I know, none of the Arnott units have this facility. Note that the spring rate, (the air spring), is never changed, it remains the same at all times.
The reason the Arnott units have the "emulator", is that with no CATS facility, the ASM would continually flag up a fault which would appear on gthe dash display every time the car was started; the emulator spoofs the ASM into thinking the units are switchable, but no switching takes place. If you really want to continue having CATS, then you need to install the Bilstein units, but be aware these are very expensive, (being German !!).
Having said all of the above, most people fitting Arnott units usually find the suspension OK. A lot of people even convert to coil spring units and again, find the suspension satisfactory. I owned two X350 saloons one after the other, and loved them a lot, but to be honest, I think the CATS system is a totallly OTT facility and unnecessary for cars driven at normal speeds on normal roads. I now have an XE with normal coil spring units, and no CATS, yet I find the car totally satisfactory suspensionwise. Sometimes these things are just fashions, and the car makers soon find out most people just don't want the complexity and the worry of potential big bills. Just having a reputation for this destroys the car's value in the used market, making the cars unattractive to buyers of the new cars who have to take a huge whallop of depreciation. The last Jaguar with air suspension, the last XJ saloon, only had it on the rear wheels, the fronts were coil, so I rest my case.

 

Welcome to the forums Falfurrias,

I've moved your question from General Tech Help to X350 forum. This is the appropriate place to post technical questions about your model.

Please read the guidance for new members ( https://www.jaguarforums.com/forum/n...ned-up-241802/ ) which answers many of the most frequent questions about getting started.

Graham

 

Thank you, sir. I spent a lot of time here, on Jag blogs, etc etc going through the dizzying array of questions, comments, points of view, and advice. In the end I came to the conclusion you referred to: Arnott air units will do. I also looked at Bilsteins and decided their price exceeded my pain threshold. Your CATS analysis is helpful in reassuring me about my decision. The mechanic said he'd installed coil-over for several customers who afterward didn't care for the ride, so between you and him my mind is at ease. Turns out I need fronts as well, so by next week all four corners will be Arnott air at about $500 a pop (plus labor but I don't feel like I've been plundered, as I did in my one experience with the dealer). For the record I also have a new compressor so hopefully no undercarriage concerns for the foreseeable future. Thanks again.

PS--The service manager at the dealer told me "we have only one or two techs who know how to work on these old cars." Maybe he meant "older," but I thought 2007 is old?!

 

Sixteen years, is old for most cars.

 

Yeah, you’re right. Most of my friends get a new car every three or four years. Besides the Jag, I have a 2001 Nissan Frontier that’s been a faithful friend and short of something catastrophic—knock on wood—we shall never part.

 

As already stated, only the Bilstein OEM struts actually have working CATS valving. Arnott has the module that fools the system into thinking CATS it there and responding, but no other non-Bilstein strut actually does CATS.

The 2889 is the correct rear strut for the "comfort" suspension, but part of your experience may be the mismatch between front and rear struts.

For myself, I changed out the air struts for Arnott coil-overs and couldn't be happier, as my air system was seriously damaged throughout by water intrusion. Valves were rusty and non functional, and water was sitting in the reservoir. The process to get working air would have been almost as much as I paid for the car, and not worth it at all. The air struts on my car when I bought it were Arnott. I don't blame the struts, I blame poor maintenance by previous owner(s), who apparently didn't know that even though it's not in the scheduled maintenance for the car, the compressor needs looking after once in a while, including new desiccant beads in the dryer chamber. My desiccant looked like clumped up cat litter, and the dryer chamber was actually a water tank. Knowing that there is no process for removing water trapped in the system, I simply abandoned the air and put on coilovers.