I've never been too sure about the whole CATS thing if I'm honest, in the fact that I don't know if or when it's working. But, if I understand it correctly then I shouldn't be able to - as far as I'm aware it is capable of continuously adjusting the stiffness of the dampers using a PWM signal (i.e. not just on and off), and is used mainly during acceleration, braking, and cornering. There is a document floating around about the theory of operation which I'll see if I can find.
So lc3566 when you talk about it being a better car to drive when it sets the shocks to firm, I just don't think that it works that way, unless I'm very much mistaken. You shouldn't be able to detect whether it's firm or soft as it's continuously adjusting and doesn't just switch between two modes. But maybe I'm wrong?

I did read somewhere that with the CATS connector unplugged they should default to firm mode, so maybe a good test is to unplug them and see if it makes any difference. Perhaps I'll give that a try.
I agree that having one side with CATS and one without could be a little strange. I've still not noticed any difference but I'll report back when I've done a few more miles.

Ben

 

On my car, the difference between the firm and soft setting is very noticeable indeed. I'm speculating that this is because the damper cores of my shocks are excessively worn, the worst one being my front O/S. I notice the change in setting the most on heavy acceleration/braking. Under these conditions the handling is much improved, with far less rebound from the worn dampers. When settling down to normal smooth cruising at a fairly constant speed - I can feel the change to soft, the hanldling deteriorates becoming very bouncy and "squishy". I also notice the suspension firm up on the motorway, usually where there are dips - or when the camber changes suddenly. I can feel each side of the car firm up seperately, according to which way the camber has shifted. (I have an early car with 4 sensors) I had no idea that unplugging the CATS connectors would make the car stay on firm, I'm seriously tempted to try this myself!
I believe there were many changes to the ASM over time, when I replaced mine - I had a hard time finding the right unit for my car, there were many different generations. It would be interesting to know what kind of changes/improvements were made with the later 350 & 358 modules.

 

Interesting indeed, I've never been able to tell when CATS is adjusting the firmness of the dampers, in fact I've often thought that my car is a little on the firm side all the time and wondering if CATS is even working at all. The reason for this I thought was clear after I read the Etis specification sheet for my car which stated that it had been built with the sport shocks instead of the usual comfort shocks. However after physically checking the air-springs they do have the green dot of the comfort version and not the red Sport version, so this doesn't really make sense.

Your theory about worn dampers sounds plausible, and along that line I was not quite correct when said that I hadn't felt any problems with my old air-spring unit other than the noise - I had forgotten that in fact I had felt a little wobble through the steering wheel which I had put down to a wheel imbalance, however with the new air-spring that is much better, so there must have been a bit of 'slack' in the damping action (I assume something was loose or worn inside and making the boinging type of noise).

Having driven a bit more in the car with the replacement air-spring I still can't feel any difference in softness/firmness from the original one. It would be quite interesting to understand more about how CATS switches from firm to soft mode, and it would be fun to build a little monitoring tool with an arduino to monitor the signals to each shock and display with a set of LEDs to show when the shocks switch from firm to soft mode. It could easily be designed with a manual over-ride to force the system into soft or firm mode. Not sure if I will find the time to make it though!

Ben

 

Anybody know if pressing the 'sport' button is meant to adjust the stiffness of the struts at all or does it just alter the transmission shift points?

 

It only alters the transmission shift pattern, CATS is separate and part of the ASM module.

 

I have a friend who's very handy with an arduino - don't think I could ever persuade him to tinker with my XJ though! My other theory regarding the inconsistent handling I experience is connected to the way I use the car. It's my daily runabout & typically I use it for urban journeys of less than 5 miles. I rarely have the chance to drive above 25mph for long enough for the compressor to cycle normally. Perhaps this means that my shocks are frequently below optimum pressure, causing a softer than normal ride. Either that, or I have leaks as well as worn dampers! (No dash faults at the moment though) I like the air ride (when it works) so I'll keep looking for low mileage used options. The Chinese option sounds worth considering, I hope yours continues to work well - would be great to hear back from you when you've stuck a few more miles on it.

 

Update:
I may have got lucky - found someone near me who is breaking a couple of X358s. Does anyone know if the air shocks are exactly the same on a 358 as they are on an early 350?
I'm waiting for the breaker to get back to me regarding price & mileage of the donor vehicles, I have my fingers crossed...........!

 

To parrot 89 Jacobra, Chinese "bargain" replacement parts are NO BARGAIN! Shipping takes weeks and when they get to their destination, the packaging is in tatters if not the merchandise as well. And don't even dream about instructions. I had an insignificant package arrive so long after placing the order, I was truly surprised at the "gift" I thought I'd received! NEVER AGAIN.

 

I have had pretty good luck with Chinese made products. Many products sold as "American" originate in China anyway.

However having said that anything that is of significant weight will cost an arm and a leg to ship back for a refund. Anything over a couple of pounds will cost a lot in shipping to China.

 

How about these?

https://aerosus.com/jaguar/xj-series...uspension.html

Trustpilot looks okay and they appear to offer the German TUV Certification and a two-year warranty?

 

Okay, perhaps nobody has experience of this particular provider? I was hoping someone would answer 'Should I stay or Should I go' (The Clash)?

Please let me explain my dilemma to you. If I was back in the UK, I would buy a Bilstein OEM shock to keep the ECATS that is so much a part of what the improvements (which include the aluminum construction and the 4.2 litre engine) of this X350 were over (what was an outstanding) X308!

However, I will probably be back in the UK within the next 2-5 years, and when I do return (after living and working for 18 years abroad), I will be leaving this (so far) very expensively OEM restored left-hand drive Jaguar behind me in Dubai....

I will not get my money back on it - They don't do 'Classic' here - 'Classic' means 'Old'!

I had the shock that is leaking replaced just six months ago! Unfortunately, the mechanic here in Dubai has obviously used a cheap and nasty Chinese aftermarket shock (in fairness he only charged me GBP265 including fitting). If this Aerosus (half the price of OEM) shock is Chinese and similar (in quality) to his, then it will not be worth me forking out the USD68 to have it shipped to me and fit it myself - I might as well pay another GBP265 and have my 'mechanic' fit something that will probably fail again six months hence!
However, this Aerosus shock does appear to offer German TUV Certification and a two-year warranty. I have checked and if the unit fails during the next two years, (although from Dubai I would have to pay the USD60-odd cost of shipping it back to them in Germany), they would then ship me a replacement free of any charges?
Anyway, 'Needs Must When The Devil Drives', so I have gone for it and I will keep you posted on the results!

 

Best of luck

 

If it is of any help to you and the forum, I have just fitted a set of MAXpeedingrods fully adjustable, to my 2006 X350. The dampers can be adjusted from race track to luxury with just the turn of a wee knob on the top of the shock. The height is adjustable also and is easy to do as is the coil spring pre tension. My X350 has travelled 94,000kms and had the front bilsteins replaced 2 years ago, then 4 months later the knocking and banging started again so the left side unit was replaced under warrantee. The initial cost for the fronts was $5.156nz but thankfully I hade a breakdown insurance. Just recently, the rears started knocking as did the fronts again, I might add that our roads are less than motorway here and some not even sealed so have come to the conclusion that air suspension won't tolerate rough roads hence the decision to go to coil over adjustable. I bought the kit from eBay in China at the cost of $995nz. The freight to New Zealand was about half of that but I had them in 15 days. This morning I did a road test and tried various damper settings but settled on the softest, that may change after a longer test. Personally, I couldn't justify spend more than I paid for the car on suspension over the next few years. Hope this has been of help.

 

Been reading good things about Suncore air suspension products. Don't know if they have UK distribution.

https://suncoreindustries.com/produc...x350-xj-series

 

Fitted both front shocks and a pump to my xjr. It feels exactly the same as it did on the original set up and came in at under £600 for the lot. My original original left shock was leaking so thought it would be best to change both. It all has a 2 year warranty to

 

This morning did a drive for half an hour on the new MAXpeedingrods coilover suspension. Very rough rural roads and it was noticeable that the ride quality was not nearly as good as the air suspension. It was also noticeable that when going over the small rough bridges, the clunking and banging that was annoying with the Billsteins, was not there, just silent. Mission accomplished. On smooth roads there was no difference between coils & air.