Dear Forum,
I continually see posts describing various ways to replace the CATS system on our X350's, and I am interested to know why this is desirable? I can see that replacement air-shocks are ridiculously expensive, but I understand that seal kits are available at reasonable prices - Do they not work?
I also note that the X351's have replaced the front air-shocks (correct me if I am wrong) with conventional shocks and springs (yet retained the air at the rear) and (again) I am interested to know why?
?

 

There are seal kits for the compressor, not for the spring assemblies. You would need some factory equipment to re-manufacture the springs, if it's even possible.

Yes, the aftermarket options do loose the active shock technology. But it's a practical consideration on 10+ year old vehicles that would be outvalued by the price of 4 OEM springs.

Jaguar was well aware of the issues plaguing the 4 wheel air suspension on the x350. The x351 has rear air springs/leveling so that the vehicle is correct stance no matter how the trunk is loaded. This was the way almost all luxury cars were done from the 1950s on (load leveling, not air suspension). The front suspension doesn't see load changes like the rear does, the front stance almost doesn't change based on vehicle loading. Also if the rear air springs fail, you could still get the car home. The front fails and you're on the hook.

For a more philosophical answer, the late 90s and early 2000s Jag was trying to climb the ladder of the luxury car market and "had" to compete with cars like the S-class Mercedes. All the Euro luxury cars had air suspensions. Those years were a constant battle of one-upmanships between the makes. Look at how the x351 now has a self-closing trunk and soft close doors. Not necessary except to look good in a spec sheet.

 

Hello Michael,
I get cost on a 10 year old car - even if you have replaced all the bushes and control arms!
So do you think that CATS is a bit of a gimmick? The pumping of air to the 'loaded' side to reduce body roll doesn't really work? Have Mercedes ditched front air struts?

 

Oh--there's a misunderstanding. CATS is not part of the air system. CATS is electronic shock valving that can firm up any shock depending on conditions. This operates completely independently of air in the spring. Yes, this system does work and you can notice the difference. But after 10 years, a new passive shock is going to work better than the original active shock.

I'm not up on the latest Merc model specs, but I think air suspension is optional, or maybe only on the top range models. Around the time the Jag x350 debuted the air suspension was standard on Mercedes S class, I remember my aunt was going to buy one to replace her W140 and even the S320 had air ride.

 

Thanks Michael, I'll have to read up a bit more on this subject - Right now I cannot picture how you firm up a straightforward shock absorber......electronically?
Please don't trouble yourself to reply - I need to do a bit of simple research!
Regards,
Ray

 

Google "magnetorheological dampers"

 

EsRay; Regarding x350 CATS varying damping rate in the 'air shock':
https://www.jaguarforums.com/forum/x...t-away-143111/

This photo thread shows the air spring (bladder) at the top of the assembly (connected to the air supply) and the damper (shock absorber) with the integral solenoid at the bottom of the assembly. It seems the default condition for the damper is partial restriction of the fluid movement. Actuation of the solenoid exposes additional paths for fluid flow thus reducing the damping effect.

Best Regards, William

 

This forum is awesome....you guys are geeks!!
Griff