XJ XJ6 / XJ8 / XJR ( X350 & X358 ) 2003 - 2009

dumb air suspension question

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Old 03-21-2021, 12:14 PM
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Default dumb air suspension question

I'm trying to confirm whether we have adaptive air suspension and too many threads show up with the word adaptive. The reason for the ask is because my tester asks me if the jag has adaptive suspension or not before it pulls data. It is Jag-specific, so it makes me wonder if some were and some were not. Data it pulls seems to be the same, but when I order replacement front shocks, I want to make sure I'm getting the correct ones.

'05 x350 LWB

Thanks,

Gordon
 
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Old 03-21-2021, 12:19 PM
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pretty sure all of them have ecats “adaptive” shocks

the factory tool asks if the car has B6 armor plating and the interior scanning alarm
 
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Old 03-21-2021, 06:37 PM
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It's not adaptive as in active suspension, the air fill is much too slow for that. The CATS system is adaptive shocks, which the ride control module can use to change the damping. CATS has nothing to do with ride height, but the air suspension computer controls it. They all came with it, aftermarket shocks won't have it, but they'll either have resistors to simulate the function back to the controller, or you get a CATS error on the dashboard.
 
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Old 03-25-2021, 01:14 AM
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Originally Posted by wfooshee
It's not adaptive as in active suspension, the air fill is much too slow for that. The CATS system is adaptive shocks, which the ride control module can use to change the damping. CATS has nothing to do with ride height, but the air suspension computer controls it. They all came with it, aftermarket shocks won't have it, but they'll either have resistors to simulate the function back to the controller, or you get a CATS error on the dashboard.
I did notice that some of the shocks say "comfort ride". I'm guessing that just means that the shock in the replacement is a comfort rather than a 'sport' damping.

Anyone have suggestions on decent ones that are no more than about $500/pair? I've looked at RockAuto as well as Amazon and there are various brands in that price range. Also, I heard they are easy to replace. I haven't looked under the car but the top part is a no-brainer. Wife is going to be visiting our daughter for three weeks (daughter is about to have a baby), so it would be perfect time for me to change them out.
 
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Old 03-26-2021, 08:47 AM
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Hey Gordon,

- You have the "comfort" air struts ("Sport" are XJR; XJ8L = "Comfort")
- New air struts (Bilstein) are ~ $1,600 per pair, IIRC; (from dealer they're twice that)
- I have a complete set of four "Comfort" RMT rebuilt air struts still new in boxes ( RMT misplaced my XJR "Sport" cores and sent me "Comfort"; I finally ended up using Arnott sport coilovers instead). Shoot me a PM if you're interested; I'll sell 'em to you for $500 set of four
 
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Old 03-26-2021, 11:20 AM
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The difference in Comfort and Sport is actually the volume of the air bag in the strut. Sport has a smaller volume, thus less "give" on compression, i.e. stiffer.

 
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Old 03-26-2021, 01:37 PM
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The suspension can never be too "comfort" if you ask me. Which you didn't. I don't even agree with 19" wheels apart from looking cool.

<rant> Local hospital has put in some terrible speed bumps. So all the patients in with broken backs, they get discharged, and on the way out break their backs again and have to do a U-turn. Even with CATS. Number of pedestrians run-over in the hospital grounds = 0.

I feel better now. Thank you.
-------------
As far as I can tell, using Wikipedia for definitions, it's both active and adaptive, albeit in several parts as mentioned (the shocks and the airbags)
The better question is whether it's Sleepy.
 

Last edited by ChrisMills; 03-26-2021 at 01:47 PM.
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Old 03-26-2021, 02:22 PM
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It is important to separate out the spring element and the damper element that are contained in the single strut unit. The air spring is not varied other than to set the height of the suspension. So, if you load several bags of cement in the trunk, the system will cause air to go into the rear shocks to restore the ride height. The damper is varied using a solenoid buried in the strut. However this only works to vary the damping from Hard to Soft by supplying a voltage to the solenoid. Thus the damping only has two states, Hard or Soft, with Hard being the default when no voltage is supplied to the solenoid. My personal view is that CATS is a real PITA and totally unnecessary in normal driving on the highway. I suppose it gave some under-employed engineers something to do. Quite why Jaguar installed this is beyond me. Everybody would be a lot better off it "Cleverclogs" was pensioned off !!
 
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Old 03-29-2021, 10:07 AM
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Originally Posted by hisport
Hey Gordon,

- You have the "comfort" air struts ("Sport" are XJR; XJ8L = "Comfort")
- New air struts (Bilstein) are ~ $1,600 per pair, IIRC; (from dealer they're twice that)
- I have a complete set of four "Comfort" RMT rebuilt air struts still new in boxes ( RMT misplaced my XJR "Sport" cores and sent me "Comfort"; I finally ended up using Arnott sport coilovers instead). Shoot me a PM if you're interested; I'll sell 'em to you for $500 set of four
I IM'ed you with my email address.
 
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