The suspension on the current XJ, (the X351), is coil spring front and air spring rear. I did wonder perhaps if the front units would fit our cars, and give more options for replacing them when they fail. Both cars have CATS, so the dampers are compatible.

Mind you, if you have to get them from Jaguar dealers, there is probably no saving of cash, just a more reliable spring.

 

Lot of messing around trying to keep CATS working if you ditch the air shocks. The Air Suspension Module manages the CATS so you need to keep the air system, or somehow fool the ASM into thinking it's still there...

 

Interesting thought, Fraser, and good points, Cambo.

Leaving the height sensor in place and connected might be part of the solution, but we'd have to think through whether just capping the air lines for the front air springs would be sufficient, or if this would create ASM issues that would either trigger DTCs and fault modes or cause problems for regulating the rear air springs/ride height. The idea could be tested if you could come up with a way of temporarily sealing off the air lines and keeping the front air springs pressurized. Something along the lines of lcmjaguar's test rig might work:

https://www.jaguarforums.com/forum/x...4/#post1062760


Don

 

Reason I started this thread is because the steel coil spring/shock units on the current saloon have the CATS shocks, so there is no need to spoof the system, it is there on all four shocks. Of course, there is the matter of the front height sensor. I suppose one could lock this up somehow and then set the ASM calibration software to use the value it sends out. (which will never change, of course !).

 

It sounds good and I have to think there must be a reason for going to coils on the newer ones, but with the availability of coilover kits to do away with the whole system for the x350/358, I'm having a hard time justifying keeping the system.

Mind you I am going through this struggle right now. I need to replace the front struts on my car just to get it back home and while replacing the air components myself is the cheaper short term fix, the coils are a permanent long term fix.

 

Doesn't seem cost effective to me at all...

There isn't a part number for a complete front damper assembly for the X351, but I priced up the 7x individual parts to assemble it, UK list price is £428 for each corner plus VAT so £513 each for a local...

Compared to the aftermarket coilover kits...not even close to being economical. And good luck finding a wrecked X351 you can take the front struts from. Not only that there are different dampers and springs depending on the model and engine, there is some different tuning involved.

If you did find some for the right price you still have to get to work on the pneumatic side of things.

MoscowLeaper here on the forum fitted S-Type R suspension to his XJR, keeping the ASM connected to run the CATS, blanked off the air lines but the compressor is still needed to maintain the air in the reservoir otherwise it throws a fault message. The ride height also needs calibration after fitting to trick the ASM into thinking that the car is at the right height and no adjustment needed, or else it will be constantly "trying" to adjust the height, but nothing happens...

So, four S-Type shocks with CATS + a bit of messing around is an option, but you also need to drill new holes in the shock towers because the S-Type mounting flange is a different pattern.

And you have no adjustment of the ride height. We saw another forum member (can't remember his name now) also fitted non-CATS S-Type suspension to his X350, the ride height was noticeably higher because the X350 weighs less than the S...

Why did Jag go to a mix of conventional struts at the front and air struts at the rear on the X351? I think it was for two reasons;

1. The varying loads in the vehicle only really affect the rear ride height. I have seen this myself, had 5 people in the car, everyone jumped out together and the rear raised up about 2 inches, the front barely moved at all.

2. The front struts failing in the X350 was such a headache, that if they were not absolutely necessary for the X351 (which it seems they aren't), then they were out.

Interesting that the XF Sportbrake also has air shocks in the back, basically the same as the X351. You can load up a wagon with a lot of weight, so it makes sense.

As for keeping the CATS. Just my opinion but I think 9 out of 10 people could not tell the difference between cars with or without CATS, myself included, I couldn't tell you what they are doing from the drivers seat. The only time I've noticed it is when they all lock in firm mode as part of the Air Suspension Fault. But out on the track, couldn't tell at all...