It is that time of the year again, where I feel like taking on some Jag project. This time, I want to continue the suspension overhaul, in the quest for an "as new" handling. Last year I replaced pretty much all suspension bushings, engine mounts and ball joints, and this year I want to tackle the remaining parts.

The current suspension symptoms I have:

- Abnormal amount of rattling on bad roads
- Clunk when driving over speed bumps etc.
- Front end low: FL 14.2, FR 14.5
- Cornering feels a bit boat-like, worse than my X5.
- Very soft feel when pushing down on trunk while parked. Even light touches seem to get the car moving. (my BMW's feel rock solid in comparison)

I guess the front upper shock mounts are bad, so these are a must. The other symptoms I attribute to the shocks. Since I have the CATS shocks, this would turn into a rather expensive operation, so I'm thinking to go with the standard B4 shocks and simply unplug the CATS controller.

The question I now have is, would it make a difference if I also replace the springs, or can I keep using the originals? They look to be in a decent condition.


Thanks for any opinions!

 

I don't think replacing adaptive dampers with standard is entirely straighforward but I post this more as a question than an answer!

With Adaptive Damping, the dampers default to 'firm' if there's a fault in the harness or a damper solenoid. This sets a Cxxxx error code to indicate which damper and displays an amber SUSPENSION FAULT warning in the Message Centre.

If you disconnect the ADCM (Adaptive Damping Control Module), the signals from the two vertical movement sensors (accelerometers) and the lateral movement sensor (accelerometer) could set further error codes.

I also expect the ADCM is programmed to the vehicle as part of the 'module set' and it could take some reprogramming with dealer level diagnostics to setup again without the ADCM in the loop.

Graham

 

I have already read in some threads, that unplugging the CATS module should cause no permanent error codes. This thread describes the feeling I have with the suspension rather well, and he replaced all shocks with the non-CATS standard version, unplugging the CATS module:

https://www.jaguarforums.com/forum/x...-*****-100701/

 

No problems disconnecting the CATS system, unlike so many other things, it is completely self contained.

If the height is within 0.5" or so then the shock mounts will likely cure it. If it is a lot more than that then the springs may be starting to sag.

If you do need springs, new stock replacements can be hard to find. I wasn't able to so ended up with a set of Adamesh springs as they have the smallest lowering.

 

Azeteg, how difficult was it to replace the ball joints?

 

Quite involved. It involved driving to the indy's garage, then picking the car up the next day.

I still haven't decided whether to also replace the springs. Anyone that has done so, and would like to share their thoughts?

 

Procedure for springs may be the same two steps as the ball joints. Drop it off & pick it up.

If you decide to DIY, have the shop compress the springs and assemble it for you. Much easier and safer to pull them and replace if that is done. Make sure the springs are rated for your year and model. Coupe vs. convertible matters!

 

My car has 150k miles, and still on the original springs. My ride height is great...I can get current numbers for you if you like. (car is at home) New upper mount, shocks, spring assister (see below), control arm bushings, tie rod ends, sway bar end links and sway bar bushings.

 

Would be great if you could post me the ride heights!

I'm thinking about going with the original springs. I have just a bit above 100k miles on the car, and I've read some posts that the existing lowering springs lower a bit too much (yes, even the Bearmach/Eibach 10mm ones).

When this little project is done, I hope to have a close-to-new handling car. Did bushings, bearings and ball-joints, tie-rods last year, and u-joints the year before. But I have a feeling I want to get new tires as well once the new upper mounts and shocks are in place

 

I think that cars with CATs have specific springs, so if you move to standard shocks you will need to get springs to match. I have been checking on the sng and rimmer bros web sites and it is not clear to me.

 

The JEPC only shows a different spring for the "R Performance" option, and for the convertible. I have the regular convertible with CATS, and cannot find anything about a specific spring just for hte CATS system.

 

azeteg, here are my numbers and gas tank is 1/2 full

LF - 15.2 RF - 15.4
LR - 16.0 RR - 16.1

 

Is there a diff from the XK8 to XKR in front ride height? I've seen these numbers before and while the rear is in line, my fronts are 14 7/8" so they are a bit low, orig springs/cats... not a problem with clearance etc just curious if my springs were flattening out.

 

Sorry for the misinformation on the XKR, I also called Jag yesterday and asked them for the part number for my car , my2003 XK8 + CATS + Super Sports Suspension and was told that the spring fitted to my car was the JLM20706 (red+purple marking), which may be different to the standard XK8 part JLM20712.


PS I'm still none the wiser as to what the "super sports suspension" listed on the build sheet is.