Recently got a '03 XJR (X308) and have a question regarding suspension.

I have determined the car has the dampening style shocks rather than air suspension. Does it only have the dampening on front axle, or is rear axle similarly equipped?

How can I make sure the electronics are functioning properly before I invest in shocks?

Any help provided is very much appreciated.

 

Air was the next model (X350) The 308 has gas shocks and springs. They came either 'Active' with the car equipped with CATS or computer aided tech suspension, and standard. The difference with the cats cars is 2 settings, normal and sport where the shock stiffens in hard driving.

You can tell which type you have by looking under the bonnet, the top of the shock has either a black plastic cover and a wiring harness attached (CATS) or plain, non-cats.

It is the same at all four corners. If replacing I'd suggest Bilstein as they were fitted as standard, you can also get them rebuilt.

 

I appreciate the response! However, how do I determine if the CATS is properly functioning before investing in shocks? Where is the switch located for the two different settings? Is it the switch by the gear shift with a "S" and a red light that illuminates when the switch is in the "UP" position?

 

That's the Sport button which you'll notice more in the 1st gear take off in the transmission, more than anything. It's not a really easy thing to notice the shocks working, but from past threads, the CATS shocks are pretty robust, and last quite a while. There's also a module that monitors them and will throw an error message on the dash, but I also believe that if they go wonky, they get "locked" in the firm setting, and might be more noticeable. What kind of symptoms are you having that have you wondering if it's time to replace them?

 

There is no switch for soft-hard settings of the dampers. They operate automatically - hard at very low speeds (up to ~10 km/h, I think) soft thereafter and also switch to hard during harder cornering (to reduce the roll) and during harder breaking (to reduce the nose dive). This operation is not really noticeable so, in order to test the system, you can unplug one of the front shock connectors and this should show an error message on the instrument panel. If the message goes away when you reconnect, the system should be fine.

 

Thanks to both of you for the response(s)

I'll try unplugging one of the fronts and see what happens.

As far as symptoms, it feels as if I have a constant "churning" while driving (speed does not seem to make any appreciable difference).

I'd love to not have to spend several hundred dollars on shocks if it can be avoided.

 

The common failures of the dampers are: 1. they lose gas pressure which causes the car to sit noticeable lower, could be as much as 2 in. at the front and 2. they become "loose" causing the suspension to be bouncy. You can try to classic method - "bounce" every corner of the car and see whether the body, after you have stopped pressing, makes a couple of bounces or whether it steadies immediately.

 

I am wondering what happens when it is "churning?" Skittish, bouncing up and down, not settling after bumps, control issues in high speed turns? Never have heard the term churning (except in making butter).

Lots of things can cause suspension issues and wandering after going over bumps: shocks are an obvious, but also links, shock mounts in these cars (that orange thingy at the top of the shock, either CAT or regular, bad tire balance or alignment, bad tie rods, and on and on.

Tell us more and let us know if you have CATs or regular shocks, please.

 

Churning, as I viewed it is a agitated feeling (not unlike a churning stomach). I installed Michelin Pilot Sport A/S 3+ with dealership balancing and alignment. Also has new Moog tie rod ends.at time of alignment. Ball joints, etc. deemed good. (for that matter, the tie rod ends were good, but has large cracks in the rubber boots)

A earlier post indicated it has the CATS system.

I'm coming to the conclusion the shock mounts (or as you called them "that orange thingy at the top of the shock") are the most likely culprit.

The agitated (churning) feeling is not unlike driving on very fine pea gravel (perhaps a mechanical resonance)

 

There are now reasonably priced replacements upper mounts with new bushing (both Uro and Mahle) from many of the on-line parts suppliers. For seventy bucks and thirty minutes per side (mostly to set the jack to take pressure off the mount) you should get a better ride and much quieter, especially when it is cold outside. I would stay away from hard, polyurethane inserts for the old mounts -- too hard and rattle when cold and requires a press to remove). The mounts are different for CATS vs green or black Bilsteins (different hole size). But, lower mount bushings deteriorate, as well.

Next to check: the drag links (pretty cheap and quick install) and front sway bar bushings. But just for s. . . s and grins, might want to check the wheel bearings. In the end, maybe need to replace the shocks, if for no other reason than it is a quick fix of the lower mount bushings.

 

You've gotten my curiosity aroused....."The mounts are different for CATS vs green or black Bilsteins (different hole size)".......

The car has the CATS system (as verified by wiring attached to tops of shocks), but the shock bodies are green. Does not say Bilstein, but rather, Jaguar.

What the heck do I have here?

 

As far as I know, green are sport and black are comfort dampers. Both colours come in two versions - CATS or non-CATS. The CATS type dampers (green or black) have thicker shafts thus larger hole in the top mount. I believe that the XJRs usually came with green (sport) shocks but one can probably go for the black (comfort) if this is preferred.

 

Yep. Although the shock says Jaguar, they are made by Bilstein. So if you order new upper mounts, make sure to order the ones for CAT suspensions. But the more I think about it, the more I think your issue is most likely badly worn lower mount bushings. They can be renewed, but most just buy new shocks which come with new bushings.

 

Just to add, if you DO go with new lower bushings - it doesn't take much to pull the shocks off and have the old pressed out and the new put in - but make sure you or whoever does it is gentle. There's a slight taper in from the outside. It's easy to see it when you look at the new bushings, but if you use too large a die to press the old out, you can end up basically shaving down the inside of the barrel which isn't a good thing. Other than that though, they're relatively inexpensive to replace.

 

What would happen if one were to put regular shocks on (not the dampening style) will this create any issues with the CATS?

 

It'll throw an error, but you can unplug the CATS module in the passenger side footwell to disable that. But you will need to purchase new upper mounts as the shock shaft diameter is different from the CATS to the Non-CATS versions. Also you'll want to make sure you do all four corners, since with the CATS disabled, they'll act harsher and that's not what you want on one end to the other. Otherwise no, works fine. I've had standards on mine going on three years now. Also, for an XJR, definitely go with Bilsteins. The KYBs, while cheaper, just don't hold up as well depending on your environment and driving conditions.

 

Thanks a million for the good info passed along by all you fine folks!

We have the car getting a new sound system with fore, aft and side looking cameras installed, but as soon as it is back in our garage I'll get into the solution of the issues I have been raising questions about.

In the not too far distant future I'll get some pix posted so y'all' can see what we've been working on.

Again, thanks a million!!

Mike