My 2000XKR (w/68k miles) has CATS dampers/shocks. I hear a thumping when going over rough roads. I can't really tell if it's front or back or both. I've srcutinized the suspension and all the bushings look really good...the car is "clean" underneath and the ball joints feel good when 2x4 tested. I can't see the tops of the dampers to inspect the cushions...could it be just them, or more likely the dampers themselves? They seem to perform okay but the thumping definetly doesn't sound right.

From other discussions I've read, the CATS suspension is not popular with the "spirited driving" enthusiasts. If you install "regular" shocks will you get a fault light?

Can someone please lead me to the thread where this may have been discussed in detail?

 

Personally I hate CATS suspension, if it was easy to remove I would do it but alas you will get a fault code and getting rid of that is possible but not easy, so I have been told.

As to your knock, all I can suggest is a little test I do for customers, lay down next to the car and feel underneath with your hand the bottom of the damper, then get someone to gently bounce the car, you will feel the knock if it is the bush, they may look good, does not necessarily mean they are.

HTH

 

As regards pushing down on the fenders of the car to induce a "bouncing" motion; I have tried this front and back on my 2005 XKR coupe and get very little vertical displacement. In the front I can get about one half inch (1.27 cm). On the back I can get about 1 inch (2.54 cm). The return is quick and the bounce is almost imperceptible. The car is a 2005 with 50k miles on the clock. Is this typical and do others on the Forum have the same findings?

Thanks for the reply.

TV

 

Plus if the shock does go bad you should be able to see that that damper has been leaking, it will look kinda greasy and dirty on the lower part. If not it is likely a bushing or possibly a sway bar link or bushing, check everything out before you purchase! good luck. Let us know what you find.

 

So a thumping over rough pavement is not normal in these suspensions?

XKRacer...what "bush" are you referring too? The shock lower bushing?
I have a lift so I can see everything underneath. The shocks are not leaking, the sway bar bushings at the frame and links are good (and no leaking of power steering fluid that could deteriorate them), the upper and lower control arm bushings show no signs of deterioration, the lower shock bushing looks good too. I've pryed on all the joints and nothing seems to have any freeplay or movement. The car/steering feels tight when driving and jerking the steering wheel hard from side to side, and there is no thumping on smooth pavement.

So??? it's possible the CATS dampers can be worn, but since the fluid can still be magnetized, or internal valving still works (not sure how these are designed to work) by the control module no fault will show? That's why I'm suspecting the shock mounts. Is it common for the upper cushions to disintegrate and cause the noise, or would it be pretty obvious with sloppy feeling suspension?

PS, the car had warranty work at 22k miles to:
"REPL FT BUSHINGS, BOTH LOWER BUSHING, 2 MNE-1360BB BUSH-WISHBO"
also says "21038 COMPLETE REPLACED CRACKED BUSHINGS, 2.7 hrs"

Isn't that a bit unusual to have lower bushes "crack" at 22k miles?

 

I am referring to below



To check the way I do you really need the car on the floor with the weight on it and just rest your hand under the bush/damper, a bit of a bounce and if there is any movement at all you will feel it. Just looking at them and even getting a pry bar in there will not always tell you if there is a prob.


I have seen bushes crack with only 5000 miles.....but the car was 10 years old and it was from lack of use the bushes had gone brittle!

 

I had a "Rattle" in my Left Rear CATS Shock at 15000 mi.
I could "Feel" the noise using XKRacer's test. It was NOT the Bushing. It was the Shock itself. This was 8yr ago and Both Rear Shocks were replaced by the Jag Dealer under the New Car Warranty. The noise was gone.

 

I was wondering about regular shocks vs the active CATS system for when mine need replacing. I was hoping they were like my old Cadillac Eldorado that I replaced with regular struts and I took it to a guy at the dealer and he pushed a few buttons, got into the program mode, and and presto, took off the warning light. I figured it wouldn't be so easy on a Jag... but was hoping.

 

How about the upper mounts? Are they crumbling and offcenter?

 

Thanks for the inputs..haven't had time to check things out yet.

Have spent last 2 days tracking down a shorted wire in an 86 Nissan 300ZX. I'd done a partial restoration, and paint and body-work on it last year. The owner hasn't been able to drive it at night as all the perimeter lights, dash lights etc keeps blowing a fuse. He swore it all worked when he brought it to me (was a 9 month restoration) Well after tearing it all apart...pulling out the interior, disconnecting everything; front bulk head connectors, cluster, ad-infinitime, etc I found the shorted wire. A little indictor lamp wire going to the radio was broken and touching metal. Seems he'd put in an aftermarket radio and caused the problem which was evidently intermitent. I was so relieved...I didn't touch the dash during the restoration..now I can charge him.

I wired a 56 Chevy last week. So I earned enough to buy, and ordered today from Jason the .....

NAMELESS PERFORMANCE CATS (catalytic converters)...ironic in that I may have to buy CATS dampers when I figure out what's causing the "thumping" on rough roads.

 

Yep that can be correct, it is something that is hard to describe as you learn which type of knock comes from which part.

If it is the bush it is a definate 'thud' in your hand, you can even place your thumb over the bolt and this will give you more of a feel. If you can feel a knock but nothing with your thumb on the bolt it is probably the shock. If you can hear it but not feel it, it is probably the top spacer bush.

That is not describing it particularly well, it is something you get 'from feeling a lot of bushes'........ OK for some reason that last statement made me smile

 

Yes, Actually my response (above) was somewhat condensed. I actually backed the rear of my car up onto a set of Oil Change Ramps. Then, I crawled under the car and felt the TOP of the Shock as a friend bounced the car up and down. I could "Feel" the "Noise" in the Left Shock, The Right Shock was OK. Of course, the dealer replaced both Shocks as a pair. This repair was done in conjunction with replacing a noisy (Whine) differential, also under warranty.

 

To the original question, I think the cats suspension works great. I like the fact that it rides great normally and can be tightened up enough to be noticable when pushing it. I guess the real question is, "Is it worth the extra cost"? On that, I have no idea. ha