Hi all,

Please forgive me if this has been posted before - I have tried searching but not seen any threads where this exact problem was identified and solved, anyway...

I have recently purchased a lovely 2008 Jag XJ, 2.7 TD, I believe it is the sport spec with the big 20" wheels, the car is great except for one thing. When driving over poor roads with high frequency short bumps the front suspension seems unable to cope, the front of the car almost feels like it bounces giving a weird vibration back through the wheel and the front of the car. It is as if the suspension is over compensating and the damping is out of sync.

I have check all the suspension bushes and replaced the shock lower bushes, but this has made no difference, if anything it's worse. The pump is on the noisy side, but seems to work fine. There are no error messages or fault codes and the car sits fine (maybe slightly lower on the left)

I don't want to start throwing parts at the car without some good idea as to what might be the problem. Has anyone else had a similar issue - any feed back appreciated

 

What speed do you get the bumping? Jags have sports suspension, good for corners, bad for rough roads.

 

Could be a shock. I had one on mine that worked fine on slow bumps. But banged with impacts, seemed it could not compress rapidly. Wasted time and money until it was swapped from right to left. Banging moved.
Replaced the shock and issue has been gone for a couple years.

 

Sounds for me too, like the shocks. In general, smaller rims with 18" will help too.

 

Get rid of those 20" wheels for a start ! There is no hope of a smooth ride with these and Sport air springs which are a bit harder than Comfort. Dampers are the same Sport or Comfort. Having said that, it might be prudent to scan for fault codes. These cars have CATS, a system that varies the dampers between Hard and Soft based on inputs from motion detectors on the car. Any suspension faults cause it to default to Hard.

If it were me, I'd look for a set of 18" wheels on the internet. You shouldn't have any problem selling the 20" as for some reason, people like the look of them. Its the usual obsession, Sport, Sport, Sport, it drives me insane. Big Jaguar saloons are all about comfort, or should be !

Was the ride as you describe it, there on the test drive ?

 

I concur with the suggestions to get smaller wheels. Nearly all modern cars (especially luxury cars) are noticeably compromised by customer demand for ever larger rim sizes because it looks cool. No amount of suspension tuning can compensate for the inherent ride harshness of a tiny tire sidewall. Also it is extremely easy to bend a wheel on common road hazards with these large wheels because there isn't enough sidewall to protect the rim. I've had my Ford Fiesta ST (in NY metro area) for 4 years and have had to have 5 wheel repairs and one of them is bent now. Low profile tires offer NO practical benefits unless you are going to drive your car on a race track.

Jeff

 

Thanks all for the input.

I've now ruled out the shocks being in the default ‘hard’ mode by unplugging the dampers, the ride gets even worse when I do this.

There are no knocks or leaks, so reluctant to start changing the shocks out and I don’t think I could the difference from side to side swap. But will get another scan done (first one showed no issues)

I would be amazed if that level of ride comfort was signed off, even with the big wheels.

It’s strange as the car seems to be really nice and floaty over certain bumps, generally at lower speeds, but it just can’t cope when the speed rises and the road gets rough. I’ve had various German cars with over firm traditional suspension, but all of these generally got better with speed. Pulling my hair out with this one!