Rough Ride on Bumpy Roads


#1

Hi,

My XK8 rides very hard and seems to jump around whenever I hit a bump. The suspension seems to be fine at least when I try to push down on any of the fenders, but I would like a smoother feel when driving over other than smooth as silk roads.
My mechanic, a master jag mechanic says everything looks ok. My question is has anyone changed anything with after market parts that rectify a rougher ride?

Thanks,

Greenie


(Eric Capron) #2

I am working my way through the front suspension changing all the rubber to rectify the same problem. The upper fulcrum bushes seize on the fulcrum bolt and if not freed off will wear the bolt hole oval in the subframe. Mine was making a creaking noise. Just about to change the lower fulcrum bushes which I think are also seized, then the damper bushes, anti-roll bar bushes, the drop links and the V mounts. Has your car been standing unused?

My XK8 is a 97 and after 21 years the rubber isn’t supple any more.

Eric

Shropshire, UK


(Grahame Loader) #3

Greenie:

Do you have low profile tires on your car? These can give a hard ride. If you’re not hearing any noises on the bumps and your mechanic says the suspension looks good, then the only thing left is the tires. Check with your mechanic about tire pressure; mine told me to run 32 psi all-round, rather than the book values. Older tires can get stiffer and less tread can give less cushion.

Pushing down on the corners will ensure you don’t have a frozen shock, while a dead shock will show up as bouncing after you hit a bump.


#4

Hi Eric,

Thanks for the response. Though my care hasn’t been sitting unused, it certainly doesn’t get a significant amount of use during the year. I never take it out of my garage in the winter, and if it gets too hot I don’t take it out either. I probably have only put 1-3 thousand miles a year on it over the past 4 to 5 years. I am not a mechanic so I can only believe what you are saying as it makes a lot of sense that the rubber will dry out and get hard over time, especially if it is not actively working to keep it more supple. I remember when I first got my car (second owner back in 2006, I had some type of bushing replaced. It was pretty expensive, but then again it was serviced by a Jag Dealer who I left after a while as I thought they were crooks.

I can’t do any of this myself. I have a good mechanic now who used to be a Master Mechanic at a Jag dealer. but this sounds like a lot of bucks. Have any idea what it would cost to do retail?


(Eric Capron) #5

Couldn’t begin to guess retail prices but the main thing is to identify what is wrong and whether it’s a front or rear suspension problem. More likely front than rear, I suppose.

The point about the tyres is good although mine is on the standard 17 inch wheels with 50 profile tyres. I have observed that the P Zeros do get noticeably harder after a few years. When I fitted a new set to my S Type it was transformed and felt so much more refined.

My upper bushes are done now and were definitely seized and in pretty poor shape. I’m just working through the rest of it slowly. None of it is that difficult, just a bit tedious as everything is rusty. (My car had been standing outside for a lengthy period). I will report back when I have finished the job.

Eric


#6

Thanks Eric,

Good luck with the work!


#7

A quick web search turns up a large number of aftermarket springs. Have you considered a softer set? Here in the States changing springs might run $50-100 per wheel labor. Or, it is an easy but somewhat dangerous DIY.


(Eric Capron) #8

Certainly a plan worth considering if the replacing the rubber doesn’t do it.

Eric


(Stephen J. Niznik) #9

I am going to be changing the front shocks and mounts on my 2000 XK8 Coupe. I made a spring compressor to remove the springs. Do I need to compress the springs to remove the shocks and springs from the car or will getting the wheels off the ground create enough clearance ? I bought the car about 2 months ago and the front shocks are pooped out. If I drive the car I have to be careful on curves and bumps because the top of the tire will rub the liner.


(Joseph T. Shaw) #10

My 2001 Xk8 runs hard all the time. Even running less than the than the recommended 32 Psi it rumbles down the highway. If I try to apply pressure to the front or rear quarters the body stays rigid and will not bounce. Every other car I have owned will at least bounce a little. Is this normal for the XK8 or should I be looking for replacement shocks?


(Grahame Loader) #11

Have the shocks checked; you should be able to push down on the corner and have it come back without bouncing.


(Bob Allen) #12

Also check with your tire dealer to examine the suspension, I had to replace my 2001 changeable suspension as it was stuck and no longer functioning correctly.

Bob Allen

kabob@wavecable.com


(Eric Capron) #13

Mine is the same and I’m gradually changing all the rubber bushes on the front suspension. Check the upper fulcrum bushes especially if you hear any creaking sounds or knocking. They can seize up and if not rectified will wear the holes in the sub-frame oval.

Eric
Shropshire, UK


(Stephen J. Niznik) #14

I got my front shocks changed and changed out the upper A arm bushes while I had them off. The bushes were a mess. The steel sleeve rusts and isn’t easy to deal with. I will be replacing the lower bushes some time in the future and at that time I am going to install grease fittings at all the bushing locations so that I can insert silicone grease at least once a year to keep them from rotting the way the originals do.
By the way , the shocks raised the front end by about 2 1/2 inches and the ride is much better. I do however get a little tire rub when pushing the car hard into a corner.


(Bob Allen) #15

Make sure that your front tires are narrower than rear. .Yours should not be full size all around.

Also, check your front wheel well access panels for being flush. The drivers side is known to

come loose and bow.

Bob Allen
kabob@wavecable.com


(Stephen J. Niznik) #16

The PO has the same size tires on the front and rear 245/50/17
Tire rack shows the same size for 17" and staggered for 18"


(Stephen J. Niznik) #17

The front tires rub slightly on big bumps and hard cornering. They rub at the top. I could go with 245/45/17 in front and 245/50/17 in the back. Both tires are the same width/contact patch but the 245/45 are an inch smaller in diameter.


(Grahame Loader) #18

I have had the same size tires, front and back, on 18" rims for years and never had problems. The tire shop that put them on, told me there would be no difference in ride and handling.


(Bob Allen) #19

Did you inspect the access portals to make sure that they are not bowed out? Your 18" wheels are as you state, mine are the larger directional 20" in back and narrower turning 20" in front with variable changing rear suspension and electronic fuel injection, all factory.

Bob Allen
kabob@wavecable.com