Went for a drive today and the Admiral was not happy with the ride quality. All previous Jags were XJ12’s, XJS and 4.0 S Type Sport, all very smooth ride. How do I go about improving the ride quality of the XK8?

 

First investigate what’s worn out. You will likely need upper shock mounts. A forum member manufacturers them, and they will last, unlike the commercial offerings which are lucky to last one year.

A-arm bushings are another area which deserves examination. The sway bar (anti roll bar) also has rubber bushings that wear out early on.

Then there’s shocks and springs to check out too.

if you have the repair or maintenance history of the car that’s helpful in determining the age of these parts.

Z

 

What are the wheel /tyre sizes?

 

All parts are original, have full service history, 118,000 km.

 

17” rims. 225/55/17 tires. Yes, undersized.

 

Has anything been replaced yet ?

 

Nothing, all original.

 

At the very least, it’s a safe bet you are in sure need of upper shock mounts and anti-roll bar bushings.

As mentioned previously, a through examination of the entire suspension system is called for. Only then will you know where you stand.

Z

PS: talk to Wayne ( member : cjd777 ) for the upper shock mounts. He’s done the homework on those
https://www.jaguarforums.com/forum/xk8-xkr-x100-17/wayne%92s-front-shock-mounts-279665/

a quick search on the forum will demonstrate how well they are doing vs every other upper shock mount.

 

Tyre pressure?

 

That will be the fist move! Currently 32/34, will reduce and see if that works, thank you.

 

Reduced tire pressure to 26/28, noticeable difference in ride quality. Jacked it up and had a good look around and could find nothing wrong. It then occurred to me that all previous jags wore Michelin (usually Pilot Sport AS), this one has Bridgestone Ecopia 422 plus. Could it be the tires that are messing with the ride quality?

 

Could very well be the tyres.

 

Took the wheels off and did a very close inspection of all suspension components. All good. Only possible cause are the tires. Reduced pressure to 26/28 and ride acceptable. No cost solution.

 

Pressure that low, while providing a cushier ride, might cost you excess and uneven tyre wear.

 

Would then justify getting Michelin pilot sports, as I am used to.

 

I think for 18" wheels the tyres should be about 29 psi all round, at least that is what I have been told will stop the tyres from wearing uneven.

 

My wife's 2006 XK8 with 19-inch wheels and tires performs best with 32 to 33 psi in the front tires (245/40/19) and 28 to 29 psi in the rear tires (255/40/19). I spent about a year experimenting with tire pressures after we acquired the vehicle in early February 2012 before I arrived at that conclusion....

 

The tyre (tire) inflation table, on the underside of the armrest gives all the different pressures for the various size wheels. Interestingly it also has the statement, on mine at least, that if you are not using the OEM tyres (Pirelli PZeros in my csse) you should inflate your tyres to 40 psi!
I did that just to see what the ride was like. I think the designer of that label produced it on the first of April! I run mine at 32 all round. Works for me.

 

17” P Zero no longer available.

 

I think your thoughts re switching to michelins has merit. I have 20" all round and was running federal evoluzion tyres, while very happy with performance they did feel a little harsh. Changed fronts over to pilot 4s and the increased refinement is quite noticeable.