XJS Ride Quality

[matthew@calvertarchitect.co.uk]

I have a 1992 XJS 4.0 Coupe which is a Japanese Import. I always feel the ride quality is poor, very stiff and jiggly whereas the contemporary road test always complement the ride. The car is low mileage (only 57,000Km) so must have sat around quite a lot could the shocks be seized ? The car even feels stiff when you push down on the wings from the outside. My XJ40 has a lot more 'give'.

[davidr]

Hello Matthew and welcome to the XJS Forum.
There are many things that can affect the ride quality. The facelift 4ltr cars were on sports suspension which were more towards the handling end of the handling vs ride equation so would naturally not give the same degree of "magic carpet" ride of the earlier cars.
It may be that, if the car has been standing for a while, the suspension joints themselves have become a little stiff (which would normally be accompanied by some noise).
Tyre pressure and condition will also have an effect. Older tyres with stiffer walls will be less compliant. Tyres at higher pressures will equally be less yielding.
To be practical, the first place I would start would be with the tyres. How old are they?
Tyre pressure, for maximum comfort would be around 28-30 psi
Perhaps give the car some exercise to free everything up and then see how it feels?

[matthew@calvertarchitect.co.uk]

Thanks David for your response.
The tyres are only 1 1/2 years old as I had them replaced when I purchased the car as the originals were very perished. The shock absorbers are the 'black' type though one on the double set up on the rear is silver. It does clunk and crash a bit over bumps but generally feels very tight and stiff.

[stuart1927]

Sorry, just re-joined the forum recently and catching up a bit!

The noises you were describing sound a bit like the infamous top shock bushings. That's always the first place to start. They are easy to change so it's a no brainer.

Some others mention the cross bracing in the engine compartment. I've never had these come loose on mine, but others have reported it can result in some noises that can be wrongly interpreted as suspension related.

The XJS suspension is a bit of a mystery. I had my first one almost completely re-built about 10 years ago and even then, was never 100% happy with the ride....or at least some of the residual "noises" I was hearing! I tracked one issue down to the winsdcreen seal rubber, which had hardened over time, causing a loud "thwack" when I went over bumps. It took me a while to figure out that's what was actually causing the noise.

The second issue was related to fitting an AJ6 TT exhaust system. I had some clunks associated with the exhaust touching the floor pan or just causing some rattles.....it drove me nuts! It eventually settled down and I think when an oil filter was replaced (needing removal of part of the exhaust) the subsequent re-fitting cured the problem.

My 89 xj-s is now riding very well (after 10 years work!) but likely I'll be back to square one shortly as that's about when you need to start replacing things! What made me realise how well it rode was a friend of mine has an old alfa romeo from the early 70's, and I had a drive in it. A huge amount of fun to drive, but compared to the xj-s....it was agricultural!

[greeban]

My '95 4.0 manual is wonderful (mileage 155k)- soaks up the bumps and has little roll in the corners; the front has had new sports shocks (green) and the front hardly moves when you push on it. For the rear I fitted new springs last year and as all 4 shocks passed the 'compress and return' test I refitted them and all good with reasonable ride height. I may fit some spacers if I can be bothered as would like to see the rear a little higher but to be honest the way it drives is fine. In tight corners the rear feels like it might push out but if the conditions are dry I find if I push harder the back reassuringly digs in. Of course is not a sports car but to be honest I am very happy with it and gives me hours of fun. I am not sure I have ever driven a car which has a better ride - perhaps a friend's Bentley GT but that had no feeling at all, except for the incredible seats!!
BTW the rear end did push out when accelerating having exited a roundabout, just got the car straight and then booted it and the back flew out - slight bottom clenching moment; reminded me that you do have to treat these cars with respect as even today the power output is pretty impressive and can get you into trouble, especially with the manual.

[PaulGover]

...
BTW the rear end did push out when accelerating having exited a roundabout, just got the car straight and then booted it and the back flew out - slight bottom clenching moment; reminded me that you do have to treat these cars with respect as even today the power output is pretty impressive and can get you into trouble, especially with the manual.

My V12 held a party with the crash barrier after just such a tank-slapper; new bonnet and wings, etc. It probably had something to do with diesel fuel dropped on the corner by an over-full fuel tank.

[greeban]

OMG - sorry to hear this; I have a friend who hung up his motorcycle having come off on a roundabout for this same reason of diesel onto the road. Hopefully you and the car are fully recovered?

[PaulGover]

Long time ago.