I've recently acquired a special beast—a 1994 XJS 4.0 convertible with a factory 5-speed manual. The car is not level. It's riding high in the rear and low in front, with a "jacked-up" look. I wasn't sure if it was weak front springs (or shorter ones) but I noticed the there's a quartet of KYB Gas-A-Just shocks in back. In doing some research I found that while these are excellent shocks, they tend to jack up the suspension due to their pressurized nature. I'm trying to figure out what correct ride height is, based upon the measurement from the ground to the underside of the front and rear wheel arch lips. If the rear was raised, it stands to reason that the front, pivoted around the front wheels, would be lower in front as a result. Can someone with one of these cars with a proper ride height help me here?

Also, if I need to change out those KYB's, what would be a good replacement as a performance shock with decent ride quality? Any other tips for improved handling without ruining the supple ride?

 

I don't know the height spec offhand, sorry

Changing shocks probably won't help. Virtually all (if not literally all) the shocks these days are pressurized, as were the originals. Yes, they can lift the car a bit.

I'm inclined to say your front springs are sagging OR the springs (front and/or rear) have been replaced and the ride height came out wrong.....which happens somewhat often when replacing springs on these cars. Aftermarket springs, which are commonly used, are sometimes not correct spec for the car

Cheers
DD

 

22 inches + or - 1/2 and inch from the centre bottom edge of the wheelarch, measuring straight down through the wheel centre to the bottom edge of the wheel rim.
If you fit Boge shocks and OEM springs, such as these, you will find the ride/handling compromise will be a very good starting point.
https://www.ebay.ie/itm/362235352838
Alternatively, the Rolls Royce answer would be Gaz adjustable hardness and adjustable ride height rear shocks, which come in at about 160 USD each.

 

+1 for the Gaz adjustable platform height rear shocks. I fitted them on my convertible when I fitted Aston DB7 springs. It seemed the only way to get both my ride height and handling as I wanted.

Paul

 

Hi Dave,
I'm a new member with a 1992 XJS 4.0 coupe. I have a CD-ROM repair manual that states the height of the rear is 190.6mm +/-6.4mm for my model, measured from the lower surface of the rear cross beam to the ground. I hope this helps.