I have a 1993 facelift 4.0 (AJ6) XJS coupe and, having had the front suspension rebuild with OEM sport-pack parts a few years (but only about 1000 miles) ago, I think it is time to start considering the same treatment for the rear suspension. As things stand, I can source original sport-pack rear dampers (CCC7466 I think) but the springs (JLM11311 I think) are out of production – the general consensus seeming to be to use Aston Martin DB7 rear springs. There seem to be polar views on this with, from what I can see, many people saying that the Aston springs are of inferior quality to the Jaguar originals and tend to sag quickly. With that in mind:· Am I best to just leave well alone? · Would it be beneficial to replace the dampers and any bushes? · It is likely that the Aston springs would still be an improvement on 25 year old originals (that have 54k miles under them) so I should just go ahead and do the work?
Thanks in advance

 

*Personally* I wouldn't replace the rear springs unless your are sagging or broken. Over the years there have just been too many tales of woe from those who have done so. Seems the car always ends up too high or too low no matter what spring is used ! But, opinions and experiences vary.

I'd vote 'yes' on replacing the 25 year old original shocks.

Bushings? Inspect and replace as needed....although the only bushings I can think of, off hand, would be the radius arm bushings. Definitely worth looking into. Rear subframe mounts as well.

Others will chime in

Cheers
DD

 

Thanks Doug, much appreciated.

As a sub-note, someone once told me if the large radius arm bushes are mounted in the radius arm with the moulded holes to the sides, the radius arm will have a stiffer action than the moulded holes mounted front to back and that is how the ' sports-pack' arms are set up. Have you ever heard similar?

 

I've heard that but never confirmed it. Some people make that change on their own....but I'm not sure if that's what Jaguar did.

Cheers
DD

 

Aston did mount the large radius arms 180 degrees out. I made this mod on my coupe and didnt like it at all. It made the car rear-steer abruptly more than I was comfortable with as it leaned. The stiffer bushing arrangement effectively shortens the trailing arm becasue it has less give. Then as the car leans over it pulls cage more on one side than the other creating a very unsettling rear steer effect.

For me the off-the-self hot setup is Good tires, a rear sway bar, Bilstein Shocks up front, KYB shocks out back. The KYB rears are stiffer than the yellow Bilsteins. The yellow Bilstein Fronts are stiffer then the KYB. I was suprised by this and checked the P/N on the Bilsteins and they are in-fact the B6 performance variants.

 

This mod was also done by TWR on some of their versions. I tried it once, and also disliked it and changed the bushes back to fore and aft. In my case it made the car "bunny hop" at certain speeds in a straight line somehow. ICSA's explanation seems to indicate why.

 

Never had a problem with the radius arm bushes 90 degrees out; just seems to tighten the rear end up a tad.