'96 super sports/adaptive springs

[painter]

I have just renewed the front and rear springs on my 96 XK8 coupe, which was originally supplied with super sports suspension and adaptive damping. The rear springs I managed to source form jaguar, part No. JJLM 20589. (the old springs were quite badly corroded). The front springs, after many calls, I managed to source from a Jag. specialist, but when compared to the old front springs they are about 1" shorter. The ride height seems ok but I didn't measure it prior to the new ones being fitted. I have been advised that the springs they sent (part No. JLM21277) were the only option available as original spec. is not produced by anyone, but that they are intended for an XK8 with super sports and adaptive damping. Does anybody have knowledge of the correct replacement spec/part No. as I am beginning to think I have been duped.
The ride if anything feels harder, which I suppose you would expect, but cornering is no better - if anything a little worse.

[mike020150]

Hi Painter,

According to SNG Barratt's XK8 parts book, early adaptive coupes used rear spring kit JLM 20190 and front spring kit JLM 20152. From the same source, JLM 21277 is listed as fitting later 4.0 litre non supercharged adaptive coupes. JLM 20589 is also listed for slightly later adaptive coupes. Unfortunately, I no longer have any other parts info to cross reference the Barratt's info or to identify whether the supersports option simply used the XKR springs/dampers or a unique kit of parts not listed by Barratt's.

If your new front springs are stiffer, relative to the new rears, than was previously the case with the originals, it will promote understeer which could be the source of an apparent worsening of the car's cornering abilities. Mike.

[painter]

Hello Mike,
thanks for that, it's very frustrating that Jaguar have produced or specified springs replacing the originals but provide little or no information as to the rating of the replacements. I still have the old front springs, which were not so badly corroded as the rear, so I guess I can still have these reinstalled until such time as Jaguar offer some clear directive for these older cars, although I won't hold my breath. I think you are right re: under steer.

[painter]

Hello Mike,
do you know if the XKR suspension had adaptive and super sports suspension as standard, or was this an option? I think if JLM21277 springs were produced for the XKR in the early years, and these had s/sports and adaptive I'll stick with it. If not there is always a chance that Jaguar may catch up with their back orders and produce some JLM20152.

[mike020150]

Hi,

Unlike XK8s, all UK XKRs had CATs fitted and the springs had to cope with significant extra weight over the front axle as well as the strain of extra performance. JLM 20689 springs were fitted to XKR coupes and even stiffer springs (JLM 21276) to the R Performance equipped coupes.

Since you have fitted the new springs and direct replacements for the originals don't appear to be available, why don't you experiment carefully with the car's tyre pressures. Slight softening of the fronts and possibly raising of the rears might give you a ride/handling compromise that you feel able to live with. Mike.

[painter]

Hello Mike,
thanks, I will try as suggested. I did get some more feed back and have been advised that the JLM21277 were produced for the XKR, which as you say had adaptive damping. Also advised by Jaguar that all cars with adaptive damping had super sports suspension. The JLM21277 spring, although shorter, is much stronger and therefore the ride height remains the same. I think it is now time for me to shed the 10 year old tyres, (lots of tread but hard rubber), and give the new springs something to work on!
many thanks

[painter]

A few pics. of the process, including the different height of old v new front springs. Alarming at first although the ride height is the same. Have put Dunlop sp sportmaxx rt on the front and the car now corners extremely well and far less noise.

[painter]

few more pics, hope I'm not clogging up the process here

[painter]

few more

[painter]

nearly finished

[painter]

last 3!

[mike020150]

Some good pics of the process. I must confess that I always like to get to the point after the springs have been compressed and released even when using the correct spring compressors. It only takes one slip for the potential for damage and injury to be realised in spectacular and horrendous fashion.
In one pic, from the marks of the disc, it looks like the front nearside caliper might be dragging and may benefit from a little attention. Mike.

[painter]

Hello Mike,
is that on image 1027 (uneven wear?). All calipers need to come off soon for an overhaul, at which time it would be good to get them recoated. Looks pretty grim at the moment.

[mike020150]

Yes, it is image 1027. The disc surface looks to be scored and rusty, possibly due to a sticking caliper not moving freely, whereas as far as can be seen in the other pics, the offside front disc looks to be in better condition suggesting it may be doing more of the braking. Mike.