Hey everybody, I've been lurking in the xjr forum a bit since I got my '04 XJR this past December.

I had and '03 STR so I would frequent the S-Type forum more often. But, since the STR got totaled last august, I had to get another Jag. Fortunately I was able to find a nice 2004 with 72k on the clock and being a former owner of a '98 XJR I loved the XJ's styling and space.

Well, here's where I need advice or input- the XJR suspension. I was surprised at how well the STR handled. With CATS and staggered tires, it handled really well. Having taken it to an autocross track a couple times, I was amazed at how well it held in corners and stuck to the road considering it's size. I'd like to get the XJR to handle better! It's a big car so I'm not expecting a miracle.

I know 2 air-shocks leak a little and the suspension feels horrible over bumps and in corners jarring the vehicle all over the place. Now with 82k miles, the shocks/struts need an overhaul.

As far as I know, there are 3 reasonable options available to me/us. I'll list each with pros and cons

1. Arnott air-spring replacements
PROS
-ability to raise lower based on load
-better ride? but this is kinda bases on opinion
-I'm a tinkerer, eventually I will find a way to ajust the ride height through either through software, hardware, or electrical.
-CATS will still work
CONS
- about $400 per air-shock/strut for a total of about $1600
-prone to more mechanical problems. air-shock leak, broken hose, compressor failure etc.

2. Arnott coil spring conversion
PROS
- Cheaper than air-shocks at $1295
- less prone to mechanical failure than air-shocks
- weight reduction by removing other components for the air shocks, compressor, tank etc.
CONS
- no CATS, possibly worse handling
- ride height... ? I would like to see photos of an XJ/XJR with these springs installed

3. Strutmasters coil spring conversion
PROS
- Cheapest Solution of all at $1195
- Eibach springs, also heard they use bilstein struts
- less prone to mechanical failure than air-shocks
- weight reduction by removing other components for the air shocks, compressor, tank etc.
CONS
- no CATS, possibly worse handling
- ride height... ? I would like to see photos of an XJ/XJR with these springs installed

With all of these solutions, $200 can be recouped by sending Arnott the old air-shock cores.

I'd love to see pictures of an XJ that has been converted to springs to see ride height.
Any reviews, comparison, or other details I may have overlooks are welcome, especially from ones who have been down this road before.

My preference is handling then comfort. The best handling solution is what i'm looking for.

thanks!

 

At 83k miles the air springs should not all need replacing, just the ones that leak. I would go for the Arnott air spring replacements assuming the shocks really do leak; has this definitely been confirmed ? Never rush to spend money on these cars without knowing it is needed, the parts can be very expensive !

You have bought an XJR which has the harder 'sport' suspension, and probably has large diameter wheels; are they 20" ? If so you can expect a rather harsh ride. It will handle well but don't expect boulevard ride comfort. I have thought hard about swapping out my air springs for the standard ones to restore a bit of comfort.

 

2 air-shocks are confirmed bad, which I knew when I bought the car but the deal was too good to pass up. I researched the XJR and it's common issues before purchase to get an idea of what I was getting into with the air-shocks. I've got JTIS and I'm comfortable performing my own work so the cost will be in parts.

I did misread the cost for replacement arnotts... it's $400 + a $150 core charge. So 2 of those will set me back at least $800. The strutmasters kit would set me back $1000, only a couple hundred over the 2 replacement air shocks - $1200 with $200 recouped by selling arnott my cores. Plus with eibach springs and bilstein shocks, it might handle even better.

Down the road, the other 2 air-shocks will eventually go bad, costing another $400 a shock. But I'm not against keeping the air-shocks if they actually do corner better than coil spring/struts and I would retain CATS. I've only read comparisons of ride comfort/quality over bumps.

It's got 19" wheels. The S-Type R was by far harsher on bumps, but it felt considerable stiffer in the corners even with 18" wheels. But as I mentioned before, I'm not necessarily looking for more comfort. I don't want a horrible ride but I want more road hugging handling on the corners.

 

YOu are lucky to have more options in the US than us in the UK. If the air shocks are leaking, it seems to me the Arnott rebuilt unit option is the way to go. That way you retain the CATS.

CATS varies individual shock settings from hard to soft and vice versa depending on what the car is doing, so cornering hard round a left-hand bend will cause CATS to harden up the shocks on the right. Same applies for heavy braking and acceleration. It works in background with no visible indication of operation.

 

www.arnottindustries.com

 

I haven't driven an STR in anger so I can't make any direct comparisons but I have driven my lowered XJR around the Nürburgring, and rode passenger in another that was driven very hard.

They actually handle quite well for the size of the car, but there is still a fair bit of body roll, and off-throttle understeer (due to the rear sway bar being too soft) even with mine being lowered it's way too soft for the track.

The next step to improve the handling will be to put urethane bushes in place of the standard rubber (majority of S-Type bushes are interchangeable) and change the rear sway bar (the XKR-S bar is a straight swap, but I will look into getting one custom made) Have a look at my post in the suspension subforum.

I'll be taking my XJR out on the track a lot more in the future, so the bushes & sway bar modification is on the to do list.

I would keep the air suspension, the CATS is a great feature, as well as being able to adjust the ride height.

Question for Doug @ Arnott:

Your replacement shocks are only available in one version, as opposed to the Comfort or Sport versions originally on our cars.

Any possibility of you guys doing a much firmer version of the air shocks? Would it just be a case of changing the valveing?

I would be up for a set if you could offer something stiffer than the OEM Sport shocks.

 

Other question for Arnottdoug is when might a UK agent be appointed to allow us Brits to buy rebuilt OEM units so we retain the CATS variable dampers ? The Bilstein OEM units are available on the internet but at a huge cost of about £650 each. I hate to think what Jaguar agents charge ! Used ones are around at about £185.

Steering-Suspension | Jaguar XJ - X350 - XJR | British Parts UK

 

I throw my vote to Arnott replacements! I bought my XJR with it hugging the ground due to leaky shocks, I got it for a STEAL too because of it. $400 later I have myself a cheap supercar. The shocks also come with a lifetime warranty should they fail, and have a redesigned bladder to make sure they last. My car had 74k, now has almost 100k and I am having suspension issues again. This time the module to control ride height, but the shocks themselves are still fine. Also fairly easy to change yourself.

 

Thanks guys for all the input!

I have been leaning towards the arnotts mainly because of the versatility and the other to spring option keep ride height at stock.

arnottdoug - Thank you for the coupon code. I too would be VERY interested in a stiffer performance version!

Cambo - How much of an improvement in handling did lowering make? I've read your post about lowering an xj using wds/ids/sdd, very good info in there! Have you possibly tinkered with handling with it set at even lower suspension levels, if so any better or worse handling? There has to be a sweet spot in there.

I was checking out the wiring diagrams, and the ride height sensors have 3 leads, a +, -, and sensor input. I'd have to agree with androulakis and my hope is that the mechanical arm provides an ohm resistance based on the angle it's at. If so, that should be a fairly easy way to mod the sensor input up or down based on more or less ohm resistance. Which could lead to an easy way to modify the ride height on the fly using a few resistors and switches. When I get some time I plan to mess around with it a bit.

Also, it seems that the trunk/rear is naturally a little higher than the hood/bonnet on the XJ even though it may be level based on the distance from tire to wheel well. One other side tangent, the stock wheels sit too far in towards the body...