Coil suspension ride quality
 

I'm looking for an X350 and recently came across one that has just been converted to coil springs. I'm aware that there can be problems with the stock air suspension and that fitting coil springs is a way to fix this. What I'm wondering about is how it affects the ride of the car? Is it noticeably different and if so what is it like? My first thought is that it would be stiffer and bumpier, which isn't really what I want, but I think it's best to ask the experts here rather than just guess. What do you think?

I think that most who have converted their XJ8 suspension over to coil/springs have never looked back. In my personal experience, the overall ride with the coil/spring conversion is exactly what one would naturally expect from an upscale luxury car. It will also handle better around the curves, and the rear will not 'bottom out' while going over road bumps like the air suspension would tend to.

I have a 2005XJR and it is supposed to have the "sports" shocks so well may be different to that of an XJ8.

Even loaded up with heavy bins moving stuff from house to house my suspension has never bottomed out even over those "policemen" bumps in the road or any other bump.
It is also quite firm with very little roll at all going at speed around curvey back lanes here.

From time to time, we read comments from people who are pissed off by leaking shocks or compressor or scared by eventual failures and who will sacrifice the superb ride of the X350 for peace of mind.

Jaguar designed the X350 with air suspensions.
Sometimes shocks need to be changed but many shocks will survive to 150k or more. And above such mileages they should be considered as consumables.
I know my car needs and deserves careful oversight and serious maintenance, but by doing so, I have the pleasure to drive a nice and sporty limo with unrivalled comfort.

Unfortunately, and not surprisingly as this is a forum for sharing and helping, we hear more here of the unhappy people than from the happy ones.
So let me tell you: I will not swap my air shocks with coils and will continue enjoing the air ride:)

It's not totally a fair comparison but I have a one year old Tesla with coil suspension and my 10 year old XJ with air. Let's just say I will pay to replace the air suspension with Bilstein/OEM if and when I need to do repairs. Air suspension is smoother and now I wish I had gone for air in the Tesla.

Look ... the X350 is a Sports Saloon ... a Sports Sedan I guess you guys would call it.

If you just want is to use it as a 'Highway/Interstate Barge', or just for traffic light straight line drag races, or just to been seen in ... then by all means fit coil conversions (and get rid of the CATS dampers as well)

If however you want a large car that can give you sports car performance and sports car road holding when you want it, and then cruise comfort when you want that ... if you want a true sports saloon ... then you need the air suspension (and the CATS dampers) that Jaguar went to the bother of designing so that you get the best of both worlds, and not an compromise between the two.

With the price of remanufactured air springs with lifetime warrantys for the same price as Arnott spring suspension conversion, why bother with the cars original design? Air springs ride better, probably handle better, I don't care what anybody says...

It rides like any other car on springs.

It devalues the car (even faster) than KBB. Why bother owning one if you're going to remove one of its most luxurious features?

What else did the owner do "on the cheap"?

Thanks everyone, I think I'll pass on this particular car.

I think it really boils down to the conditions of the streets in your part of town. Air suspension is garbage on the potholed streets of LA. I converted to coilovers and haven't had a single regret. The car handles better at speed, I can go over speedbumps without having to slow to a stop, and I will never have to worry about whether my suspension will work on a cold morning or evening ever again.

If you're planning on the keeping the car for a long time, do the conversion. If you plan on selling it again down the line, keep the factory system.

Because the actual air springs are just 1 component of the problematic system. You always have to worry about the compressor, height sensors, air lines, reservoir, valve block, relays, fuses, and the control module. I wasted a lot of money and time trying to track down my suspension issues. I should've converted from the beginning.

I'm in the process of switching over to the Arnott coils after owning my 2004 XJR for just 5 months and popping a spring.

If I had the money, I'd probably stick with air, and fix what needed to be fixed. However, I'm looking at about a $1,600 total Bill to convert knowing these will last the life of the car. Sure, I'm crossing my fingers hoping for a good ride quality, but the peace of mind is worth it for me.

It is a little known fact that when the aluminium XJs were announced in 2002, the details on the suspension stated that lower spec models would have coil springs like the S-type has. In the end, Jaguar decided to fit air springs to all cars. The reason for the air suspension was given as the light weight of the car meant the load of passengers and luggage was a greater percentage of the car weight, so it as difficult to have a comfortable ride and at the same time, handle all possible loads. OK seems logical, except that later aluminium cars - new XF, the XE, and the F-pace, all still mostly aluminium, use steel coils. Even the current XJ only has air springs at the rear, the fronts are steel coils. SO Jaguar have rolled back considerably on air suspension, realising its much more costly to repair, and this affect the cars on the used market.
Me, I just wish Jaguar would give us replacement steel on the front and a new ASM software to handle it. Maybe the front springs on the current XJ are backwardly compatible with the X350 cars, so CATS remains available.

That's an area that I'd be concerned about. I've lost track of how many times I've replaced the shocks in my current car. The springs are fine, but it's got to be at least 4 times, in 120k miles and 8 years. They're not as expensive as the air suspension parts, but I can't view any suspension component as truly "lifetime". I plan on keeping the car for a long time, maybe I'll change my mind after living with it for a while, but I kinda doubt it.

It may vary with the different makesof coil spring sets available but I find the the Arnott's ones for my XJR ride probably a little softer than my original sport air springs. They are probably very similar to the standard air springs. Handling however is definitely not as good as with the CATS system with the OEM sport air springs. Unfortunately, new sport air springs are apparently no longer available, and the new Arnott's ones don't have CATS, so for the R owner, you're limited to the Arnott's reconditioned sport air spring units. I don't know what the R will be like with the normal air springs.

Another issue is of course the weather. Air springs, as a whole, irrespective of whether they are Jag, Mercedes or Bentley etc don't last more than 3.5 years in the tropics. The air springs really don't like the year round hot and humid weather start to leak around the 2.5 to 3 year mark and need to be changed by the 3.5 year point. If they lasted significantly longer than 3 years, I would keep them but to change whole set every 3 years, and wondering when they will finally give way was too much of a strain.

The car does bottom out more with the Arnott's coil springs and the handling is inferior to the CATs equipped car. I have a set of uprated anti-roll bars all ready for installation, to improve the handling. Hopefully I will be able to get them installed soon.

Where do you live?
 

Another issue is of course the weather. Air springs, as a whole, irrespective of whether they are Jag, Mercedes or Bentley etc don't last more than 3.5 years in the tropics. The air springs really don't like the year round hot and humid weather start to leak around the 2.5 to 3 year mark and need to be changed by the 3.5 year point. If they lasted significantly longer than 3 years, I would keep them but to change whole set every 3 years, and wondering when they will finally give way was too much of a strain[/QUOTE]

I am in Houston, not quite tropics, they hold up fine here. I have the Bilstein air shocks on my A8 and XJR. No problems.
It will be a 100 degrees today and humidity is high. There are worse places.
From forum contacts the cold weather leads to air leaks. Houston very seldom see's 40 degree weather.

90-100F year round with humidity of 80-100% does take a toll on the rubber, plastics and electronics unfortunately.