after reading DonB s article on the x350 /358 air suspension system, I am considering replacing my shocks with Arnott ones but no one can tell me if there is a point at which the Ieffort and expense is worth the difference in ride. Would you notice it or would you notice more renewing all the suspension bushes all round.Ive already put Bagpipe Andys kit in the compressor. Just trying to bring the car to as close as new feeling. By the way ZF do NOT say their gearbox is sealed for life .Jaguar used to but not now.

Present cars 2003 X350 XJ6 100,000 miles
2005 X Type 2.5 Estate 145,000 miles

Employment None retired airline pilot.
Previuos Jags, !st 1956 Mk1 2.4 various Mk!! 1967 3.4 S Type 1969 daimler 420 4.2 1963 E type 3.8 Mk 1 1967 Eytype 4.2 both conv 1972 V12 E type 2+2 coupe 1998 Vanden Plas XJ 4.2 2005 X type 2.5 estate

 

Hi Lazarus,

I've moved your post to start your own thread so we can deal with your specific questions. As always, it helps if you take the time to re-read what you have typed before you click "Submit." If you have earned editing privileges I would suggest you clean up your post so we can better understand your inquiry, and please also add the year and model of your Jaguar so we can provide the most accurate replies.

No one can tell you whether you should convert to a conventional coil suspension, you'll have to decide for yourself. If your system is working well, why not just enjoy it?

I have converted several X350s to Arnott coils, and all the owners seem to be happy with the results. For most of the owners, the deciding factor was the failure of an original Bilstein air spring, though for a couple of them the concern was reliability for a wife to use as a daily driver.

Having driven these cars after the conversion, my personal impression is that the ride is comfortable and reasonably well-controlled, but with more body roll while cornering than the stock air suspension. And of course the self-leveling function is lost. One of my favorite things about the stock air suspension is that we can fill the trunk with heavy luggage and the suspension maintains its ride height and control going down the highway. The loss of cornering control and ride leveling are the reasons I'm maintaining the original air suspension in our '04 XJR. But if sporty handling is less important to you than a comfortable ride, you will probably be very happy with the Arnotts.

I haven't done a conversion with any of the other brands, such as Strutmasters, so I can't offer any comparative thoughts.

Regarding the transmission being sealed for life, that topic has been discussed in countless threads. But for the record, when the 6HP transmissions were introduced (in 2000 IIRC), ZF did claim they were "Filled for Life with Oil." This same claim was made by the automakers that used these boxes, including BMW, Jaguar, Audi, Bentley and others. ZF also made the seemingly contradictory statement that "An oil change is not necessary before 160 000 km or 10 years." Both of these statements appear on pdf page 6 of the 2001 ZF repair manual which you can download at this link:

ZF 6HP26 Repair Manual 2001

ZF subsequently revised their recommendation to: "Depending on the driving style, ZF therefore recommends a transmission oil change every 80 000 to 120 000 km, or after 8 years at the latest." This can be found at the bottom of page 1 of a ZF service document dated 2013, available at the link below:

ZF Service Information 5HP 6HP 2013

Cheers,

Don

 

I have experience of both Arnott coil and air suspension. Read #51, my post, in another thread here. With the additional info Don B provided above, and there being other happy members switching to coil suspension, you should be able to assess which one, coil or air, is more suited to your needs.

 

On the ZF transmission, many Jaguar owners in Hong Kong were led to believe that the driver's handbook says no need to change the transmission fluid, and an innocent local "Jaguar specialist" told his customers that the transmission was sealed and there is no way one can change the fluid.... My mechanic has just changed mine. He said the ZF transmission is the same in some BMW cars, and periodic renewal of the fluid is the right way to go. He found my transmission sump pan never touched in the last 12 years, and the fluid drained out was all black. Common sense is no lubricant of any kind can last forever without deterioration.

 

Many thanks Don for the time you took to reply to my posts. Forgive me if I screw up the posting protocol but I am a newbie to the forum.The other thing I was looking for Is there a time to change the air bags on the Biltsteins air bags on the suspension strut or do they keep working as well right up to getting a tear in them . Im only asking because I have had one go and was considering at 100,000 miles to change the other ones or is it a case of leave wel alone until they fail. I am just trying to decide between spending money on this car and if so what or buying a low mileage 2009 X358 with the advantage of the diesel engine but higher initial cost and depreciation.

Thanks again for you time

Gordon Young

 

A UK firm that refurb the Bilsteins: -

https://airdominance.co.uk/product-c...uar/jaguar-xj/

I have never used this firm so cannot say what the units are like or how long they last in service, or what they replace in the unit. I suspect the air spring diaphragm and the lower mount bush are the only replacements, as I am not aware the shock absorber can be dismantled. However they will no doubt be able to tell you what is done to the units.

Up to now, only Arnott did any refurbing, and they have now stopped. Yet these units are a bit like McPherson struts; you don't throw them away just because a coil spring breaks, so there really does need to be a service for maintaining these things.

 

Many thanks for the info Fraser. I never knew about this firm. Though still unable to find any info at what point in time or mileage when to change them. No one seems to know so is there anyone out there who has replaced the air struts and noticed a big difference in ride. Consensus at the moment is dont fix until they do. Replacing the bottom shock bushing seems to be advised though.
Thanks again Gordon Young

 

I converted nearly 2 years ago and there is definitely a difference in the ride, but I think you'd only notice if you were really in-tune and paying attention to it. I never liked the air suspension to begin with, but I don't like the coilovers either. In my opinion, the Jag engineers really messed up the suspension on this model. Its not sporty and its not comfortable, but somehow you get the negatives of both. I had an Infiniti M45 for a while, and the suspension in that thing was incredible. Super smooth and comfortable but still handled so well. Its a shame that a car like the X350 could leave the factory with such an abysmal setup.

The air suspension handles minor imperfections in the road more smoothly, especially at lower speeds, but can't handle the big stuff. I was always bottoming out on speedbumps and big potholes. The coilovers handle those much better, BUT you can feel those minor bumps and ripples in the road more.

Besides all that, I have much more peace of mind with the coilovers. I'll never have to go on a wild goose chase with the dumb Air Suspension Fault message again, and I'll never have to worry that my Jag will be a lowrider during cold weather.

So in my opinion and in my experience, the coilovers were the way to go.

 

If the air suspension is working just leave it be. If something, or ANYTHING with the air suspension breaks, coil-overs are the way to go... Unless you have unlimited funds and are willing to replace the entire air suspension in short order.

Think about it. Assuming you're rolling all-stock original stuff- if one shock goes, the others aren't far behind. (Personal experience) That's not even considering the compressor, lines, sensors, etc. The entire coil conversion costs pretty much the same as any single one of the air parts.

If you live in the states, the auto-lowering doesn't matter because you can't go over 90 for extended periods anywhere. (legally, at least) Load leveling isn't too big a deal either. Who hauls a ton of bricks in a Jag?

I was happy with the ride quality Arnott coil-overs and as others have said, the peace of mind of never having to mess with that damned "air suspension fault"

 

Exactly this. There are just way too many things to go wrong. Been there, done that.

I also made made decent money back selling my compressor and valve block on ebay.

 

I have 94K on my XJR and have replace the front air shock units with Arnott. I plan to keep the air suspension system as long as its relatively trouble free. I have the air compressor rebuilt kit ready to go as well.

RyeJag

 

I'm trying to keep my air suspension for as long as possible. RMT sells a rebuilt strut for $351, with shipping. I put one in 2 weeks ago - supposed to have dampening, and it has a lifetime warranty. We'll see how long it lasts, but it replaced a Bilstein front strut that the dealer had put in 27,000 miles ago.