After a little searching on the forum it seems front air spring failures are much more common than rear. I am concluding the rear air springs last much longer than the fronts, due to there being minimal weight on the rear versus supporting all the engine weight up front all the time. Perhaps there are other unknown reasons the fronts are more prone to failure, especially at the top seal, due to the constant heating and cooling temperature fluctuations of the engine bay.

Most of the air ride components in our cars are not prone to early failure, such as the valve block, tank, air lines, ASM, etc. By far the two main components that fail are the compressor (cheap fix normally) or the air springs (most expensive). Every once in a while someone will have an air connector leak or a ride height sensor problem, but are usually remedied fairly easily.

We had a front spring leak at the top come up with the cold weather. Our second XJ8 had the front air springs replaced with 2 Arnotts around the same mileage (50,000 miles). I have not been very impressed with the Arnott ride versus factory springs. To me, failures of front springs at 50,000 miles on any car seems to be pretty early. I have read quite a bit on spring conversions, different air springs, etc, so I am not trying to turn this into “which is better.” I am not opposed to a spring conversion at $1,000, but one of the reasons I like the x350 was for the ride leveling capability as we load the trunk down fairly frequently and I’m afraid of the car sagging all the time in the rear.

I realize none of this can be reproduced in a lab, and all of this is real world experience, so failure rates are going to vary widely. I have heard some front springs failing very early, while others go over 100,000 miles on the original.

While I don’t mind replacing a front air spring here and there, I am not too fond of doing the same to the rears, as that doubles the price. With two XJ8’s, if all the springs were to fail, I would have $6,000-7,000 just in Bilstein springs alone, with chance of them failing again. For that price, I could buy another XJ8!

I am more curious if there has been anyone that has had a rear air spring fail before the front springs?

For those that have had any rear air spring fail, what was the mileage?

 

The general place of failure is front, and at the upper seal. The primary difference between the front and rear failures, is that the rears are not exposed to the elements and the under-hood environment, and protected by the boot's environment. Replacement for all 4 with Bilstein's B4 modules runs about $1700 a pair, so the total is closer to about $3400.

 

Hi David,

Thanks for the quick reply. You are correct, replacing 4 springs in one car would run about $3400 in parts. Since we have two XJ8’s, I had factored in 8 springs failing, at a cost of $6,000-7000.

 

Ah so! said the blind man...

 

I am having today my front springs replaced with B4's (winter cold requesting its toll...). Only the driver's front spring is leaking (with a strong hissing when temp is below 6°C), the passenger's front spring looks still OK. (btw would be interesting to know if driver's side suffers more than passenger's side due to usually more weight...)
The car has only 68.000 km but it had an early life in Qatar. I suspect the very high temps there may be the reason of the rather early failure.
Hoping that the rears will resist as they only suffered the external temps and did not have to suffer the seals cooking imposed under the hood

 

There is no need to replace in pairs unless the damper part of the unit is failing, as unlike steel coils, air springs can't 'sack out'. The ASM always sets the car to the correct height using air pressure.

 

Unless I am mistaken, I thought that the Jaguar recommendations were changed some time ago so as to change in pairs.
In addition , my new shocks are B4's that may be slightly different from the original Bilstein's.
Finally, there is a good chance that the second front spring may show in a next future the same wear than the currently leaking one and I don't want to suffer the same issue being blocked on some winter road.
I will not take the risk and will sell the still good one...

 

I too would never recommend single replacement. Primarily because of age and shock performance difference. New modules perform quite different than one which has a decade or more of use.

 

Another wear factor not mentioned, involves the same factors as the front brake pads do. All the weight is shifted towards the front of the vehicle, the faster the speed, with fast stops, increases the wear on all the front ends suspension, as well as the brake parts. Brake pads usually wear two front sets to one set of rears, in my experience on cars as well as bikes passing through my shop.

 

If you drive on the right side of the road, the right shoulder beats up the car more than the left. If you drive on the correct side of the road the left side generally gets beat up more.
Many here have stated that the x350 burns thru rear brakes faster than the fronts.