I've read several people say in these forums that changing the air shocks is easy, but I've run into 4 problems.

It's easy enough to remove the old busted air shock, but hell to get the new one in.

First, how do you insert the nuts on the upper end of the new shock through the 4 holes they have to line up with, when you can't see the holes, and you have to hold the shock in place from UNDER the car (or it will fall down) while screwing on the nuts from inside the trunk??? If I had someone else working with me it would be easy, but I don't. I fiddled around positioning the upper end for a LONG time before the nuts all lined up with their holes by chance, then shoved something under the shock to hold it there while I moved to the trunk side. But I don't want to do that again.

Second, the new air shock is fully extended, and too long to fit into the space available when the top half of the car hangs down low because there's no shock there. I don't see any way to jack up the upper half of the car; I can only put the jack under the lower suspension, which jacks up the part of the car that would connect to the lower end of the new air shock. So somehow I need to squeeze the new air shock to be about 6 inches shorter, in order to screw its lower end into the "bottom track control arm" (#7 in this figure from Miessler):


I did this to the left rear shock by putting a jack on rollers underneath the lower end of the air shock, and jacking up the lower end of the shock until it was exactly the height of the bolt I had to screw it to, then rolling and kicking the jack into place to line up the hold through the lower end of the shock with the holes in the bottom track control. But this was very fiddly and took a long time, and I don't know if I can do it again. How did you squeeze the new shock absorber down short enough to fit, or jack the upper half of the car up high enough?

Third, there's an air line in the trunk that goes into the upper end of the air shock. It screws in. It's #2 in this photo from Miessler:

Inside trunk, attachments for upper end of rear left air shock

The old one screws off easily enough, but I'm supposed to replace it with a new nut. But the new nut is the entire metal assembly on the end of the plastic tube. I have no way to remove the old one from the tube except to cut it off, in which case the tube won't be long enough to reach. Nor do I know how to attach the new nut onto the tube.

So I tried just screwing the old one back in, but I can't. I screwed it in as much as I could, but it still leaks. The tube twists along with the nut, so now the tube has terrible rotational stress on it from being twisted several times. What to do?

Fourth: the gasket inside that nut. Should I try to remove the new gasket from the new nut and put it on the old nut? Can I coat the old gasket with something that will make it seal, but won't break it down over time?

 

When I went to NP04 (New Product 2004, intro to the X350) training class, the first thing the instructor said was "The first person that says AIR SHOCK will be dismissed from class and sent back to their dealer"!!!!!!!!!!!

He reminded us that they are AIR SPRINGS with HYDRAULIC DAMPERS.

That first encounter has been burned into my memory.

 

If I understand you correctly, you are jacking the car improperly. Jaguar has a diagram for lifting the car showing the trolley jack placement on the trailing arm and the jack stand on the body pinch line forward of the rear wheel where indicated for the trunk jack. This will allow you to use a bottle jack to maneuver the strut into position.

As to lining up the studs into blind holes, I have been using a 1/4 inch socket extension as a guide. The female end goes into one of the four holes through the trunk and is placed over one of the studs. Use it to position the strut. Use the bottle jack to lift the strut. Once the first stud clears attach the nut and the rest is easy..

Use silicon spray to enable the airline nut to rotate and eliminate rotational stress on the line. Use silicone grease on the o ring and threads for a good seal.. I have replaced an o ring which appeared damaged with a resulting good seal. I don't know if this is a recommended procedure, but it worked for me..I hope this helps.

 

The rears with a lift, & another person to assist you, is still a pain.

 

This sounds like what I need to know! But my shop manual chapter on the chassis doesn't mention a "trailing arm" anywhere, nor can I find a trailing arm for Jaguar X350 XJ8 suspensions in parts stores. Are you sure this model has a trailing arm? There's a "lower arm", which looks like a lower control arm, but not like a place to put a jack.

I placed my jack on the part labeled 2 in this photo, near the door (where the nuts are in the photo). 1 is the labeled jack placement area, which seems flimsy and isn't large enough to fit my jack head pad into anyway. 3 is the only other possible place to put a jack. Where should I put my jack?

 

Also, it's not the rubber o ring or the nut that seals the air line to the strut.

It's the brass "olive".

When replacing a nut you need to snip about 3/8" off the end of the existing air line. Same with disassembly of the nut on the air line.

You can re use the olive (the small brass piece the is below the nut and o ring. The olive "grips" the air line and when you snip a bit off the plastic line (There is a special tool to ensure the cut is square - that's also important) it gives the olive a new section of plastic air line to grip.

There is enough extra line to splice 3/8" off the end of the existing line.

You can accomplish the square cut with a new razor blade on a piece of wood.

If you don't do this it's 50/50 that olive will properly grip the air line and you need to slide that off to install the new nut and o ring that usually comes with a new air damper anyways.

 

If you google Jaguar X350 you will see the factory diagram for recommended lifting points for floor jacks and jack stands. I apologize for my misleading use of trailing arm. I was referring to the support which runs from the body corner in front of the rear wheel angled back and inward. I believe it is number 2 in your photos. This is what happens when one's memory ages faster than the car.

 

First time I did one the stars must have aligned. Shoved the new deflated strut in, hit the holes and propped up to install nuts. Struggled reconnecting the toe adjuster.
Next time it would not stab into the holes. Must have shoved it up a hundred times. Finally looked at the mount in body. The strut has to have the bottom kicked out and forward to enter the mounting plate. There is crap in the way, so all the way out and forward works fine. Then prop up with jack or whatever.
To deflate break the check valve loose to bled residual air. I still use a racing jack to raise up to insert the bolt. Retighten rhe check valve first. There is a warning about overtightening. But it has to be tight enough to not spin if backing off the air connector. If this happens you will have to pull the strut off again.

 

That bottom bolt, on the rear shocks, was the only real issue on mine.
But i had use of a lift, and help from its owner,

 

In this video from Bilstein:
at 3:53 the mechanic puts in the bottom bolt just by tugging the control arm down with 1 hand. I guess it's a lot easier if you have a lift and are standing underneath the car, so that gravity pulls both the control arm and you down. You just have to reach up and grab it with 1 hand, then let your own body weight pull it down.

Also that car's underside is a LOT less rusty than mine.

 

put a couple top nuts on finger tight and just tug on the entire suspension

are you sure you’re not fighting the sway bar or something stupid

 

The issue on mine was the rear shocks were fully extended.
To the point you had to compress them, to fit into their place.
The Arnott's are charged with a certain amount of air, when made.
It was the same on both vehicles, having a lift, with a helper was a real plus.

 

I just did my rear shocks and found that if you have both sides of the car jacked up it makes it much easier to get the bottom of the shock into place. I only had one side jacked up at first and could not get it to fit. Jacked up the other side of the car and it fit right into place with little effort. Make sure you leave the top nuts loose until you get the bottom bolt in. Jack stands placed on the pinch welds (#1 in your above photo).

As for the air line, there is no need to cut it. You have to take a small screw driver and separate the little brass collar at the bottom of the fitting and then the whole thing slides off. Screw the new brass fitting into the shock and then slide the air line into it until it wont go anymore.

The toe adjuster goes back on last and I found if you jack up the lower control arm assembly until the toe adjust fits in flush it slides in much easier.

I installed the Arnott units and have been happy with them so far.

 

You should detach the air line and bleed the air out before trying to compress the shocks.
One of the manuals I read mentioned a bleeder valve for the shock, though I never saw it, and I think just detaching the air line bleeds them. Not sure, though.

 

What's a toe adjuster?

 

There is a check valve screwed into the top of the shock. If air bag and rest is holding pressure the trapped pressure makes compressing the strut difficult. Back it off a turn, listen for air releasing.
The toe adjuster is item 8 in your first post.

 

It is number 8 in your first photo