Wednesday, January 28, 2015

How to change the front air springs (suspension struts) on your Jaguar XJ

Just like the title says, here is how to change the air springs on your Jaguar XJ. I replace them for Arnott springs, I believe them to be a good quality product and so far I never warrantied one, they don't go out here even though they are subject to Miami's heat!

Here is what you'll need:

Click to enlarge
  • We have to set up the front of the car and place jack stands. Remove the wheels also.
  • Alright guys, first, we disconnect the connector that goes to the strut's adaptive shock.

  •  After we unplug the shock, you need to undo the air line, is a 12 mm. Set it aside. Then we remove the four 13 mm nuts that hold the top shock in place.

  •  Here is a pic of the nuts removed.

  •  Now we need to undo the nut that holds the top control arm to the knuckle.

  •  To do that you'll need an 18 mm wrench, and a 5 mm hex like in the pic below.

  1.  When the nut is completely out the arm is going to swing up, so be careful and hold down on that arm like a man!

  •  Now that the top of the knuckle is disconnected, we need to remove the front lower control arm nut and bolt. It's a 15 mm at the top and an 18 mm at the bottom.

  •  Here is a pic of the front control arm with the nut and bolt removed and the arm detached from the knuckle.

  •  Now we need to remove the nut and bolt that hold the sway bar in place.

  •  It's a 13 mm on one side and a 15 mm on the other. Below is a pic of the bolt removed.

  •  Now to remove the big ass torx (TX60) that holds the bottom of the strut in place.

  •  Here is a pic of the strut Torx removed.

  •  Now with a buddy (I can do it by myself but I got practice), have him pull down on the top of the knuckle and you fish out the air spring.

  •  Enjoy the picture of the piece of crap Jaguar calls air springs.

  • This is the Arnott air spring. I think is much better, andcheaper! And no, Arnott is not paying me. If I recommend something is because I stand behind it.

  •  Remove the nuts that come on the Arnott spring (Those I don't like, I put back the originals!). Not you need to remove the 12 mm adapter. 

  •  With the adapter removed, you might need to put it on a vice and remove the 12 mm nut at the top. DON'T LOSE THE PIECES, THERE ARE 3! THERE IS A LITTLE RING INSIDE AS YOU CAN SEE IN THE PIC BELOW, WHEN YOU REMOVE THE NUT DON"T LOSE THE RING THAT IS INSIDE.

  •  Now put back the adapter.

  •  Tighten the adapter with needle nose pliers.

  •  Now you can put the new strut in place, and have your body pull down on the knucle while you catch a top nut. The pic below shows you that I only catch one nut at first. Make sure that the air adapter lines up with its proper hole.

  •  Enjoy a good beer and the photo of your new spring below.

  •  Now pull up or down on the arm to catch the big ass Torx by hand first. Then tighten.

  •  Now you have to catch the sway bar bolt and nut, you might have to pry up or down on the sway bar to align the hole. Then catch the nut by hand and tighten!

  •  Now place the front control arm in place, and catch the nut and bolt. Tighten them.

  •  Now pull down (I hope you had breakfast, you'll see what I mean) on the top control arm and catch the knuckle, catch the nut by hand then tighten with the 5 mm hex and the 18 mm wrench.

  •  Now what I'm about to tell you is the reason why you read my posts. How to change the front suspension ride height. The pic below depicts the front height sensor, which is located on your left wheel. If you bend that bracket down just a little bit, your suspension ride height will increase. Is a cool feature, but remember, just a little bending changes your ride height a lot! so be careful with this new acquired power I just gave you. 

  •  Now put back the wheels and lower the car. Now the pieces I told you not to lose before, we are replacing on the line. Below there is a pic of how they came out.

  •  Pull them with pliers and put first the nut and then the ring. The ring has an orientation, look at the photo for reference.

  •  As you can see I also placed new shielding in the wire (Look at the first photos you'll see that the cable going to the strut was wide open). I am very picky, that's why my customers love me. I don't leave anything, so I fix the wire shielding too. Connect the shock and make sure those 13 mm at the top of the strut are tight.

  •  Then ease your car down and drive it slow because your car is low and you don't want to scrape the bottom of your cat. Drive it around the block three times, then reverse park it, then put it on park and stay inside, don't open the doors and don't shut the car off, the car should now lift itself up. If it doesn't, repeat this step until it does. Below there is a photo of the computer faults. I have a fancy 20000 dollar computer that can do this, but you don't need it, I'm just showing it off :D

  •  This is about the proper ride height for your car. That's why I bend down the sensor a little bit.


  1. How great! I can’t wait to see the projects you did with the new saw!It’s still one of my very favorite tools. It comes in handy for so many projects.Donald

  2. As much as I'd like a 4-post lift in my garage, I don't have one, which is probably the case with many mere mortals. However, That is actually a plus with this project, as using a small jack to manipulate the suspension as you're uncoupling (and re-coupling) assemblies makes this a straightforward one person job.

    Also, it helps to not fully remove all of the nuts from the top, just so that the shock doesn't come down and misalign from the holes resulting in less maneuverability during the subsequent removal steps. Similarly, when you position the new one in, get one or two (opposite corner) of the nuts slightly on to hold it up, and when you've got the lower torx bolt in, then tighten them up.

    If the hub assembly is held up by a jack, the control arm and upper connection won't fly apart when you remove the nut (and similarly, bringing them together by jacking the hub upwards when you go to reassemble is a cinch).

    You can use a decent sized punch tool (or even a screwdriver, but I prefer a hardened punch) to get holes on linkages to align from the side opposite where you're trying to insert the bolt through.

  3. you saved my day, installed new air struts on the front of a 2004 xj8 and was confused why they would not air up. read your guide here and backed the car in and out a few times and viola! air up! thank you for taking the time to help us all out!!

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