Hi guys I need to change the rear shocks of my 1998 Vanden Plas. Do I need to take out the rear seat to get to the nut of the shock, or do I have to clamp the spring and take out the mount. Need your help ,thanks

 

you have to clamp the springs,jag has a slip spring compressor that fits nice,its not an easy task if you have never done them

 

Thanks Teck4Jag, I've never taken out this system, what I understand is you have to clamp the spring, take the 4 nut holding the shock mount, and bolt holding the shock and take out the whole thing. Is this correct.
Do you think this will be difficult to do on car jacks.
Can you buy a slip spring compressor in an auto store.
Thanks again for your help

 

You have a grasp of the general principle. Safely compress the spring, remove the 4 nuts holding upper mount to chassis, remove through bolt at lower spherical joint, replace the shock. Sounds simple but reality is another matter.

Safely compressing the spring requires 2 compressors expertly placed to avoid blowout on one side or the other. The Jaguar/OTC/Rotunda compressors are designed exrpressly for the job and barely fit in the allotted space even though they are very small compared to the smallest aftermarket unit. They are very strong and I've risked my hands and life with them several times. Any aftermarket compressor is a compromise and is unlikely to get the job done due to space constraints and the amount of compression required. After compression is started the 4 nuts are a no brainer, just make sure there is no pressure on the plate before removing the nuts. The lower through bolt can go 2 ways. #1, you are lucky enough to have either a low mileage example or a southern car(ie, Florida, Georgia, Arizona, California, ETC.) and the bolt will be easily removed from the swingarm. #2, you have a high mileage car or it has spent its life in the rust belt(ie, Michigan, Ohio, Indiana, ETC.) and the through bolt is seized in the swingarm and will require at least a couple of hours of torch(oxy/acetylene) work to get the bolt out without replacing more expensive parts. This very problem was in the dealership a few days ago, the repair went like this. Heated through bolt with torch for 10 minutes(it's long and in a heat sink) nut was already removed. Hit bolt with ice water to quench and shrink. Blasted bolt with strongest air impact wrench in the dealership and it did not move at all. Heated bolt for 15 minutes. Attached 36" Snap-On breaker bar and socket to bolt head, bolt would not move, added 4 feet of fence post to end of breaker bar, lowered car on hoist until breaker bar/fence post assembly contacted the ground, continued to lower until Snap-On breaker bar broke. Bolt did not move. Used cut off wheel on die grinder to cut the head off of the bolt. If you try to drive it from the shock side you will just mushroom the end and spend another couple of hours working on getting the end back down to size. Drove the bolt fragment from the swingarm with the strongest air hammer in the dealership. Unfortunately the other side was a repeat of this. 6 hours later both lower shock bolts were out. Now you would think the whole assembly would just fall out on the ground right? Not so, if you really want the whole thing out you still have to remove the swaybar links without breaking them(rust belt, remember), loosen the giant inner pivot bolt on the swingarm for more swing, remove one time use axle nut for more travel and then still fight to get the assembly out after compressing to the limit of the factory supplied compressors and having the fattest guy in the shop lean on the 4 foot pry bar you have stuck in between the hub carrier and swingarm. No thanks! The easiest way but often frightening is to compress the spring to near the limit of the compressors. Of course you still have to remove the 4 upper plate bolts and lower through bolt. Snake your hand in above the plate with the proper sized wrench to remove the upper shock nut and hope that after the nut comes loose you can just spin it off with your fingertips and remove the shock. If you are lucky enough to have adaptive damping there will be a hex in the top of the shock rod where the electrical connector plugs in you can stick an allen wrench in to hold the rod while you loosen the nut. Without adaptive damping I usually just use the torch to blow the top of the shock rod and nut off as trying to get the nut loose without damaging the threads while working blind with your hands in position for destruction just isn't my cup of tea.

Maybe I should have asked this first. What makes you think you need shock replacement? I've only had to replace a few pairs of shocks on this model car in the last 12 years and honestly they really only needed replacement of the upper bushings/cushions due to deterioration. The only problem being that the shock has to be removed to replace the bushes and after all that work you might as well put the shock in just in case you damaged it during removal(see above).

The typical fault with these cars is looseness of the lower spherical joint causing a clunk from the rear on small bumps. The lower joint is much easier to replace. Remove the lower through bolt by whatever means necessary. Use a screw jack to force the swingarm upwards by placing it under the lower pivot of the hub carrier. Sometimes, and especially with XK8s it helps to place a second screw jack under the front core support to keep from pushing the car off of the hoist/lift. Press upwards with the rear screw jack until enough clearance is acheived to allow positioning of a typical ball joint press on the rear shock lower spherical joint. It helps to have the special tools as they are a perfect fit for the joint but I'm sure an enterprising tech could make due with a good ball joint press kit alone. Press the old joint out, press the new joint in using the ball joint press. If you use the special tools the insertion tool is self limiting and always installs the joint properly. If you use the ball joint press kit alone be sure to center the joint to avoid contact between the shock and swingarm/spring/etc.

Sorry for the diatribe but this does work on both XJ8 1998-2003, XK8 1997-2006. As always I am trying to keep someone from spending way too much time on their back in the driveway.

 

So Real_Tech, to replace the lower spherical bush, are you saying you can get to the lower end of the shock by jacking the swing arm up and without using spring compressors? This does sound doable!

I've got a noise which I believe is my nearside lower shock bush. How can I be sure it is this before replacing? Any suggestions?