I assisted another member do some suspension work today and thought I would document it so others can use it for reference. Among other things, we replaced his strut mounts & added a spacer to lift the front of his car to give more clearance for his new steel skidplate.
Now normaly I would remove the struts completely & remove & replace the parts with the assistance of my bench vice. But in an attempt to save some steps and time, we tried it with the struts still installed in the vehicle. It is possible, but still requires the use of a spring compressor to compress the spring enough to remove & replace the parts.
NOTE: This task can be dangerous and should only be completed by someone who can work safely, The springs can be placed under high tension and if the spring compressor breaks, serious injury can result!
7mm alen wrench
13/16" spark plug socket
Spring compressor (available as a loan-a-tool at many auto parts stores with a deposit)
2 Strut mounts: 1J0 412 331 C
2 Strut bearings: 1J0 412 249
2 Spacers (if necessary): 1J0 412 311 A
First thing is to do is to remove the nut on top of the struts. There are two on each side. The first nut holds a cap and the one underneath it holds the mount, bearing & spring perch. Here is how to remove it. Place the 13/16 spark plug socket on the nut and run the 7mm allen wrench through the hole in the center of the socket. Using a pipe to hold the allen key stil, use the 7/8 wrench to loosen the socket:
Repeat this for both nuts on each side (4 nuts in total). Once the four nuts are removed, you can lift the front of the vehicle to release the spring tension on the mounts. Jack up both sides & secure with jackstads for safety. Then remove the wheels for acces to the wheel well.
There will still be some tension on the springs at this point. Use the spring compressor to compress the spring to relieve the rest of the tension on the upper perch & mount:
Once the spring is compressed a bit, the parts will easily come out. Beware of your hands inside the wheel well. The spring is under tension and if the compressor breaks, you can injure yourself. BE CAREFUL! Here are the parts removed:
Here are the replacement parts. Notice the adition of the spacer. This goes in between the bearing and the upper perch:
Now just put the parts back in the same order shown in the picture. This can be quite frustrating getting all the parts to line up & stay in place, but we did it. An extra set of hands would come in handy here. Once the parts are in place, use a jack to raise the lower control arm to raise the shaft of the strut up through the parts so you can secure everything with the nut. Here is a diagram of the components in case you need a reference on how to put everything back:
Note: #28 is the mount, #24 is the bearing, #40 is the spacer & #29 is the spring perch.
Oh, and since it was mentioned in a post below, the top retaining nut is supposed to be replaced as per the Bentley Manual (#27 in the illustration). If you have to get the parts at the dealer, then you might as well get these to, but I have never changed one. It does not support the weight of the vehicle in any way. In fact, all it realy does is hold the top hat piece so that when you raise the car, the strut doesn not fall through the hole in the inner fender. But I have to mention it to be diligent. For the price of them, why not change them?
Here are before & after pictures of both the mounts as seen from the gap at the top of he strut towers & the wheel well gap:
Here is a picture of the old & new mounts. Notice not only the height difference, but the shape as well. The new one is tappered & the old one is mushroomed:
The total lift was about 20mm. 10mm of that was from the spacer and 10mm was from the new mount. The old mounts had 150k km on them. The new mounts will settle a few mm, but should take a long time before they go as low as the old ones.
Again, I can't stress this enough. PLEASE be careful when workig in the wheel well while the springs are compressed.
If anyone has any other tips or if I left something out, please feel free to let me know so I can update the post.
I do plan to do a complete suspension swap at a later date. When I do one, I will document it as well so that it can be used as a suspension install how to. So stay tuned for that one.