318i Tech Procedure -
Rear Shocks, Springs, and Rear Shock Mount Replacement

In my ongoing crusade to repair, replace, and refurbish every part in the 318i, I decided to replace the suspension with an aftermarket suspension. While I'm not sure, I believe that the shocks in the car were the original shocks. The car at this time had about 155K miles on it.

I decided to upgrade to H&R sport springs with Bilstein Sport shocks. The sport springs and shocks will dramatically improve handling and will lower the car approximately 1.25" all around.

I ordered all the parts from eap4parts.com. Be sure not to order HD shocks with sport springs or sport shocks with OE springs.

Now is a good time to put in some new rear shock mounts. They are relatively inexpensive and the design is a weak point in the rear suspension. If you start hearing a clunking noise from the rear end of your car, chances are that your rear shock mounts have failed. The rear shock mount is the piece or rubber that holds the end of the shock into the car. They do take a beating. The stock E30 RMS is awful. The E30 convertible RSM is a bit beefier than the standard one. The RMS got a bit better with the E36 and even a bit better in the Z3 when a reinforcement plate was introduced. The E46 RSMs are currently the best ones to use. They are all interchangeable. I purchased the RSM kit from EAP4Parts.com with my shocks and springs. They came with E46 rear shock mounts, gaskets, Z3 rein forcer plates, and nuts. I highly recommend using the E46 rear shock mounts. Aftermarket companies sell rear shock mounts with urethane bushings that are much harder than even the E46 RSM but the aftermarket ones exhibit more noise and vibration. I think the E46 ones are the best compromise, but for people who don't care about noise, stiffness, and vibrations, check out the aftermarket ones.

Required tool list:
H&R Sport Springs
Bilstein Sport Shocks
E46 Rear Shock Mounts (with gasket, lock nuts, and Z3 reinvestment plate)
Various Sockets
(2) Spring Compressor

Click on the thumbnail for larger pictures. I apologize for the low resolution pictures. I had forgotten my new camera at work the weekend I did this procedure.

	Lift the rear end of the car and support it properly with a bottle of beer... or a jack stand. Your choice.
	Peel back the linking in the trunk to expose the rear shock mounts and the rear shock towers.
	Remove the rear shock from the rear trailing arm. Remove the lock nuts from the top of the rear shock mount and remove the old shocks.
	To make the task of removing the rear shock easier, let the rear end drop a little by removing the bolt that holds the rear end to the frame of the car through a bushing.
	While removing this bolt, support the rear end of the car and the trailing arms.
	Disconnect the rear sway bar links to allow the arms to drop.
	At this time, some people report that they are able to remove the spring by hand, but I was unable to do this and had to wedge my spring compressor in there to get the springs out.
	Here is my old rear shock mount. Judging by it's condition, it is definitely not the original rear shock mount. It still shows signs of wear.
	Here is the E46 rear shock mount. The black boot is reusable.
	Compare the stock rear springs to the H&R Sport rear springs.
	Install the new rear springs by hand if possible, or with a spring compressor.
	Install the new rear shock mount and attach the new shock to the spindle and the rear shock mount. Reconnect the differential mount and the rear sway bar links.
Performed:	August 16, 2004
Difficulty	2/5 - Much easier than the fronts.

After replacing my front and rear springs and shocks, the car feels like a much different car. The body roll is significantly reduced, the ride is firm, and the steering is more responsive. The ride is comfortable enough for my daily driving, but firm enough to have some fun with during spirited driving at the track. My first comment after driving the car with the new suspension was "This is how the car should have been set up from the factory!". While less important, the car also looks a lot nicer sitting 1.25" lower and has less fender gap.

Disclaimer: I am not a professional mechanic. Information this page should be used at your own risk and discretion. Different models and model years may be different than my 1991 318i. Read: If you screw your car up following my instructions, sorry. Isn't it sad that in this sue crazy world you have to put a disclaimer on your web page?