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Pelican Technical Article:

Replacing Rear Shock
 Mounts
on Your BMW

Difficulty Level: 4
Difficulty scale: Adding air to your tires is level one
Rebuilding a BMW Motor is level ten

  This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your BMW 3 Series.  The book contains 272 pages of full color projects detailing everything from performance mods to timing the camshafts.   With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any 3 Series owner's collection. The book was released in August 2006, and is available for ordering now. See The Official Book Website for more details.
 
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[click to enlarge]

     The 3 Series rear shock mounts (RSMs) are weak. These mounts hold the top of the rear shocks to the chassis. Repeated wear and tear on these mounts causes them to crack and break after many years of use. The worn-out shock mounts result in a clunking noise that emanates from the rear suspension while you’re driving. Left unchecked and unfixed, the broken mounts can inflict permanent damage on the chassis by tearing the sheet metal in the rear wheelwells.

     Begin by opening the trunk and removing everything from it—including the carpeting. If you have an E36, you’ll also have to remove the rear speakers to gain access to the rear shock mount (see Photo 1). If you have a convertible, the rear shock mounts are located in the convertible top compartment behind the rear seat. Carefully pull back the molded carpeting in the trunk and remove whatever carpet fasteners hold the carpet down. Then remove the two retaining nuts that hold the rear shock mount to the chassis.

     At this time, also disconnect the rear shock where it attaches to the rear trailing arm (see Project 61). Remove the entire assembly from the car disassemble it on your workbench (see Photo 3).

     Around the time that the Z3 was designed, BMW realized that this rear shock mount design placed a lot of stress on the sheet metal surrounding the rear shock towers. As a result, BMW engineers have included a top-mounted support bracket that sandwiches the rear shock mount and distributes the load better (part number 51-71-8-413-359, about $15). BMW also redesigned the mount for the E46 3 Series cars, making sure the mount was backward compatible with the earlier 3 Series cars. This upgraded mount is used on the E46 M3 and E46 convertible cars, and is the mount to use if you swap out your rear shock mounts for replacement stock units (part number 33-52-6-754-096).

     If you wish to go a step further in performance, install an aftermarket rear shock mount kit. I prefer the aluminum billet kit manufactured by Ground Control and available from PelicanParts.com for about $150. This kit replaces the rubber inner bushing with a polyurethane bushing that is much stiffer and far more secure than the stock mount. In addition, the aftermarket kit contains a beefy support plate that reinforces the sheet metal at its weak point. Installing the aftermarket kit is very similar to installing the stock mounts.

     Reuse the plastic dust cover and the two concave washers from your old shock. Don’t reuse the rubber bumper, as these are typically near disintegration by the time most people replace the mounts. Use new self-locking nuts on top of the shock, and affix the rear shock mount to the chassis. Finally, use a new gasket to seal the base of the shock mount to the chassis. Reinstall the shock mount and replace the rubber boot on top if it was there when you removed the old mount. Reattach the shock at the bottom, reinstall any speakers or carpet removed, and you’re finished.

     If you find your chassis sheet metal torn around the mounts, there is a BMW factory retrofit part that can be welded into place to repair the metal (part number 41-14-8-169-027 for the left side and 41-14-8-169-028 for the right side). Count on spending about $100 or so for a good welder to fit and weld these plates into the rear of your trunk.

     If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.

Figure
Figure 1
To access the rear shock mounts, remove everything in your trunk. On E30 cars, you only need to pull back the carpet, and the mounts should be easily accessible underneath. On E36 cars, the rear speakers interfere with access to the mounts (yellow arrow). From the back seat, pry off the speaker grille and remove the two screws that attach the speakers to the chassis (green arrows, lower left). The speakers should drop into the recesses of the trunk (lower right). No need to unplug them—the wires should be long enough to simply place them aside.
Figure
Figure 2
Here’s a photo of what the rear shock mounts in the rear of an E30. On some cars, there may also be a factory rubber boot installed (inset photo). The red arrow points to the actual rear shock mount (RSM), and the blue arrow points to the very tip of the rod that runs the length of the rear shock.
Figure
Figure 3
With the rear shock assembly removed from the car, disassemble it by removing the top retaining nut from the top of the shock. Hold the shock tip with a pair of locking pliers or a similar tool. Closer examination of this rear shock mount upon disassembly reveals a large crack (red arrow).
Figure
Figure 4
On the left is the aftermarket rear shock mount kit from Ground Control. If you’re planning on some spirited driving, this kit is just what you need. On the right is a stock mount with the Z3 reinforcement plate, a less-expensive alternative to the aftermarket kit.
Figure
Figure 5
This photo shows the proper assembly order for the rear shock mounts. Red arrow: shock absorber dust cover. Green arrow: rubber/foam bumper stop. Blue arrow: lower cup washer (cup faces the rubber/foam bumper). Purple arrow: rear shock mount (stock unit shown). Yellow arrow: shock mount/body gasket. Orange arrow: upper cup washer (cup faces upward toward the top). White arrow: shock retaining nut.
Figure
Figure 6
Here’s a photo of the finished product. Secure the top of the shock with a set of locking pliers so you can tighten and affix the top locking nut (inset). Only use new locking hardware—don’t reuse the old hardware here. Add the Z3 reinforcement plates to the rear shock mounts (green arrow). They are very cheap insurance against tearing your sheet metal.
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Comments and Suggestions:
budweiser68 Comments: are the e36 and e46 rear shocks the same as i can buy a cheap pair of e46 ones for my e36
June 29, 2014
  Followup from the Pelican Staff: They are not the same. Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
MartyJ Comments: The rear shock mount reinforcing plate does not seem to fit on top of the shock tower in my '88 325is due to some kind of caulk/glue. Any recommendations?
May 6, 2014
  Followup from the Pelican Staff: Is it a body seam sealer? You may be able to remove the excess sealer. It is hard to say without seeing it. Can you share a photo? - Nick at Pelican Parts  
RP808 Comments: Where do I find 'project 61'? When I enter it into the search box all I get is a list of parts. Thanks!
March 31, 2014
  Followup from the Pelican Staff: All article are here:

http://www.pelicanparts.com/BMW/techarticles/tech_main_e36.htm - Nick at Pelican Parts
 
that dude Comments: the z3 shock mount reinforcements do work on a bmw e30 convertible
October 11, 2013
  Followup from the Pelican Staff: Thanks for the additional Info. We appreciate it.
- Nick at Pelican Parts
 
Rachel Comments: Hi there. My shock has completely ripped the metal and iv been told to use a sheet of metal to fix it. Question is, do I need to weld the metal on there or?? What is the process I need to do to fix it?? E36 series .. Tia!
September 30, 2013
  Followup from the Pelican Staff: It is going to have to be welded, I would take it to a body shop and have them repair it.
- Nick at Pelican Parts
 
nef Comments: Thank you you for all your help, I will attempt to change the shocks and let you know how it went, again, thanks.
August 22, 2013
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
desotodesign Comments: What are the torque specifications for tightening the bolts on the lower shock arm, the upper shot mounts?
August 1, 2013
  Followup from the Pelican Staff: I would grab a repair manual. It will have the procedure, special tools and torque specs.
- Nick at Pelican Parts
 
inflectionpt Comments: For the ground control rsm, can you still install the factory shock dust cover?
February 14, 2013
  Followup from the Pelican Staff: It should fit, you may have to stretcg it a bit if there is a small size variation. - Nick at Pelican Parts  
ady Comments: hi there, love this info.
i am going to attempt to do this to my 318is 93 car. the question i ask is, i also have an adapter part no 33531091598, this is not really listed anywhere other than realoem websites, its an adapter that goes on top of the rubber buffer, do we still use the metal ring/washer before the actual top mount then?
thanks
January 26, 2013
  Followup from the Pelican Staff: If your vehicle has the adapter, then reassemble in the order the parts were removed. I would not add antyhing to the mix, unless it is noted in the repair instructions. - Nick at Pelican Parts  
sammy7 Comments: should there be any play between the new shock mount and the rod of the new shock? I have so much rod tip that I cant put the rubber dust boot over the shock mount.
November 28, 2012
  Followup from the Pelican Staff: There should be no play when the mounts are installed correctly, you might have one of the washers in the wrong place.
- Nick at Pelican Parts
 
automaticftp Comments: From reading this tech article, it appears as if you do NOT jack the rear of the car up to remove the shock? Is that correct?
October 19, 2012
  Followup from the Pelican Staff: You do not have to.
- Nick at Pelican Parts
 
Neal S. Hershenson Comments: @ ronnie 4/8/12: Check your wheel bearings. If the noise stops on left turns, check the left side - or vice-versa.
June 9, 2012
  Followup from the Pelican Staff: Thanks for the Info. We appreciate it.
- Nick at Pelican Parts
 
ronnie Comments: Not sure if I need shocks, shock mounts, something else or a rebuild of suspension, but here is my situation. 1999, M3 Convertible E36, about 120,000 miles of fairly easy driving. Problem started several months ago with excessive "road noise" as speed increases. I guess it could be the new tires, but the noise started with the old tires. Regardless, when going straight, the noise is a constant humming sound. When go around curve, and weight shifts to one side or other, the noise disappears. Appreciate any trouble shooting advice. Thanks
April 8, 2012
  Followup from the Pelican Staff: Check your wheel bearings, drive the car and turn from left to right, the noise will quiet down on the side that is loaded with the bad bearing.
- Nick at Pelican Parts
 
Jeff Comments: ??Does the car need to be on a jack or jack stands for this job??
August 2, 2011
  Followup from the Pelican Staff: You should always use jack stands after you have raised the car with a jack, and yes it will make the job easier.
- Nick at Pelican Parts
 
Nicolas Comments: Does the Z3 reinforcement plate work on the BMW e30 convertible rear shock mounts?
May 5, 2011
  Followup from the Pelican Staff: I don't think it will fit.
- Nick at Pelican Parts
 
Noah Comments: Do you know of a replacement sheet metal piece for the Right Rear strut tower mount for a convertible Z3? My shock just recently tore through the sheet metal. The part number 41-14-8-169-028 is shaped differently than the convertible. All I can seem to find is the small reinforcement additions.
Thank you so much...
-Noah
April 23, 2011
  Followup from the Pelican Staff: You are going to have to take It to a body shop and have them repair it.
- Nick at Pelican Parts
 
Paul Comments: Does the top of the Sleeve get pulled up over the bumper and does it lock onto the top large washer just below the mount? Thank you, Paul
April 7, 2011
  Followup from the Pelican Staff: That's a good question, it doesn't lock in there - the grooves in the plastic are to hold the foam bump stop. When you drop the car back down, the sleeve will compress and cover the foam bump stop. - Wayne at Pelican Parts  
dave Comments: Hi, thanks for your post. What would be a reasonable cost to replace rear shock mounts on a 97 z3?

Thanks again,
Dave
March 18, 2010
  Followup from the Pelican Staff: Call around to several shops in your area and take a average of what they are quoting.
- Nick at Pelican Parts
 
Funcrew Comments: The original totally blown OEM shocks on my '88 325i did not have bump stops, nor did my new KYB shocks. I'm using full length KYB shocks on lowered springs, so omitted the bump stop to make sure I don't run out of suspension travel. Will this cause any problems?
February 12, 2010
  Followup from the Pelican Staff: Could cause the shock to bottom out and damage the valve inside of it.
- Nick at Pelican Parts
 
jayson Comments: how do you install the new bump stop? I can't seem to figure out how to get the lower cup washer off? I thought it was welded, but I must be wrong. Should i just pull harder?
July 7, 2009
  Followup from the Pelican Staff: Hi there. It just must be slightly stuck on there, you should be able to simply tap it off with a small hammer and then remove the bump stop. - Wayne at Pelican Parts  

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