BMW Z4 Rear Shock Replacement Time – 2-3 Hours
You will first recognize the need for a BMW Z4 rear shock replacement in your backside. Worn out rear shocks and shock mounts cause a rough and noisy ride – expect to change out your BMW Z4 rear shocks every 100,000 miles.
The BMW Z4 is a great car, plain and simple. It is one of our personal favorites here at the BMW Repair Guide. It’s design is iconic…it’s handling is superb. The BMW Z4 is just a fun car to drive, especially here in South Florida where we can enjoy the retractable top for most of the year. The BMW Z4 is known as a pretty solid car, and when maintained properly and driven with respect (watch the pot holes and speed bumps) your suspension should give you hundreds of thousands of trouble free miles.
A BMW Z4 rear shock replacement should be considered a normal maintenance item and we suggest it’s performed before your teeth start rattling – about every 100K miles. The Z4’s low stance and artful handling tends to place greater loads on the rear shocks, which in turn tends to wear down the trunk located rubber shock mounts. A tell tale sign of a worn rear shock mount is a “clunking” sound coming from the trunk on rough roads or tight turns. In extreme cases of neglect, the shock mounts have been know to cause structural damage to the body of the vehicle as they try and pull out of their mounting holes. Newer shock mount kits include an aftermarket reinforcement plate to eliminate this catastrophic problem – we highly suggest using this plate on any BMW Z4 rear shock replacement.
BMW Z4 rear shock replacement is a rather simple, straightforward repair for the DIY mechanic…EXCEPT FOR ONE MAJOR ISSUE. The adjustable soft top stowage base in the rear of the Z4 trunk must be removed to gain access to the top of the rear shock towers. We will be up front with you now…this is the trickiest part of the repair and requires extreme patience and the heartbeat of a yoga master to reassemble. We detail every step from removal to reassembly to make the repair journey as comfortable as possible for you. Again…it can be done! And doing it yourself will save you hundreds of dollars from taking it to a local independent mechanic that has probably never done the repair themselves either.
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Tools and Supplies
Jack and jack stands stands – Click here to learn how to properly jack and support your vehicle for this repair
17mm deep socket with impact wrench or breaker bar (for wheel lug nut removal)
10mm socket wrench with extension
13mm socket wrench
16mm socket wrench
18mm socket wrench
17mm open end wrench
flat blade screwdriver
needle nose pliers
- Jack and support the rear of the vehicle using the jack stand method. Please click here to learn how to properly jack and support your vehicle for this repair.
- Using a 17mm deep well socket, remove the lug nuts and rear wheels.
Adjustable soft top stowage base removal
In order to gain access to the BMW Z4 rear shock mounts , the trunk’s folding top compartment must unfortunately be removed. BMW really should have put more thought into this during the design of the Z4….for removing and ESPECIALLY reinstalling the compartment floor is a royal pain in “das arsche”. Take it one step at a time and move slowly.
- The first step is to turn the side mounts and raise the compartment floor to its top position. Release the cover from the compartment floor by pulling it loose with your hands…it is clipped on and just snaps on and off.
- With the compartment floor in the raised position, it is time to remove the infamous plastic clips that anchor the floor to the side mounts. There are four plastic clips, two on each side of the compartment floor, that must be removed. The following image shows the plastic clips on the left (drivers) side of the floor. In order to remove them, you must squeeze the lobes together then push them UP and out. Be careful when pushing them up and out…they can get lost behind the top and you will be stuck ordering new clips (I have added a link for new clips in case this happens – for new floor clips click here).
- With the four clips removed, it is time to remove the compartment floor from the trunk. The compartment floor rests on the side mounts hinged rails. To remove, gently lift up the floor until it releases from the rails on each side mount. ***Important Note – the compartment floor has a tab on the rear of it that activates the convertible top’s microswitch (allows the top to be raised or lowered). Use extreme care when removing the compartment floor from the trunk so you do not break the microswitch (located on back wall of trunk). If you break the microswitch, you will not be able to raise or lower the top until replaced.
- Use a 10mm socket wrench with extension to remove the two bolts anchoring the side mounts to the trunk.
- There is a plastic rivet on top of each side mount that needs to be removed as well. Use a flat blade screwdriver and a pair of needle nose pliers to remove the stem from the fastener. Then just pry the fastener out with the screwdriver. Remove the side mounts from the trunk when you have finished removing the rivet.
Rear shock removal and replacement
- Starting in the trunk, you will need to remove just enough trunk liner and rubber insulation to expose the top of each shock mount.
- Start by removing the left side panel cover by twisting the release handle and pulling free of car.
- Pull the trunk liner and the underlying rubber insulation away from the side of trunk exposing the shock mount. There is one plastic rivet that will have to be removed near the back of the trunk…use a body trim tool to remove it. ***It is common for the rubber insulation to break apart when removing…this is normal and does not effect the integrity of the vehicle in any way.
- Position a floor jack under the left rear wheel hub. Jack up the hub about 6″ to release the pressure on the shock…this makes the shock easier to remove and install.
- Use a 13mm socket wrench to remove the two nuts anchoring the shock mount to the vehicle chassis. Note that on the BMW Z4 you cannot get a socket on the self locking plate nut because stowage base frame is in the way. It can only be removed after the shock is removed from the vehicle.
- Use an 18mm socket wrench to remove the lower shock mounting bolt. This bolt will be tightly torqued…use a breaker bar or a piece of galvanized pipe to help break the bolt free.
- Remove the rear shock from the vehicle and place in a bench vise for disassembly. There are some parts on the old shock assembly that will be reused.
- Use a 16mm socket wrench to remove the shock mount nut. Make sure the shaft of shock is tight in the vise…it will want to spin with the nut.
- Remove the top washer, the old rubber shock mount, the shock mount plate, any remaining bump stop, and the guard tube from the shock. You will be reusing the top washer, shock mount plate and guard tube, so do not discard!
- Now its time to set up the new shock for installation. Lay the new shock on a bench. Start by installing a guard tube (open end of tube faces bottom of shock). Next add the new rubber bump stop, the shock plate (concave side down), and the new shock mount.
- Place the shock in a vice (or any other means) to hold it steady. If you use a vice, make sure to wrap rags around the shaft so you don’t score them. Using a 17mm open end wrench and an adjustable wrench, install the self locking nut on the top of the shaft (see image below). The nut is supposed to be torqued to 10 ft/lbs, which means make it as tight as you can without grunting like you are in a weight lifting competition. Unfortunately a torque wrench won’t work in this situation, since turning the nut on its own spins the entire shaft inside the shock. Try it for fun if you don’t understand what I’m getting at. DO NOT attempt to put the shaft in a vice, or use any other means (vice grips, etc) to stop the shaft from spinning so you can use a torque wrench. You will score the shaft which will ruin the shock.
- Insert new gasket on shock mount (gasket should have been included in shock mount kit).
- Insert shock back inside wheel well. Install lower mounting bolt and torque to 100 Nm (74 ft-lb).
- If you are installing a shock mount reinforcement plate, which the BMW Repair Guide highly recommends you do, position it on top of the shock mounts as shown below.
- Install the two 13mm nuts and torque to 28 Nm (21 ft-lb).
- Replace the rubber insulation and trunk liner. Repeat installation on right side of vehicle.
Installation of adjustable stowage base – PLEASE READ
- Reinstalling the stowage base side mounts is easy…just replace the two 10mm mounting bolts and plastic rivet as shown in the above steps.
- Reinstalling the stowage base compartment floor is ridiculously difficult and will definitely test your patience. But look at it this way…even the most seasoned mechanics struggle with it, and it does not take any more skill or knowledge than you already have. It is just really tough to get the floor mounted correctly on the hinged rail while reinstalling the plastic clips. The two rear clips are are extremely nauseating to install since you have to wedge your entire arm above the stowage base to insert them. If you get upset, walk away and cool off. You can even send us a nasty email to vent your frustration…we will be more than happy to talk you through it. But it can be done, and you will do it. Our best advice is to get someone to help hold the compartment floor in place on the hinged rails while you try and install the plastic clips. Start with one side, and install the front clip first. The front clip is relatively easy and will help keep the floor in place while you grapple with the rear. The following image shows the proper alignment of the plastic clip for reinsertion into the floor:
Once you get all four clips in, verify the tab on the back of the compartment floor is properly aligned in the convertible microswitch.
If you have any questions or comments, please feel free to comment on this article or contact us. And congratulations for Doing It Yourself!
The Repair Difficulty Level displays graphically how challenging the repair is, from easy to advanced. Easy repairs usually require very few tools, have short repair times and do not require jacking and supporting the vehicle. As the difficulty level rises, expect the repair to demand more time, specialized tools, and better understanding of mechanics to complete the job.