Replacing the Hydrobearings incl. Tension Strut

Guide for BMW F models

Home page " Replacing the Hydrobearings incl. Tension Strut | Instructions BMW F models

Here, we guide you step-by-step with instructions on how to replace the tension strut, including the hydrobearings. This DIY guide can be applied to all BMW F models (including xDrive). To learn more about how damage can occur and the symptoms of a defective hydrobearing, click here: Causes & Symptoms of a Defective Hydrobearings.

Contents
  1. Video instructions:
  2. Required Parts & Tools
  3. Step 1: (Only for xDrive) Lose the collar screw
  4. Step 2: Jack up or lift the Car correctly
  5. Step 3: Unscrew the Plastic Cover
  6. Step 4: Remove the old Hydrobearings incl. Tension Struts
  7. Step 5: Install new Tension Strut (do not tighten)
  8. Step 6: (Only for xDrive) Install new Collar Screw
  9. Step 7: Move the car to the normal position and tighten the screws
  10. Step 8: Screw the Plastic Cover back on
  11. More Articles:

Video instructions:

The video for the instructions summarized below

Required Parts & Tools

We generally recommend replacing the entire tension strut if the hydrobearing is defective. The cost difference between the hydraulic mount and the complete arm is negligible, and the repair is significantly easier as a result.

The purchase of parts and the repair process depend on whether or not you have an xDrive. However, both situations will be covered in this guide.

INFO BOX:

Attention: The part numbers are from a BMW F30. Please check the part number for your vehicle before purchasing the spare parts.

Spare parts:

2 x tension strut incl. hydromount for BMW F3X (NOT xDrive)*
Part number not xDrive: 36939 01 , 36940 01 (Left, Right)
OR
2 x tension strut incl. hydromount for BMW F3X (xDrive)*
Part number xDrive: 37114 01 , 37115 01 (left, right)

2 x hexagon head screw with flange M12 x 136
Part number: 31106885777

2 x hexagon nuts if not already included with the tension struts

Only for xDrive: collar screw with compression spring M16 x 1.5*
Part number: 31206795249

* Affiliate links are marked with a *. When you purchase one of these products, we receive a small commission. Nothing changes for you and the offer/price remains the same. You can find more information about affiliate links here.

Lemförderer hydromount incl. tension strut
New tension struts incl. hydrobearings
Recommended: New bolts when replacing tie rods
New hexagon bolt and nut for the new tension struts

Tools required:

Ratchet set + Torx attachment: * You need these wrench sizes: 8 mm, 18 mm, 21 mm. However, it is worth buying a complete set, as you can always use a ratchet set.
Wrench with 21 mm width across flats: * You need this to be able to loosen the nut. Here you have to insert the Torx attachment between the jaws: see step 4.
Torque wrench: * To be able to apply the required torque when tightening.
Only for xDrive: HEX attachment 17mm: * You will need this attachment to remove the collar screw. See step 1.
An impact wrench if necessary: * To make it easier for you to get the screws out.
If necessary, a longer hollow iron barThe screws can be screwed tight. A slightly longer iron rod is suitable for creating a leverage effect. See step 1.
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Step 1: (Only for xDrive) Lose the collar screw

When removing the tension strut on an xDrive, you will quickly notice that the drive shaft is in the way.

Drive shaft prevents the hydromount incl. tension strut from being pulled out on the xDrive
xDrive: You can only get the tension strut out by removing the
Pull out the drive shaft and push up

To still remove the tension strut, including the hydrobearings, you can slightly move the drive shaft to the side in Step 4. To do this, you only need to loosen the collar screw with a HEX 17mm wrench.

New collar bolt for the drive shaft on the BMW F30
Collar bolt Drive shaft

It is recommended to loosen the flange bolt while the vehicle is still on the ground.

If the car is already on a lift, a second person can apply the brakes while you loosen the flange bolt. If it doesn't work with the impact wrench, you can use a hollow metal rod. This will extend the ratchet and create a lever effect. This should do the trick.

Leverage effect for more Newton meters
Collar screw tight: Create leverage with an iron rod for more force

Step 2: Jack up or lift the Car correctly

If you have a lift, it is clearly the best choice. However, a lift is not a must. You should be able to lift the car high enough so that you can work underneath it while lying down. Theoretically, you wouldn’t even need to remove the wheels. However, it is still recommended, as it makes it easier to reach the trailing arm bolts.

Options for lifting a vehicle without a lift:

One or better two jacks at the same time
Jack up the car wheel by wheel on blocks (secure against rolling away)
Putting the car on ramps
MEthode to pick up a car
Car on two jacks offers enough space for changing the tension strut

Step 3: Unscrew the Plastic Cover

The plastic cover on the underbody (directly in front of the wheels) is covered with 8 mm screws attached. You can easily unscrew these and put them aside. Now you have free access to the hydromount and the hexagon head screw.

On the left side, you will find the sensor for the outside temperature on the plastic cover. When removing it, be sure to pay attention to the sensor and temporarily disconnect it from its socket.

Positions of the screw connections of the plastic cover on the hydromount
Screw connections of the plastic cover

Step 4: Remove the old Hydrobearings incl. Tension Struts

First, remove the hexagon bolt on the hydrobearing using the impact wrench or ratchet. You will need a 18mm wrench size for this.

Screw to be opened on the hydromount
Position of the hexagon head screw on the hydromount for unscrewing

Second, remove the nut at the other end of the trailing arm (on the wheel suspension). You will need a 21mm wrench size to loosen the nut, while using a Torx screwdriver to counter the screw inside. In the beginning, you can try it with just the impact wrench. However, for the last few turns, you will need to hold the screw in place with a Torx tool.

Bolting the hydromount incl. tension strut to the wheel suspension
Connection between tension strut and wheel suspension: Nut and Torx screw
How to loosen the nut-Torx screw connection
How to loosen the nut without turning the screw

If you don't have an xDrive, you can now loosen the trailing arm and easily pull it out.

Only for xDrive:

With an xDrive, the drive shaft is in the way and prevents the tension strut from being pulled out. This is why you loosened the flange bolt in Step 1. As a result, you can now pull the drive shaft slightly out (towards the interior of the car) and push it upward. This will give you just enough space to pull out the tension strut. This method saves you from having to remove the drive shaft, which would be much more complicated.

Step 5: Install new Tension Strut (do not tighten)

Now, reassemble the tension strut arm in the reverse order of disassembly. Be sure to use the new hexagon bolts and the new nut.

Attention: The bolt and nut must not be tightened to the required torque yet. It is perfectly fine to only tighten the bolt slightly to keep the tension strut in place. Tightening to the correct torque will be done in Step 7, once you have set the car to its normal position.

Newly fitted tension strut
New tension strut fitted

INFO BOX:

The new hexagon head bolts probably look different to the ones you removed. BMW switched to the new bolts at some point, so this is nothing to worry about. The old bolts are almost no longer available on the market.

The difference between old and new lies in the thread, which now runs along the entire length of the screw. However, it is not a must to change to new screws and there are no known advantages of the new screws.

Difference between new hexagon head bolt and old hexagon head bolt of the hydromount incl. tension strut
Comparison of hexagon head bolt hydromount (left = old, right = new)

Step 6: (Only for xDrive) Install new Collar Screw

With a xDrive you can now use the Replace the drive shaft and screw back the collar screw. BMW recommends the Purchase of a new collar screw with spring. In the chapter Required Parts & Tools you will find a suitable collar screw for the BMW.

The flange bolt must be tightened to 210 Nm plus 90° angle of rotation.

Screw the collar screw to the drive shaft
Refit the new collar screw after resetting the drive shaft

Step 7: Move the car to the normal position and tighten the screws

The normal position of a car is reached when the axle joints are no longer under load. In other words, the suspension is neither hanging down nor being pushed up, such as when driving over a pothole. The normal position is reached when the vehicle is standing normally on a flat surface on its wheels.

tighten the tension strut bolts to the required torque. There are several ways to position your vehicle in the normal position while still being able to access the bolts of the trailing arm.

If your car is on a lift, you can lower it slightly and then pump up the front steering knuckle (wheel suspension) until the vehicle is Hovers 1-2 mm above the lift arm. You can use a normal jack to pump up the steering knuckle.
Another method would be to use the Jacking up the vehicle. Either with tires or without. The only important thing is that the steering knuckles do not hang down. However, do not forget to secure the vehicle against rolling away (handbrake).
As the tension strut is easily accessible from below and from the front, a kind of Grube will also do. The only important thing is that you can get to the screw connection of the hydromount and the tension strut.
The car is clearly in the normal position here, as it is standing on the ground.
MEthode for jacking up a car--> accessibility of the tension strut
Car on blocks to reach the normal position -> Easy access to the tension struts from below for tightening

Once the vehicle is in the normal position, tighten the bolts with the following torque and angle specifications:

The hexagon head screw on the hydromount with a torque of 100 Nm + 90° angle of rotation.
Tighten the nut at the other end of the tension strut to a torque of 175 Nm (no angle of rotation).

Step 8: Screw the Plastic Cover back on

In the final step, reinstall the plastic cover. On the left side, reconnect the temperature sensor, and the vehicle is ready to drive again. One small tip: Don’t forget to re-torque the wheel nuts to the required torque after approximately 100 km.

Have fun screwing!

* Affiliate links are marked with a *. When you purchase one of these products, we receive a small commission. Nothing changes for you and the offer/price remains the same. You can find more information about affiliate links here.

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