Skip to content

Welcome to our BMW and MINI tech blog!
There are more than 1,000 Q&As and DIY guides posted here. Feel free to search by keyword (upper right), browse by category (lower right), or watch one of our helpful videos. Once you've found the answer to your question, you can get the parts you need in our online store –

I Want to Work at BavAuto! Bavarian Autosport is Hiring, March 2015

Mar 3 15


Dear fellow BMW enthusiasts,

Ever thought about how much fun it would be to make a living from your passion for BMWs? At Bavarian Autosport, we do it every day. Want to join us? We’re hiring! Here’s the pitch…

Bavarian Autosport is a leader in internet, catalog, and showroom sales of parts and accessories for BMW and MINI automobiles. We have an opening in our call center for an incoming customer Advisor.

Experience in retail (any field), wholesale or dealer parts sales, plus in-depth auto-hobby experience preferred. Basic automotive knowledge is required. Applicants must possess strong communication skills, be able to work in a fast-paced environment, be computer literate and committed to customer satisfaction. This is a full-time in-house position with benefits and excellent earnings potential in a friendly environment. Some evenings and Saturdays required.

Please note: relocation expenses are not covered.

If interested, please forward your resume to Ian Nersesian (e-mail address:

We look forward to hearing from you!

Happy motoring,

Bavarian Otto

BMW DIY Video – Replace X3, X5 Transfer Case ServoMotor Actuator Gear, E83, E53 How To

Mar 2 15

The BMW  X3 04-10 and  X5 10/03-06 (late E53) models employ the ATC 400/500 xDrive transfer case for 4wd operation.  This transfer case uses the BMW Active Torque Control (ATC) system to control the drive-line torque split between the front and rear drive wheels.  The torque split is actuated by the transfer case (BMW calls this VTG) Servomotor Actuator.  A common fault in these units is a worn drive gear within the actuator assembly.  BMW does not offer the gear as a replacement unit.  The complete servomotor actuator assembly must be replaced.

BavAuto does offer an aftermarket replacement gear for the servomotor actuator which allows the actuator to be rebuilt rather than replaced …. at far less cost.

Click image below for Transfer Case Servomotor replacement gear:

Common symptoms of a faulty servomotor actuator gear include; ABS, BRAKE and 4X4 fault warning lights, servomotor actuator makes a clicking sound after engine is shut off, drivetrain vibrations, shuddering or chatter.  If disconnecting the harness plug from the servomotor reduces or eliminates the symptoms, the servomotor gear may be faulty.

Once you purchase your replacement servomotor gear, from BavAuto, this DIY video from Bentley Publishers will guide you through the installation.  The full procedures, along with more detailed diagnostics, are in the X3 Service Manual from Bentley Publishers (available from

Click below for Bentley repair manual:

* Used with permission – Bentley Publishers

BMW DIY Video – Replacing Rear Trailing Arm Bushings, RTAB, Stock, Powerflex and Ultimate – E36 E46 E83 E85 Z3 Z4 X3

Feb 20 15

This article will discuss the function of the trailing arm bushings and how to replace them, in our DIY video.  Continue to the text below the video link for a description of the function and the failure modes of the Rear Trailing Arm Bushings (RTABs).

In replacing the RTABs, we have various options on the replacement parts:

* Stock replacement - These bushings are available as either Genuine BMW or various other quality aftermarket manufacturers.

* Urethane upgrade - Installing urethane RTABs will provide a tighter control of the trailing arm.  Not only will the rear suspension feel more “planted” in spirited driving, the steering inputs will feel more direct as will transitions between braking and acceleration.

*  Ultimate RTAB upgrade - The Ultimate trailing arm bushings provide all of the benefits of the urethane upgrade bushings along with full articulated spherical bearing action, while still damping vibrations through the chassis.  The Ultimate RTAB uses a fully articulated suspension bearing installed in a billet housing.  This design eliminates all flex yet provides 100% articulation of the trailing arm.

Click the image below for RTABs:

Click below for RTAB removal/install tool:

Click below for anti-seize compound:

Follow along with our DIY video as we discuss the different bushings and show how to remove the old bushing and install the three different types of new RTABs.  We will be performing this install on an E36 M3.  We will show the install steps for each type of bushing, but the final install will be with the Ultimate RTABs.  The applicable Bentley Publishing repair manual will detail model and bushing type specific steps and procedures.

Click below for Bentley manuals:

On the BMW models noted in this article, the rear suspension hub assembly is incorporated into a larger cast iron suspension assembly that we just call the rear trailing arm.  The trailing arm is attached to the vehicle chassis and articulated via two lateral control arms (upper and lower) and a forward longitudinal pivot point at the front of the trailing arm.  As with all of the connection points for the control arms (to the trailing arm and the chassis), the forward pivot point uses a large bushing for attachment to the chassis as well as allowance for articulation.  As the wheel moves up and down during suspension movement, the forward trailing arm bushing becomes the pivot point.  Additionally, the forward trailing arm bushing is performing the task of locating the rear wheel longitudinally and through this, also absorbs the majority of the torque loads that are transmitted from the tire’s contact with the pavement and ultimately into the chassis.  In other words, the bushing is the contact point for the positive loading under acceleration and the negative loading during braking, keeping the wheel in place on the vehicle.

With the above points noted, the Rear Trailing Arm Bushing (RTAB) is a highly stressed suspension component. As the RTABs age, the vehicle will feel less secure on the road.  The rear of the vehicle can move around as the torque loads of acceleration and braking act on the bushings, effectively steering the vehicle from the rear.  As the bushings continue to age, a clunking can be experienced as the vehicle goes over bumps or transitions between braking and acceleration.  Note that these symptoms can be present, yet a visual inspection of the bushings may not show any apparent problems.  The bushings are simply too soft at this point.