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BMW DIY Video – Replacing Rear Trailing Arm Bushings, RTAB, Stock, Powerflex and Ultimate – E36 E46 E83 E85 Z3 Z4 X3
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.
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.
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.
The Bavarian Autosport Ultimate Maintenance Schedule (blog.bavauto.com/go/maintenance) is invaluable for BMW and MINI owners who wish to do all they can to keep their Ultimate Driving machines in top shape. At BavAuto, we have been working on completing sample DIY videos for each of the maintenance tasks listed on the Ultimate Maintenance Schedule. In this DIY video we will cover the thermostat replacement on the BMW 24-valve 6-cylinder engines from the early ’90s through the mid 2000s. These engines are known as the M50, M52, M52TU, M54, M56, S50 and S52.
This video will show the specific thermostat replacement for the M54 engine in an E46 3-series (99-05). The general steps will be the same or similar for all 3, 5, X and Z models that use the M50 through S52 engines, as noted above.
DIY Video – How to replace thermostat on M50/52/52TU/54/56 & S50/52
In the Fall 2013 issue of Fast Times we showed the DIY replacement of a common late model BMW electric water pump and thermostat. (Click HERE for Electric Water pump DIY). In this DIY video we will cover the thermostat replacement on the very common later model 6-cylinder engines. While some details will vary depending on the specific BMW model, this DIY thermostat replacement will apply to the 6-cylinder engines (M50, M52, M52TU, M54, M56, S50, S52) in most 3-series from 1992 through 2005, 5-series 91 through 05 and the X and Z series through the mid-late 2000s.
In most cases, the majority, if not all, of the work in replacing the thermostat can be accomplished from under the hood. We do recommend draining the coolant from the engine block before removing the thermostat. While this does require getting under the car, in most cases, it does provide a neater way to drain the coolant from the engine as opposed to having it gush from the thermostat mounting recess as it is removed.
** This DIY video is specifically applicable to the BMW E60 (sedan) and E61 (wagon) xi and x-drive models (2004-2010). Please see our DIY article and video on replacing control arms on Non-xi/X-drive BMW E60 & E61 5-series models (click on the link below).
For more information on why we need to consider replacement of the front control arms as well as the specific DIY details for the standard rear wheel drive models. Click the link below:
Our BMW suspensions are very susceptible to vibrations induced through worn bushings, ball joints, wheel bearings and tire and wheel issues. Of these, the most common source of front-end vibration is weak control arm bushings. These bushings absorb all of the vehicle’s front-end loading during braking, cornering and even steady highway driving. The original bushings become weak (although they may look just fine) with age and mileage and allow the control arms to oscillate ….. creating the vibration, or shimmy, that we feel.
Follow along as we replace both the upper (thrust, strut, pull, etc.) and lower control arms on an E61 530xi wagon. Note that the main difference on the E60/E61 4wd models (vs the rear wheel drive models) is that the outer ball-joint for the upper/thrust arm is mounted in the hub/steering-spindle, not into the end of the arm. Therefore, the new control arm will not come with an outer ball-joint.