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Bavarian Autosport has been sponsoring BMW project cars for the online automotive performance magazine, MotoIQ, for some time. BAVauto, in partnership with author and BMW performance geek, Pablo Mazlumian, has assisted in various E36 and E46 M3 project car builds as well as maintenance.
In Part-19 of the Project E46 M3 articles, pablo installs PowerFlex RTABs (Rear Trailing Arm Bushings), using the BAVauto RTAB remover/installer tool, which allows easy bushing replacement “on the car”.
We have found that the BMW models that use these rear trailing arm bushings will show unstable road manners and even a sense of “rear steering” as the bushings age and become soft (or worse). Additionally, worn RTABs can cause a clunking over bumps or when transitioning between acceleration and deceleration.
In Pablo’s article, he notes:
“The rear trailing arm bushings (RTAB) on BMWs are rubber and are prone to cracking. I’ve had them go bad on previous E36 M3s, and the symptoms were simple to discover and quite obvious. One of the easy ways was to accelerate the car hands-free of the steering wheel. If the rear pulled to a side, you most likely had bad bushings.
I didn’t figure it out so easy on this car, however. It wasn’t until I took a high-speed, four-gear turn on an uneven cement on-ramp that I could feel the rear end dancing around with so much grip from the surface (cement usually has higher grip than asphalt). It was very unnerving, and quickly made me lose confidence in the car.
Upon a quick look underneath, it was obvious the car’s RTABs were wasted. The car just clicked 70k miles, so it was no surprise.”
Here are some highlights from Pablo’s MotoIQ, Project M3 article:
These polyurethane pieces are modular and go together like so. These bushings allow for an easier install, because with a rotating mass there is no pre-tensioning. These particular RTABs should fit all E36 (except ti), E46 and Z Series cars.
Trying to remove a factory bushing without the proper tools can become an act of futility. Bavarian Autosport sells its own trailing arm bushing tool that is specific for this job. It will be used both for removing the old ones and installing the new Powerflex units. The Bav Auto trailing arm tool appears to be very high quality, and it features CNC machined components.
With the bolt out, the bushing was now able to be free of the housing. That sucker is really torn up! It’s no wonder the car felt so unsafe during high speed cornering, especially mid-turn when you’re trying to maximize the G-load to the front tires so you can get pointed where you want to and immediately get right back on the gas. It was all over the place, feeling like something was loose or practically broken. It was like driving a car with a mild, yet unpredictable rear steering!
These bushings are going to be really on there so to remove them, line up the Bavarian Autosport tool like so. Now simply start tightening the inside nut with your wrench or gear ratchet. You’ll notice the bushing’s stickiness start to give way, and little by little come on out.
Here’s another look at the original bushing fully removed. One can opt to purchase factory bushings again, by why when you’ve got polyurethane units from Powerflex that will give you a tighter feel and much crisper response without really any drawbacks.
What we did was mount up the tool again in order to start pressing the new bushing in.
“With the new Powerflex RTABs in there, the confidence in the car is back. You can throw the car into a turn under hard trail-braking and not worry about that back end stepping out. Also, the worry of driving over an uneven payment is a thing of the past. That new, tight feel is back!”
Since 2005, SeaSucker has been designing and producing innovative mounts and racks for the marine market, using vacuum technology for ultimate mounting flexibility. In 2009, SeaSucker used their vacuum mounting system in designing a unique vehicle rook rack system. The SeaSucker racks can be mounted on any vehicle (BMW, MINI or others) in many varied configurations, be it coupe, sedan, convertible (yes, convertible), SUV or whatever you can come up with.
SeaSucker rack systems have been tested at 140 mph and have fully proven their durability for carrying bikes, boards, skis, kayaks and more. The systems require no vehicle specific fit kits so they can be transferred from one vehicle to the next. They truly are a “lifetime” rack system that allows you to keep your system when you sell or change your vehicles. Or, move them between your current vehicles. Installation requires no tools and can be accomplished in seconds, as shown in the video at the top of the page.
I have a coolant leak that I can’t seem to find the source of. Over the past few weeks, I have had to add a pint, or so, of coolant once in a while. Lately, this has become a daily ordeal. I noticed a puddle under the car, for the first time, a week ago. It was on the passenger side, just inboard of the wheel. I can’t see anything at all from above. I have looked from under the car and the coolant is dripping off the engine subframe and the control arm. I can’t really see much up there, but the water pump does not seem to be leaking …. it’s dry between the pump and the pulley. Any idea where this leak may be coming from? Thanks, Mike
We are at a disadvantage in not having the car in-hand to inspect it, but we do have a thought on the source of your coolant leak. The R55/56/57/59 MINI models (Cooper, Clubman, Convertible and Roadster – in base, S and JCW) use engine variants that have a plastic coolant transfer pipe that runs from the thermostat (on the left side of the engine) to the water pump housing (right side of engine), along the rear of the engine, under the intake manifold. This pipe commonly starts to leak at the point where it seats into the “back” of the water pump mounting housing. Either the o-ring starts to leak or the end of the plastic pipe starts to crack apart. Leakage is also a common problem after the thermostat has been replaced, as the pipe’s o-ring seal has been disturbed during the thermostat replacement.
While the pipe itself is rather easy to replace, the access to the pipe is a bit more work. The intake manifold and the thermostat must be removed in order to access and remove the coolant pipe. This is a bit tedious, but not especially difficult. A moderate DIYer (with a Bentley Publishers repair manual) can have the pipe removed in about 2 hours. Of course, this is a good time to preemptively replace the thermostat and any crankcase ventilation and vacuum hoses that look dry and/or cracked. Additionally, new intake manifold seals (gaskets) will be needed and a thermostat gasket (if the thermostat is not being replaced).
Finally, if you are considering some performance gains for your turbocharged S model, The FTP turbo charge pipe upgrade kit which eliminates the muffler in the turbo to intercooler piping and the “sound maker” in the intercooler to throttle body piping, is a great upgrade and you will have the piping to the throttle body already disassembled … and the access to the turbo to intercooler piping will be clear as well. Even if you just install the piping to the throttle body that eliminates the “noise maker”, and install the turbo to intercooler piping later, this is a good time to make the purchase and the perform the partial install.
Click image below for intake manifold gaskets: