E36 325i RTAB Replacement

The Longest Spec3 Build: Reassembly, With a Side of RTAB

When we last saw Taylor’s green BMW 325i, it was in full-on “hover mode” as he waited on several boxes of parts to arrive from various vendors. Everything finally arrived, and he’s had some time to get the car back on its wheels again.

One five-hour marathon of wrenching saw the entire front end come back together. New lower control arms were installed, alongside fresh “lollipop” control arm bushings, tie rods, sway bar end links, and the gently-used “old Spec3” front suspension. Hawk HP+ brake pads were installed with new rotors to provide a much-needed upgrade in stopping power.

New “lollipop” bushing, ready to be pressed in and put back on the car

Taylor added strut tower reinforcement plates between the top of the front struts and the sheet metal of the strut tower. The sheet metal is fairly thin, and with extended track use, drivers can see cracks or “mushrooming” of the metal, where the tower slightly deforms. The metal plates are inexpensive (far cheaper than having cracks welded back together) and will save the front end from some abuse.

Finally, Taylor and his roommate Tyler turned to the back half of the car. BMW’s rear suspension uses a trailing arm to locate each rear wheel left-to-right (setting the toe of the alignment). There is a large rubber bushing in each trailing arm that, over 10+ years, wears out. Many owners ignore the bushings as they don’t tend to affect gentle driving much. However, Taylor’s rear trailing arm bushings – lovingly known as RTABs – were severely worn, so much so that hard acceleration would send the rear of the car crabwalking a lane to the right.

Well, RTABs are not the most fun to replace. Bimmerworld will sell or rent a tool that helps press them out of the trailing arm. Taylor and Tyler got the left RTAB removed with ease. The right RTAB put up far more of a fight, and the threaded rod that the Bimmerworld tool relies on for its operation broke mid-removal.

The guys resorted to drilling through the bushing’s rubber, using a torch on the trailing arm, and an angle grinder to help cut through the metal lip of the bushing. Four hours of struggle later, it was freed. The new RTABs were (relative) cake to install, and the car was back on the ground.

I’ve struggled with RTABs on several BMWs, but they are important to replace in a track environment. My M3 came to me with worn RTABs and they were a factor in my first crash at VIR, just six weeks into ownership. The car would pull very hard under acceleration. With rain and old tires, it was a nasty combination that ended in a light tire wall impact.

Speaking of tires, that’s the final hurdle for Taylor to tackle between now and our first event in March. He’s looking at a few options given he won’t be competing right away. We’ll cover the benefits of various tire types in a later post.

Sitting pretty (for now) on some “bottlecaps” with snow tires. That’ll have to change.

About Jake Thiewes

Fan of all things wheeled. Competes on four wheels with a 1997 BMW M3, and two feet in Spartan Races. Queso enthusiast. Will badger you to come to the track and get rides and/or HPDE seat time, because everyone deserves to be a slightly better driver.

2 thoughts on “The Longest Spec3 Build: Reassembly, With a Side of RTAB

  1. Boo to 4 hours of struggling with RTABs, did you have enough pizza & beer to keep the enthusiasm and positive attitude at optimal levels? I’ll be anxious to read what you’re going to publish about tires. Glad to see the build coming along!

    1. I managed to avoid helping with the reassembly – T & T were on their own but know what they’re doing! I think the positive attitude has come back after being able to drive the car a bit (it’s street legal for now) to and from work. He’s excited to get out there in a few months!

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