Bearings for FCAB & RTAB locations

[radr]

I picked up an E46 M3 recently and started to get familiar with the infamous RTAB issues. Which led to reading up on bushings vs. bearings and where to use which. I thought about my E30 track car, and I realized that I have poly in the RTAB location and Delrin TrackCABs.

The general idea is that while these work to stiffen up the area, the types of forces (twisting/pivoting) are not ideal for a poly-type material, instead a ball joint bearing should be used.

I found a BW FCA bearing for E30s (https://www.bimmerworld.com/BimmerWo...aring-E36.html) along with GC's version of the same thing, but only one RTAB bearing (https://stim.tech/product/e30-z3-e21...l-bearing-set/) for E30s.

I just wanted to see what other track/race E30 people thought about this topic. Is it just a matter of not too many people making them for E30s? There are a ton of RTAB bearings for the E46, is there something different about the E30 suspension that makes it a moot point?

Thanks!

[Digitalwave]

Spherical bearing FCAB's are available from various companies including AKG and SLR.

For the RTAB there isn't an easy off the shelf solution. The E30 M3 DTM cars had a pretty crazy spherical fully adjustable setup for the TA's. They require extensive modification of the control arm and subframe. MRT in Europe makes a kit for less than $500 to convert to this style of setup. It is in my opinion the holy grail for rear end adjustment on an E30.

Keep in mind rulebooks may either disallow bearings in the suspension entirely, or assess a penalty for using them. This is common in NASA classing, at least.

By the way, I like the thought of bearings especially in these locations where twisting is involved, but in practice, I doubt the benefits are noticeable even in the long term. Using delrin/uhmw/aluminum bushings will have more or less the same "feel", and they not likely to wear out much faster than an open spherical bearing would.

[radr]

Thanks for the response! It's a dedicated track car, but I'm just doing DEs so no class rules to worry about. That last part rings true, and is probably why there aren't many options...