Project #YAE92 M3: Part 2 – Why Do We Have All of These Extra Bolts?

Project #YAE92 M3: Part 2 – Why Do We Have All of These Extra Bolts?

by Mike Bonanni, photos by European Auto Source

I know I know, it’s been months since we first introduced you to Yost Autosport’s Project #YAE92 M3 endurance race car build, but we have a good excuse.  Truth be told, the past few months have been slow moving on this project as we entered the R&D phase.  We’re helping a number of companies develop new products for the E9X M3 platform and when you do that, things tend to end up in an engineering black hole.  Turns out, it takes time to build parts from scratch, especially since a lot of these companies don’t have access to the actual car. So we begin part two of our saga with tearing down the car even more than it already was.

First things first, we made our way over from Las Vegas to European Auto Source in Anaheim, CA. We arrived with a list of parts that needed to come off of the car and be sent out to various companies to make replacement parts from.  We had already lost sleep over the fact that we completely tore apart the interior and wiring harness of a perfectly good E92 M3 to get caged, but now we were about to take it to a whole other level.

Everything else was due to come off of the car with the exception of the engine.  All suspension arms were removed and sent out to SPL Parts in Texas.  Our sway bars were removed and sent out to a company with whom we are not allowed to announce yet.  Our brakes were removed in anticipation of a brand new brake kit from AP Racing and Essex Parts. The radiator and oil cooler were removed and sent off to Forge Motorsports all the way in the UK.   Numerous other things were removed in the frenzy leaving us with bloody knuckles and a lot of extra bolts.


Rear subframe bushings fresh out of the 3D printer. When time and money are a factor, this process can significantly aide in product development allowing you to check, alter, and re-check fitment quickly and cost effectively before building the actual product.

Unfortunately as I write this article we are still waiting on a lot of our parts to be finished but that’s the price you pay for developing brand new purpose built parts.  We did manage to get some stuff done though. One of the brand new parts that were created were solid aluminum bushings from Macht Schnell to replace the sloppy rubber bushings in both the rear differential mounts and rear subframe mounts. It’s well known in the E9X M3 world that the rear subframe and differential bushings are just plain crap. The factory rubber bushings allow so much deflection that it can, and often does cause rear axle failure and in some cases the subframe moves so much it can actually be damaged beyond repair. As you can imagine, that much deflection is not only dangerous for other drivetrain components but it absolutely hinders handling and the ability to put power to the ground.  Being that we are going endurance racing, arguably the most brutal test of a car, this was something that had to be addressed without question.

Luckily for us, Macht Schnell stepped up to the plate to make solid aluminum bushings!  The first step in their process was using awesome new 3D printing technology to create prototypes.  The 3D printer prints plastic pieces that can be used to expedite and dramatically reduce the cost of test fitment and R&D.  Once the fitment is perfect the drawings can then be used to machine the parts out of solid aluminum or other materials.  For Project #YAE92 we decided to go with solid aluminum bushings for zero flex and ultimate reliability.  Because it’s a race car there’s really no downside, but on a street car the solid aluminum will create more NVH (in-cabin noise and vibration) so Macht Schnell also plans on releasing a delrin option for these bushings which are still a substantial upgrade over factory while still allowing enough movement to absorb vibration.


The finished result; beautiful solid aluminum bushings for our rear differential ready for install. Getting rid of deflection in the rear differential will help effectively transfer more power to the ground and put less stress on our axles.
Solid aluminum rear subframe bushings will eliminate flex and movement in the rear subframe which can dramatically help responsiveness, drivability, and handling!

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