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!
Page 1 of 2 Next Page
Bookmark and Share
Dusty Duster
Dusty Dusterlink
Tuesday, March 04, 2014 6:07 AM
3D printing used for rapid prototyping? Awesome idea.
Tuesday, March 04, 2014 7:52 AM
Interesting about the engine bearing wear. Is that seen in 100% street driven cars too? I could understand that happening with cars that see the track and perhaps too high of oil temperatures. But if that's happening on pure street driven cars, well, that's an engineering failure.

The Evo X had plastic gas pedal failures. Give me metal every time!
Tuesday, March 04, 2014 10:24 AM
Yeesh on the bearings. That car used to be a street car and was stock, so even if it did see a track, they shouldn't have worn like that...
Dusty Duster
Dusty Dusterlink
Tuesday, March 04, 2014 10:41 AM
Wow, and BMW knows about that bearing issue?
Mike Kojima
Mike Kojimalink
Tuesday, March 04, 2014 10:55 AM
what are you planning to do to fix it? I am glad I didn't get one of these cars now!
Tuesday, March 04, 2014 11:36 AM
I saw AE92 and could only think Corolla, but is sure as hell doesn't look like one.
monster cookie
monster cookielink
Tuesday, March 04, 2014 11:57 AM
You're going to have a hard time convincing me that 3D printing the subframe mounts is cheaper and easier than just making them out of aluminum in the first place. 3D printing has its place but, sheesh, that's not it.
Tuesday, March 04, 2014 10:08 PM
Hmm... So I did some digging around on oil specification for the engine as my initial hypothesis is high oil temps thinning out the oil. So question #1 is what type of oil temps does the car see? Regardless of knowing that, I looked up the specified oil.


BMW Long-life rating LL-01 Synthetic Oils for BMW M vehicles equipped with S54, S62, S65 or S85 engines
Castrol EDGE Professional TWS Motorsport SAE 10W-60 Synthetic Engine Oil
BMW part number 07 51 0 009 420
Castrol EDGE Professional OE 5W30 Synthetic Engine Oil
BMW part number 07 51 0 037 195

10W-60 or 5W-30? WTF!!!! Hmm... anyone want to take bets on which oil was used more often in the engines with damaged bearings? Well, just an initial investigation.

As for the 3D printing, I've actually used that exact model machine before. Well, it could potentially be cheaper and easier. The 'easier' part is if you have the machine in your office and you do not have a lathe. Hit the go button and it starts printing. Now, it can be made solid which would be more expensive and take much longer, or 'sparse' which basically makes it honeycomb interior saving material and time. Of course, the downside is it's weaker. If it was done as sparse, I'd guess the material cost was in the $100-$150 ballpark and take about 24-36 hours.
Wednesday, March 05, 2014 7:15 AM
As far as we know and can tell this car had never seen a track and I am almost certain it's an issue that will eventually plague most E9X M3s. Now that they're WPC treated we're going to check them a couple of times throughout the season and probably replace them again before the 25 Hours of Thunderhill. I haven't done much research personally but from what I am told nobody has really nailed down a cause or reason for it. Since it happens on even daily drivers I am not sure oil temps would be an issue. The car comes with a pretty substantially sized oil cooler from the factory which I would assume could take care of oil temps under normal driving conditions.

As for the 3D printing. They have that printer in-house but they have to outsource their machining. I am not sure the details on how much it cost them but if it was harder to do and more expensive it wouldn't make sense.
Dusty Duster
Dusty Dusterlink
Wednesday, March 05, 2014 11:27 AM
I've never even HEARD of 10W-60. Lemme guess: it's a viscosity that only BMW makes, right?

That's just as bizarre as the 5W-50 spec'd for Ford Mustang track pack cars, which just so happens to only be made by Ford Motorcraft.
Wednesday, March 05, 2014 9:00 PM
Rod bearings are a big issue in the S65, with many rod bearing issues in low mileage street motors that are daily driven with regular oil changes of the recommended TWS 10W60 oil. The problem is not isolated to cars that were driven hard.

You can read over 2,000 posts here in regards to the issue:


A few engine builders including a NASCAR Sprint Cup engine builder have been researching the bearing failures on the S65 and the S85 V10 M5 engines -which the S65's V8 is almost identical to (and both of which have bearing issues).

The facts are, the main & rod bearing clearances are very tight:

OEM: 0.00120 - 00185" (for a 2.04" rod journal)
WPC: 0.00160 - 0.00175" (opens up the clearances a bit from stock)

And BMW mandates Castrol TWS (10W60 -which is more of a heavy 50 weight oil) which many feel is very thick for such tight tolerances, and many point out that Hondas with similar tolerances run 0W20 and 0W30 weight oils. Poor warmup processes and driving the car hard before the oil has warmed up to temp are a possible cause for excess wear.

The oil recommendations on BMW's website that Spdracernut posted is a hot topic of debate and varying interpretations, with some saying that BMW still says 10W60 is the only oil for M engines while others interpret that any LL01 approved oil (including M1 0W40) is now allowed for M engines. There really isn't anyone who has put 5W30 Castrol in their motors since dealerships seem to be oblivious of the issue and the relatively recent post by BMW which might allow something other than the TWS in M engines, so dealerships almost always stick with using the 10W60.

There's a movement switching from 10W60 to Mobil 1 0W40 and many blackstone oil analysis' have reported a drop in lead ppm after going to the lighter oil -with better cold flowing properties and gets up to temperature quicker.

Project E90 M3 has over 50K miles on it and thankfully only had 2ppm of lead -which is one of the best on record out of over 50 UOA's that are on M3post.com

I look forward to more of Project YAE92 and further bearing teardowns in the future. I'd also urge you guys to post your results of the WPC bearings on that thread on M3Post.
Thursday, March 06, 2014 7:07 AM
So what oil for Project E90, and any other plans for bearing/oiling modifications?
Thursday, March 06, 2014 3:24 PM
That was with TWS its whole life. It was a TX car and climate could be an issue with northern cars possibly having more issues than southern cars, but so can beating on it before the oil is up to temp.
Friday, March 07, 2014 5:01 AM
Very interesting stuff on this oil issue.

I find it baffling that BMW has stuck with a super-heavy 10w-60 oil for engines as modern as the S85. They specced similarly heavy oil for the original M3 and M5, which makes sense in those older inline engines. However, these new V-engines are completely different animals with tight tolerances and hydraulically-actuated variable valve timing.

It makes no sense at all to go with something like TWS 10w-60 in an E90 M3. That's madness.

The go-to solution for an E90 M3 should definitely be Pennzoil Ultimate 0w-40, and it sounds like a growing contingent of the BMW community agrees what with the movement towards the very similar Mobil 1 0w-40.

If it were my E90 M3 I would go slightly up-market from those options and use Red Line Synthetic 0w-40 along with a bottle of Ran-Up in every oil change. Red Line oil in that weight is *already* a BMW LL-01 oil. It is slightly heavier than the 0w-40 made by Pennzoil or Mobil 1 while still having fantastic cold-weather properties. My main motivation for this choice would be the absurdly high film strength of Red Line oils.

The ideal E90 street-car engine oil would have gargantuan film strength while still having low enough cold-temp viscosity to avoid scuffing the bearings. To the extent of my knowlege, Red Line products would do that better than just about anything else available.

Post Comment Login or register to post a comment.

MotoIQ Proudly Presents Our Partners:

© 2018 MotoIQ.com