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      01-17-2022, 12:04 PM   #1
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Drives: E92 M3
Join Date: Oct 2014
Location: NJ

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polyurethane differential bushing with no diff whine.

So I am planning to upgrade to solid sub frame bushings and polyurethane differential bushings. After doing some research, I read that the powerflex diff bushings is what everyone uses for the diff bushing. I read that there is still a slight diff whine at certain speed. Is true that if i keep the stock rubber diff bushing, there a higher percentage of snapping the diff bolts under hard acceleration.

I contacted poweflex requesting if they can make a 65A or 70A bushings instead of the 80A that they currently offer.

There response was
"Hello, unfortunately these are the only durometer ratings offered in that location. This is on purpose. Anything lesser and we would worry about a failure.


Mike Haskins"

I also contacted Ronald from Autosolution. He made a custom short shifter for me 2 years ago and I know he make his own shifter bushings.

Ronald's response was very interesting.
"Hi Marc

I do cast my own bushings but making new bushings is a bit of an endeavor.

Basically one makes a copy of the bushing out of aluminum , then a mold in resin is created then the actual bushings are poured. The aluminium piece must be built correctly to account for shrinkage so it is a bit of trial and error plus experience with the particular compound used before a final mold is ready to go.

Right now i have just completed a move and have just restarted production after 3 months so backorder have accumulated something fierce. No R &D for me for a little while until i am caught up.

The nugget of knowledge is that 95a or 80a or 50a for that matter have little if anything to do with noise control. The name of the game in urethane noise control is additives.
Most of what you see on the market is pure urethane. That is relatively noisy but simple to build. Additives change the molecular structure of the urethane to affect its rebound properties. So that an 80a compound with proper additives will be much quieter than a 50a of pure urethane.
Additives however especially the more exotic ones require a slower production process and can be pricey. So not suited for profit in a price competitive environment. So I'd be surprised if they are to be found with what circulates out there

I do not know where powerflex stands. If it is a small shop then they probably can change the compound but if it is a vendor that subs its production elsewhere likely not. Not many artisans left in urethane these days.

I am not saying no but first i need to tend to my own house because i am still reeling from the move. The $50 job is feasible but the $200 one of the upper link would require a lot of prep work which means that i would have to commit to this product line.

Kind regards


So is there anyone else that can make differential bushings for the E9X M3 and add the additive that Ronald is talking about so that the diff whine can be eliminated?

Or maybe we can setup a group buy with Ronald to make these bushings worth his time for the R&D. But I'm sure it will be awhile before he can have them in production. What do you guys think?
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      01-17-2022, 01:03 PM   #2

Drives: 2008 E93 M3
Join Date: Jun 2010
Location: Philly, PA

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FWIW I have the ECS tuning diff bushings and AKG subframe bushings and I have zero whine
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      01-17-2022, 01:30 PM   #3

Drives: E93 m3
Join Date: Apr 2021
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      01-17-2022, 07:10 PM   #4
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Drives: 2010 BMW E92 M3 Dakar Edition
Join Date: Jul 2015
Location: Malaysia

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Originally Posted by Mog-10 View Post
Sometimes the simplest solutions are the best.
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