OEM Rear Diff Bushing Failure/Upgrade to OEM Poly?

[E92TiAg335i]

Hey guys. I have a 2016 m4 with 50k miles. Found out the rear diff bushing is cracked (see photo). I understand that they updated to the poly bushing in 2017.

My question is do I the OEM pre-2017 rubber bushing or the newly updated Poly bushing?

If I do the poly bushing - is there a noticeable increase in NVH? While i do drive the car hard on weekends, it’s my daily and don’t want to go too crazy like i did with my e46 m3.

[MineralWhiteF80]

the poly bushing they started using on 2018MY cars is a much better design and should always be used over the original bushing design.

The new OEM poly bushing style will not increase NVH at all.

A better alternative is to use two of the new OEM poly bushings in conjunction with a dual mount rear diff brace.

You also have the option to install the PowerFlex purple poly diff bushings for a little extra strength (with no additional NVH).

There are lots of threads on this already that discuss these details.

[theweebabySeamus]

Can confirm, the single poly does not increase NVH. If I had to do it again I would do both poly with the dual mount bracket @MineralWhiteF80 mentioned. If you were REALLY concerned about NVH, you could try the dual mount bracket with the old style rubber bushings. I wouldn't do it, but it would definitely be better than just replacing the old style with the old style 1 for 1.

[GREYF80]

I’d stay away from OEM and go power flex.

[Dabeamerking]

Originally Posted by E92TiAg335i

Hey guys. I have a 2016 m4 with 50k miles. Found out the rear diff bushing is cracked (see photo). I understand that they updated to the poly bushing in 2017.

My question is do I the OEM pre-2017 rubber bushing or the newly updated Poly bushing?

If I do the poly bushing - is there a noticeable increase in NVH? While i do drive the car hard on weekends, it’s my daily and don’t want to go too crazy like i did with my e46 m3.

You don’t get neither. You go straight to a Dual rear bushing setup with a updated bracket from ECS or Powerflex or KmP

[E92TiAg335i]

Originally Posted by Dabeamerking

You don’t get neither. You go straight to a Dual rear bushing setup with a updated bracket from ECS or Powerflex or KmP

For a daily driven car that i do not want any more NVH?

[spidy512]

Originally Posted by E92TiAg335i

For a daily driven car that i do not want any more NVH?

Yes.

Unfortunately, NVH is a very subjective thing. I have a plate and dual Pflex purple bushings in the back. I also have ECS stupid hard bushings in the front plate. I can hear the ring and pinion clacking around and some faint whining at lower speeds. But for me, that is fine. This car is a racing tank for the street, and I nor my wife find it annoying.

That is my subjective opinion though. The wife doesn't drive it on her own, and she thinks of it as my "weekend" car. Which isn't a reality as I do commute in it regularly. Point being, if we want to go on a quiet drive, we take the Grand Cherokee.

Search up the Engine and drivetrain forums. As others have said this subject has been discussed in great detail many times.

Good luck!
josh

[heitzke]

Purely anecdotal since I haven't made the jump yet (lots of labor) but I'm going to do Powerflex poly in the front and then the ECS plate with dual Powerflex poly in the rear.

From what I gather the NVH isn't noticeable with the powerflex pieces. The ECS are a good big stiffer and are known to transfer some noise.

[theweebabySeamus]

FWIW, I checked the hardness on the poly OE and it shows 50.5a. So similar to the OE rubber bushing.

[phefner]

I found mine cracking earlier in the year and did the Turner Bracket and Poly Bushings. Definitely some diff whine, captured it with the attached YouTube. After about 6 months now, it’s abated some.

https://youtu.be/9_gKudd9SXU?si=97UBqry0RQ8ufnF8

[Drifter2090]

Mine was worse than yours, I just replaced the rear bushing only with purple powerflex poly. Car feels amazing now. No NVH as long as the front bushings are stock rubber.

[phefner]

I didn’t consider that. The attached is what I used. And agree, there is definitely a different feel to how power gets put down.

[Track/S]

Originally Posted by theweebabySeamus

FWIW, I checked the hardness on the poly OE and it shows 50.5a. So similar to the OE rubber bushing.

Which of 2 models? Now only the yellow one is sold, in 2019 black ones were assembled with another part number

[theweebabySeamus]

Originally Posted by Track/S

Which of 2 models? Now only the yellow one is sold, in 2019 black ones were assembled with another part number

The yellow one. Poly/foam