[Blown95ImpalaSS]

Title says it all, is anyone who uses their car for DD duty happy with poly (like Powerflex purple or black) upgraded diff bushings?

I decided to go with new OEM diff bushings, Powerflex yellow RSFBs and (eventually) a diff lockdown brace because I'm afraid of noise on our crappy roads... but I'm curious about others?

[avocet]

I have whiteline poly diff bushes and have no complaints. Sure there is a bit of whining going on but nothing excessive. Keep in mind I also have M3 RSFB, poly engine mounts and stiffer trans mounts so there is considerable drivetrain NVH with my entire set up...

Also, using a diff lockdown is like using a solid metal bushing on half of your diff. When your bushings deflect with a lockdown, something that is solid and shouldn't be flexing is flexing.

[Kevin_The_Clean1]

Originally Posted by Blown95ImpalaSS

Title says it all, is anyone who uses their car for DD duty happy with poly (like Powerflex purple or black) upgraded diff bushings?

I decided to go with new OEM diff bushings, Powerflex yellow RSFBs and (eventually) a diff lockdown brace because I'm afraid of noise on our crappy roads... but I'm curious about others?

I have the purple in my 335i & love it. Have all 4 bushings in my rear subframe & all 3 in the differential mounting points. Nice & quiet but super strong & just right for the street.

You won't be disappointed at all...

[mjn77]

My old E46 was polybushed front to rear, running on Eibach springs with 18” alloys.

The ride was hard, you felt every bump. There was also additional vibrations in the cabin when usually the rubber bushes would absorb some of these.

[Blown95ImpalaSS]

Ha, this thread reads exactly how I debate this mod in my head

So subjective

[Kevin_The_Clean1]

Originally Posted by Blown95ImpalaSS

Ha, this thread reads exactly how I debate this mod in my head

So subjective

I have the purple everywhere & not the softer yellow & still love it. Do it & you won't regret it man... ! ;-)

[mjn77]

Originally Posted by Kevin_The_Clean1

I have the purple everywhere & not the softer yellow & still love it. Do it & you won't regret it man... ! ;-)

Yup, my E46 was all purple bushings plus some custom harder ones for the diff.

[N54POWR]

Power flex black in the subframe and diff bushings for me. Along with diff lockdown and upgraded arms. It's definitely a lot more rough than stock but it doesn't bother me at all. Car is mainly driven on crappy canyon roads.

[BB_cuda]

Im actually considering going other way!! I have purple powerflex bushings and diff lockdown kit (not the bracket one). Also powerflex Black on RSFB. I get sort of a roar noise when I nail it hard at around 40 mph. I disconnected the lockdown to see it would stop nope.

I’m considering going back to OEM M3 front diff bushes and a stock rear one. I drive a tuned 335 diesel with deletes so high torque might be a unique thing for me. I have a Wavetrac LSD as well. All was quiet before the bushes were put in with Wavetrac already installed

[Stevesmokeman]

Originally Posted by BB_cuda

Im actually considering going other way!! I have purple powerflex bushings and diff lockdown kit (not the bracket one). Also powerflex Black on RSFB. I get sort of a roar noise when I nail it hard at around 40 mph. I disconnected the lockdown to see it would stop nope.

I’m considering going back to OEM M3 front diff bushes and a stock rear one. I drive a tuned 335 diesel with deletes so high torque might be a unique thing for me. I have a Wavetrac LSD as well. All was quiet before the bushes were put in with Wavetrac already installed

You said you get a roar when you nail it, but what is it like normal driving conditions. What happens when you nail it at highway speed?

[Blown95ImpalaSS]

Did purples in the diff. No additional noise whatsoever. Very happy with them. Can actually feel the clutch engage now! OEM bushings were soooo shot

[fleetfoot]

Quick bit to add here: Back in ~2018 I installed poly rear subframe and differential bushings at the same time. The rear end stability improved a lot, but the differential whine on the interstate was infuriating. This week I finally had the poly differential bushings removed from the diff and went back to OEM rubber. I kept the poly RSFB. The rear end still feels great, and the diff whine is totally gone. Hopefully this post saves someone from making my same (labor intensive) mistake.

[mikee5]

I put Whiteline bushings in my car to replace the buggered stock ones at 250,000 kms.
My only regret was the diff bushings which I also changed, I should have left them alone or used new rubber.

Mike

[Jklad]

I’m in the same boat with a daily driver and trying to decide. So it sounds like rsfb can be a little stuffed like a 95a, but to avoid diff whine go softer with like a pf purple. Can anyone confirm?

This is on e92 n54 6MT 160k miles, fresh bmw PS suspension with stiffer trans mounts and 335is mounts, m3 front arms.

[fleetfoot]

Originally Posted by Jklad

I’m in the same boat with a daily driver and trying to decide. So it sounds like rsfb can be a little stuffed like a 95a, but to avoid diff whine go softer with like a pf purple. Can anyone confirm?

This is on e92 n54 160k miles, fresh bmw PS suspension with stiffer trans mounts and 335is mounts, m3 front arms.

I’d recommend sticking with rubber diff bushings as I saw no performance change after going from 95A diff bushings back to rubber. The performance gains are had from getting the poly RSFB (mine are 95A).

I was curious if a softer poly diff bushing might be ok, but this m3 post suggests probably not since they experienced diff whine with powerflex purple:
https://www.m3post.com/forums/member.php?userid=148054

[Jklad]

Originally Posted by fleetfoot

I’d recommend sticking with rubber diff bushings as I saw no performance change after going from 95A diff bushings back to rubber. The performance gains are had from getting the poly RSFB (mine are 95A).

I was curious if a softer poly diff bushing might be ok, but this m3 post suggests probably not since they experienced diff whine with powerflex purple:
https://www.m3post.com/forums/member.php?userid=148054

I’ve seen some with purple diff bushings experience whine, and others not. How would transmission type play into the equation? Mines a 6MT. And it seems like mfactory makes diff bushings that are between rubber / polyurethane in terms of stiffness that folks said caused no nvh

[fleetfoot]

Originally Posted by Jklad

I’ve seen some with purple diff bushings experience whine, and others not. How would transmission type play into the equation? Mines a 6MT. And it seems like mfactory makes diff bushings that are between rubber / polyurethane in terms of stiffness that folks said caused no nvh

I’m not sure on your questions, but someone else might know. But if there isn’t a perceivable performance gain from going with a stiffer diff bushing, what’s your motive to switch to them when you run the risk of (very annoying) NVH?

[BB_cuda]

I wrote back in 2018. My roar noise has disappeared. I do still hear diff whine but not too bad.
I am thoroughly enjoying the Wavetrac with the other mods. Still running the Powerflex purples on diff and the diff brace from the seller in Chicago. I’ll remember his name (on N54performance).