Powerflex purple diff bushes - replace rear only?

[pbonsalb]

I think the diff damper is thing the size of your fist you screw into the subframe.

[Hujan]

Originally Posted by Move Over

Hm. I may pull my AKG black and give the purples a whirl. Hopefully it gets rid of some of my whirl. See what I did there? Lol

Where can I find this diff damper? I did a search yielded no results. It's not the defiv diff brace correct?

Originally Posted by MFL

+1

Originally Posted by aus

What's the diff damper??

The diff damper is an OEM damper that comes on the 1M from the factory. It is basically a big rubber isolator that attaches to the differential and absorbs some of the noise.

I believe it needs some modification to retrofit to the E9x M3 chassis. MRF Engineering pioneered the use of that damper on this chassis and would be the one to contact for more information.

That said, I think the damper is a cherry on top of the sundae and isn't going to be a cure-all if you have a noisy diff and go with solid differential bushings (aluminum or delrin).

Originally Posted by aus

Are there PowerFlex poly rear sub-frame bushings available. If yes, has anyone compared them to aluminum?
Great info here.

I believe there are, but I wouldn't waste time with them. There is absolutely zero downside to solid aluminum subframe bushings. There is no additional NVH over the factory rubber bushings. Honest. But the improvements to handling and feedback from the rear end cannot be overstated, IMO, when you are driving it hard.

IMO, the recipe for success (particularly on a DCT car) is solid aluminum subframe bushings and PowerFlex purple differential bushings. The damper is an optional add on to further keep noise to an absolute minimum.

[aus]

Originally Posted by Hujan

The diff damper is an OEM damper that comes on the 1M from the factory. It is basically a big rubber isolator that attaches to the differential and absorbs some of the noise.

I believe it needs some modification to retrofit to the E9x M3 chassis. MRF Engineering pioneered the use of that damper on this chassis and would be the one to contact for more information.

That said, I think the damper is a cherry on top of the sundae and isn't going to be a cure-all if you have a noisy diff and go with solid differential bushings (aluminum or delrin).




I believe their are, but I wouldn't waste time with them. There is absolutely zero downside to solid aluminum subframe bushings. There is no additional NVH over the factory rubber bushings. Honest. But the improvements to handling and feedback from the rear end cannot be overstated, IMO, when you are driving it hard.

IMO, the recipe for success (particularly on a DCT car) is solid aluminum subframe bushings and PowerFlex purple differential bushings. The damper is an optional add on to further keep noise to an absolute minimum.

Thanks man. Going to have to get this done at some point. I don't like how the rear end dances around under hard braking with track pads on and NT05 rubber. I'm hoping the solid rear subframe mounts will help this.
.

[pbonsalb]

Damper appears to be #6 on the diff parts list for the 1 series M in the link below. You also need the spacer holder off the rear mount.

http://www.realoem.com/bmw/enUS/show...diagId=33_1599

The E36 328i had something similar, but attached to the front of the subframe. Called vibration absorber in the link below. My E36 M3 does not have this part.

http://www.realoem.com/bmw/enUS/show...diagId=33_0366

[///Mobbin]

Originally Posted by pbonsalb

Damper appears to be #6 on the diff parts list for the 1 series M in the link below. You also need the spacer holder off the rear mount.

http://www.realoem.com/bmw/enUS/show...diagId=33_1599

I'm curious what all parts one should order here.

Differential view for 2011 M3

It looks like part #'s 3,4,5,6,7 and 8 are needed. Then combination nut, part #9, looks to be the same as M3 part #4, though for the price perhaps we should just get that part as well.

[Hujan]

Originally Posted by aus

Thanks man. Going to have to get this done at some point. I don't like how the rear end dances around under hard braking with track pads on and NT05 rubber. I'm hoping the solid rear subframe mounts will help this.
.

Happy to help. I think you will be pleased with the results, though I will also say that alignment is a big piece of the puzzle to keeping the rear end planted and stable under hard braking (that and downforce, but that's another conversation).

I just got the Fall Line toe links and camber shims on the car, so my car no longer has any eccentric adjustors on the rear end (which are prone to losing their spec when they are tightened down and/or as a result of dynamic forces when in use). According to MRF, the car was more precise and easy to align than any other he's worked on and I can tell you that the rear end feels absolutely phenomenal now.

I truly could not be happier with how the car is setup now. The feedback and stability is unreal and the NVH is essentially at stock levels. Win win.

[Move Over]

Originally Posted by Hujan

Happy to help. I think you will be pleased with the results, though I will also say that alignment is a big piece of the puzzle to keeping the rear end planted and stable under hard braking (that and downforce, but that's another conversation).

I just got the Fall Line toe links and camber shims on the car, so my car no longer has any eccentric adjustors on the rear end (which are prone to losing their spec when they are tightened down and/or as a result of dynamic forces when in use). According to MRF, the car was more precise and easy to align than any other he's worked on and I can tell you that the rear end feels absolutely phenomenal now.

I truly could not be happier with how the car is setup now. The feedback and stability is unreal and the NVH is essentially at stock levels. Win win.

Can you snap a picture of your rear differential? I want to see how the Diff Damper is put together. I am trying to picture it on the M3, but can't see where it would squeeze in. Thanks!

[MFL]

This set up is...perfect.

[Hujan]

Originally Posted by Move Over

Can you snap a picture of your rear differential? I want to see how the Diff Damper is put together. I am trying to picture it on the M3, but can't see where it would squeeze in. Thanks!

I would be happy to but it will be tough. My car is pretty low and it's really hard to get under there to grab a pic of the diff. I can try to look around to see if I have any pics of my diff since it got put on there. Otherwise, it may have to wait until I get the car back in the air.

[Move Over]

Originally Posted by Hujan

I would be happy to but it will be tough. My car is pretty low and it's really hard to get under there to grab a pic of the diff. I can try to look around to see if I have any pics of my diff since it got put on there. Otherwise, it may have to wait until I get the car back in the air.

That's fine, no rush. One thing you can do is back up over the edge of a curb. Gives you an additional 8" or so to see under there.

[Emm Tree]

Originally Posted by Hujan

I would be happy to but it will be tough. My car is pretty low and it's really hard to get under there to grab a pic of the diff. I can try to look around to see if I have any pics of my diff since it got put on there. Otherwise, it may have to wait until I get the car back in the air.

Cliff Notes -- Purple Powerflex = Stock diff whine on DCT cars?

Looking to upgrade the stock diff components without sounding like I'm hiding an ESS kit in the trunk.

[MFL]

Originally Posted by Emm Tree

Cliff Notes -- Purple Powerflex = Stock diff whine on DCT cars?

Looking to upgrade the stock diff components without sounding like I'm hiding an ESS kit in the trunk.

Highly recommended, minimal impact to wine over stock for DCT cars.

[Hujan]

Originally Posted by Move Over

That's fine, no rush. One thing you can do is back up over the edge of a curb. Gives you an additional 8" or so to see under there.

Man, I'm tired and read that wrong the first time! That's not a bad idea, but there's no curbs like that near where I live. I'll see what I can do, though.

Originally Posted by Emm Tree

Cliff Notes -- Purple Powerflex = Stock diff whine on DCT cars?

Looking to upgrade the stock diff components without sounding like I'm hiding an ESS kit in the trunk.

Exactly. I suspect the only reason I can hear any whine at all now is because I know exactly what I'm looking for, having lived with the delrin diff bushings for so long. But even then it's only in a very narrow speed range with windows up and music off and still it's extremely, extremely faint. Frankly, I'm not sure the OEM bushings would be silent in those "perfect" conditions.

Originally Posted by MFL

Highly recommended, minimal impact to wine over stock for DCT cars.

[JsL]

Checking in on this. Solid frame bushings + Powerflex Purple diff bushings still the way to go for DCT cars?

[Shredicus]

I've had my AKG black bushings with solid subframe mounts in for about 1000 miles now and honestly the whine is very minimal even at cruising freeway speeds. You'd really have to be sensitive to this type of resonance to be perturbed by it considering how much noise our diffs and DCT(if applicable) makes already. The AKG blacks are an 95A durometer so I'd imagine the purples must have an even more imperceptible NVH change.

[becausephilchow]

I did Solid Aluminum Subframe Mounts & Powerflex Purple.

There's a very very very small hint of whine, but I only notice it because I know it's supposed to be there. But, even with the radio at a very low volume, it drowns it out.

That, and my exhaust also drowns it out (Akrapovic Evo)

When I was stock exhaust, my wife would be in the car and wouldn't even notice anything different, so, I think that passes the test.

DCT vehicle btw.

[JsL]

Originally Posted by Shredicus

I've had my AKG black bushings with solid subframe mounts in for about 1000 miles now and honestly the whine is very minimal even at cruising freeway speeds. You'd really have to be sensitive to this type of resonance to be perturbed by it considering how much noise our diffs and DCT(if applicable) makes already. The AKG blacks are an 95A durometer so I'd imagine the purples must have an even more imperceptible NVH change.

Originally Posted by becausephilchow

I did Solid Aluminum Subframe Mounts & Powerflex Purple.

There's a very very very small hint of whine, but I only notice it because I know it's supposed to be there. But, even with the radio at a very low volume, it drowns it out.

That, and my exhaust also drowns it out (Akrapovic Evo)

When I was stock exhaust, my wife would be in the car and wouldn't even notice anything different, so, I think that passes the test.

DCT vehicle btw.

Great. That's reassuring.

I'm running a akra xpipe and corsa rear, so the low volume whine will be drowned out by the exhaust.

[becausephilchow]

Originally Posted by JsL

Great. That's reassuring.

I'm running a akra xpipe and corsa rear, so the low volume whine will be drowned out by the exhaust.

Yup, nothing to worry about at all. In fact, prior to reading this thread, I forgot there was even a whine at all, lol. I only noticed it very slightly when I first installed it, because I was trying to listen for it.

[tlrid3r]

I have solid subframe and zero noise from that and never regret it.

Recently installed powerflex purple diff bushing but only the two front ones and left rear the oem foam one. To see if it would be more direct but less noise. I still hear diff whine specially since I don't have my rear seat. The whine is worst on freeway speed of 65-70 but almost gone at 80+ it's weird how that happens.

Curious to see this diff damper.

[JsL]

Originally Posted by tlrid3r

I have solid subframe and zero noise from that and never regret it.

Recently installed powerflex purple diff bushing but only the two front ones and left rear the oem foam one. To see if it would be more direct but less noise. I still hear diff whine specially since I don't have my rear seat. The whine is worst on freeway speed of 65-70 but almost gone at 80+ it's weird how that happens.

Curious to see this diff damper.

So you hear the whine over the akra evo on the freeway?

[pbonsalb]

Originally Posted by tlrid3r

I have solid subframe and zero noise from that and never regret it.

Recently installed powerflex purple diff bushing but only the two front ones and left rear the oem foam one. To see if it would be more direct but less noise. I still hear diff whine specially since I don't have my rear seat. The whine is worst on freeway speed of 65-70 but almost gone at 80+ it's weird how that happens.

Curious to see this diff damper.

Put the rear seat bottom back in to dampen sound. Works on the E36.

[tlrid3r]

Originally Posted by pbonsalb

Put the rear seat bottom back in to dampen sound. Works on the E36.

Originally Posted by JsL

So you hear the whine over the akra evo on the freeway?

Yes I hear it over the akra.

Originally Posted by pbonsalb

Put the rear seat bottom back in to dampen sound. Works on the E36.

I have a cage. Working a seat delete cover. To reduce noise.