[Phil325i]

Is it me, or does the Powerflex bush sit 10mm or so higher in the subframe than the OEM bush? And won't that mean the car's rear ride height will be raised by the same amount..?

[Radical_53]

Originally Posted by AWDBooSTIn90

Has anyone who has done this mod daily drive their car? My bushings are shot. (120kmiles). I want to change them out to improve handling. Do they create more vibration or any more stiffness?

How about these poly subframe bushings and poly diff bushings? Too much as a combo for a DD?

I'm curious about this as well. How's the situation today, 3 years after the install?

I love Powerflex for their ease of installation (I think they're much easier to get in at home than OEM bushings), but I'm a little worried about noise and vibration.
My car isn't intended for track use, so I'm torn between the Powerflex and the M3 subframe bushings to go with my mix of Michelin PSS & KW V2 / ST XA coilovers.
As I'm going to use the other M3 "bits" for front and rear, I thought I'd use the full "kit". These aren't part of any arm or rod and could really make a difference with all that torque.

As some guys seem to be using Delrin or even metal, are vibrations and noises an issue with these?

[J. Dub]

Didn't Rob prefer delrin subframe bushings to these powerflex?

[AWDBooSTIn90]

Originally Posted by J. Dub

Didn't Rob prefer delrin subframe bushings to these powerflex?

Curious about this as well... I think it will be that he would have preferred to go with a stiffer or even solid bushing. The yellow Poly Bushings are too soft for the subframe..

There seems to be a good compromise between handling improvement and NVH when you know the different available materials and their stiffness level, and choose each bushing based on the bushing it's replacing. The different "levels" of stiffness for different types of Bushings really makes a big difference, so do alittle research forst so you're not disappointed with the outcome. This would still prob need be based on the car's actual real use the majority of the time, as well as your driving style.

Howefer, i can never seem to get straight answers on the best setups for aggressive street cars. Like Improvement vs NVH for each different bushing set replaced, and was it worth it. Was it the correct choice?


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Here's a quick list of the different levels of upgrading, that each bushing style provides

----List of Subframe Bushings Upgrades----

-OEM Bushings: Too soft even for a stock 335i. Handling and NVH are Bad...

--OEM M3 Bushings: Somewhat hard to install, expensive, and still pretty soft..
Good for a strictly DD type car, because of cost and effort required to DIY.

---Poly Inserts: Very good bang for the buck! Makes a noticeable improvement in handling, same ride quality. Very cheap! Can easily be DIY'd. Great for 328/330's.
~Still alittle soft for a modded N54, but will work for a spirited DD type car

---Yellow Poly: Definitely an improvement, not too expensive, doesn't seem hard to DIY install. Easily available. Need to grease to avoid squeaking, as with any Poly Bushing. But with the "softest poly" available for the E9x is not that stiff for spirited driving on a modded car. PowerFlex doesn't even offer the Yellow Poly Bushings if you shop for an E9X M3 because they aren't a big enough improvement from the OEM M3 Bushings you would already have... So they list the Purple/Black Poly Bushing Kits as a Great Improvement. So brings me to the next "Step Up..."

----Purple/Black Poly Bushings: As stated before these are the only two Poly Bushings available for an M3. Yellow Series Poly wouldn't be enough of an "upgrade." If your going Poly, then i would strongly consider the stiffer Purple or even the Black, "Racing level," Poly Bushings. These Poly Bushings are either the same price as the softer, Yellow Series, or sometimes just slightly more expensive. So still a good value. Cheaper than M3 subframe bushings. Better choice for those looking for a "locked down" subframe feel without sacrificing ride quality or too much extra NVH..

-----Solid Subframe Bushings (Delrin, Aluminum, Welded): The ultimate way to achieve no Unwanted Movement form the Rear Subframe. It will absolutely increase NVH. However, the handling level available with other suspension/drivetrain Mods is undeniable. Usually around $400.
-One thing to consider is that some of the Newer Model BMW's have a Rear Subframe that is directly bolted to the unibody with no bushing. Solidly mounted in the truest form..

These cars still ride good, handle good, and are relatively quiet...

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The thought behind this is that the subframe is exactly what it sounds like it is, its a secondary frame connected to the unibody, which is the frame. So it adds strength, rigidity, and it provides a solid mounting point for the suspension arms, rear diff, hubs/brakes, etc...

So with the rear subframe engineered by BMW to be solidly mounted, all the Bushings are well designed and spec'd out to be complaint, but at the same time still stiff enough for a car like the M5/6...

So in my opinion, the Bushings should be different levels of stiffness whether its for the rear subframe, the rear diff, motor mounts, trans mounts, front/rear suspension arm bushings, sway bar bushings....
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For example, this might be good for a spirited driver with a modded to FBO/E85 car, while not making the car sound and feel like a loud "full-out track car"...

-Rear Subframe: Solid Aluminum/Black Poly
-Rear Diff: Yellow Poly/OEM M3 Diff Bushings
-Rear Suspension: M3 Arms/Ylw Poly in stock arms
-Front Suspension: M3 Arms/M3 arms with ylw poly for bushing sides..


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Anyone that drives a car with any of these mods using M3, poly, or solid Bushings please post your setup, level of improvements, and any advice you might have. Like would you go the same route if you could do it again...???

Mods Like:
-Upgraded Subframe/Diff Bushings
-Suspension Arm Bushings
-Sway Bar Bushings

Now that more people have modded their cars, new products, reviews now more available, and setup combo's. I think that we need to have a new thread on this after we get some more reviews from people with personal experiences.

So any experiences/advice/thoughts is appreciated

[AndyW]

Necroing this thread...first to say "Thanks" and second, to say that, for me, heating doesn't make anything come out "like butter". I have one rear bushing about 1" out. Time to buy or rent the proper tool...

[Radical_53]

Thanks a lot for this guide. I had the original M3 bushings installed by my shop and without this guide, I'm sure the car would still be hanging in the air...

On the other hand, I would've wished I had just bought the tools (no chance to rent them here) instead.

The mod itself is great though. I also upgraded the sway bars to H&R and the car handles so much better now, it's unbelievable. Great mod and a big difference in handling.
The car is perfectly planted now.

[CRCE90]

I am planning to attempt this in the next few weeks. Does anyone know if this mod can be done without removing the Diff? Thanks.

[AndyW]

Originally Posted by CRCE90

I am planning to attempt this in the next few weeks. Does anyone know if this mod can be done without removing the Diff? Thanks.

Yes. I did whiteline 2-piece on my 135i but the procedure is the same. You just have to use Jack's to raise/lower the front or rear of the subframe to make room. Definitely recommend using the correct tool for removal.

[P.atty]

Hello!

This DIY helped me a lot replacing my subframe bushings a few month ago, thanks for the work
I changed the subframe bushings to the M3 ones, installed new front diff bushings and braided brake lines. Unfortunately I am not that happy with the ride quality since then, because I experience some noticable cabin drone and vibrations, propably coming from the drivetrain. Especially at speeds around 75 to 95mph and activated cruise control.

I checked the differential for horizontal alignment (due to the new, front bushings) and corrected that with one washer. Now it is centered to the drive shaft and this helped a bit. Then I checked the vertical alignment and I measured some difference between top and bottom, meaning that the drive shaft joins the differential at an angle (top is closer than bottom, difference only about 1mm). I was told this is normal, because under torque the diff moves up on the front and honestly I do not know the situation with the stock parts.
I tried to equalize this difference between top and bottom with one or two washers between body and the rear subframe mounts, slightly tilting the whole subframe with the diff. I reduced the drone somehow, but not completely. Center bearing was also replaced, the old one was fine.
So now I am running out of ideas and it is freaking me out, because with the old stock bushings the car was absolutely quiet at every speed. I am one click away from buying stock ones and reinforcing them with some sikaflex or these PU inserts. But the work sucks...
Bushings sit correct, no problems during install. Meanwhile I suspect the M3 bushings to simply not work in my car. It is an 2010 E91 325D (N57), manual. A few guys in the german E90 forum did get the M3 bushings mounted, also in a 330D, but all I see is automatic gearboxes. Maybe manual and automatic subframe are different, like for example their rear diff bushing are different.

Any ideas? Anybody running a manual with the m3 subframe bushings here? Rest of the car is completely the same, same (balanced) wheels and everything.
Thanks a lot!

[P.atty]

Ok, now that is a bit embarrassing...
I installed my winter wheels (M270 8x18 all around) yesterday and removed the shim/washer between the subframe and the body, because this was kind of my last straw.
So after the wheel change I made a little tour to Nürburgring and to my surprise I did not feel vibration or resonance anymore, at least not at the speeds and loads like before.
The summer wheels are balanced, but obviously not good enough. There are no missing balancing weights, so the summer wheels have not changed during the bushing change. My guess is that the soft stock bushings absorbed these vibrations before, but the harder M3 bearings send these vibrations straight to the body.
So for the next summer I will have these wheels balanced again

And as a little fun fact: You get the aftermarket Lemförder M3 subframe bushings (as BMW uses them) here in germany for 20€ a piece. Even with a ///M on it BMW retail price is about 70€ per bushing.

[keninger]

My custom LSD is currently being built and I have ordered 90ShA subframe and diff polyurethane bushings. My mechanic says that the diff bushings are fine, but I shouldn't install the subframe bushings, because the car could rip the whole subframe.

Has anyone had issues with stiffer bushings in the subframe, or has anyone ripped a subframe?

[Boony]

Originally Posted by keninger

My custom LSD is currently being built and I have ordered 90ShA subframe and diff polyurethane bushings. My mechanic says that the diff bushings are fine, but I shouldn't install the subframe bushings, because the car could rip the whole subframe.

Has anyone had issues with stiffer bushings in the subframe, or has anyone ripped a subframe?

Good question. Resurrecting this thread for insight

[Malikhajn54]

hey guys iam about to install the powerflex set for the subframe but wondering how it is on street is it noisy while driving !! is there any winning sound coming from the back side !