Powerflex inserts at 30K

[uberschnell]

Removed my stock subframe bushings and Powerflex inserts and replaced with full poly bushings from Prothane.

Inserts have around 30K and the bushings have 77K. While the inserts look beat up they are actually in really good condition. They feel just like the day I installed them. Also, bushings at 77K still look in decent shape.

Overall I say the inserts are a 100% improvement over stock. The full bushing replacements are a 100% improvement over the inserts. And shockingly no increase in NVH

I used to think (from my e90 days) the subframe bushings were not the most important upgrade but I have since changed my mind. I think it should be one of the first suspension mods. The stock ones are junk.

[brocklanders]

Good to know, I just received my whiteline subframe bushings and plan to install them next week along with front tension strut bushings, eibach sways and now the koni strt kit. I should have a completely different car.

[brocklanders]

I just checked out the prothane website, prothane and whiteline are the same product.

[uberschnell]

Originally Posted by brocklanders

I just checked out the prothane website, prothane and whiteline are the same product.

Right.

http://www.whiteline.com.au/product_..._number=KDT917

The 2-piece bushings make the job easy. I did it in my driveway on jacks.

[e36addict]

Are you guys buying the whiteline bushings striaght off their website?

[TheSt|G]

Originally Posted by uberschnell

I used to think (from my e90 days) the subframe bushings were not the most important upgrade but I have since changed my mind. I think it should be one of the first suspension mods. The stock ones are junk.

This can't be stressed enough, especially once people move off the run flats.

[uberschnell]

Originally Posted by e36addict

Are you guys buying the whiteline bushings striaght off their website?

I picked them up off of Amazon, but the price is the same. Search by part number KDT917 - full replacement
KDT918 - inserts ($45 on their site)

For a little more$ and an hour or so of extra effort I would suggest the full replacement.

[uberschnell]

Originally Posted by TheSt|G

This can't be stressed enough, especially once people move off the run flats.

Check out the picture above with the air gap, they are literally designed to move side to side and up and down. Suspension not only has to deal with the road but also the oscillations created by the subframe’s movements. I believe it’s designed that way to induce even more oversteer for safety.

[TheSt|G]

Originally Posted by uberschnell

Check out the picture above with the air gap, they are literally designed to move side to side and up and down. Suspension not only has to deal with the road but also the oscillations created by the subframe’s movements. I believe it’s designed that way to induce even more oversteer for safety.

Oh I know, I tossed them for the M3 version awhile ago. I was laughing as I took them out when I saw the design.

To their credit, that design also helps mitigate RFT NVH.

[e36addict]

Originally Posted by uberschnell

I picked them up off of Amazon, but the price is the same. Search by part number KDT917 - full replacement
KDT918 - inserts ($45 on their site)

For a little more$ and an hour or so of extra effort I would suggest the full replacement.

Thanks. Just ordered the KTD917 off Amazon.. I'm sorta excited

[TwinTurboed]

Do you track your car? Is that why you felt that the full bushings were necessary?

My car is a daily and never sees the track. Just a lot of city driving and mountain roads every once in a while. For someone like me, would the inserts suffice?

[TheSt|G]

Originally Posted by TwinTurboed

Do you track your car? Is that why you felt that the full bushings were necessary?

My car is a daily and never sees the track. Just a lot of city driving and mountain roads every once in a while. For someone like me, would the inserts suffice?

Full bushings are the street option(hence why they are stock on the M3). The track version would be the solid aluminum mounts.

[TwinTurboed]

Originally Posted by TheSt|G

Full bushings are the street option(hence why they are stock on the M3). The track version would be the solid aluminum mounts.

The full bushings are a good compromise for a daily/track car. I have read that the solid aluminum ones can shake your teeth fillings loose (not that I have any) .

I have the inserts on hand waiting to be installed, hoping they will fulfill my needs.

[dcaron9999]

As mentioned in this thread, the stock RSFB's (Rear SubFrame Bushings) have voids in them, designed for movement of the subframe, as the stock Run Flat tires have stiff sidewalls. This isolates the harshness of the RunFlats, but makes the rear end of the car float and wave when NON- RUNFLAT tires are used.

The M3 RSFB's are a direct replacement for the stock RSFB's. I could not believe the difference the solid rubber M3 RSFB's made on my 135i, even for street driving. My 135i now feals planted. No more sideways, vague, detached fealing from the rear of the car. This is very noticeable when going over bumps while driving on twisty roads.

There is more labor involved in replacing with full bushings versus inserts. Mechanics typically need 7-8 hours of labor to do this.
Many enthusiasts managed this as a DIY, but you need to be comfortable with detaching brake lines, bleeding your brakes, loosening your subframe without completely removing it from the car, operating a bushing puller tool, etc.

For less labor, and cursing, one can replace with one of the several models of inserts and results are still worthwhile. The tow type of inserts are designed to either fill the voids of the soft stock 1-series rear subframe bushings, or replace them as a top half and bottom half. The void filling type is the easiest of the three options.

[uberschnell]

Yeah, definitely. This is one of those mods you can enjoy in everyday driving.

[CAVU]

I'm running non-runflats (Michelin PSSs) and the rear end shimmy and general feeling of not being planted was a bit disconcerting, even noticeable to non-enthusiast passengers. I just installed a set of Whiteline rear subframe inserts over the weekend and the improvement significant. Definitely an upgrade that is noticeable in everyday driving. Certainly not the full improvement of running M3 bushings, but perhaps a 50% improvement (from what I hear). If the M3 bushings can get me another 50% improvement, I may keep them in mind as a future project.

[brocklanders]

Originally Posted by uberschnell

Right.

http://www.whiteline.com.au/product_..._number=KDT917

The 2-piece bushings make the job easy. I did it in my driveway on jacks.

What all needed to be removed or loosened? I had one shop tell me that they needed to remove the rear springs, I thought they were mistaken but I don't know for certain.

[brocklanders]

Also I chose whiteline front tension strut bushings, I will give a review on this thread as well to report on noise and vibration. I should have all the parts installed by mid next week.

[DietTab]

Originally Posted by dcaron9999

There is more labor involved in replacing with full bushings versus inserts. Mechanics typically need 7-8 hours of labor to do this.
Many enthusiasts managed this as a DIY, but you need to be comfortable with detaching brake lines, bleeding your brakes, loosening your subframe without completely removing it from the car, operating a bushing puller tool, etc.

Lower cradle, stick 1" socket above bushing, jack cradle up into socket. Apply torch to bushing saddle part of cradle, watch bushing slide out like butter, using car's weight as leverage to press it out. Repeat * 3 other sides. Takes 10 minutes to get them out, maybe a 1-1.5 hour job tops if you do it this way, including getting the car in the air

[mlifxs]

Originally Posted by brocklanders

Also I chose whiteline front tension strut bushings, I will give a review on this thread as well to report on noise and vibration. I should have all the parts installed by mid next week.

did you get the tension strut bushings with the caster adjustment? either way, would love to hear about the results.

[uberschnell]

Originally Posted by brocklanders

What all needed to be removed or loosened? I had one shop tell me that they needed to remove the rear springs, I thought they were mistaken but I don't know for certain.

I saw no need to remove the rear springs. I just disconnected the 2 brake lines and detached a couple of sensor lines from their clip. The rest is about dropping the subframe low enough to pop the new bushings in.

Sure, fully dropping the subframe (disconnecting drive shaft and all) would make it easier but definitely not needed.

The socket and torch method mentioned above to remove the original bushings is the best and easiest way to do it. I left the subframe bolts in (about 3 turns) on one side as I dropped the other. This helped me make sure the subframe wouldn't squirm around too much when you dropped it and it left plenty of drop on the opposite side to get the bushings in.

The full replacements are every bit as good as the M3 bushings without the $700 install costs.

[brocklanders]

Originally Posted by mlifxs

did you get the tension strut bushings with the caster adjustment? either way, would love to hear about the results.

I bought the ones without, I don't want to change anything on the suspension just tighten it up.