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Discussion Starter #1 (Edited)
Ever since getting back to E46 world I couldnt stop thinking about subframe damage and eventhou I had none it still worried me.

So I ordered a reinforcement kit from bimmerwold.com http://store.bimmerworld.com/e46-rear-subframechassis-reinforcement-kit-p1176.aspx in order to forget about that once and for all.

And since the subrame would be all down I thought why not change the mounts as well. That took a little of a debate. Some recommended OEM replacement ones, some said OEM M3 mounts and then there were those that said Solid mounts. Well I began researching and found that solid mounts are WAY too much for a street car, OEM replacement are just pretty much same sh1t and OEM M3 ones aren't anything to be spending your money on.

My choice came down to my favorite product > Polyurethane. I already have Powerflex (purple) FCAB and I'm in love with them so my choice was obvious, Powerflex. I later discovered that Powerflex offers 2 versions for E46 rear subframe, one is Black and is somewhat very hand poly and the other is yellow and is a little softer. I decided on the yellow ones(reason being is that my car would experience about 80% of daily use and only about 20% of track use), also purchased here http://store.bimmerworld.com/powerflex-3-seriesz3-rear-subframe-mount-kit---high-durometer-p97.aspx

My advise to ANYONE who will not do this themself is to ask around and make sure you go to a reputable shop. I had my reinforcement kit and mounts install done at the shop that does BMWs exclusively and has alot of reputation.

So, here it goes my first impression.


WOW, simply wow.

The difference is day and night for me, the car feels really tight around the turns and when accelerating. Very stable at high speed turning and braking. Its hard to explain but I noticed the difference as soon as I took the first turn when leaving the shop. The car has less body roll, or should I say subframe roll, anyway it doesnt roll as much as it did. Shifting became a little more precise, not actual shifting but rather gear changes. And the question that probably bothers alot of people, NO the was no increase in vibration inside the cabin. So far I've driven just over 200kms on them.

For the record, I already had Powerflex FCAB and 80A poly tranny mounts.

Lastly I want to say that this mod is not for everyone as its pretty expensive, this mod is for people who want to experience BMW to its fullest potential.

Hope this helped anyone.
 

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Good review. I have the same bushings.

I went with the powerflex over OEM to tradeoff some comfort for durability. What a PIA to change these bushings, right? So I wanted them to last. The general consensus among the "experts" is that worn bushings are the root cause of subframe failures since a worn bushing allows a lot more movement and twisting. Thus, more stress on the subframe floor...leading to failure.

I've had them on for 8k miles. Even on the bad roads in Seoul (way worse than anything I've ever seen in Philly) and PSSs, the ride is borderline tolerable...which means you should be good to go in the US.
 

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Discussion Starter #3
I knew that the install would be a PIA, so I went to a shop where they welded the reinforcement kit as well.

You are absolutely correct about worn out subframe bushings being the root of the subframe stress and therefore failure.
 

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I also had the shop repace the bushings when I did the subframe reinforcement. I did the reinforcement as preventive maintenance.
 

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Very nice write up, I'd like to do this very soon. So you have the Purple FCAB bushings and yellow rear subframe bushings and reinforcement plates? How much did the rear set-up run you?
 

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Discussion Starter #6 (Edited)
Very nice write up, I'd like to do this very soon. So you have the Purple FCAB bushings and yellow rear subframe bushings and reinforcement plates? How much did the rear set-up run you?
Correct.

Rear set up ran me $1070 CAD (220 bushings+150 plates+700 install for both) they also turned off my DRLs.

I knew it would be pricey but I dont regret it.
 

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There is some increase in NVH which will drive some crazy. Most importantly, no squeaking so far...its been about 13 months. I can deal with the NVH...my squeaking poly RTABs drove me crazy.
 

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Discussion Starter #10
Any noticeable NVH ?
Not that I can notice. Maybe because I have Powerflex FCAB and also poly tranny mounts and free flow exhaust :hmm:

I'm pretty sure that if you install these on a bone stock car you will feel a little NVH as you would expect from poly bushings, but I doubt it would be uncomfortable.

I can definitely say that I dont experience any more vibration in the cabin nor do I feel any more noise from the rear end.

What I can feel is my tranny mounts, but definitely not the RSFM, even when I installed my FCAB (first poly bushings on this car) I did not feel any vibration increase, all I felt was more control and stability (on the other hand you hear a lot of people who say powerflex FCAB are unbearable :hmm: )

No squeaking what so ever !
 

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What I can feel is my tranny mounts, but definitely not the RSFM, even when I installed my FCAB (first poly bushings on this car) I did not feel any vibration increase, all I felt was more control and stability (on the other hand you hear a lot of people who say powerflex FCAB are unbearable :hmm: )

No squeaking what so ever !
I wasn't concerned with the NVH as much as the squeaking. Imagine having to drop the rear subframe every 6 months to re-lube those bushings.

I have the Vorshlag red engine mounts which made the most noticable increase in NVH. I think any poly drivetrain mount will increase NVH a lot more than a suspension bushing.

Again, my problem with my poly RTABs was the squeaking, not NVH.
 

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Excellent info, the yellow bushings are what I'm in the market for. I installed a rear subframe reinforcement kit with the 3M epoxy method. Anyone have any experiece using poly or solid bushing using this method? Any issues with sheering force? Thanks to all,
 

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Excellent info, the yellow bushings are what I'm in the market for. I installed a rear subframe reinforcement kit with the 3M epoxy method. Anyone have any experiece using poly or solid bushing using this method? Any issues with sheering force? Thanks to all,

Yes.

The thinking in the racing world is that the poly/solid bushings are better because they don't rock back & forth like a rubber OE bushing, thus less failures. If you wanted to take your subframe reinforcement plate kit a step further, pull out each bolt in the rear of the subframe & drill the hole up & through into the trunk. Purchase a set of long bolts, each will terminate in the trunk using a large 8x8" plate that you can glue or weld in place. This "Bolt Through" method increases the overall strength of your subframe greatly.



Good luck,
Rob43
 
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