New vibration after replacing bushings

[hunterm]

Hey everyone!

So I just completed installing my rear subframe reinforcement plates, putting new polyurethane bushings in the subframe, trailing arms and changing transmission mounts. I also have a new guibo and center support bearing that I replaced less than 5,000 miles ago.

So I got in my car this evening and noticed it vibrating a lot more than usual. This is at idle and also on the move at all speeds. I installed the driveshaft back in the same exact position (marked it with a marker) on both sides. All my bolts are 100% tight, I quadruple checked all of them on the lift.

It’s not coming from the wheels because it does it when I’m not moving, and I also have weights correctly placed on my wheels. There are also zero codes from the engine and is most definitely not a misfire.

Is this added vibration due to me replacing my bushings with stiffer ones? All of my mounts are Street polyurethane except for my engine mounts (they are OEM rubber).

Thanks for any advice! Much appreciated!


This is a 2004 BMW M3 with 120k miles, true 6-speed manual.

[E39 Newbie]

How old are the engine mounts? When the age they collapse, the engine starts to ride on the crossmember and you get lots of vibration.

[mcbru]

+1 to at least checking engine mounts. I suspect that the polyurethane trans mounts are the culprit. Nothing else you did would have an effect on vibration when stationary. Trans mounts can transmit noticeable vibration since they are fairly close to the driver

[amancuso]

+1 to at least checking engine mounts. I suspect that the polyurethane trans mounts are the culprit. Nothing else you did would have an effect on vibration when stationary. Trans mounts can transmit noticeable vibration since they are fairly close to the driver

Poly bushings 100% the cause of your issue. rubber dampens vibrations, the poly ones transmit it into the chassis. poly is really not good for comfort. I'd remove and replace with factory originals.