Non-M E46 330i Subframe and Differential Bushings OEM or Poly

[Fanatic10]

I am going to replace the seals on my differential because they are leaking and thought this would be a great time to do the differential bushings and subframe bushings. To give some context, this is going to be my second e46 and I have another e46 to DD. It will be used for autox and possibly some daily driving.

From what I have read on here it seems that differential bushings cause a lot of NVH while subframe bushings cause minimal NVH.

I bought polyurethane differential bushings before I read this and now I have to decide on which subframe bushings to buy.

I was going to get these Solid Delrin rear subframe bushings:

https://store.garagistic.com/bmw-per...frame-bushings

But now I think I might just go with OEM to buffer the polyurethane differential bushings to let it have some give.

What do you individuals think?

[por911]

I'd go with factory replacement bushings. The only place I like urethane bushings is at the sway bars.
Regards

[MarcoZandrini]

Delrin bushings are stiffer than the factory bushings. That will make the rude harsher.

[RobertDenali]

I would always go with genuine BMW rubber bushings on drivetrain for non track driving unless you are ok with feeling the vibrations in the cabin.

[Liquidity]

If you’re really talking about NVH being a problem - don’t even bother with poly bushings on anything anywhere.

[Jackson42]

Delrin is as close to solid as you are going to get without putting in metal bushings. I put Delrin suspension bushings in another car some years ago and it was one of the biggest mistakes I ever made - they were so stiff I swear my vision would blur from the harshness every time I hit even a minor bump.

Here's another thing to consider: I work in aircraft engineering and one of the basic principles of aircraft structural design is that you have to keep the stiffness of all of the members that react a load to the airframe in balance - if you make one member too stiff, it will transfer the load to a weaker member that then may fail. In other words, there is such a thing as a part that is too stiff. Given the E46's reputation for having a weak floorpan where the rear carrier mounts, unless you also went in and stiffened up the floorpan when you installed Delrin bushings, you might just be setting yourself to rip holes in the floorpan, especially if you are thinking about autocrossing the car.