[Denny347]

Refreshed my front suspension some time ago only to find that the front was nice and tight but the rear end was kicking to the side whenever I drove over bumps. Bought Whiteline subframe inserts for $45 back in May, figured I'd try them first. Well, I finally got around to installing them today, pretty easy. Spent about 2 hours at the most, I was not rushing around at all. Pulled the car up on ramps then jacked the rear up, getting the car pretty level but up in the air. With jack stands under the car, I used the jack to raise/lower the rear subframe. Loosened up the front bolts and removed the rear all together. The inserts come with grease, use it liberally. The inserts pretty much only go in one way and the instructions tell you which ones go where. The fronts were a bit trickier. After getting the inserts in the rear, I loosely installed the rear bolts. However, I could not drop the front enough to get the top insert in. I found that I needed to completely remove the rear bolt of the same side as the front I was trying to install. Then the front gave me plenty of room. I had to do that for each side on the front bushings. I couldn't get them to fully seat by hand but using my cordless impact wrench, they seated nice and snug. Man what a difference those inserts make. Well worth the $45 investment.

[dleccord]

Thanks but can you elaborate on the driving experience?

[Denny347]

Originally Posted by dleccord

Thanks but can you elaborate on the driving experience?

Well, before, when I was at speed and hit a bump, the rear would kick out to the side. The car hopped to the side. Very annoying to say the least. Driving it last night, the rear is staying planted now over bumps. I'm lowered on a ST suspension so it's pretty stiff anyway. Now it might be my imagination, but I swear it feels more responsive at launch. Could be the bushings, could be in my head. The rear just feels a bit tighter overall. $45 and 1.5hrs or so. Well worth it.

[dleccord]

nice. you are quick if you that job took you 1.5 hours!

[hellokitty]

Inserts are great at tightening up the rear end upon launch. However they are not a full replacement. I have the inserts and the rear end still feels floaty on curved sweepers. However it helped tremediously in keeping the rear end in check on a full launch.

I have aluminum bushings going in soon. Will report back.

[mpathic]

What about installing the hard rubber //M3 subframe mounts instead of solid, or inserts on what were probably mushed out old stock mounts?

[maddmatth]

I recommend full solid polyurethane.
They add no NVH so I don't see any point going with anything less.

I also don't think aluminium is worth the extra expense and effort though. I have the AKG race subframe bushings. IMO I'd feel more comfortable with poly over metal, it might help for hard impacts and some vibration as it'll have more flex than the metal around it, if pushed to an extreme it'll flex before the metal deforms. Aluminium wont.
That's based on my imagination and no real research so don't go around quoting me.

[mpathic]

Matter of opinion that PU doesn't add NVH. A good softer PU molded inside an outer shell, Whiteline style, behaves like fresh stock on the rear front lower control arm and rear middle upper outer bushing. That's also with new BMW OE bushings on the camber arm inner and toe arm inner and outer.
Will get to the subframe mounts in the spring after the rainy season stops so I can take the 330 apart for a few days and drive the E86M if I need to use a car for anything.
Seriously, the factory OE bushings I took out at 130k miles are still quite firm. These are much longer lasting longer lasting now than the all solid rubber stuff from earlier series that turned to jello by 50k miles. Now they in-mold two rubber shells around very dense rubber. The new OE bushings I put in might be perceptively lightly a touch firmer when I tried flexing the control arms with only one end bolted in, but not much.
Only bushings that are different between M and non-M E9x are the rear subframe mounts. Do check out and consider M3 subframe mounts instead of PU. PU subframe mounts can and do squeak up a bit, might take 20k miles til they do, but they will. Way too much linear side loading, and no rotational and twisting forces like E36/46 RTABS take. Went through that ordeal on my old E36M3 and Z3 with urethane subframe mounts, and rear trailing arm mounts on the Z3, not going there again. Glopped all the copper bushing grease that the sleeves could retain, but didn't matter.
Between street level soft PU and BMW OE, its matter of opinion and how long do you need the bushings to last before slightly softening up more than anything else.

Btw, installation tip for first timers changing control arms bushings, real easy oversight to make:
install the bolts loosely with the suspension unloaded. Then jack up on the axle/hub/wheel carrier til you load the suspension up to the normal ride height. Then torque them down, ~55ft/lbs. Otherwise you're putting a permanent twisting force on the new bushings, instead of them being loaded up only when the car is leaning.

[dleccord]

Originally Posted by maddmatth

I recommend full solid polyurethane.
They add no NVH so I don't see any point going with anything less.

I also don't think aluminium is worth the extra expense and effort though. I have the AKG race subframe bushings. IMO I'd feel more comfortable with poly over metal, it might help for hard impacts and some vibration as it'll have more flex than the metal around it, if pushed to an extreme it'll flex before the metal deforms. Aluminium wont.
That's based on my imagination and no real research so don't go around quoting me.

for someone who already has m3 subframe bushings installed, will we need to press the m3 ones out to install the solid polyurethane bushings? also do you think it will be harsh with the stock RFT tires?

[maddmatth]

Originally Posted by dleccord

for someone who already has m3 subframe bushings installed, will we need to press the m3 ones out to install the solid polyurethane bushings? also do you think it will be harsh with the stock RFT tires?

I don't know about installation but it's probably not worth the effort of upgrading if you already have the M3 bushings, I doubt they have significant flex in them when installed.
I'd go straight to poly if coming from the stock bushings, but from M3 bushings I doubt I'd bother upgrading.

For the runflats I guess it depends on the wheels, hard to say, but I don't think you can even push your car hard enough to benefit from your suspension upgrades with the stock runflats. They lack that feel that lets you judge the grip limit, and they just don't have as much grip either in my experience.

Dumping the runflats is the best handling upgrade you can do IMO. My car, after M3 arms, poly SF bushings and diff brace, is far more comfortable than it was before the upgrades on the 19 inch runflats.

[dleccord]

Originally Posted by maddmatth

I don't know about installation but it's probably not worth the effort of upgrading if you already have the M3 bushings, I doubt they have significant flex in them when installed.
I'd go straight to poly if coming from the stock bushings, but from M3 bushings I doubt I'd bother upgrading.

For the runflats I guess it depends on the wheels, hard to say, but I don't think you can even push your car hard enough to benefit from your suspension upgrades with the stock runflats. They lack that feel that lets you judge the grip limit, and they just don't have as much grip either in my experience.

Dumping the runflats is the best handling upgrade you can do IMO. My car, after M3 arms, poly SF bushings and diff brace, is far more comfortable than it was before the upgrades on the 19 inch runflats.

hey thanks. ur experience resonate so much. yes, its super hard to tell how much grip is left with the bridgeston rft's. did you have the 313 wheels?

[maddmatth]

Originally Posted by dleccord

hey thanks. ur experience resonate so much. yes, its super hard to tell how much grip is left with the bridgeston rft's. did you have the 313 wheels?

I had the style 225s, same size. They were bone rattling with runflats, but not bad with regular tyres.
But I've since downsized to 18s which are even better especially with rough roads.