M3 Rear Subframe Bushings

[aloksatoor]

I have had a 335 with sport suspension before this car and the 335 never felt right to me in stock form. It felt very soft and cumbersome in addition to a harsher ride (even with a longer base) on the RFTs (thats the best I could describe it), it went like a rocket in a straight line but super hard for the tail to break loose as well (felt super planted at speed). The braking was also sub par compared to the 1er.

As others said somethings wrong with the setup on your 1er, did you get a stealership /performance oriented shop alignment done as well? Maybe that would solve your handling issues? I did notice the year of the car as well. Maybe some of the other bushings are tired as well (drivetrain since it shimmies on acceleration or the rear multilink)? That could cause her to be floppy.

[ASAP]

Originally Posted by HooningB2G

I am getting the rsfb installed next month and I can't wait.

Let's just say I was disappointed.

Originally Posted by chris82

Something doesn't sound right . . .

This is my experience.

Originally Posted by chris82

I've been on these forums a while and everyone who does the bushings say they make a huge difference. You could always try the solid aluminum ones from turner. They're $300 and from what I read do no introduce much extra NVH

They do make a difference, not enough of one to satisfy me (especially given the cost).

Originally Posted by fboutlaw

Finish the job.

You're probably getting ~50% the benefit, but you're going to destroy the new bushings since you have 2 supporting the movement of the car now. The stock ones are doing nothing other than being a placeholder. The new ones will prevent the car from moving much and the old ones won't provide much resistance at the small amounts of deflection.

Long done.

Originally Posted by TS135i

@ASAP
I also have RSFB along with rear upper/lower M3 control arms, I dialled the Koni's at front 1&1/4 turns, rear 1 turn - car feels right now.

It could be setting a thing, you are correct. Read my thoughts below.

Originally Posted by John_01

If you feel the car is unstable due to the short wheelbase, you can use a front sway bar upgrade to make it settle down. Especially if you use non-staggered tires sizes and have increased the front camber.

They are staggered with stock camber.

Originally Posted by aloksatoor

I have had a 335 with sport suspension before this car and the 335 never felt right to me in stock form. It felt very soft and cumbersome in addition to a harsher ride (even with a longer base) on the RFTs (thats the best I could describe it), it went like a rocket in a straight line but super hard for the tail to break loose as well (felt super planted at speed). The braking was also sub par compared to the 1er.



As others said somethings wrong with the setup on your 1er, did you get a stealership /performance oriented shop alignment done as well? Maybe that would solve your handling issues? I did notice the year of the car as well. Maybe some of the other bushings are tired as well (drivetrain since it shimmies on acceleration or the rear multilink)? That could cause her to be floppy.

I did not feel this way at all... the 335 felt better in every way even stock. The suspension is perfect we inspected it all around and nothing is worn.

[ASAP]

I don't think anyone understands what I am saying. The car does feel better, it is more stabled and planted, it does however still exhibit excessive side to side flex. This is especially apparent when taking an onramp and merging into highway traffic and switching lanes... It is unbelievably annoying.

How do I know everything is done right? I have a set of 17 inch winter runflats and the car exhibits none of this and feels like it should. The car is clearly designed for runflats and the shorter chassis makes everything worse. Conversely, my 3 series never exhibited any of this and the only upgrade it had was the same tires as I have now. Like I said, these are my thoughts... If I had to do it again, I would be an M Sport 335i from the same year.

[Pyrat 2]

Maybe you should sell the one and buy the 335. Problem solved.

[Dackelone]

Originally Posted by ASAP

I don't think anyone understands what I am saying. The car does feel better, it is more stabled and planted, it does however still exhibit excessive side to side flex. This is especially apparent when taking an onramp and merging into highway traffic and switching lanes... It is unbelievably annoying.

How do I know everything is done right? I have a set of 17 inch winter runflats and the car exhibits none of this and feels like it should. The car is clearly designed for runflats and the shorter chassis makes everything worse. Conversely, my 3 series never exhibited any of this and the only upgrade it had was the same tires as I have now. Like I said, these are my thoughts... If I had to do it again, I would be an M Sport 335i from the same year.

Maybe one of your subframe bolts has broken. They should have been replaced - since the bolts are alu stretch bolts.

Also... what is your rear toe? Sounds to me like something is outta whack.

[Solo_M_Tech]

Originally Posted by HeelToe

Maybe you should sell the one and buy the 335. Problem solved.

+1

I track my car a lot, and I can definitively say my car handles better the PSS's.

[ASAP]

Originally Posted by Dackelone

Maybe one of your subframe bolts has broken. They should have been replaced - since the bolts are alu stretch bolts.

Also... what is your rear toe? Sounds to me like something is outta whack.

The suspension has been looked at completely, the bolts are fine. As expected no one read my comments... the car feels perfect on runflats...

[ASAP]

Originally Posted by HeelToe

Maybe you should sell the one and buy the 335. Problem solved.

With the release of the F80, I can assure you that all of my qualms have been resolved... but this is not a discussion about my next car but rather the deficiencies in the 1s suspension.

[Pyrat 2]

If the car is fine with the run flats on then install them. There are many on here that don't have an issue as you describe so something gives. I own both an e90 and e82 so can easily compare the two. I don't feel what you are talking about.

The run flat tires seem to get a beating on these boards for reasons I don't fully understand. It almost seems like people are embarrassed to admit they prefer them. They have stiffer sidewalls and tend to be more responsive than non run flats. I'm not running them but only because I track my cars and their ultimate grip on the track isn't as good as alternatives out there. In any event if the problem isn't present with them and the issue is significant enough in your mind then switch.

[justpete]

Originally Posted by ASAP

The suspension has been looked at completely, the bolts are fine. As expected no one read my comments... the car feels perfect on runflats...

Weak or worn trailing arm bushings can cause toe out under hard accel as can bent or flexing trailing arms. There are spherical bearing replacements that can minimize the problem. And weak or worn toe arm bushings can lead to similar problems, I think.

[TS135i]

Originally Posted by Dackelone

Maybe one of your subframe bolts has broken. They should have been replaced - since the bolts are alu stretch bolts.

Also... what is your rear toe? Sounds to me like something is outta whack.

Are you saying if you haven't replaced the subframe bolts when replacing the bushings they're not performing as they should?
The shop I had my bushings replaced didn't mention anything about replacing the bolts, they have maybe replaced 30+ cars... Or is it a matter of time they break?

[Dackelone]

Originally Posted by TS135i

Are you saying if you haven't replaced the subframe bolts when replacing the bushings they're not performing as they should?
The shop I had my bushings replaced didn't mention anything about replacing the bolts, they have maybe replaced 30+ cars... Or is it a matter of time they break?

Take a magnet to your subframe bolts... IF its alu I would replace them. Sure you can reuse them... but one day they will snap. BMW says to only use alu bolts ONCE.

[fe1rx]

Originally Posted by TS135i

Are you saying if you haven't replaced the subframe bolts when replacing the bushings they're not performing as they should?
The shop I had my bushings replaced didn't mention anything about replacing the bolts, they have maybe replaced 30+ cars... Or is it a matter of time they break?

This bolt (p/n 33326760340) is actually a grade 10.9 steel bolt, not aluminum. Specified torque is 100 Nm (74 lb.ft.), which does not constitute torque-to-yield for a bolt of this size and grade. If these bolts aren't corroded, there is no real reason to replace them. Replacing as a matter of course would make sense if the vehicle was old enough to have worn out its bushings, but in the context of this forum it is more likely they are being replaced simply as an upgrade and the vehicle is still young.

All aluminum bolts (painted blue head) should be replaced not reused.

Steel bolts that are torqued to a torque value, plus a specified rotation angle are (potentially) permanently stretched and should also be replaced not reused.

Generally steel bolts that are not tightened more than the maximum permissible specified in DIN 267 have not been stretched and can be reused. I have reproduced the maximum torque value list from the Bentley 3 Series Service Manual (under the fair use doctrine - great manual, you should get one):



That said, BMW and thus Bentley do recommend replacing them, but there isn't a really compelling technical reason to do so.

[JTB]

Originally Posted by Dackelone

Also... what is your rear toe? Sounds to me like something is outta whack.

I think Dack is on the right path. Oddities in the alignment can be responsible for what you are feeling. I recently had mine set, very slight toe in both front and rear, and it made a noticeable difference to how the car felt and drove.

[gap]

Originally Posted by ASAP

I don't think anyone understands what I am saying. The car does feel better, it is more stabled and planted, it does however still exhibit excessive side to side flex. This is especially apparent when taking an onramp and merging into highway traffic and switching lanes... It is unbelievably annoying.

How do I know everything is done right? I have a set of 17 inch winter runflats and the car exhibits none of this and feels like it should. The car is clearly designed for runflats and the shorter chassis makes everything worse. Conversely, my 3 series never exhibited any of this and the only upgrade it had was the same tires as I have now. Like I said, these are my thoughts... If I had to do it again, I would be an M Sport 335i from the same year.

Went through the same thing. Started upgrading the suspension last year.
I have the BMW PS with Koni yellow external adjustable.
I added the Whiteline inserts first, somewhat better but not what I wanted. Added M3 front parts and M3 subframe bushings and it was much better but still had the rear bump steer and torque steer like you describe. Just installed the rear M3 upper control arm, guide arm and Rogue Engineering toe arms and that got the handling problems solved. Glad to be finished!

[dcaron9999]

Originally Posted by gap

Went through the same thing. Started upgrading the suspension last year.
I have the BMW PS with Koni yellow external adjustable.
I added the Whiteline inserts first, somewhat better but not what I wanted. Added M3 front parts and M3 subframe bushings and it was much better but still had the rear bump steer and torque steer like you describe. Just installed the rear M3 upper control arm, guide arm and Rogue Engineering toe arms and that got the handling problems solved. Glad to be finished!

How long have you had are your RE toe arms, and how are they holding up? Any corrosion, noises, rattles?

Aftermarket adjustable toe arms are on my short term wish list, to deal with added torque from Quaife 3.46 FD LSD, and custom tune + FBO.

[gap]

Originally Posted by dcaron9999

How long have you had are your RE toe arms, and how are they holding up? Any corrosion, noises, rattles?

Aftermarket adjustable toe arms are on my short term wish list, to deal with added torque from Quaife 3.46 FD LSD, and custom tune + FBO.

1 day and no noises, too early to tell about long term. They do have rubber dust boots over the Heim Joint.

[ASAP]

Originally Posted by gap

Went through the same thing. Started upgrading the suspension last year.
I have the BMW PS with Koni yellow external adjustable.
I added the Whiteline inserts first, somewhat better but not what I wanted. Added M3 front parts and M3 subframe bushings and it was much better but still had the rear bump steer and torque steer like you describe. Just installed the rear M3 upper control arm, guide arm and Rogue Engineering toe arms and that got the handling problems solved. Glad to be finished!

It's really sad that it takes that much for this car's suspension to be decent... it really is a great little car with some serious Achilles heels imho.

[HP Autosport]

Originally Posted by ASAP

I apologize in advance but this is a random question...

From the M3 rsfb's, would the 2 fronts make a bigger difference or the rears?

Some guys choose to do the rear two only to cut down on labor time and no need to drop the subframe completely.

How do you quantify the difference between doing two and four bushings? Well, that is kinda tough.

[ASAP]

Originally Posted by ASAP

It's really sad that it takes that much for this car's suspension to be decent... it really is a great little car with some serious Achilles heels imho.

Any idea on which of these parts or what would be most effective to correct the rear side to side flex? My car no longer bounces up and down as the bushings and konis fixed that but on hard acceleration and lane merging, you can feel the rear flex and move side to side substantially? What would help alleviate that the most?

[tracer bullet]

Originally Posted by ASAP

the car feels perfect on runflats...

I'm trying to figure out why this is the case but not with non-rft's.

What tires do you run? I'm guessing they are good but... what if they aren't? Some sort of internal damage? If they're directional is one of them installed such that it's not rotating the correct direction? Is it simply the tread pattern you're feeling (much like I do w/ my winter Blizzak's)?

Could be something else, tire related or not the tires at all but - if it's tied to one set of tires and not the other, I'd focus on the tires.

[ASAP]

Originally Posted by tracer bullet

I'm trying to figure out why this is the case but not with non-rft's.

What tires do you run? I'm guessing they are good but... what if they aren't? Some sort of internal damage? If they're directional is one of them installed such that it's not rotating the correct direction? Is it simply the tread pattern you're feeling (much like I do w/ my winter Blizzak's)?

Could be something else, tire related or not the tires at all but - if it's tied to one set of tires and not the other, I'd focus on the tires.

I run PSS in the summer...

With the rft's, the up and down bounce no longer exists but the side to side flex does.

With the pss both the up and down bounce and thr side to side flex exists.


And trust me, with the latter it is in some cases still unacceptable imho.This is after Koni Yellows and M3 rsfb's.