Rear End Wiggle on Bumps

JStang · 10-15-2014, 07:18 AM

I recently had new Michelin PSS's put on and since have noticed that the back end seems to move a little side to side when one wheel hits a bump in the road. I haven't noticed this if both wheels hit a bump.

What could be the cause? Worn subframe bushings, struts going bad, control arm bushings, bump stops etc? It's really an odd feeling.

raceyBMW · 10-15-2014, 10:24 AM

What did you have before, RFTs?

JStang · 10-15-2014, 10:27 AM

Quote:

Originally Posted by raceyBMW

What did you have before, RFTs?

Hankook V12's.

raceyBMW · 10-15-2014, 04:08 PM

Hmm, I know I picked up on that feeling when I switched over from RFTs to non-RFTs, but never had it happen between brands of tires.

I believe the general consensus is that the soft subframe bushings the non-M E9x's come with are the cause of this squirreliness/softness in the rear end on launch and over bumps mid-turn. The non-M E9x's were setup softer to compensate for the stiff sidewalls of the RFT's that come stock on the car.

JStang · 10-15-2014, 04:18 PM

Quote:

Originally Posted by raceyBMW

Hmm, I know I picked up on that feeling when I switched over from RFTs to non-RFTs, but never had it happen between brands of tires.

I believe the general consensus is that the soft subframe bushings the non-M E9x's come with are the cause of this squirreliness/softness in the rear end on launch and over bumps mid-turn. The non-M E9x's were setup softer to compensate for the stiff sidewalls of the RFT's that come stock on the car.

Yeah I have never experienced this feeling and I have owned the car for about 50k miles without RFT.

135Pats · 10-15-2014, 10:11 PM

IDK why the tires have made you notice it - but what you are noticing is the slop in the OE subframe bushings.

JStang · 10-16-2014, 07:15 AM

Quote:

Originally Posted by 135Pats

IDK why the tires have made you notice it - but what you are noticing is the slop in the OE subframe bushings.

I've always noticed how soft they were under load but I never noticed it on a small bump in the road. Maybe they are on the way out.

ashmostro · 10-16-2014, 07:26 AM

PSS's have a lot of grip, which will exacerbate any looseness already present in the suspension.

That said, I felt the subframe wigglyness on my car when it was bone stock, low miles, and with RFTs... it's that bad

135Pats · 10-16-2014, 07:58 AM

Quote:

Originally Posted by JStang

I've always noticed how soft they were under load but I never noticed it on a small bump in the road. Maybe they are on the way out.

Actually bumps are what first made me notice it. Esp. with the wheelbase of E8x, the back end wants to hop and skip over those bumps with the OE bushings. It was awful....

Sidewinderpb · 10-16-2014, 03:13 PM

JStang · 10-17-2014, 07:56 AM

Quote:

Originally Posted by Sidewinderpb

Exactly!

abhishriv · 10-20-2014, 10:23 PM

i had the same feeling, upgrade your rear suspension.i went with power flex race subframe bushings and also m3 rear control arms.... rear feels PLANTED now. i also got m3 rear sway but i have an LSD. don't do sway without the limited slip.

zero2sixtyZ · 10-21-2014, 07:51 AM

I've noticed this recently as well. I have PSS' all around, and for a while, was convinced it was my rear struts. Changed them out to TCKline/Koni adj. struts, and still the rear end wiggles around over bumps. I'm starting to look at the strut mounts (Dinan for upper, Meyle for lower), and shortly after the M3 guide rods, and upper links.

Hope to report back with better results before looking at the subframe bushings but at 80k, it's a definitely possibility for slop.

raceyBMW · 10-21-2014, 02:46 PM

If you are looking to get rid of the wiggles over bumps, I would start at the subframe bushings.

DrRobert · 10-21-2014, 09:00 PM

IME my 335 had two distinctly different types of rear bounce. See my post #41 in this thread for my detailed description:

http://www.e90post.com/forums/showthread.php?t=1024256

Based on the photo of the kitty (sideways rear end wiggle going over a bump while turning) I would agree you are most likely feeling the inherent weakness of the stock subframe bushings. That is an expensive repair though (if you are paying someone to do it for you), so I'd make sure you are talking about the same rear bounce as the other people who have replied. If it is more of an up and down rear bounce when going over bumps I'd have a look at your dampers.

cwarren · 10-21-2014, 09:51 PM

trailing arm ? i would look into it pretty sure if its bad it will wiggle just like the cat lol. when i put on pss i felt that it was a soft side wall feeling and had to inflate them pretty close to max to get rid of that feeling . i must say i did love the tires other than that though.

whosdady · 10-22-2014, 08:28 AM

I have this wobble/wiggle and I have the 235F/265R PS2 tires as well. My suspension has been replaced 100%. Ohlins, Power Flex, M3, OS Giken, Megan, etc... I have had 6 different alignments and my car pulls/steers to the right under hard acceleration. It drives completely straight under normal acceleration. The only thing I don't have is a lockdown kit or brace.

This is not the first time I have heard of issues with the PS2's. SteveAZ had similar issues prior to changing tires...

JStang · 10-22-2014, 08:35 AM

Quote:

Originally Posted by cwarren

trailing arm ? i would look into it pretty sure if its bad it will wiggle just like the cat lol. when i put on pss i felt that it was a soft side wall feeling and had to inflate them pretty close to max to get rid of that feeling . i must say i did love the tires other than that though.

This is exactly what I did lat night. Not max pressure but I added some air to see if I felt a difference. It definitely didn't happen like this prior to new tires.

abhishriv · 10-22-2014, 12:47 PM

Quote:

Originally Posted by JStang

This is exactly what I did lat night. Not max pressure but I added some air to see if I felt a difference. It definitely didn't happen like this prior to new tires.

upgrading one area reveals weaknesses in others.

upgrade the looks of your car ... realize now you need the "Go" to match the "Show"

upgrade power... realize you need better cooling

upgrade cooling... realize now you need more grip

upgrade tires... realize rear suspension cant cope

upgrade rear suspension.... realize front end is weak

upgrade front end... now brakes are not at par with rest of car

upgrade brakes... realize your bank account took a big hit by buying this car

ashmostro · 10-22-2014, 01:27 PM

ding ding ding.

The stickier tires are revealing what was always there, but now can be felt more "telepathically."

whosdady · 10-23-2014, 08:13 AM

I'm not sure where you live or what the weather is like now but I would recommend switching out wheels/tires with a friend (with similar size, offsets, non PS2) and see if that helps.

It could be that a lot of modified 335i guys have PS2's and they just happen to have issues. Or it could be there really is a problem with PS2's?

ashmostro · 10-23-2014, 12:49 PM

PSS's you mean, right? Very different from PS2's.

I run PSS's on the street. I have all the M3 bits on both front and rear. No wiggle at all.

10-15-2014, 07:18 AM	#1
JStang Brigadier General 562 Rep 3,625 Posts Drives: FDB M3 CS Join Date: Dec 2010 Location: St. Petersburg, FL iTrader: (9)	Rear End Wiggle on Bumps I recently had new Michelin PSS's put on and since have noticed that the back end seems to move a little side to side when one wheel hits a bump in the road. I haven't noticed this if both wheels hit a bump. What could be the cause? Worn subframe bushings, struts going bad, control arm bushings, bump stops etc? It's really an odd feeling.
	Appreciate 0 Tweet Quote

10-15-2014, 10:24 AM	#2
raceyBMW king of the hills 92 Rep 2,915 Posts Drives: 2011 M3 w/ESS55, 2001 540i/6 Join Date: Dec 2006 Location: Arvada, CO iTrader: (1) Garage List 2001 BMW 540i/6 [8.17] 1994 530i [9.00] 2007 335i Coupe [8.37]	What did you have before, RFTs?
	Appreciate 0 Quote

10-15-2014, 10:11 PM	#6
135Pats Major General 456 Rep 6,478 Posts Drives: A few BMWs Join Date: May 2012 Location: Maryland iTrader: (3)	IDK why the tires have made you notice it - but what you are noticing is the slop in the OE subframe bushings. __________________ E88 N54 Alpinweiss/Coral Red/Motiv HTA 3586r Tial .82AR/Other stuff...652WHP F30 N55 XDrive EBII
	Appreciate 0 Quote

10-16-2014, 07:26 AM	#8
ashmostro Brigadier General 1251 Rep 4,087 Posts Drives: 2020 M4cs \| 2022 M550i Join Date: Jan 2013 Location: Falls Church, VA iTrader: (27)	PSS's have a lot of grip, which will exacerbate any looseness already present in the suspension. That said, I felt the subframe wigglyness on my car when it was bone stock, low miles, and with RFTs... it's that bad
	Appreciate 0 Quote

10-16-2014, 03:13 PM	#10
Sidewinderpb Banned 329 Rep 1,739 Posts Drives: 2017 340i xDrive 6mt Join Date: Nov 2013 Location: CT iTrader: (7)
	Appreciate 3 StradaRedlands4919.50 PhaceN52173.50 Quote

10-15-2014, 04:08 PM	#4
raceyBMW king of the hills 92 Rep 2,915 Posts Drives: 2011 M3 w/ESS55, 2001 540i/6 Join Date: Dec 2006 Location: Arvada, CO iTrader: (1) Garage List 2001 BMW 540i/6 [8.17] 1994 530i [9.00] 2007 335i Coupe [8.37]	Hmm, I know I picked up on that feeling when I switched over from RFTs to non-RFTs, but never had it happen between brands of tires. I believe the general consensus is that the soft subframe bushings the non-M E9x's come with are the cause of this squirreliness/softness in the rear end on launch and over bumps mid-turn. The non-M E9x's were setup softer to compensate for the stiff sidewalls of the RFT's that come stock on the car.
	Appreciate 0 Quote

10-20-2014, 10:23 PM	#12
abhishriv Major 100 Rep 1,384 Posts Drives: 2007 335i Coupe (Space grey) Join Date: Oct 2011 Location: Toronto iTrader: (0)	i had the same feeling, upgrade your rear suspension.i went with power flex race subframe bushings and also m3 rear control arms.... rear feels PLANTED now. i also got m3 rear sway but i have an LSD. don't do sway without the limited slip.
	Appreciate 0 Quote

10-21-2014, 07:51 AM	#13
zero2sixtyZ Colonel 951 Rep 2,669 Posts Drives: e92 + f15 Join Date: Jan 2012 Location: Cambridge, MA iTrader: (4) Garage List 2007 335i Coupe [9.50] 2015 X5 xdrive50i [10.00]	I've noticed this recently as well. I have PSS' all around, and for a while, was convinced it was my rear struts. Changed them out to TCKline/Koni adj. struts, and still the rear end wiggles around over bumps. I'm starting to look at the strut mounts (Dinan for upper, Meyle for lower), and shortly after the M3 guide rods, and upper links. Hope to report back with better results before looking at the subframe bushings but at 80k, it's a definitely possibility for slop.
	Appreciate 0 Quote

10-21-2014, 02:46 PM	#14
raceyBMW king of the hills 92 Rep 2,915 Posts Drives: 2011 M3 w/ESS55, 2001 540i/6 Join Date: Dec 2006 Location: Arvada, CO iTrader: (1) Garage List 2001 BMW 540i/6 [8.17] 1994 530i [9.00] 2007 335i Coupe [8.37]	If you are looking to get rid of the wiggles over bumps, I would start at the subframe bushings.
	Appreciate 0 Quote

10-21-2014, 09:00 PM	#15
DrRobert Normal Person 147 Rep 862 Posts Drives: 2011 E90 335i Join Date: May 2014 Location: paradise iTrader: (0) Garage List 2011 E90 335i [0.00]	IME my 335 had two distinctly different types of rear bounce. See my post #41 in this thread for my detailed description: http://www.e90post.com/forums/showthread.php?t=1024256 Based on the photo of the kitty (sideways rear end wiggle going over a bump while turning) I would agree you are most likely feeling the inherent weakness of the stock subframe bushings. That is an expensive repair though (if you are paying someone to do it for you), so I'd make sure you are talking about the same rear bounce as the other people who have replied. If it is more of an up and down rear bounce when going over bumps I'd have a look at your dampers.
	Appreciate 0 Quote

10-21-2014, 09:51 PM	#16
cwarren Captain 82 Rep 725 Posts Drives: 08 e92 Join Date: Jan 2012 Location: portland iTrader: (1)	trailing arm ? i would look into it pretty sure if its bad it will wiggle just like the cat lol. when i put on pss i felt that it was a soft side wall feeling and had to inflate them pretty close to max to get rid of that feeling . i must say i did love the tires other than that though. __________________ ptf MHD E85 /Hexon rr550 turbo's/PRE custom intakes/CP / bms dp's/hfs4 / er fmic/PSS/spec stage 2+/kwv2/steveAZ stage 3 lpfp /m3 control arms/powerflex black/MF LSD /fuel it port injection
	Appreciate 0 Quote

10-22-2014, 08:28 AM	#17
whosdady Major 135 Rep 1,075 Posts Drives: 335i Coupe Join Date: Aug 2012 Location: STL iTrader: (10)	I have this wobble/wiggle and I have the 235F/265R PS2 tires as well. My suspension has been replaced 100%. Ohlins, Power Flex, M3, OS Giken, Megan, etc... I have had 6 different alignments and my car pulls/steers to the right under hard acceleration. It drives completely straight under normal acceleration. The only thing I don't have is a lockdown kit or brace. This is not the first time I have heard of issues with the PS2's. SteveAZ had similar issues prior to changing tires...
	Appreciate 0 Quote

10-22-2014, 01:27 PM	#20
ashmostro Brigadier General 1251 Rep 4,087 Posts Drives: 2020 M4cs \| 2022 M550i Join Date: Jan 2013 Location: Falls Church, VA iTrader: (27)	ding ding ding. The stickier tires are revealing what was always there, but now can be felt more "telepathically."
	Appreciate 0 Quote

10-23-2014, 08:13 AM	#21
whosdady Major 135 Rep 1,075 Posts Drives: 335i Coupe Join Date: Aug 2012 Location: STL iTrader: (10)	I'm not sure where you live or what the weather is like now but I would recommend switching out wheels/tires with a friend (with similar size, offsets, non PS2) and see if that helps. It could be that a lot of modified 335i guys have PS2's and they just happen to have issues. Or it could be there really is a problem with PS2's?
	Appreciate 0 Quote

10-23-2014, 12:49 PM	#22
ashmostro Brigadier General 1251 Rep 4,087 Posts Drives: 2020 M4cs \| 2022 M550i Join Date: Jan 2013 Location: Falls Church, VA iTrader: (27)	PSS's you mean, right? Very different from PS2's. I run PSS's on the street. I have all the M3 bits on both front and rear. No wiggle at all.
	Appreciate 0 Quote