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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > E9x rear end feels 'floaty'



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      08-15-2010, 02:56 PM   #1
badass335
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E9x rear end feels 'floaty' (Updated first post!)

I'm just not happy with the way the car handles. I have an 07 335i very modified engine wise. I had the suspension upgraded as well with Swift springs 400/800 and Ohlins Road&Track's. I replaced my wheels with brand new 19" Breyton GTP's on Michelin PS2 A/S and still same issues. The alignment shop (Dales Alignment) has a hoist with my name on it as i'm there so much! (just to be sure it wasn't an alignment issue)

The issue:
When accelerating hard or driving, the car 'feels' like its not planted. A little unsteady to be honest. Due to HPFP and possible bad water pump, i've had a few bmw loaners and they feel very solid driving around with the regular bmw sports suspension. It's gotten worse over the last year. Another thing to mention, when the car takes off from a stand still or while coasting and a WOT run, the car 'feels' like its doing a side to side dance.

Now, any ideas on what i should go with? I know a few of you guys have upgraded with M3 bits etc. I did things piece by piece so i knew what actually solved the problem. Do you guys think it's the bushings? Any other suggestions?

Thanks in advance


UPDATE:

So i figured it all out at least in my case. As most of you may have read through my posts, i was having an issue with stability on my car. Now i should clarify, most are feeling and having different issues but it all gets lumped in the same group. I actually was part of this said group. My rear end (car) wasn't stable. I put in new tires, coilovers, springs, rims and it still didn't solve my issues.

So after talking to a few people, i decided to go with some upgraded parts for the rear end of my car. I did this all in stages to really figure out what was happening and if it did in fact resolve my issues.

-Wavetrak LSD. I had this installed and it didn't solve my issues. It had a bit more grip but it still felt like crap and i definietly didn't 'feel' like how most felt with LSD's. The' wow, my traction light barely comes on' thing wasn't my story. Mine still looked like a christmas tree.

-M3 Subframe Bushings and rear M3 control arms. I had both of these installed at the same time. Now, with the installation of these pieces, the car did feel better in corners. Before when going into corners and WHILE in the corners, the car would shift weight from all 4 corners of the car. Once the bushings got changed, i didn't feel that sensation anymore. This is what most people feel usually.

-Velocity Rear Toe arms. Now this is what my major issue was! I had my alignment done almost once a month it seems and i tried what Harold had suggested increasing total toe in the rear from 1/16 to 3/16 and still had issues. I finally had this installed and got an alignment done and FINALLY, no more side to side issues when accelerating hard etc. The rear feels more buttoned down.

So in a nut shell, it's something i'd highly recommend. Under hard acceleration, my rear toe settings were changing (deflecting) causing my instability issues.

Last edited by badass335; 09-26-2010 at 03:40 PM.
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      08-15-2010, 03:00 PM   #2
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If your car goes side to side from a hard take off I would suggest getting an LSD.
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      08-15-2010, 03:27 PM   #3
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If your car goes side to side from a hard take off I would suggest getting an LSD.
I have the wavetrac LSD installed.
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      08-15-2010, 03:32 PM   #4
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you already have the M3 bushings for the rear subframe? The original are soft and wear fast especially when driving it hard.
I did the swap in mine and can feel the back is much more solid. Do a search on the rear subframe bushings.
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      08-15-2010, 03:35 PM   #5
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You have Ohlins Coiloversl and an LSD. What is your alignment spec because I never really liked factory spec alignments and just made my DD with an aggressive street setup that I can run on the track. Those symptoms sound similar to E36s and E46s was resulted by the Rear Trail Arm Bushing being shot and they usually go out on E36 and E46s around 40k. So I guess it can be from your subframe bushings as well.
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      08-15-2010, 03:36 PM   #6
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Quote:
Originally Posted by marcel b View Post
you already have the M3 bushings for the rear subframe? The original are soft and wear fast especially when driving it hard.
I did the swap in mine and can feel the back is much more solid. Do a search on the rear subframe bushings.
Hey Marcel,

Not yet. Thats my next purchase. I just wanted to see how people felt about this before i start spending more money.
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      08-15-2010, 03:47 PM   #7
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Quote:
Originally Posted by sales@bavarianx View Post
You have Ohlins Coiloversl and an LSD. What is your alignment spec because I never really liked factory spec alignments and just made my DD with an aggressive street setup that I can run on the track. Those symptoms sound similar to E36s and E46s was resulted by the Rear Trail Arm Bushing being shot and they usually go out on E36 and E46s around 40k. So I guess it can be from your subframe bushings as well.
Alignment specs:
Front:
Caster: L= 6.54 | R=7.02
Camber: L= -0.64 | R=-0.64
Toe: L= 1/16 | R= 1/16 | Total= 1/8

Rear:
Camber: L= -1.16 | R=-1.17
Toe: L= 1/16 | R= 1/16 | Total= 1/8
Thrust Angle: -0.01
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      08-15-2010, 03:50 PM   #8
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Well your alignment seems to be in order for the street. So I think its the bushings in your rear control arms. People do the upgrade to M3 front and rear control arms as the bushings are more heavy duty and there isn't a replacement bushing for your control arms.
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      08-15-2010, 04:25 PM   #9
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M3 rear subframe bushings for sure. They will eliminate rear end bounce, add a lot of stability, and add a lot of road feel. It is a big change.
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      08-15-2010, 05:13 PM   #10
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yes, thats what i felt immediately after having the rear subframe bushings swapped. It makes a huge difference especially in the rear floatiness that youre talking about.
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      08-15-2010, 09:36 PM   #11
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Thanks for confirming! M3 bushings will be ordered tomorrow!!
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      08-16-2010, 01:54 AM   #12
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Thanks for confirming! M3 bushings will be ordered tomorrow!!
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      08-16-2010, 03:09 AM   #13
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As everyone has said already, you must replace the rear subframe bushings. On a modified car, with an LSD, you have much more torque going through the rear suspension and that accelerates wear of the bushes. The M3 bushes are a big improvement, though only noticeable to people who actually have a good feel and understanding of what their car is doing


One question for you - how do you like the Ohlins R/T suspension? Did you go from stock to the Ohlins, or did you have something in between? I'm having a custom-valved Ohlins suspension installed on my car tomorrow morning - in the afternoon we're joining the Industry Pool day at the Nurburgring to set everything up
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      08-17-2010, 10:19 AM   #14
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I have this same annoyance (at leasat I think its the same thing). When I come to an abrupt stop and lift the brake pedal slightly the rear end wallows and wobbles. I cant stand it.

I thought it had something to do with the brakes but maybe it is bushings.
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      08-17-2010, 11:50 AM   #15
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I did a full cycle. Stock sports suspension -> hr springs -> kw v2 -> ohlins

the sports were nice when the car was stock. Hr springs only, car was too low and harsh. The v2's were nice for the first year and half and then serious downhill. Very stiff ride even on soft settings and the car felt worse than a Kia in corners. Ohlins, very complient. Comfortable even when it's set to a stiffer setting. I'm running high spring rates as well and the ride quality is great.

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As everyone has said already, you must replace the rear subframe bushings. On a modified car, with an LSD, you have much more torque going through the rear suspension and that accelerates wear of the bushes. The M3 bushes are a big improvement, though only noticeable to people who actually have a good feel and understanding of what their car is doing


One question for you - how do you like the Ohlins R/T suspension? Did you go from stock to the Ohlins, or did you have something in between? I'm having a custom-valved Ohlins suspension installed on my car tomorrow morning - in the afternoon we're joining the Industry Pool day at the Nurburgring to set everything up
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      08-17-2010, 12:37 PM   #16
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Wait.

You're saying, on your car, with stock rear subframe bushings, the car feels floaty and darty on acceleration, but on LOANERS with the same stock rear subframe bushings, the car feels solid and planted?

And people are suggesting a set of M3 rear subframe bushings is the solution?

I don't get it.

I suspect it has more to do with the OTHER parts of the suspension, like the spring rate or shock adjustment...Maybe compression is set too high in the rear not allowing weight to transfer to the back quickly/properly?
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      08-17-2010, 12:49 PM   #17
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I'll try to clarify. My car has 70000ks. The first 2 years, felt rock solid. Over the last year it's progressively gotten worse. The loaners like the one I'm driving today have less than 2000k so practically new.

With this in mind, something has to be worn out for this to get worse..

Make more sense?

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Wait.

You're saying, on your car, with stock rear subframe bushings, the car feels floaty and darty on acceleration, but on LOANERS with the same stock rear subframe bushings, the car feels solid and planted?

And people are suggesting a set of M3 rear subframe bushings is the solution?

I don't get it.

I suspect it has more to do with the OTHER parts of the suspension, like the spring rate or shock adjustment...Maybe compression is set too high in the rear not allowing weight to transfer to the back quickly/properly?
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      08-17-2010, 12:57 PM   #18
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I don't get it.
He has 800 lb rear springs. HPA Shop recommends M3 rear subframe bushings if you exceed 600 lbs. TC Kline says you need M3 rear subframe bushings with any suspension upgrade. Of course the loaner cars do not have upgraded springs.

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Per Kline's own words: "One of the first things you need to do with the 135i if you upgrade the suspension is put the M3 subframe bushings in it. The bushings are way too soft in the 1- and 3- series cars. If you do any kind of suspension upgrade and keep the stock bushings, the back end will bounce... Even if you put the stock M3 rear springs in a 135 or 335, the car would be really bouncy over bumps, because the subframe bushings are going to deflect 1-1 1/2 inches... For the M3, BMW used better bushings instead of the mushy stuff used in the other cars... Replacing the bushings is key."
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      08-17-2010, 05:05 PM   #19
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Quote:
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He has 800 lb rear springs. HPA Shop recommends M3 rear subframe bushings if you exceed 600 lbs. TC Kline says you need M3 rear subframe bushings with any suspension upgrade. Of course the loaner cars do not have upgraded springs.
This was happening on my kw v2 before and that spring rate was lower, but you are right now as I have increased the rates so time to upgrade the other components.
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      08-17-2010, 05:24 PM   #20
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yes, also another member on the forum who was on stock subframe bushings, which while switching to the m3 ones, discovered that the OEM ones were shot. I suspect yours may be in similar condition
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      08-17-2010, 08:36 PM   #21
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Hey buddy...let me know how the install goes, it sounds like PITA ...are you gonna rent the bushing tool from HPA and let Dale's do the install?
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      08-18-2010, 11:17 PM   #22
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Hey buddy...let me know how the install goes, it sounds like PITA ...are you gonna rent the bushing tool from HPA and let Dale's do the install?
Hey bud,

probably get Nixon automotive to do it. I know it sucks but hey, it's a BMW!
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