BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > E90/E92 M3 Technical Topics > Suspension | Brakes | Chassis
 
Lux Angel Eyes
Post Reply
 
Thread Tools Search this Thread
      03-13-2011, 11:04 AM   #1
wwjd15
Banned
 
Drives: 11 E92 M3 MR
Join Date: May 2009
Location: Orange County

Posts: 1,322
iTrader: (6)

How to fix bouncy issue at track?

I tracked at Buttonwillow yesterday, found that the rear was some sort of bouncy, typically at some corners like Bus Stop. How can I fix this issue? I played with Rebound and compression a bit, but didn't help. I have KW V3 BTW

Thanks in advance.
wwjd15 is offline   United_States
0
Reply With Quote
      03-13-2011, 11:45 AM   #2
elh0102
Captain
 
Drives: E92 M3
Join Date: Apr 2010
Location: USA

Posts: 704
iTrader: (0)

I'm no expert, but I think that is typically indicative of needing more rebound damping.
__________________
2011 Space Gray Coupe, DCT, ZCP, StopTech ST-60/ST-40 BBK.
elh0102 is offline  
0
Reply With Quote
      03-13-2011, 12:00 PM   #3
STALKER
Brigadier General
 
Drives: 2008 E90 M3
Join Date: Feb 2009
Location: Toronto, ON

Posts: 3,632
iTrader: (5)

What are your settings?
Did you try softening the rebound?
__________________

2008 AW/FR E90 M3-SOLD
2013 991 C4S
STALKER is offline  
0
Reply With Quote
      03-13-2011, 12:44 PM   #4
JAJ
Captain
 
Drives: 2014 Shelby GT500
Join Date: Apr 2008
Location: Vancouver, BC

Posts: 924
iTrader: (4)

Quote:
Originally Posted by wwjd15 View Post
I tracked at Buttonwillow yesterday, found that the rear was some sort of bouncy, typically at some corners like Bus Stop. How can I fix this issue? I played with Rebound and compression a bit, but didn't help. I have KW V3 BTW

Thanks in advance.
This will be tricky to diagnose, but lets give it a try:

- what does "bouncy" mean?
a. the rear of the car wallows around while you're in the corner
b. the rear of the car bounces off bumps in the road
c. the rear of the car kind of skitters sideways

a. is caused by too little rebound
b. is caused by too much compression
c. is caused by too much rebound

When it's properly adjusted, the chassis will move around on the springs more than you might be used to, but it will produce maximum grip.
JAJ is offline  
0
Reply With Quote
      03-13-2011, 09:02 PM   #5
Radiation Joe
Veni Vidi Vici
 
Radiation Joe's Avatar
 
Drives: '11 JB/BBe-6sp-e90
Join Date: Jul 2008
Location: Macungie PA

Posts: 2,749
iTrader: (0)

Garage List
2011 e90 M3-Sold  [4.25]
2003 RS6 - Sold  [0.00]
2009 e90 M3 - Gone  [0.00]
2003 M3 SOLD  [0.00]
old 2002  [5.00]
Here's a suggestion.

Keep your car stock until you understand why you should mod it. If you buy a double adjustable coil-over kit and don't know how to adjust it ... or explain what it's doing ... you probably had no business modding it in the first place.
__________________

Dinan compliment of stuff plus PF rotors and RG63s. Enough for now.
Why, yes. I am an abrasive bastard.
Radiation Joe is offline   United_States
0
Reply With Quote
      03-13-2011, 09:05 PM   #6
Radiation Joe
Veni Vidi Vici
 
Radiation Joe's Avatar
 
Drives: '11 JB/BBe-6sp-e90
Join Date: Jul 2008
Location: Macungie PA

Posts: 2,749
iTrader: (0)

Garage List
2011 e90 M3-Sold  [4.25]
2003 RS6 - Sold  [0.00]
2009 e90 M3 - Gone  [0.00]
2003 M3 SOLD  [0.00]
old 2002  [5.00]
Quote:
Originally Posted by JAJ View Post
This will be tricky to diagnose, but lets give it a try:

- what does "bouncy" mean?
a. the rear of the car wallows around while you're in the corner
b. the rear of the car bounces off bumps in the road
c. the rear of the car kind of skitters sideways

a. is caused by too little rebound
b. is caused by too much compression
c. is caused by too much rebound

When it's properly adjusted, the chassis will move around on the springs more than you might be used to, but it will produce maximum grip.
Good advice. I used to decrease rebound at the track in my e46, but liked the feel of more rebound damping on the street.
__________________

Dinan compliment of stuff plus PF rotors and RG63s. Enough for now.
Why, yes. I am an abrasive bastard.
Radiation Joe is offline   United_States
0
Reply With Quote
      03-13-2011, 09:09 PM   #7
UA
///M User
 
Drives: 2011.5 M3
Join Date: Jan 2011
Location: Boston, MA

Posts: 203
iTrader: (0)

Quote:
Originally Posted by Radiation Joe View Post
Here's a suggestion.

Keep your car stock until you understand why you should mod it. If you buy a double adjustable coil-over kit and don't know how to adjust it ... or explain what it's doing ... you probably had no business modding it in the first place.
why not offer some advice since you sound like you know this subject so well instead of bashing the guy?... At least he is tracking his modded car and getting some use out of that suspension instead of the 90% of people who buy fully adjustable coil-overs for daily driven street use.

I don't mean to sound like an ss but you came off like one with your post so it's only fair.
UA is offline   United_States
0
Reply With Quote
      03-13-2011, 09:14 PM   #8
rzm3
Moderator
 
rzm3's Avatar
 
Drives: E92 M3
Join Date: Aug 2007
Location: USA

Posts: 4,600
iTrader: (14)

Typically, the initial loss of adhesion (the bounciness) is due to having too much rebound damping. As the car starts to roll in a corner, the inner wheel droops to the ground. If you have too much rebound damping, this slows down the process, and hence you loose traction at the inner wheel.

Also, if this happens at a corner after hard braking, you may want to increase the front compression damping to reduce the amount of diving.

So at what part of the corner do you experience this? Initial turn-in, mid-corner, or exit?
__________________
E92 M3 DCT - AiM EVO4 Data Logger / AiM SmartyCam HD / KW Competition 2-Way / OMP ARS Racing Seats / Brembo GT 365 / Pagid Yellow RS-29 / Rear Seats Delete
rzm3 is offline  
0
Reply With Quote
      03-14-2011, 08:42 AM   #9
Radiation Joe
Veni Vidi Vici
 
Radiation Joe's Avatar
 
Drives: '11 JB/BBe-6sp-e90
Join Date: Jul 2008
Location: Macungie PA

Posts: 2,749
iTrader: (0)

Garage List
2011 e90 M3-Sold  [4.25]
2003 RS6 - Sold  [0.00]
2009 e90 M3 - Gone  [0.00]
2003 M3 SOLD  [0.00]
old 2002  [5.00]
Quote:
Originally Posted by UA View Post
why not offer some advice since you sound like you know this subject so well instead of bashing the guy?... At least he is tracking his modded car and getting some use out of that suspension instead of the 90% of people who buy fully adjustable coil-overs for daily driven street use.

I don't mean to sound like an ss but you came off like one with your post so it's only fair.
I know. I'm just a crotchety old man. I also sit on park benches and yell at little kids.

I have this annoyance with all the vendors out there selling people things they don't need. I'm also annoyed with the people out there gullible enough be believe they need this stuff or that it makes their car "better". How much do you want to bet that pretty much any driver would be faster in the OPs car around Buttonwillow with the stock suspension compared to it's current configuration?
__________________

Dinan compliment of stuff plus PF rotors and RG63s. Enough for now.
Why, yes. I am an abrasive bastard.
Radiation Joe is offline   United_States
0
Reply With Quote
      03-14-2011, 09:03 AM   #10
Gearhead999s
Major General
 
Gearhead999s's Avatar
 
Drives: E93 335is(wifes)E92 M3
Join Date: Apr 2007
Location: Toronto

Posts: 6,685
iTrader: (0)

Quote:
Originally Posted by Radiation Joe View Post
I know. I'm just a crotchety old man. I also sit on park benches and yell at little kids.

I have this annoyance with all the vendors out there selling people things they don't need. I'm also annoyed with the people out there gullible enough be believe they need this stuff or that it makes their car "better". How much do you want to bet that pretty much any driver would be faster in the OPs car around Buttonwillow with the stock suspension compared to it's current configuration?
I just saw this and I find this pretty humourous as I have seen many guys with modded cars that are so disapointed that they are no quicker after spending tons of money on suspension stuff and they are no faster than a stock suspended car.Without having the ability to set these suspensions you might as well have old worn out stuff holding your car up off the ground or stick to the stock stuff and spend the time learning how to drive properly.
Gearhead999s is offline  
0
Reply With Quote
      03-14-2011, 10:12 AM   #11
wwjd15
Banned
 
Drives: 11 E92 M3 MR
Join Date: May 2009
Location: Orange County

Posts: 1,322
iTrader: (6)

Quote:
Originally Posted by elh0102 View Post
I'm no expert, but I think that is typically indicative of needing more rebound damping.

Quote:
Originally Posted by STALKER View Post
What are your settings?
Did you try softening the rebound?
Quote:
Originally Posted by JAJ View Post
This will be tricky to diagnose, but lets give it a try:

- what does "bouncy" mean?
a. the rear of the car wallows around while you're in the corner
b. the rear of the car bounces off bumps in the road
c. the rear of the car kind of skitters sideways

a. is caused by too little rebound
b. is caused by too much compression
c. is caused by too much rebound

When it's properly adjusted, the chassis will move around on the springs more than you might be used to, but it will produce maximum grip.

Quote:
Originally Posted by rldzhao View Post
Typically, the initial loss of adhesion (the bounciness) is due to having too much rebound damping. As the car starts to roll in a corner, the inner wheel droops to the ground. If you have too much rebound damping, this slows down the process, and hence you loose traction at the inner wheel.

Also, if this happens at a corner after hard braking, you may want to increase the front compression damping to reduce the amount of diving.

So at what part of the corner do you experience this? Initial turn-in, mid-corner, or exit?
Thanks a lot guys.
I played with the suspension a bit on sunday, ended up increasing the rear's rebound by 4 and compression by 2.(I don't remember where they are at, I adjust them only think they are needed) That gave me the best feel at the track. I had better feeling through the corners, more crispy feel.
However, the "bouncy" didn't go away. it happens only at high speed cornering which requires acceleration or going downhills. It's mid-corner to exit. It didn't slow the car like tires aren't stick to the ground. it just bouncy during turns makes me have less confidence to keep pushing it.
wwjd15 is offline   United_States
0
Reply With Quote
      03-14-2011, 10:17 AM   #12
wwjd15
Banned
 
Drives: 11 E92 M3 MR
Join Date: May 2009
Location: Orange County

Posts: 1,322
iTrader: (6)

Quote:
Originally Posted by Radiation Joe View Post
I know. I'm just a crotchety old man. I also sit on park benches and yell at little kids.

I have this annoyance with all the vendors out there selling people things they don't need. I'm also annoyed with the people out there gullible enough be believe they need this stuff or that it makes their car "better". How much do you want to bet that pretty much any driver would be faster in the OPs car around Buttonwillow with the stock suspension compared to it's current configuration?
Why didn't you provide some solid advice before BS'ing me? Are you coming to this thread to troll?
wwjd15 is offline   United_States
0
Reply With Quote
      03-14-2011, 11:58 AM   #13
Richbot
Lieutenant Colonel
 
Drives: Jerez Black E90
Join Date: Sep 2007
Location: STL

Posts: 1,970
iTrader: (2)

Quote:
Originally Posted by Gearhead999s View Post
I just saw this and I find this pretty humourous as I have seen many guys with modded cars that are so disapointed that they are no quicker after spending tons of money on suspension stuff and they are no faster than a stock suspended car.Without having the ability to set these suspensions you might as well have old worn out stuff holding your car up off the ground or stick to the stock stuff and spend the time learning how to drive properly.
+1
__________________
Richbot is offline  
0
Reply With Quote
      03-14-2011, 11:59 AM   #14
Richbot
Lieutenant Colonel
 
Drives: Jerez Black E90
Join Date: Sep 2007
Location: STL

Posts: 1,970
iTrader: (2)

If it's happening mid-corner to exit on accel, you could be too low in the rear, I would try increasing front rebound a little and raising the rear ride height. Put something on your rear bump stops to check if you're riding on them, I suspect you are hitting them intermittently on accel. Take a grease pencil and mark surface of the bump stops and see if anything transfers from the bump stop to the other side.

Quote:
Originally Posted by wwjd15 View Post
Why didn't you provide some solid advice before BS'ing me? Are you coming to this thread to troll?
Don't call people trolls when you haven't even asked the right questions. Your lap time in your signature is more than 2 seconds slower than a 140hp Spec Miata with an average driver gets around that track. Not something I'd be bragging about with 420+bhp. An M3 with a few upgrades should be in the mid-40's, so you obviously have lots to learn. You can call me a troll all you want, but the other guys in this thread are making pretty valid points, I think, so maybe you should try learning from them instead of getting defensive?
__________________

Last edited by Richbot; 03-14-2011 at 12:10 PM.
Richbot is offline  
0
Reply With Quote
      03-14-2011, 12:04 PM   #15
wwjd15
Banned
 
Drives: 11 E92 M3 MR
Join Date: May 2009
Location: Orange County

Posts: 1,322
iTrader: (6)

Quote:
Originally Posted by Richbot View Post
If it's happening mid-corner to exit on accel, you could be too low in the rear, I would try increasing front rebound a little and raising the rear ride height.

Don't call people trolls when you haven't even asked the right questions. "Why is my car bouncy" is a pretty newb thing to ask.
Thanks for the help. I know what it is. But I don't know how to explain in english.
wwjd15 is offline   United_States
0
Reply With Quote
      03-14-2011, 12:16 PM   #16
wwjd15
Banned
 
Drives: 11 E92 M3 MR
Join Date: May 2009
Location: Orange County

Posts: 1,322
iTrader: (6)

Quote:
Originally Posted by Richbot View Post
Don't call people trolls when you haven't even asked the right questions. Your lap time in your signature is more than 2 seconds slower than a 140hp Spec Miata gets around that track. Not something I'd be bragging about with 420+bhp. An M3 with a few upgrades should be in the mid-40's, so you obviously have lots to learn. You can call me a troll all you want, but the other guys in this thread are making pretty valid points, I think, so maybe you should try learning from them instead of getting defensive?
Not trying to defend myself, a professional driver drove Z06 on R-compund did high-40's at Infineon at the same day. So, I just don't see the mid-40's thing coming in an M3. I just got my M3 for two weeks and I know I have a lot to learn. Why not just get back to the topic? If I were born to know how to drive, I would not even post this thread here.
wwjd15 is offline   United_States
0
Reply With Quote
      03-15-2011, 01:24 PM   #17
Mavrick151
My M treats me right
 
Drives: E92 M3
Join Date: Mar 2009
Location: CA

Posts: 297
iTrader: (1)

Quote:
Originally Posted by Radiation Joe View Post
Here's a suggestion.

Keep your car stock until you understand why you should mod it. If you buy a double adjustable coil-over kit and don't know how to adjust it ... or explain what it's doing ... you probably had no business modding it in the first place.
+1
Mavrick151 is offline   United_States
0
Reply With Quote
      03-15-2011, 09:24 PM   #18
wwjd15
Banned
 
Drives: 11 E92 M3 MR
Join Date: May 2009
Location: Orange County

Posts: 1,322
iTrader: (6)

Quote:
Originally Posted by Richbot View Post
A pull to the left on accel could be a toe problem or you may have the car "crabbing" down the track, might want to get it on an alignment rack or do a string alignment to see if you've got a thrust angle issue.

My last post on the thread which definitely is in danger of derailing if I don't shut up:

Mastek - You sound like you spend some time at the track, but you're off on a couple facts.

Spec Miatas do not weigh under 2000lbs. They weigh, at minimum, 2285 with driver. I've been on track in a Spec Miata with T2 E46 M3's and know what they're capable of (4+ seconds a lap faster even at very tight, technical tracks). A modified E92 should be much quicker than a T2 M3. The T2 lap record there is 1:52.5 and that was back in 2006 with a car that is no longer competitive. Maybe nobody has tried yet, but a 1:47 doesn't seem out of the question to me knowing what other cars can run at that track (T1 equivalent). E92 M3 3800lbs? Maybe completely stock with driver and a full tank. My heavier E90 weighed 3666 without driver with a full tank of fuel, completely stock. A modified car should be well below that. A member here is at 3500lbs with driver after a few mods and a rear seat delete. I'm not saying that power is everything, but ask any racer how to go faster around a racetrack and horsepower (power/weight, really) is the first place to look. It doesn't need tuning, it usually doesn't add weight, it doesn't cause you to go slower in one corner than another, you just shorten the time spent between corners. Horsepower isn't everything, but it's a huge, huge part of any car's lap time.
I had my car aligned 2 days before the track day, but you are right, I think the toe is off.

I just did some search about Infineon. I think you are talking about different layout. The layout I ran was called "Full course with Carousel CW". Here's a list of laptime who ran at the same day with me: http://www.speedventures.com/results/Default.aspx
wwjd15 is offline   United_States
0
Reply With Quote
      03-15-2011, 10:35 PM   #19
calintexas
Major
 
calintexas's Avatar
 
Drives: 2010 E90 M3
Join Date: Nov 2009
Location: North Texas

Posts: 1,416
iTrader: (1)

Quote:
Originally Posted by wwjd15 View Post
I had my car aligned 2 days before the track day, but you are right, I think the toe is off.

I just did some search about Infineon. I think you are talking about different layout. The layout I ran was called "Full course with Carousel CW". Here's a list of laptime who ran at the same day with me: http://www.speedventures.com/results/Default.aspx
Infineon is actually Sears Point, right? The layout you are referring to is essentially the original track?
__________________
calintexas is offline   United_States
0
Reply With Quote
      03-15-2011, 10:56 PM   #20
wwjd15
Banned
 
Drives: 11 E92 M3 MR
Join Date: May 2009
Location: Orange County

Posts: 1,322
iTrader: (6)

Quote:
Originally Posted by calintexas View Post
Infineon is actually Sears Point, right? The layout you are referring to is essentially the original track?
I don't know. It was my first time there.
wwjd15 is offline   United_States
0
Reply With Quote
      03-16-2011, 08:46 AM   #21
Richbot
Lieutenant Colonel
 
Drives: Jerez Black E90
Join Date: Sep 2007
Location: STL

Posts: 1,970
iTrader: (2)

First of many, hopefully! I need to get out there on that track again
__________________
Richbot is offline  
0
Reply With Quote
      03-16-2011, 01:09 PM   #22
calintexas
Major
 
calintexas's Avatar
 
Drives: 2010 E90 M3
Join Date: Nov 2009
Location: North Texas

Posts: 1,416
iTrader: (1)

Quote:
Originally Posted by wwjd15 View Post
I don't know. It was my first time there.
Ok, North end of San Francisco Bay between Novato and Vallejo?

You were on the dark layout?
__________________
calintexas is offline   United_States
0
Reply With Quote
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 03:53 PM.




m3post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST