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


Go Back   ZPOST > BMW Z4 Technical Talk > Suspension and Braking Chat
  TireRack

SUPPORT ZPOST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS!
Post Reply
 
Thread Tools Search this Thread
      10-30-2014, 07:27 AM   #1
iTuneCars
New Member
1
Rep
14
Posts

Drives: Turbo Lexus
Join Date: Oct 2014
Location: 'Murica

iTrader: (0)

Question Z4M Widest Track Width after mods?

Hi Zpost Community ,

T he BMW Z4mc seems "twitchy" to me in stock form and I was thinking making the track width (front & rear) wider, might improve the car's handling. I also understand too wide is bad, hence my question to you Z4M coupe gurus:

What are the best wheel and suspension upgrades (including hub extenders & spacers) you guys found to widen this car's track width? (i.e. optimal wheel size and offsets, etc) Also, how much wider is optimal?
Appreciate 0
      10-30-2014, 10:27 AM   #2
inTgr8r
Lieutenant General
inTgr8r's Avatar
Canada
2422
Rep
11,665
Posts

Drives: M2 Comp
Join Date: Mar 2006
Location: Toronto

iTrader: (10)

going wider is not going to help much IMO.
I'm out to the fender lines but dont see much need to go wider.

With detail setup of the chassis (corner balancing, alignment, springs, shock rebound & compression) huge improvements are possible.

The 'twitch' is one of the things that makes this car such balls out fun to drive.
__________________
'21 M2C Hockenheim Silver
'18 718 Cayman S Lava Orange (sold)
'13 E92 M3 Santorini Blue (sold)
'07 Z4 M Coupe Alpine White (sold)
Appreciate 0
      10-30-2014, 10:51 AM   #3
iTuneCars
New Member
1
Rep
14
Posts

Drives: Turbo Lexus
Join Date: Oct 2014
Location: 'Murica

iTrader: (0)

Hi inTgr8r,

I prefer smooth and controllable ride that is least likely to have the rear-end slide out in an uncontrollable manner, cause backlash when steering tries to correct, and crash. I just saw a youtube video of a Red Z4 M Coupe doing exactly that on a race track...very sad sight to see. So, the car's side-to-side "twitch" is more scary than fun for me.

Regarding fenders, I don't mind modifying them via rolling, shaving, or adding (+welding) methods to fit a wider stance IF it will make the car more stable and less twitchy to drive.

If I find a concave wheel with a super low-offset, that should push the wheel out further and perhaps help me avoid wheel spacers right?

inTgr8r, because you seem knowledgeable in this area, what would you do besides your previously mentioned upgrades to eliminate that side-to-side twitch from the car's narrow track width?
Appreciate 0
      10-30-2014, 11:56 AM   #4
F360C
Major
United_States
366
Rep
1,373
Posts

Drives: E86 S54
Join Date: Apr 2006
Location: Hoboken, NJ

iTrader: (2)

Before thinking of mods... have you confirmed everything is okay with your car? Alignment check, bushings etc? All of those could have the affect of making the car twitchy.
__________________

07 Z4 M Coupe AW/IR
Appreciate 0
      10-30-2014, 01:31 PM   #5
Finnegan
Dog Listener
Finnegan's Avatar
United_States
701
Rep
7,850
Posts

Drives: Z4M/. Z3M, E36/46 M3
Join Date: Oct 2008
Location: Teaching the dog to slalom

iTrader: (22)

Quote:
Originally Posted by F360C
Before thinking of mods... have you confirmed everything is okay with your car? Alignment check, bushings etc? All of those could have the affect of making the car twitchy.
^ This.

Unless you know the current alignment settings and state of bushings I'd stop and start with basics.

Going towards a greater amount of toe-in rear in the stock range has a big impact on handling. Difference between rolling on throttle at apex and a tail happy car in my experience.

Also, worn RTabs mean toe is changing dynamically, which leads to a twitchy feel and no confidence. RTAB limiters help stock bushings from moving too much, helping avoid dynamic changes in toe.

Recommend checking RTabs, possibly installing RTAB limiters, and going with higher side of stock toe-in recommendations.

More can be found here on set-up. http://www.zpost.com/forums/showthread.php?t=968488
Appreciate 0
      10-30-2014, 02:01 PM   #6
inTgr8r
Lieutenant General
inTgr8r's Avatar
Canada
2422
Rep
11,665
Posts

Drives: M2 Comp
Join Date: Mar 2006
Location: Toronto

iTrader: (10)

Quote:
Originally Posted by iTuneCars View Post
Hi inTgr8r,

I prefer smooth and controllable ride that is least likely to have the rear-end slide out in an uncontrollable manner, cause backlash when steering tries to correct, and crash. I just saw a youtube video of a Red Z4 M Coupe doing exactly that on a race track...very sad sight to see. So, the car's side-to-side "twitch" is more scary than fun for me.

Regarding fenders, I don't mind modifying them via rolling, shaving, or adding (+welding) methods to fit a wider stance IF it will make the car more stable and less twitchy to drive.

If I find a concave wheel with a super low-offset, that should push the wheel out further and perhaps help me avoid wheel spacers right?

inTgr8r, because you seem knowledgeable in this area, what would you do besides your previously mentioned upgrades to eliminate that side-to-side twitch from the car's narrow track width?
I think my definition of twitch & yours might be a little different
Control is definitely desirable & I find it achievable without getting into fender widening etc.

very good points above. ^
I'm running poly bushings on my FCABs and RTABs.
They made a huge difference on how the car communicates and definitely improves the dynamic toe situation in the rear.
__________________
'21 M2C Hockenheim Silver
'18 718 Cayman S Lava Orange (sold)
'13 E92 M3 Santorini Blue (sold)
'07 Z4 M Coupe Alpine White (sold)
Appreciate 0
      10-31-2014, 10:05 AM   #7
dc_wright
Captain
dc_wright's Avatar
249
Rep
758
Posts

Drives: 2006 Z43.0si Roadster
Join Date: Oct 2014
Location: Orlando, FL

iTrader: (0)

Quote:
Originally Posted by F360C View Post
Before thinking of mods... have you confirmed everything is okay with your car? Alignment check, bushings etc? All of those could have the affect of making the car twitchy.
This x 2. Definitely need to get the alignment checked. Just a slight bit of toe out in the front will make a Z4 a handful to drive. It'll tramline like crazy and want to dart in the direction of every slight groove or surface change in the pavement. A bad toe setting in the front coupled with a bad toe setting in the rear could make the car feel very unstable....
Appreciate 0
      11-01-2014, 12:16 AM   #8
seank
enthusiast
seank's Avatar
48
Rep
1,695
Posts

Drives: e30 m3,e90 wagon,sprinter,z4m
Join Date: Dec 2011
Location: sacramento, ca

iTrader: (4)

It wont help the ride. The stable and commonly compared car, the cayman, has a shorter wheel base and With the same front track and only a total rear discrepancy of 1/2 inch. I believe the issue is the stock suspension and weight distribution. Sitting farther back also makes you feel like you are rotating more than you are.

The biggest problem with our cars is that they have not been seriously raced much, so there is little info to help you set up the car to be crazy fast.
Appreciate 0
      11-11-2014, 10:09 PM   #9
Jumbosock
Captain
Jumbosock's Avatar
76
Rep
987
Posts

Drives: 2007 M coupe
Join Date: Apr 2011
Location: San Diego

iTrader: (0)

I initially added wider rims and tires and a 10mm spacer up front but it still felt twitchy.

It only lost its twitch when I switched to KWV3 coilovers. The car transformed into a predictable fun machine.
__________________

CSL headers*Euro cats*Arqray exhaust*DKF hangers*Evolve Tune*Genuine CSL rims*10mm Macht Schnell front spacers*modified Hamann bumper*Tekarbon 2X2 CF spoiler*Turner CF grills*AS SSK*KWV3*OEM Strut bar*Rogue RSM*Polyurethane anti-roll bar bushings*Deka ETX30L battery*Nav Video module*front & rear cameras*Ipod module*stubby antenna*R-Dash LED license lights*LED Ziza interior lights
Appreciate 0
Post Reply

Bookmarks

Tags
track width, z4 m coupe, z4 track width, z4m, z4mc

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



All times are GMT -5. The time now is 06:34 PM.




zpost
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
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