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10-30-2014, 07:27 AM | #1 |
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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? |
10-30-2014, 10:27 AM | #2 |
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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.
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10-30-2014, 10:51 AM | #3 |
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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? |
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10-30-2014, 11:56 AM | #4 |
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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.
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10-30-2014, 01:31 PM | #5 | |
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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 |
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10-30-2014, 02:01 PM | #6 | |
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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.
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10-31-2014, 10:05 AM | #7 |
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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....
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11-01-2014, 12:16 AM | #8 |
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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. |
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11-11-2014, 10:09 PM | #9 |
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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.
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track width, z4 m coupe, z4 track width, z4m, z4mc |
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