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      08-12-2018, 09:43 PM   #1
Powerslide
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Progressive Oversteer ZCP v Non-ZCP

I had my 2015 M3 for about 3 years - had the chance to drive it on the track about 6-7 times.

I now have the 2018 ZCP M3 - but have not yet had the chance to track or autocross it. However, today I drove it on some empty country roads outside of the Chicago area - and in making several sharp 90-degree right and left turns, with DSC fully off - I seemed to be able to slightly rotate or oversteer the car with very small "jabs" of the throttle (in a controllable way) and on a couple of occasions, the car would start to oversteer in a more sustained, but progressive and controllable way (although I was not by any means flooring the gas).

If I was on a track with a very large and flat run-off area, I'd have more confidence to test the limits and induce more oversteer - but until then I'm looking for experiences of those who have tracked/autocrossed both the non-ZCP and ZCP with similar tires (either PSS or PS4S) - and specifically - how much difference do you notice in terms of being able to better control the slide or do short bursts of pivoting the car in a turn with short jabs of the throttle on the ZCP vs. the Non-ZCP?

Thanks in advance for your feedback!
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      09-21-2018, 04:18 PM   #2
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Not directly answering your question, but when I coded the GTS LSD calibration into my non-ZCP, the car seemed much more eager to rotate under throttle exiting a corner (DSC off). It seemed to help me maintain larger yaw angles and gave the car a really loose, playful character. I haven't tried it, but I can imagine that the ZCP diff has a bit of this character compared to the early base cars as well.
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      09-21-2018, 08:45 PM   #3
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Thanks for the reply - my experience seems to back up what you're saying
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      09-22-2018, 09:33 AM   #4
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My impression is that the base suspension was too soft in the rear relative to the front, which had the rear grip more but would snap in a less predictable manner.

On the CP, they proportionnaly stiffened the rear more than the front, which in my opinion slightly increases the bias towards oversteer. So the rear on the CP will start to come out a bit earlier, but in a smoother more predictable manner.

I experienced the same improvement on my base 2015 M4 when I installed Eibach springs, that also propotionally stiffened the rear more than the front, where the car became more nimble and predictable.
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      09-22-2018, 01:02 PM   #5
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Never played with my 16 with stock suspension, but with Eibachs, GTS diff coding and CP EDC coding it is quite fun. Very easy to modulate throttle (in sport+) and chassis yaw on a mini road course (Limerock). Chassis balance is def on the side of understeer, but not terribly so. I was quite surprised at how stable and predictable it was, assuming you're not "toggle switch Tony" with the throttle. If you want to drift at larger angles just mash or stab the throttle.
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      09-23-2018, 05:00 PM   #6
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Quote:
Originally Posted by CanAutM3 View Post
My impression is that the base suspension was too soft in the rear relative to the front, which had the rear grip more but would snap in a less predictable manner.

On the CP, they proportionnaly stiffened the rear more than the front, which in my opinion slightly increases the bias towards oversteer. So the rear on the CP will start to come out a bit earlier, but in a smoother more predictable manner.

I experienced the same improvement on my base 2015 M4 when I installed Eibach springs, that also propotionally stiffened the rear more than the front, where the car became more nimble and predictable.
I will defer to our "in-house engineer" on this one! That being said - could the diff programming and EDC programming changes in the ZCP vs non-ZCP offset the stiffening of the rear suspension?

Either way - definitely agree that once oversteer does start on my '18 ZCP - it is undoubtedly more controllable and predictable (and less prone to "snap" oversteer vs. my 2015.
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      09-24-2018, 03:53 PM   #7
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With my non-zcp, it's doable to power oversteer just a little bit with more throttle when it's near limit (like tracking out). But it takes concentration and can be overdone easily. I've never driven a ZCP so I don't know how it's easier to control in it.

Slightly off-topic:
I wish there was a complete minimal setup guide (thinking cost effectiveness) for a fun track car. (i.e. making the car oversteer or neutral biased) Like, not to throw coil-overs and cambers and tires and everything, but like just tires and coding (that would be cool if what OP said is possible), or plus camber plates and alignment. Yes, I did not mod my M4 yet as I have other cheaper track car and still hesitating to throw $$$ in it.
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      09-24-2018, 04:42 PM   #8
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Quote:
Originally Posted by Powerslide View Post
I will defer to our "in-house engineer" on this one! That being said - could the diff programming and EDC programming changes in the ZCP vs non-ZCP offset the stiffening of the rear suspension?

Either way - definitely agree that once oversteer does start on my '18 ZCP - it is undoubtedly more controllable and predictable (and less prone to "snap" oversteer vs. my 2015.
After trading in my 2015 for an '18 zcp, my amateur interpretation of the handling change is the same as you guys.
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      09-29-2018, 10:09 AM   #9
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Stepping through the changes that transformed my car from a base to a CS with MPHAS, I can say that the proportionally stiffer rear and the EDC calibration both contribute.
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