Definitive answers on the difference b/t ZCP vs. Standard M3 Dampers

[Racer20]

Edit: after installing and driving these dampers along with the rest of the CS suspension + MP HAS, I can say that my speculation below was mostly correct, but BMW's engineers did better than expected. There are no negative trade offs with this set up. These dampers are far more capable than the base 2015 dampers, and the car performs beautifully in its current state.
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I have a 2015 M3 with adaptive suspension and recently purchased another forum members MP HAS kit that also includes the adaptive dampers from a 2016 M3 ZCP.

I also happen to have a shock dyno at my disposal, so I took the opportunity to test both sets of shocks to see exactly what the differences are between the ZCP and non-ZCP adaptive shocks.

Here are the dyno differences along with some quick comments/observations. I haven't installed them or ever driven a ZCP car, so any comments below about ride/handling performance are just speculation for now.

Front:



(Full soft) The front ZCP's seem to have the same lowspeed orifices as the standard shocks but are stiffer in the midspeed range for both rebound and compression. Keeping lowspeed damping the same in full soft helps maintain some ride comfort and isolation of the base package, but ensures that the system can properly damp mid-size impacts and body motions better without relying on the software control as much. The difference might seem small, but because the overall damping is low in this mode, small differences on this chart end up being surprisingly noticeable on the vehicle.

(Full stiff) These shocks have significantly more damping in key areas: Compression across the range for support during roll and heave motions and lowspeed rebound for responsiveness and steering precision. The changes in rebound might seem small, but at any given speed, the difference is about 20% in the lowspeed range, which is quite significant.

In general, slowing down unwanted motion sooner prevents inertia build, which means later motion is much less. Therefore, a little bit of lowspeed damping is worth a lot of midspeed damping. These curves indicate a significant improvement in damping capability.

Rear:



(Full soft) More damping across the range in compression and in midspeed rebound, but less lowspeed rebound. This could be a nod towards comfort, as lowspeed rebound can make the ride feel tense and busy. On the other hand, too much rear lowspeed rebound is a common cause of poor steering feel or vague response.

If the front and rear lowspeed rebound is not properly balanced, the initial response and weight transfer of the rear will be too slow to keep up with the front and there will be a time delay during the entire steering action, both during the initial steer and during the return to center. On the return, the phase delay will be compounded because the rear will get "stuck" in the rebound stroke again as it tries to recover to straight ahead. This results in a less "connected," less agile car.

(Full Stiff) Same thing as front, more damping everywhere, but the overall difference is a bit less than the front. Overall more damping capacity should bring quicker response and better performance. The difference looks small on the graph, but the area under the curve and responsiveness increases by quite a bit.

Overall, The soft-mode lowspeed damping balance of the rear shock has shifted from being rebound heavy in the standard car to being compression heavy in the ZCP car. Common damper tuning myths might lead one to believe this is bad, but this is likely to result in a better balanced car with improved agility and steering feel.

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Adding damping to both ends of the car at all speeds will improve handling, but it's difficult to do this without also making the ride suffer. BMW's damper and algorithm guys need to be on the ball to achieve both at once. My commute is on some pretty poor roads, so I'm really interested to see if they pulled it off once I get these parts installed. I expect the car to be a bit busier over small bumps and quick road undulations, but if the higher damping reduces the crashiness of the front over large impacts, I'll be able to live with that trade-off.

[knightarmor]

Thanks for doing all of this and posting the info. I'm pretty satisfied with my zcp MPHAS setup, however. Sometimes i find a little bit is left to be desired. Will run this setup through the end of warranty and see what i do then.

[Racer20]

Originally Posted by knightarmor

Thanks for doing all of this and posting the info. I'm pretty satisfied with my zcp MPHAS setup, however. Sometimes i find a little bit is left to be desired. Will run this setup through the end of warranty and see what i do then.

Can you describe what you don't like about it? Based on the data, I'm a bit afraid I won't be happy with the ride quality on my commute.

My backup plan is to put my stock springs back on the adjustable perches, get the ZCP rear bar, and basically have the CS suspension.

[SanchoDivine]

What is being compared? Base suspension vs MPHAS with ZCP dampers?

[Racer20]

Originally Posted by SanchoDivine

What is being compared? Base suspension vs MPHAS with ZCP dampers?

The charts are for the base adaptive shocks vs. the ZCP adaptive shocks. They show how stiff the shocks are in rebound and compression at various piston speeds.

The MP HAS is a spring kit, which is not relevant to my first post.

[SanchoDivine]

Originally Posted by Racer20

The charts are for the base adaptive shocks vs. the ZCP adaptive shocks. They show how stiff the shocks are in rebound and compression for at various piston speeds.

The MP HAS is a spring kit, which is not relevant to my first post.

Then why mention the MPHAS kit at all? You should just state that you purchased some ZCP adaptive dampers. It seemed like you tested a base suspension and then installed the MPHAS and the adaptive dampers and then did a comparison which would end up being a comparison of MPHAS springs and zcp dampers vs base springs and base dampers. It's a little surprising someone would test base set up then only replace dampers for testing and finally install the MPHAS and not do a test.

Edit: I should add that I have driven base adaptive suspension, base adaptive suspension with MPHAS, stock ZCP adaptive suspension, and ZCP adaptive suspension with MPHAS on the track.

Base suspension was firm but had slightly more body roll than ZCP. However, it is very difficult to tell if there was a difference between base with MPHAS and ZCP with MPHAS. Both feel planted, firm, and smooth. Significantly better overall than the stock set up of either base and ZCP. A portion of that is most likely contributed by a lower center of gravity.

[Racer20]

Originally Posted by SanchoDivine

However, it is very difficult to tell if there was a difference between base with MPHAS and ZCP with MPHAS.

Did you do any coding to try the ZCP or CS EDC calibrations?

My goal is to find the best balance of ride and handling from an OEM+ set up so I can keep the adaptive dampers.

[SanchoDivine]

Originally Posted by Racer20

Did you do any coding to try the ZCP or CS EDC calibrations?

My goal is to find the best balance of ride and handling from an OEM+ set up so I can keep the adaptive dampers.

No, only got to drive the cars with stock coding via one of the more recent iSteps. I'm curious to know what the CS feels like but I'm doubtful I will get an opportunity to experience it unless I perform the retrofits and coding like you are investigating.

The ride with the MPHAS and updated iStep is a pretty good one. I got to drive the ZCP with MPHAS and ZCP without the kit back to back at Circuit of the Americas and the difference is very noticeable. The car is definitely improved with the kit.

[knightarmor]

Originally Posted by Racer20

Can you describe what you don't like about it? Based on the data, I'm a bit afraid I won't be happy with the ride quality on my commute.

My backup plan is to put my stock springs back on the adjustable perches, get the ZCP rear bar, and basically have the CS suspension.

What I seem to experience at times is that the rebound through the turns is inconsistent from one drive to the next (this is the best way for me to describe it). I drive almost exclusively in Sport for the damper setting. Only when I am going to take slow <30mph streets that are not good do I switch the dampers over to Comfort. My F80 is a ZCP but fitted with the 19" 437 OE wheels/tires.

I went with the MPHAS because I wanted to retain the EDC dampers (only because I want to see where technology is nowadays, this is the only car I've ever gotten with electronic dampers because they were included, I had to give them a chance and see for myself how I would like or dislike the setup) and the cars I drove at the M Track days with MPHAS were outstanding (those cars were ZCP with the 20" 666 wheels). At the track days I was 100% satisfied with the setup.

On daily driving roads with my setup I would have to say i'm 99.9% satisfied. The comfort is there and the handling is there the majority of the time but as I mentioned sometimes the car doesn't feel like the car I drove the day before.

I've also attributed this feeling to the OEM tires. I don't like the stretched sidewall that the OE 19's have so I will be switching to a wider rubber when I get new tires next spring to see if that helps any. I'm also contemplating getting a set of 666's just to see how the car feels after that (thinking a reduction in sidewall may improve things).

Another issue could just be me, the driver. I've only had this car almost a year and half and still learning to drive it and communicate with it. When everything lines up though it's freakin awesome!

[SanchoDivine]

Originally Posted by knightarmor

What I seem to experience at times is that the rebound through the turns is inconsistent from one drive to the next (this is the best way for me to describe it). I drive almost exclusively in Sport for the damper setting. Only when I am going to take slow <30mph streets that are not good do I switch the dampers over to Comfort. My F80 is a ZCP but fitted with the 19" 437 OE wheels/tires.

I went with the MPHAS because I wanted to retain the EDC dampers (only because I want to see where technology is nowadays, this is the only car I've ever gotten with electronic dampers because they were included, I had to give them a chance and see for myself how I would like or dislike the setup) and the cars I drove at the M Track days with MPHAS were outstanding (those cars were ZCP with the 20" 666 wheels). At the track days I was 100% satisfied with the setup.

On daily driving roads with my setup I would have to say i'm 99.9% satisfied. The comfort is there and the handling is there the majority of the time but as I mentioned sometimes the car doesn't feel like the car I drove the day before.

I've also attributed this feeling to the OEM tires. I don't like the stretched sidewall that the OE 19's have so I will be switching to a wider rubber when I get new tires next spring to see if that helps any. I'm also contemplating getting a set of 666's just to see how the car feels after that (thinking a reduction in sidewall may improve things).

Another issue could just be me, the driver. I've only had this car almost a year and half and still learning to drive it and communicate with it. When everything lines up though it's freakin awesome!

Your wheel and tire setup could contribute to the inconsistency. Temperature and tire air pressure can fluctuate and you will probably feel it more with a 19 inch wheel than a 20 inch wheel because of the side wall differences of the tires.

[mechanic75]

Originally Posted by SanchoDivine

Your wheel and tire setup could contribute to the inconsistency. Temperature and tire air pressure can fluctuate and you will probably feel it more with a 19 inch wheel than a 20 inch wheel because of the side wall differences of the tires.

Exactly my thoughts when I read that. Keep an eye on your tyre temps and see is there any correlation.