Are the M Performance HAS and KW HAS identical?

[matty088]

Originally Posted by CanAutM3

I had also read the same, but I don't believe ir is true. The MP-HAS have a progressive spring rates on the front spring whereas the Comp pack springs are linear, so they cant have the same rate across the entire wheel travel.

Further, lowering the car does benefit handling even if the springs aren't stiffer. Lowering the car reduces the amount of weight transfer during cornering which increases total grip. On the other hand, stiffer springs do no necessarily translate to an "increase" in handling. As a general rule, a softer suspension improves grip while a stiffer suspension improves response. The fine art of suspension tuning resides in achieving the perfect balance.

I follow. But we are talking a very small drop if you go to the recommended height. The rears are perfect as is. The front is high. Anyways. I think it’s a very clear no Brainer that going from civic hardware to mp has will yield a significant increase in handling. I base this off the fact that the car community uniformly agrees that the ZCP suspensions is significantly better than the civic. But it gets murky if you are adding it to a ZCP car. Lots of people I spoke to thst are very happy with mp has on their ZCP are typically coming from an Eibach spring or something similar. I really haven’t read much from people going from stock and really pounding the table that there is an increase in firmness roll or general handling. I’ve asked these questions. Many ZCP owners call this an aesthetics mod. Teust me. I want to believe. I want to add the kit. It’s hard to know what I am getting though. If I am getting simply a lower front end then I can pass.

[allinon72]

Originally Posted by matty088

I follow. But we are talking a very small drop if you go to the recommended height. The rears are perfect as is. The front is high. Anyways. I think it’s a very clear no Brainer that going from civic hardware to mp has will yield a significant increase in handling. I base this off the fact that the car community uniformly agrees that the ZCP suspensions is significantly better than the civic. But it gets murky if you are adding it to a ZCP car. Lots of people I spoke to thst are very happy with mp has on their ZCP are typically coming from an Eibach spring or something similar. I really haven’t read much from people going from stock and really pounding the table that there is an increase in firmness roll or general handling. I’ve asked these questions. Many ZCP owners call this an aesthetics mod. Teust me. I want to believe. I want to add the kit. It’s hard to know what I am getting though. If I am getting simply a lower front end then I can pass.

If the recommended heights aren't low enough for you, you have lots of room to go lower. But it sounds like you are expecting miracles from a HAS kit, so you should probably look towards coilovers anyway.

[matty088]

Originally Posted by allinon72

If the recommended heights aren't low enough for you, you have lots of room to go lower. But it sounds like you are expecting miracles from a HAS kit, so you should probably look towards coilovers anyway.

No. Again.

Not looking for miracles at all. Just looking to know what I am buying versus what I have

It seems we have a disconnect.

[allinon72]

Originally Posted by matty088

No. Again.

Not looking for miracles at all. Just looking to know what I am buying versus what I have

It seems we have a disconnect.

There is no disconnect. You say that the HAS kit will handle the same as your stock ZCP suspension, and that the HAS is simply a lowering kit and won't improve handling. Sorry, that is false for a number of reasons, not limited to your belief that the spring rates are the same.

[CanAutM3]

Originally Posted by matty088

I follow. But we are talking a very small drop if you go to the recommended height. The rears are perfect as is. The front is high. Anyways. I think it’s a very clear no Brainer that going from civic hardware to mp has will yield a significant increase in handling. I base this off the fact that the car community uniformly agrees that the ZCP suspensions is significantly better than the civic. But it gets murky if you are adding it to a ZCP car. Lots of people I spoke to thst are very happy with mp has on their ZCP are typically coming from an Eibach spring or something similar. I really haven’t read much from people going from stock and really pounding the table that there is an increase in firmness roll or general handling. I’ve asked these questions. Many ZCP owners call this an aesthetics mod. Teust me. I want to believe. I want to add the kit. It’s hard to know what I am getting though. If I am getting simply a lower front end then I can pass.

I have the MP-HAS on an M4cs, which has the same stock springs as the comp pack. I definitely felt an improvement in handling with the MP-HAS. The car feels noticeably more planted and responsive.

It does not take a huge drop to reduce the amount of weight transfer.

As for the amount of drop, mine is lowered a bit more than the recommended height. I am not sure what you mean by "the rear is perfect as is", but I assume you mean that it does not aesthetically need more lowering on an M3. In my case, I lowered the front and rear by almost the same amount to maintain the handling balance. Mine is also an M4, which can tolerate more drop in the rear than an M3 without being aesthetically unpleasant.

[CanAutM3]

Originally Posted by FaRKle!

I wonder how many of the MP-HAS spring's coils are in bind at static ride height. I've seen companies (like Bilstein) use progressive springs, however all of the low-rate coils were bound already at static height. They're using the low-rate coils to keep pre-load during droop, performing the same function as a helper spring in a dual-spring configuration. It's possible then that since the MP-HAS spring has to be able to allow a lower ride height, that the final rate could be similar to ZCP rates, and reasonable since they probably wouldn't change the rate drastically while keeping the damping the same.

You cannot really compare it to a helper spring. A helper spring is a completely separate spring that only starts to expand when the main spring has reached maximum expansion. The rate transition is instantenuous.

With the variable rate springs, when some of the coils are resting against each other in static, the distance between the coils where they stop touching very progressively increases, which means that with every incremental load, more of the coils touch making the spring coil effectively shorter and hence stiffer. The opposite being true on expansion. The rate transition is progressive.

[matty088]

Originally Posted by allinon72

There is no disconnect. You say that the HAS kit will handle the same as your stock ZCP suspension, and that the HAS is simply a lowering kit and won't improve handling. Sorry, that is false for a number of reasons, not limited to your belief that the spring rates are the same.

Ok.

[F80Speed77]

Quick question on DDC shocks with HAS kits how does the controller know what spring rates you are running? Does it adjust to whatever you throw at it, can you code custom values?

[FaRKle!]

Originally Posted by allinon72

Here's what mine looks like (not sure why the pic is upside down)

Good pic! So a fair amount of the coils (3, about half) are already bound/not active at static ride height. Therefore when plugging the spring characteristics into a spring rate calculator you'd say the spring only has 3 active coils, because the bound coils don't come into play until the suspension gets unloaded.

Originally Posted by CanAutM3

You cannot really compare it to a helper spring. A helper spring is a completely separate spring that only starts to expand when the main spring has reached maximum expansion. The rate transition is instantenuous.

With the variable rate springs, when some of the coils are resting against each other in static, the distance between the coils where they stop touching very progressively increases, which means that with every incremental load, more of the coils touch making the spring coil effectively shorter and hence stiffer. The opposite being true on expansion. The rate transition is progressive.

What you describe is true for a continuously progressive spring (like the KW conical front spring), however there are dual rate springs with a sharp knee in the spring force curve showing a short transition period from one rate to another. For these types of progressive springs the low-rate coils don't start to unload/space apart till the high-rate coils are uncompressed. An example of a spring like that is the rear Bilstein spring in the picture below. At static ride height the smaller spaced coils are all in bind already, so really only the final rate is in play. The smaller coils don't control any spring rate till the suspension is unloaded like when cresting.

KW conical continuously variable progressive rate spring:


Bilstein dual-rate progressive spring:

[CanAutM3]

Originally Posted by FaRKle!

Good pic! So a fair amount of the coils (3, about half) are already bound/not active at static ride height. Therefore when plugging the spring characteristics into a spring rate calculator you'd say the spring only has 3 active coils, because the bound coils don't come into play until the suspension gets unloaded.



What you describe is true for a continuously progressive spring (like the KW conical front spring), however there are dual rate springs with a sharp knee in the spring force curve showing a short transition period from one rate to another. For these types of progressive springs the low-rate coils don't start to unload/space apart till the high-rate coils are uncompressed. An example of a spring like that is the rear Bilstein spring in the picture below. At static ride height the smaller spaced coils are all in bind already, so really only the final rate is in play. The smaller coils don't control any spring rate till the suspension is unloaded like when cresting.

KW conical continuously variable progressive rate spring:


Bilstein dual-rate progressive spring:

Sorry, I did not want to imply that it was not possible to have a dual rate spring with a single coil.

My description was aimed at the MP-HAS front spring which IMO has a progressive rate. This is seen in picture on the previous page of the compressed front MP-HAS spring. Note that the “bound” coils dont need to be fully expanded to contribute to the spring rate, only a partial expansion from the static position, like when cresting a hill or when hitting a hole will have an effect.

[RevNev]

Originally Posted by CanAutM3

As for the amount of drop, mine is lowered a bit more than the recommended height.

Which recommended height, street or track? Street is 614mm front and 626mm rear from the bottom of the rim to guard with 19/20" wheels. Track recommendation is 609mm front and 619mm rear on the M4 chassis.

[CanAutM3]

Originally Posted by RevNev

Which recommended height, street or track? Street is 614mm front and 626mm rear from the bottom of the rim to guard with 19/20" wheels. Track recommendation is 609mm front and 619mm rear on the M4 chassis.

Good question. I never heard of BMW recommended track height for the MP-HAS. Could you share the documentation regarding this “track height”?

[RevNev]

Originally Posted by CanAutM3

Good question. I never heard of BMW recommended track height for the MP-HAS. Could you share the documentation regarding this “track height”?

The published ride heights for the MP-HAS is intended for street use however the data testing an M4 ZCP with the 763M wheel option at Nürburgring with the MP-HAS was set lower probably similar to the GTS track ride heights. A dealer technician showed me a PDF on a laptop in relation to this a couple of weeks ago.

The fact you've lowered yours a bit more and found a good handling balance reflects what BMW discovered track testing.

I guess they can't lower the car too much for street compliance and they're on the conservative side with their published ride heights for the MP-HAS.

[CanAutM3]

Originally Posted by RevNev

The published ride heights for the MP-HAS is intended for street use however the data testing an M4 ZCP with the 763M wheel option at Nürburgring with the MP-HAS was set lower probably similar to the GTS track ride heights. A dealer technician showed me a PDF on a laptop in relation to this a couple of weeks ago.

The fact you've lowered yours a bit more and found a good handling balance reflects what BMW discovered track testing.

I guess they can't lower the car too much for street compliance and they're on the conservative side with their published ride heights for the MP-HAS.

Interesting. I wonder why they do not officially publish those “track” specs?

BTW, my car is set at 595mm front and 619mm rear with the 19”/20” 763M wheels, whci is even lower in the front. Maybe I should try raising it a bit.

[RevNev]

Originally Posted by CanAutM3

Interesting. I wonder why they do not officially publish those “track” specs?

BTW, my car is set at 595mm front and 619mm rear with the 19”/20” 763M wheels, whci is even lower in the front. Maybe I should try raising it a bit.

I'd try raising the front and see how it feels on the track. It'll raise the front roll centre and theoretically, the car should be less loose in the rear to enable power down earlier on corner exits. At worst it'll understeer more with the front raised. Even stock, they're higher at the front, the tyre gap everyone dislikes, but it may be to maintain a particular roll axis.

[CanAutM3]

Originally Posted by RevNev

I'd try raising the front and see how it feels on the track. It'll raise the front roll centre and theoretically, the car should be less loose in the rear to enable power down earlier on corner exits. At worst it'll understeer more with the front raised. Even stock, they're higher at the front, the tyre gap everyone dislikes, but it may be to maintain a particular roll axis.

for the insight. It got me to dig a bit more. My car is indeed a bit loose on corner exit.

Looking at the GTS technical docs, I found that the OE "street" ride height with the 19"/20" wheel setup is 624mm/631mm. The GTS is fitted with "C-clips" that allows quick switchover to the "track" ride height. The front C-clip is 15mm with a 1:1 wheel-to-spring ratio and the rear C-clip is 7mm with a 1.6:1 wheel-to-spring ratio. This means that the GTS "track" ride height is 609mm/619.8mm. Pretty close to the numbers you posted

What is peculiar with the MP-HAS height recommendations is the specifications for 20" wheels. For some reason, it is not consistent with the 1.0" (25.4) and 0.5" (12.7mm) change in wheel radius compared to the 18" and 19" wheel ride height specifications. I yields a ~6mm higher ride height with 20" wheels than it does with the 18" and 19" wheels. I wonder if they did this due to the wider tires fitted to comp pack 20" wheels to ensure proper fender clearance .

Anyhow, I went to a level surface and took several measurements with the car in different positions. My car was setup at 597mm/618mm, which is a bit too low in the front according to the GTS track specs. I adjusted the front by 4 turns which raised it by 6mm. I now have 603mm/618mm. I am eager to see how the car behaves on track this coming Wednesday. If I feel an improvement, I might try to raise it by 2 more turns.

[RevNev]

Originally Posted by CanAutM3

for the insight. It got me to dig a bit more. My car is indeed a bit loose on corner exit.

Looking at the GTS technical docs, I found that the OE "street" ride height with the 19"/20" wheel setup is 624mm/631mm. The GTS is fitted with "C-clips" that allows quick switchover to the "track" ride height. The front C-clip is 15mm with a 1:1 wheel-to-spring ratio and the rear C-clip is 7mm with a 1.6:1 wheel-to-spring ratio. This means that the GTS "track" ride height is 609mm/619.8mm. Pretty close to the numbers you posted

What is peculiar with the MP-HAS height recommendations is the specifications for 20" wheels. For some reason, it is not consistent with the 1.0" (25.4) and 0.5" (12.7mm) change in wheel radius compared to the 18" and 19" wheel ride height specifications. I yields a ~6mm higher ride height with 20" wheels than it does with the 18" and 19" wheels. I wonder if they did this due to the wider tires fitted to comp pack 20" wheels to ensure proper fender clearance .

Anyhow, I went to a level surface and took several measurements with the car in different positions. My car was setup at 597mm/618mm, which is a bit too low in the front according to the GTS track specs. I adjusted the front by 4 turns which raised it by 6mm. I now have 603mm/618mm. I am eager to see how the car behaves on track this coming Wednesday. If I feel an improvement, I might try to raise it by 2 more turns.

I've seen the 20" front wheel ride height with the MP-HAS doesn't correspond with the 18 or 19" wheel diameter and is higher. The ZCP along with 20" wheels has a stiffer front sway bar with the same springs as the CS.

To digress a little, we discovered the ZCP with a sunroof had CS springs and having recently removed the sunroof and fitting a carbon roof to my ZCP, it didn't alter the ride height with Eibach V1's despite the weight reduction of 20lbs+. I'm assuming perhaps the weight in the roof has a high centre of gravity effect increasing body roll is the reason they used the stiffer CS springs with the sunroof option.

The ZCP with the MP-HAS with a higher front ride height and stiffer sway bar would tend to understeer more than the CS for what reason they'd do that, I don't know other than perhaps a safety buffer for people of limited driving skill and the car takes more provocation to snap sideways.

We've got one M4 racing in Production Cars in Australia that has coil overs in the front and the HAS like spring setup in the rear with better shocks on 18" wheels, is pretty low in the rear I noticed on the weekend possibly 3/4" lower than the front. Other than the shocks, springs and camber plate freedom, the suspension has to remain stock.

It is similar to the GTS published track suspension height and I'm sure it's about maintaining a particular roll axis. From racing Holden Commodore's down under which is the same car as the Pontiac G8 and Chevy SS in the US with the suspension modelled on the 5 Series BMW similar to the F8X, altering roll centres with ride height adjustment has a profound effect on handling balance and corner exit power down. I'm interested to know how it reacts with the M4 chassis.

I've swapped my 20" 666M wheels for the MP 763M's with CS EDC and steering coded made a massive difference over bumpy corners with the ZCP coding, the car was loose in the rear and unpredictable in sports+. It feels as if the CS coding increases the rebound dampening and transforms the car into greater predictability to drive faster through the same bumpy corners. The CS coding appears softer on compression dampening in comfort mode and improves the ride over the ZCP harshness. I'm not sure of ZCP EDC coding purpose compared with CS coding that's far better in every mode.

[CanAutM3]

Originally Posted by RevNev

I've seen the 20" front wheel ride height with the MP-HAS doesn't correspond with the 18 or 19" wheel diameter and is higher. The ZCP along with 20" wheels has a stiffer front sway bar with the same springs as the CS.

To digress a little, we discovered the ZCP with a sunroof had CS springs and having recently removed the sunroof and fitting a carbon roof to my ZCP, it didn't alter the ride height with Eibach V1's despite the weight reduction of 20lbs+. I'm assuming perhaps the weight in the roof has a high centre of gravity effect increasing body roll is the reason they used the stiffer CS springs with the sunroof option.

The ZCP with the MP-HAS with a higher front ride height and stiffer sway bar would tend to understeer more than the CS for what reason they'd do that, I don't know other than perhaps a safety buffer for people of limited driving skill and the car takes more provocation to snap sideways.

We've got one M4 racing in Production Cars in Australia that has coil overs in the front and the HAS like spring setup in the rear with better shocks on 18" wheels, is pretty low in the rear I noticed on the weekend possibly 3/4" lower than the front. Other than the shocks, springs and camber plate freedom, the suspension has to remain stock.

It is similar to the GTS published track suspension height and I'm sure it's about maintaining a particular roll axis. From racing Holden Commodore's down under which is the same car as the Pontiac G8 and Chevy SS in the US with the suspension modelled on the 5 Series BMW similar to the F8X, altering roll centres with ride height adjustment has a profound effect on handling balance and corner exit power down. I'm interested to know how it reacts with the M4 chassis.

I've swapped my 20" 666M wheels for the MP 763M's with CS EDC and steering coded made a massive difference over bumpy corners with the ZCP coding, the car was loose in the rear and unpredictable in sports+. It feels as if the CS coding increases the rebound dampening and transforms the car into greater predictability to drive faster through the same bumpy corners. The CS coding appears softer on compression dampening in comfort mode and improves the ride over the ZCP harshness. I'm not sure of ZCP EDC coding purpose compared with CS coding that's far better in every mode.

Just as a precision, the MP-HAS recommended ride height for 20" wheels is higher by ~6mm front AND REAR compared to 18" and 19" wheels

[NYG]

Very noticeable difference between MP HAS and stock suspension on my M4CS.

Originally Posted by JcLusso

I know everything from that thread. I basically am looking to confirm spring rates. Surprising nobody has just measured them by now on some machine that can apply force or maybe that's not that easy to do....

Also the thread mentions the guy in the MP HAS gigantic thread who says he went from KW. He didn't post if he had the original or v2.

They're progressive so you'll have to plot it to get the stiffness vs displacement

[Vastyle]

So consensus says that the MP HAS will give the best ride? I got some front wheel gap I need to close up.

[rapindrive]

I'm also thinking of installing them. I see you are happy right?

[JcLusso]

I've been happy with mine!