ZCP Anti-Roll Bar; Worth Upgrading?

[m4282]

Originally Posted by Bucketsbentley

Yes, I have one. It's a straight replacement. Get the software update from BMW too.

What software update? I picked up my m4 in June it's a 2016 non zcp last one they had on the floor- it was a trade in.

when did this update come out? How do I know what version I have of the software?

[Der]

Dont worry if its so new, your are already running the latest version, or one of the latest versions.

[kitw]

Wait, I sell my 15 M4 and come back and people are trying to make these cars oversteer MORE?! Really? haha

I thought my 15 m3 and 15 M4 were both extremely neutral handling cars, some of the best BMW has produced. I thought the damping wasn't fantastic, but that they were at least a lot less understeer prone than the e9x cars (of which I owned 6)

Now that I'm on my 3rd F8x, I'm surprised to find that my 16 M4 passive suspension car feels a TON better damped than my 15 M3 (also passive.) I'm shocked - the M3 had me searching for suspension almost immediately in 2015, and I got JRZs for my M4 before I even got the car, but my 16 feels like it's set up really well. I can't imagine a larger rear sway bar adding anything useful...

[m4282]

Originally Posted by SO17

Front sway bar is the same thickness but the narrow section is shorter on the ZCP. Rear sway bar is 25.26mm on ZCP vs 22.9 on non ZCP.

Sorry for bringing this up again but wouldn't a thicker sway bar in the rear also being stiffer cause the "kick out" in f8x to become even more prominent? Given the amount of torque output a "softer" sway may put more power down..... sorry if I have this info backwards.

[CanAutM3]

Originally Posted by m4282

Sorry for bringing this up again but wouldn't a thicker sway bar in the rear also being stiffer cause the "kick out" in f8x to become even more prominent? Given the amount of torque output a "softer" sway may put more power down..... sorry if I have this info backwards.

Correct. A softer swaybar on an axle (or a stiffer one on the other axle) will improve grip on that axle.

[m4282]

Originally Posted by CanAutM3

Correct. A softer swaybar on an axle (or a stiffer one on the other axle) will improve grip on that axle.

Thanks this is what I thought and is how the non CP m4 is set up now. I think (and correct me if I'm wrong) the reason the CP M4 has less "kick out" is a result of the revised differential with perhaps more linear torque along with bigger wheels...... I always thought for decreasing kick out in a non CP M4 in terms of mods you should increase contact patch of tires and change toe links and lower the car to a stiffer spring rate while keeping softer sways in the back...... that's my plan for the spring once the weather "warms up" in the north east US

[CanAutM3]

Originally Posted by m4282

Thanks this is what I thought and is how the non CP m4 is set up now. I think (and correct me if I'm wrong) the reason the CP M4 has less "kick out" is a result of the revised differential with perhaps more linear torque along with bigger wheels...... I always thought for decreasing kick out in a non CP M4 in terms of mods you should increase contact patch of tires and change toe links and lower the car to a stiffer spring rate while keeping softer sways in the back...... that's my plan for the spring once the weather "warms up" in the north east US

Note that increasing rear springs rates (proportionally more than the front) will have the same effect as a stiffer swaybar in terms of increasing lateral weight transfer on the rear axle.

I am however not convinced that proportionally softer rear springs/swaybars is what is needed to improve the F8X...

[m4282]

Originally Posted by CanAutM3

Note that increasing rear springs rates (proportionally more than the front) will have the same effect as a stiffer swaybar in terms of increasing lateral weight transfer on the rear axle.

I am however not convinced that proportionally softer rear springs/swaybars is what is needed to improve the F8X...

Understood and agreed- yes the springrate in front would still be higher than rear with the dinan HAS upgrade.

So another question - would you think reduce the "kick out" from your Opinion- will a focus on More rubber(wider tires) be enough here?

[CanAutM3]

Originally Posted by m4282

Understood and agreed- yes the springrate in front would still be higher than rear with the dinan HAS upgrade.

So another question - would you think reduce the "kick out" from your Opinion- will a focus on More rubber(wider tires) be enough here?

In my opinion, the "kick-out" is more a question of overall handling dynamics than about ultimate grip. It is more about getting a more progressive transition in slip angle.

The Eibach springs I installed on my car have a relatively higher rate increase in the rear than in the front (+3% front and +6% rear). Since I have a also installed camber plates and gotten a good alignment at the same time as the springs, I am not sure how each component individually contribute, but I now find my car much more planted and stable with more progressive breakaway characteristics. I think the altered front-to-rear spring rate have something to do with it.

[m4282]

Originally Posted by CanAutM3

In my opinion, the "kick-out" is more a question of overall handling dynamics than about ultimate grip. It is more about getting a more progressive transition in slip angle.

The Eibach springs I installed on my car have a relatively higher rate increase in the rear than in the front (+3% front and +6% rear). Since I have a also installed camber plates and gotten a good alignment at the same time as the springs, I am not sure how each component individually contribute, but I now find my car much more planted and stable with more progressive breakaway characteristics. I think the altered front-to-rear spring rate have something to do with it.

Thanks- what camber plates did you go with? And what degrees was it set at to get this? I'll be installing the HAS Dinan kit so not sure if the camber plates will work well with it ..... but I value your opinion as you always have very sound advice for all on this forum.

[CanAutM3]

Originally Posted by m4282

Thanks- what camber plates did you go with? And what degrees was it set at to get this? I'll be installing the HAS Dinan kit so not sure if the camber plates will work well with it ..... but I value your opinion as you always have very sound advice for all on this forum.

I went with the Ground Control ones. I had them on my E46 and E92 and a good experience with them. I originally had ordered the TCK because they were the first on the market, by I cancelled my order when I found out they only allowed adjustments in step increments, which prevented having an "exact" camber setting.

I have my camber set at -2.5deg front and -1.6deg rear with stock toe settings. I get nice and even temperature distribution across the tread on all four tires with those settings at the track.

[m4282]

Originally Posted by CanAutM3

I went with the Ground Control ones. I had them on my E46 and E92 and a good experience with them. I originally had ordered the TCK because they were the first on the market, by I cancelled my order when I found out they only allowed adjustments in step increments, which prevented having an "exact" camber setting.

I have my camber set at -2.5deg front and -1.6deg rear with stock toe settings. I get nice and even temperature distribution across the tread on all four tires with those settings at the track.

Thank you!

[elmerzasty]

I upgraded both my sway bars to comp pack. Have not tracked them yet, so cannot say much about balance, but stability is noticably improved, as is steering feel. I fell a lot more confident when switching lanes etc. - to be honest, the car feels like it should have come with these sway bars from the factory, almost as if it was developed with the CP sway bars and then downgraded to create the "base" version.

[JamesGames]

Originally Posted by elmerzasty

I upgraded both my sway bars to comp pack. Have not tracked them yet, so cannot say much about balance, but stability is noticably improved, as is steering feel. I fell a lot more confident when switching lanes etc. - to be honest, the car feels like it should have come with these sway bars from the factory, almost as if it was developed with the CP sway bars and then downgraded to create the "base" version.

Not that I don't believe you when you say the sways made a difference but to say you feel more stable switching lanes is stretching it.. how are you switching lanes? Yanking the wheel and initiating body roll?

[elmerzasty]

For me the regular F8x gives a definitive feeling of weight transfer when turning, noticable even in daily driving, almost as if the tires were lacking pressure. The sway bar upgrade helps remedy this. Bear in mind that I do have the sunroof on my car and am currently riding on 18s, which probably exposed the issue to a greater extent that on the average F8x Joe's car with carbon roof and 19"+.

[CanAutM3]

Originally Posted by elmerzasty

For me the regular F8x gives a definitive feeling of weight transfer when turning, noticable even in daily driving, almost as if the tires were lacking pressure. The sway bar upgrade helps remedy this. Bear in mind that I do have the sunroof on my car and am currently riding on 18s, which probably exposed the issue to a greater extent that on the average F8x Joe's car with carbon roof and 19"+.

Important not to confuse weight transfer and body roll.

[m4282]

Originally Posted by CanAutM3

I went with the Ground Control ones. I had them on my E46 and E92 and a good experience with them. I originally had ordered the TCK because they were the first on the market, by I cancelled my order when I found out they only allowed adjustments in step increments, which prevented having an "exact" camber setting.

I have my camber set at -2.5deg front and -1.6deg rear with stock toe settings. I get nice and even temperature distribution across the tread on all four tires with those settings at the track.

Quick question with the drop alone did the steering feel improve ? Did it become less "numb"? Or still the same- considering adding the dinan monoball upfront to get rid of the rubber bushings but not sure if almost at 800-900 installed its worth it.....

[Tuner1]

Originally Posted by SO17

Front sway bar is the same thickness but the narrow section is shorter on the ZCP.

It would be nice to know the actual difference in front bar stiffness between the standard and ZCP unit. Did BMW ever reference an actual number?

Presumably BMW wouldn't bother creating a new front bar unless it was at least 10% stiffer

[stonecliff]

Originally Posted by CanAutM3

I went with the Ground Control ones.

How have you found the change in NVH with these compared with stock? I've been leery about making the change after the impact they have had on past cars, but I'm getting tired of cording expensive tires...

[CanAutM3]

Originally Posted by stonecliff

How have you found the change in NVH with these compared with stock? I've been leery about making the change after the impact they have had on past cars, but I'm getting tired of cording expensive tires...

NVH will be increased with any camber plate due to the smaller top bearing. It is no worse and no better than what I had experienced with my E46 and E92. I don't mind sacrificing a little NVH for the sharper handling and improved tire wear from a good alignment.

[momo3605]

Originally Posted by Tuner1

It would be nice to know the actual difference in front bar stiffness between the standard and ZCP unit. Did BMW ever reference an actual number?

Presumably BMW wouldn't bother creating a new front bar unless it was at least 10% stiffer

I had it measured when I swapped to the zcp roll bars. Its 3mm thicker front and rear.

[elmerzasty]

That is not precise - the sway bars have variable diamaters, thus it is not a simple calculation of the increase of maximum cross sectional area to determine how much stiffer they are one to another.

As stated before, the front CP bar has the same maximum diameter as the non-CP one (thus uses the same bushings and brackets), although the thickest portion is longer on the CP. The rear CP bar's maximum diameter is in fact thicker in the thickest part than non-CP, thus it comes with new brackets and bushings, but again - the thickness is not constant on the whole length of the bar.

To sum up, stating diameters means nothing about their actual stiffness.