E89 Z4 Track-ready Sleeper Build

[Asbjorn]

You have to delete the entire factory braking setup except for the pedal and lines (pedal and brake lines) and replace everything with aftermarket parts. So instead of having one master cylinder you would have two, one for the front and one for the rear and there are valves to proportion fluid to the front and the rear based on pedal imput.

Here is a kit but it is not cheap nor do you want to cheap out on something like this: https://www.boefab.com/products/brake-bias-cage


Me personally I think ABS is one of the best inventions on the modern day car so I would never delete it. Plus I think the factory brake bias setup by bmw is pretty good so no real need or desire on my end to change it in any way.

Thanks for explaining! Running without ABS in the wet is not something I would consider unless its a gokart and a cheap one at that haha.

I am also wondering what kind of error codes and software problems (DCT?) one would get by converting the master cylinder setup, or even converting to a standalone ABS.

That being said, I do believe the setup on your M2 must be better from factory. That car was built to use cup2 tires which can achieve semi-slick levels of grip when new. I studied a 718 running the same tires as myself, and it looks rock stable under hard braking (same track, same day). The E89 was born with street RFTs, and it seems the system was calibrated based on that.

 

[F87Source]

Thanks for explaining! Running without ABS in the wet is not something I would consider unless its a gokart and a cheap one at that haha.

I am also wondering what kind of error codes and software problems (DCT?) one would get by converting the master cylinder setup, or even converting to a standalone ABS.

That being said, I do believe the setup on your M2 must be better from factory. That car was built to use cup2 tires which can achieve semi-slick levels of grip when new. I studied a 718 running the same tires as myself, and it looks rock stable under hard braking (same track, same day). The E89 was born with street RFTs, and it seems the system was calibrated based on that.

No problem. Yeah no ABS is sketchy as hell, I used to have a car with no ABS and in Canada with black ice on the road that was insanely scary.


I think the m2 has a decently good setup, it feels fine to me. AP racing has even designed their 6 pot setup to be used with the factory 2 pot rear setup without affecting brake bias, which is nice.


You will probably get alot of error codes if you delete the factory ABS setup and likely limp modes too. IMO you probably should look at ESYS (or what ever the coding software is on the e89) and see if it is capable of being coded to have the 1m ABS setup. You might need to update your istep if your car preceedes the 1m build date. Or check on real oem if the abs module is the same etc.


But despite the e89 being calibrated for street tires I would believe as long as you are running the same tire compound front and rear, and the tire contact patch ratio (if staggered) was the same front to rear as factory you would not have an issue.

 

[Asbjorn]

No problem. Yeah no ABS is sketchy as hell, I used to have a car with no ABS and in Canada with black ice on the road that was insanely scary.


I think the m2 has a decently good setup, it feels fine to me. AP racing has even designed their 6 pot setup to be used with the factory 2 pot rear setup without affecting brake bias, which is nice.


You will probably get alot of error codes if you delete the factory ABS setup and likely limp modes too. IMO you probably should look at ESYS (or what ever the coding software is on the e89) and see if it is capable of being coded to have the 1m ABS setup. You might need to update your istep if your car preceedes the 1m build date. Or check on real oem if the abs module is the same etc.


But despite the e89 being calibrated for street tires I would believe as long as you are running the same tire compound front and rear, and the tire contact patch ratio (if staggered) was the same front to rear as factory you would not have an issue.

The tires I use are Hankook Z214 squared at 275/35R18. Stock is 225/255 RFT. More grip means more weight transfer to the front which means the brake bias becomes too rear-biased. Its not an ABS problem as such, although the ABS itself can probably also be optimized depending on wet/dry and street/semi-slick/slick tires setup.

 

[F87Source]

The tires I use are Hankook Z214 squared at 275/35R18. Stock is 225/255 RFT. More grip means more weight transfer to the front which means the brake bias becomes to rear-biased. Its not an ABS problem as such, although the ABS itself can probably also be optimized depending on wet/dry and street/semi-slick/slick tires setup.

Oh yes that is indeed correct regarding brake biasing, I never really had to think about brake bias before since my cars mostly felt fine.

I guess maybe you could look at adjuster valves that are sold on line, but it probably will interfere with ABS functionality.

 

[sancho78rus]

How did you realize the brake bias adjustment? Any DIY guide?

We made custom brake balance bar with 2 master cylinders and bias adjuster.

 

[sancho78rus]

Me personally I think ABS is one of the best inventions on the modern day car so I would never delete it. Plus I think the factory brake bias setup by bmw is pretty good so no real need or desire on my end to change it in any way.

Braking with abs is not informative, especially when the abs has already worked on only one wheel - you do not understand what is happening, you cannot normally brake in a corner, etc.

You will probably get alot of error codes if you delete the factory ABS setup and likely limp modes too. IMO you probably should look at ESYS (or what ever the coding software is on the e89) and see if it is capable of being coded to have the 1m ABS setup. You might need to update your istep if your car preceedes the 1m build date. Or check on real oem if the abs module is the same etc.

Yes, I got a lot of errors after cutting out the abs block. Strange, but the windshield wipers even stopped functioning normally - they always worked and it was impossible to turn them off. We had to return the block, we just cut out the actuator itself, which weighs too much

 

[NoQuarter]

The windshield wipers coming on is often a symptom of something wrong in the PT-can bus from my experience.

 

[sancho78rus]

A couple of times there was an error 29F1 DME: Fuel Pressure, Plausibility
Other time just lack of power.
And its ok when I race on full tank.

Btw, the problem was solved by replacing fuel filter bucket to new OEM and fuel pump to DW 65C (in stock bucket).
Now I can run even on empty fuel tank.

 

[aus335iguy]

The ABS modules in the Z4 may well be the same as the unit on the 1 and 3 series cars. You’ll need to check. If it is the same you can force flash the module with 1M or M3 calibration

Coding M modules in a non M car

Hi All There are a number of you who are trying to access m3 and 1m modules in BMW standard tools and thats an issue as they aren't showing up from this thread here https://bmw.spoolstreet.com/threads/discussion-about-issues-encountered-whilst-converting-to-m3-flash-and-gws.3011/page-12 Ok...

bmw.spoolstreet.com

 

[aus335iguy]

Also There’s a thread in the DCT section where a retrofit of M3 DCT and Mdrive including M Dynamic mode Can be activated via a steering wheel button press.

N54 DCT w/M3 Conversion

::DISCLAIMER:: This conversion requires expert knowledge of module coding and flashing. It will include the requirements to spoof an M3 Vehicle Order inside NCS Expert to allow NCS Expert to code certain modules correctly without modifying the actual Vechicle Order. If you use NCS Expert to...

bmw.spoolstreet.com

 

[Asbjorn]

The ABS modules in the Z4 may well be the same as the unit on the 1 and 3 series cars. You’ll need to check. If it is the same you can force flash the module with 1M or M3 calibration

Coding M modules in a non M car

Hi All There are a number of you who are trying to access m3 and 1m modules in BMW standard tools and thats an issue as they aren't showing up from this thread here https://bmw.spoolstreet.com/threads/discussion-about-issues-encountered-whilst-converting-to-m3-flash-and-gws.3011/page-12 Ok...

bmw.spoolstreet.com

Thanks for the recommendation. Maybe the electronic parking brake "feature" on the Z4 will turn out to be a road block here? @carabuser

 

[carabuser]

Haven't tried flashing the ABS module. How would M division improve ABS?

 

[Asbjorn]

Haven't tried flashing the ABS module. How would M division improve ABS?

I assume ours was calibrated for non-grippy RFTs and eco brake pads whereas M would have been meant for PSS tires and possibly sportier pads? Something about G-force expectations and how much ABS needs to release the brake force to regain traction (less on stickier tires and less on grippier brake pads).

 

[carabuser]

That's a possibility. If that were the case then the software on the ABS module would differ between the various models of Z4 as they all have different brakes.

 

[aus335iguy]

By most accounts the M division DSCs are less sophisticated and less intrusive.. Dunno if thats what youre after. Its a moot point though given the electric handbrake. Unless what ive read about netTodat coding M division calibration on non M DSCs is true...

 

[Asbjorn]

By most accounts the M division DSCs are less sophisticated and less intrusive.. Dunno if thats what youre after. Its a moot point though given the electric handbrake. Unless what ive read about netTodat coding M division calibration on non M DSCs is true...

DSC=off is actually fine on the Z4. Does not stop you from rotating/sliding the car with trail braking like it does on the the 1M. So main point of interest would be the ABS. But is is probably all interlinked...

 

[Asbjorn]

Are you running -3 camber front and -2 rear? Did you tried more?
What caster?
Do you use wheel spacers?

So it turned out I am running around -4 camber front and -2.5 rear. Still in the blind about caster and actual toe degrees. But I was definitely running too much toe out last time. I also found out that my car is now at stock ride height rear and -1cm front. Excellent!

Report from last time attack running the square Hankook Z214 semi-slicks.

And below a report from this weekends time attack, this time running staggered Hankook RS4 tires.

Some conclusions:
1) Running Hawk DTC70 front and EBC Orange rear definitely moved the brake bias forward. More than enough also.
2) 275 semi-slicks rear is a good match for the weight and power of this car. Could even use a bit more rear grip at times. With 265 "street tires" and below the tail is just all over the place.
3) More testing is needed running the Z214 275 square setup to dial out the last mid-corner under steer. I might try one step softer on the front sway bar.

 

[Lurcher]

stock ride height rear and -1cm front

Running that Red Bull F1 angle of attack!

 

[Asbjorn]

stock ride height rear and -1cm front

Running that Red Bull F1 angle of attack!

That's exactly right. I can't even start to calculate the amount of downforce it must have. But no, in reality it looks pretty flat and stock. Just a bit funny how the right side is lower than the drivers side. Not sure how that happened.

Some pictures from last weekend running street tires below. I really like how the car looks from above, and I guess the camera guy agreed.

I made an updated dual language version of the setup sheet. Sometimes I need to communicate with chinese instructors and mechanics so this should make it easier. Its attached in case anyone wants to use it. I will try to get the car corner weighted next week.

Had some fun playing around with AiM data from previous session. It turns out the software can make a power estimate using the speed, rpm, acceleration and pedal position channels it logs. You just need to input drag coefficient, weight and frontal area.

Different sensors yield different results, but all of them indicate that power increases with rpm. So at least I can conclude that I need to shift near the red-line, not earlier.

Also did these heat maps to visualize how the water and engine oil temperatures develop over one hot lap.

Above was done in 88F humid heat, and the lap clearly exceeded the cooling capacity of my car. Still, it is interesting how the oil reacts with a delay compared to the coolant.

Here's another interesting x-y plot (longitudinal vs lateral acceleration G), showing the difference in grip available with Hankook Z214 semi-slicks (black) vs Hankook RS4 street tires (blue)

 

[derekgates]

The videos you post are incredible. You are flying through the course. Your Accusump certainly kicks in often, you weren't joking.

I am in awe of how much data you collect and how you are constantly improving. I am gracious you share this journey with us.