[M1500Z]

Originally Posted by richard in NC

I've also learned to ease into the brakes a bit which helps, say the first 50 feet from 100 mph, and then hard on them. They also made some rear camber/toe adjustments that could help.

I think this is the way to drive around the problem. I cannot say why this happens, but the idea that it's due to intervention from the car's safety measures is interesting.

Anecdotal evidence aside, I decided to look at some data from my Solo DL to see what it might tell me. There are 2 turns I've experienced this issue pretty strongly, one is T12 at COTA, the other is T15 at Eagle's Canyon Raceway. I decided to use data from ECR where I encountered the issue and then adapted to drive around it later in the day.

Braking at the left-hand T15 isn't what I would call complicated. I position the car track right and brake hard at or just after the #2 marker, and trail into the turn, so there really shouldn't be any steering movement in theory. But what happens when you try and "kill the brakes" as my instructor said, is the car shifts inward what feels like a car's width and I would correct, trying to reposition the car back wide. I think you can see that in the data capture below (unfortunately I don't have video).

What's interesting about this screen capture is that it shows the ASC activating and appearing to slow the rear-left wheel, but only deeper in the braking zone. Note that ABS is on through the majority of this heavy braking and that the Brake P F (front brake pressure) is not indicative of brake pedal pressure.



I'm still thinking about this, but I am beginning to think it's a combination of not enough spring/damping to control the rapid transfer of weight unloading the rear, and alignment/geometry. In that case, I think the ASC may just be exacerbating the issue, but not the root cause. I may be right or wrong (doesn't matter to me), I just enjoy investigating and learning from data.

My car setup

• 275/35 18 square
• AP Racing 9668 front kit
• DS 3.12 pads
• Öhlins Road & Track @ 3 clicks from full stiff

[OG Shark]

Originally Posted by M1500Z

I think this is the way to drive around the problem. I cannot say why this happens, but the idea that it's due to intervention from the car's safety measures is interesting.

Anecdotal evidence aside, I decided to look at some data from my Solo DL to see what it might tell me. There are 2 turns I've experienced this issue pretty strongly, one is T12 at COTA, the other is T15 at Eagle's Canyon Raceway. I decided to use data from ECR where I encountered the issue and then adapted to drive around it later in the day.

Braking at the left-hand T15 isn't what I would call complicated. I position the car track right and brake hard at or just after the #2 marker, and trail into the turn, so there really shouldn't be any steering movement in theory. But what happens when you try and "kill the brakes" as my instructor said, is the car shifts inward what feels like a car's width and I would correct, trying to reposition the car back wide. I think you can see that in the data capture below (unfortunately I don't have video).

What's interesting about this screen capture is that it shows the ASC activating and appearing to slow the rear-left wheel, but only deeper in the braking zone. Note that ABS is on through the majority of this heavy braking and that the Brake P F (front brake pressure) is not indicative of brake pedal pressure.



I'm still thinking about this, but I am beginning to think it's a combination of not enough spring/damping to control the rapid transfer of weight unloading the rear, and alignment/geometry. In that case, I think the ASC may just be exacerbating the issue, but not the root cause. I may be right or wrong (doesn't matter to me), I just enjoy investigating and learning from data.

My car setup

• 275/35 18 square
• AP Racing 9668 front kit
• DS 3.12 pads
• Öhlins Road & Track @ 3 clicks from full stiff

T12 at COTA like you said is definitely the most noticeable for me.

On the suspension - different platform but on my race E92 M3 it really didn't change much going from stock to full race car with a relatively high sprung & well sorted suspension. Starting down the suspension rabbit hole hopefully next week with the M2C - will see if there are any changes with it.

Side note - how are you getting along with the 3.12's & ABS? I like the 3.12's but have pretty much settled on them being only for competition cars while on slicks. Feel like they are just a bit too easy for my liking to get into abs when not at that level of grip. Sticking with 1.11's for pretty much everything else & been putting my customers in them as well to start.

[M1500Z]

Originally Posted by OG Shark

T12 at COTA like you said is definitely the most noticeable for me.

On the suspension - different platform but on my race E92 M3 it really didn't change much going from stock to full race car with a relatively high sprung & well sorted suspension. Starting down the suspension rabbit hole hopefully next week with the M2C - will see if there are any changes with it.

Side note - how are you getting along with the 3.12's & ABS? I like the 3.12's but have pretty much settled on them being only for competition cars while on slicks. Feel like they are just a bit too easy for my liking to get into abs when not at that level of grip. Sticking with 1.11's for pretty much everything else & been putting my customers in them as well to start.

Curious to see what you learn. There are threads about wiggle under braking all the way back to E36—various chassis, various suspension setups, various methods of intervention if any. Perhaps it's just the nature of BMWs or FR cars in general?

On braking might want to move this to the chit-chat thread
I generally like the 3.12s although I may try the 1.11s next. I love how the 3.12s almost never feel hot at my grip levels and are consistent no matter what—basically they're always better than my 220TW street tires. But I do find myself over-braking and could use a tad more finesse to properly use them.

Regarding ABS, I need to check my data, but I have read differing opinions on ABS with some saying use it to it's maximum and others saying brake right to the cusp of where ABS comes one. Ross Bentley, for example says (paraphrasing) in modern BMW/Porsche ABS systems (i.e. advanced), wait for the last moment and hit the brakes as hard/fast as you can, letting the system do the work for you. He does say that you'll likely need to adapt your driving to this style and still need to make sure you're not in ABS when beginning turn in.

So I don't know—I generally use ABS in heavy braking zones and don't feel it negatively effects me. I'm concentrating more on things like managing the weight transfer, trailing in without too much brake, and a smooth release. But there's always that other argument that ideal braking is with a hint of under-rotation and maybe our systems don't allow that.

[OG Shark]

Originally Posted by M1500Z

Curious to see what you learn. There are threads about wiggle under braking all the way back to E36—various chassis, various suspension setups, various methods of intervention if any. Perhaps it's just the nature of BMWs or FR cars in general?

I haven't really seen it with any other FR cars that I have tracked - to me it feels like a BMW thing. If it is suspension related I'm not sure what we are going to do with the comp will correct it since we are still intending to keep street manners relatively friendly. But definitely going to check for it & will update.

Other stuff moved to the chit-chat, good call

[AWC-F87]

Hey guys! I'm very happy to report that thanks to David aka daap1193 and his magic brake coding and steering coding I noticed a tremendous difference in my cars feel. The car had significant more modulation In braking along with a huge decrease in wagging under threshold braking. The car was honestly night and day better!

[daap1193]

Originally Posted by AWC-F87

Hey guys! I'm very happy to report that thanks to David aka daap1193 and his magic brake coding and steering coding I noticed a tremendous difference in my cars feel. The car had significant more modulation In braking along with a huge decrease in wagging under threshold braking. The car was honestly night and day better!

Thanks for your feedback, our theories about the side to side squirming are correct. The development has been a success and all the forum members that code the brakes with me are extremely satisfied. Hope more people code their brakes and feel the difference. The improvement is that noticiable, that any one get a full refund if doesn´t notice any improvement.
Im curretly working with a BMW specialist from the UK, helping them to achieve a record on the Nürburgring. They have a Bmw test pilot for the attemp so will be sharing his feedback when we finish working on their car.

Really aprecciate all the comments from the forum members that code their brakes with me. If any one else still interested just PM me.

[blitzyo]

Do you mean Pittard is driving it?
If it is, then I need this coding.

[FaRKle!]

I also disabled the emergency pre-pressurizing function and felt it made a big difference at the track in braking zones.

With the AP brake kit it makes a noticeable difference on the street too. Even at just 1/3 throttle and cruising at street speeds if you lift off the throttle abruptly the DSC would pre-pressurize enough to cause the AP brakes to clamp slightly causing a forward weight shift (felt like engine braking).

At the track I'd always have to get on the brakes a bit slower than preferred in this one zone where you start braking a bit before a crest that drops off, otherwise the front wheels would lock up as soon as the car got a bit light. After disabling the pre-pressurize function I no longer have that problem since the system isn't applying more force than what my foot is telling it to.

[TrackdayThierry]

I really need to do this, My car had a long pedal at Sebring. but when I tapped the brakes before I applied full braking force really kept the brake pedal high and firm and was able to reach a much higher braking pressure.

This is a much-needed fix to achieve more confidence in the braking zone and be more consistent.

[TrackdayThierry]

Originally Posted by daap1193

Thanks for your feedback, our theories about the side to side squirming are correct. The development has been a success and all the forum members that code the brakes with me are extremely satisfied. Hope more people code their brakes and feel the difference. The improvement is that noticiable, that any one get a full refund if doesn´t notice any improvement.
Im curretly working with a BMW specialist from the UK, helping them to achieve a record on the Nürburgring. They have a Bmw test pilot for the attemp so will be sharing his feedback when we finish working on their car.

Really aprecciate all the comments from the forum members that code their brakes with me. If any one else still interested just PM me.

daap1193 please look out for my PM.

[bmwracer12]

Originally Posted by TrackdayThierry

I really need to do this, My car had a long pedal at Sebring. but when I tapped the brakes before I applied full braking force really kept the brake pedal high and firm and was able to reach a much higher braking pressure.

This is a much-needed fix to achieve more confidence in the braking zone and be more consistent.

I forgot about this post until I saw your reply. The changes Daap1193 made to my car are noticeable and helped me gain confidence on track. My brake pedal is much more consistent.

At first I was concerned about remote programming especially when it involved the brakes. I asked lots of questions and got comfortable with the idea. I was able to see all the changes he made, real time while my PC was connected to the car.

He did a great job explaining how everything works and why the changes we made should help, and what to expect.

I went to a couple different tracks over the last year and tested the settings. One weekend, daap1193 was available remotely while I was at the track and we tried a few different settings. I could tell a difference at track and we were able to settle on what worked best for me.

I recommend reaching out to daap1193 if you have similar issue with lack of consistent brake feel from your M2. It made a big difference for me on track.

[m dizzle]

I'm so happy I found this thread....

Relatively new M2 CS owner....and with around 15 years of track experience, racing, and driving a plurality of BMWs and other cars, the only gripe I have with the car seems to be similar to the one the OP was experiencing here.

For me its not the ABS engagement but the booster overboosts inconsistently, so if entering a turn where a light brake is required due to coming in with some yaw and needing to settle the car, or in other turns to allow weight transfer onto the front axle for better grip....again not at the threshold but light braking....it grabs just too hard and aggressively.

My brake pad selection is quite aggressive so I was thinking it may be due to that (Ferodo DS1.11)...so my plan was to move to a less aggressive pad which has a lower initial bite/torque curve....but happy to read about programming options?

Is this something familiar to others who track their F80/F82/F87?

[daap1193]

Originally Posted by m dizzle

I'm so happy I found this thread....

Relatively new M2 CS owner....and with around 15 years of track experience, racing, and driving a plurality of BMWs and other cars, the only gripe I have with the car seems to be similar to the one the OP was experiencing here.

For me its not the ABS engagement but the booster overboosts inconsistently, so if entering a turn where a light brake is required due to coming in with some yaw and needing to settle the car, or in other turns to allow weight transfer onto the front axle for better grip....again not at the threshold but light braking....it grabs just too hard and aggressively.

My brake pad selection is quite aggressive so I was thinking it may be due to that (Ferodo DS1.11)...so my plan was to move to a less aggressive pad which has a lower initial bite/torque curve....but happy to read about programming options?

Is this something familiar to others who track their F80/F82/F87?

Try out my coding, if not 100% satisfied will revert back to stock and refund all. DM if interested

[-Eidos]

Originally Posted by daap1193

Try out my coding, if not 100% satisfied will revert back to stock and refund all. DM if interested

+1. Brake pedal pressure is super consistent and predictable now. I run DS1.11 f+r as well. 4 track days on new coding with only positive things to say. daap1193 was prompt and threw in some extra coding work in for free since he was already in there.

[OG Shark]

Originally Posted by daap1193

Try out my coding, if not 100% satisfied will revert back to stock and refund all. DM if interested

Originally Posted by -Eidos

+1. Brake pedal pressure is super consistent and predictable now. I run DS1.11 f+r as well. 4 track days on new coding with only positive things to say. daap1193 was prompt and threw in some extra coding work in for free since he was already in there.

This is awesome to hear. daap1193 is coding mine today & we are off to COTA this weekend. Very excited to see the difference it makes.

[Yuri96]

Interested in brake coding. daap1193 can you send me PM with contact information.
Anyone know what is needed in terms of ECU codding to replace stock ABS with Bosh M4 unit ?

[Wolfman’s Brother]

Originally Posted by OG Shark

This is awesome to hear. daap1193 is coding mine today & we are off to COTA this weekend. Very excited to see the difference it makes.

Same here. Look forward to hearing your thoughts.

[OG Shark]

Very happy with the daap1193 's brake coding. Ran the M2C pretty hard out at COTA this weekend and there is definitely a noticeable improvement. David is also excellent to work with and he coded some other things for us while he was in there. All in all extremely happy with his work.

[blitzyo]

I had disabled the brake pre-pressurising system coding earlier and that immediately helped the car stop braking when letting off throttle and stop the pedal over boosting into ABS in high speed braking zones.

The pedal was still inconsistent, didn't feel linear and was hard to modulate with high mu brake pads.

Had daap1193 code the car with two more of his functions and pedal is consistent braking at the limit now and has a bit better feel for modulation.

Actually feel confident enough to left foot brake with this setup now.

[ksalih]

Can confirm daap1193's brake coding translated into a noticeable increase in brake pedal feel consistency this last weekend at the track in Phoenix. There appeared to be less ABS intervention as well. Overall, I have nothing but positives to say regarding this change.

David was also very easy to work with as we troubleshot a few issues (low battery voltage when attempting to code, etc.). A pleasant experience!

[nando_514]

Throwing in my 2c here as well!

I've had 2 track days since applying daap's brake coding and all I can say is WOW! The pedal feel is a night and day difference. Before the brake coding, the pedal felt dead and assisted at random points through the braking phases.. Now, I can really feel the deceleration through the pedal. You can feel what the brakes/wheels are doing under braking. It's unbelievable! It's made braking on uneven pavement an absolute joy! Before the coding, braking on uneven pavement was hit or miss. Now, it feels more analog, almost like throwing it around in an older car, not a 2018 computer

David was a joy to work with and even applied some other coding like Euro MDM mode, and some differential magic! It was the best 100 bucks Ive spent on the car hands down

[CSBM5]

Originally Posted by daap1193

Thanks for your feedback, our theories about the side to side squirming are correct. The development has been a success and all the forum members that code the brakes with me are extremely satisfied. Hope more people code their brakes and feel the difference. The improvement is that noticiable, that any one get a full refund if doesn´t notice any improvement.
Im curretly working with a BMW specialist from the UK, helping them to achieve a record on the Nürburgring. They have a Bmw test pilot for the attemp so will be sharing his feedback when we finish working on their car.

Really aprecciate all the comments from the forum members that code their brakes with me. If any one else still interested just PM me.

Any update on the above work with the BMW test driver?