12-06-2020, 10:55 AM | #1 |
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M2 threshold braking - ABS interference
Hey Guys! I'm new to the forum. I recently bought a 2017 M2 and took it to the track. I have been driving an E36 on track for years as an instructor.
My question pertains to ABS and if there is any way to "raise the threshold" with some coding before ABS is activated or possibly even disable it completely. My E36 didn't have ABS and I was able to brake at the limit without locking the tires up. When I tried similar levels of braking in the M2, ABS engaged early and I felt like I had more pressure to give before losing traction. I did go from stock pads to performance friction 08 pads just for the event and I'm running re-71r tires. Around 2.5 degrees of neg. camber up front and stock camber in rear One of the guys I talked to said that the pad change may have made the ABS module think something was wrong because the deceleration rates changed so much from the stock pads for a given pedal pressure. Is there a way to code the ABS to a higher pedal pressure or something similar to give more room to manually manage traction? By the way, I'm driving on track with traction control completely disabled. Thanks in advance! |
12-06-2020, 02:48 PM | #2 | |
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But to fully disable ABS you need to basically disconnect 1 or 2 wheel speed sensors. ABS is one of the last systems still alive, even when steering angle, or yaw rate sensor failure causes stability or traction control to switch off. Even with a single WSS disconnected, you'll likely still have Electronic Brake Force Distribution, which will limit pressure increase on the rear tires, in order to ensure the fronts lock first. This is why I suggest 2 WSS, one front and one rear. I don't think there is a SW way to code it off, as it is heavily mandated legally. P.S. I find that getting deep on the brakes once the weight transfers at 1/3 stroke apply for 0.5s or so leads to best ABS performance. You likely have tried this as well, just an observation.
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12-06-2020, 03:37 PM | #3 | ||
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12-06-2020, 04:31 PM | #4 |
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I found PFC08 really challenging to modulate and seemed to go from no friction to ABS intervention very quickly. Maybe this is what you’re experiencing?
I didn’t find this quite as challenging with Pagid RSL29 or RSL1. RSL1 seemed to handle the temps of the blue brakes a bit better but didn’t last as long as the 29. Might be worth trying a pad change before diving into the brake system itself. Generally though, vs my 2002 and the Chevy SS Sedan I tracked before the M2, the M2 takes a pretty fine level of input to maximize braking but stay out of ABS for me. |
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12-06-2020, 04:58 PM | #5 | |
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I've heard the ABS threshold can be coded higher... I'm guessing that means a higher level of slip before ABS begins to pulse. Have you heard of that before? Is that really an option? |
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12-07-2020, 12:52 AM | #7 |
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Might be worthing asking a coding expert to check if there's any OEM coding for 400/380 MPBBK retrofit (red calipers) or 2NH option (grey calipers) - this may help with calibrating ABS etc ??
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12-07-2020, 06:37 AM | #8 |
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I like that idea. Is there an area on this forum for coders? Any suggestions for how to find one? I'm located in Alabama.
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12-07-2020, 11:24 AM | #9 | ||
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PFC08 is much grabbier than RS/RSL29, and is more difficult to modulate, but I like it way better than the RS/RSL29 on my F31. The RS/RSL29 there required too much pedal travel and force before you really felt like you're stopping IMO.
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12-07-2020, 11:50 AM | #10 |
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I must be the oddball here who doesn’t find PFC 08s hard to modulate. Granted, difference between just before ABS and well into ABS is probably 2mm, but at that point it’s more about force your foot exerts vs the pedal travel.
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12-07-2020, 11:50 AM | #11 |
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Even on stock pads, I find the M2C hard to modulate the brakes for smoothness at threshold levels. Best solution so far is quick but gradual application of the brakes. I can definitely tell ABS intervention if I overshoot a braking point and really mash into the pedal.
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12-08-2020, 08:13 PM | #12 |
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Ran PFC08s on my E46M3 MANY years ago but never had a problem with ABS there...granted, brakes were much smaller
Have only run RS29s on the M2 and have NEVER engaged ABS on track...I'm not hard on brakes (and actually just leave the RS29s on the car full time) and I'm not the fastest but I'm pushing |
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12-09-2020, 02:28 AM | #13 | |
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https://www.trackdayforum.com/index....#comment-26122 I haven't experienced the issue you are referring to (constantly getting into ABS too early) but I have experienced inconsistent brake pedal pressure feel due to intervention of BMW safety systems when the throttle to brake transition is either too fast or too hard/abrupt. I have noticed this in virtually every M car I have driven on track. (F87,F87C,F87CS, F80/2C, M8 Comp) and have learned that these cars like a slightly slower throttle to brake transition. Its possible that this same scenario could be leading you into ABS. When talking to BMW instructors, I learned that when the car thinks you are in a panic braking situation it rapidly boosts the brake pressure. They agreed it can be annoying, but suggested this is a street car first and the safety systems are necessary. With a slightly more gradual ramp up in brake pedal pressure this scenario is avoided. It also allows little more time for weight to transfer to the front wheels for braking which could help if there is an ongoing issue with loss of front wheel grip in braking and ABS intervention. |
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12-09-2020, 09:49 AM | #14 | |
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PS: Even during slow speeds on a wet skid I experienced varying brake feel as I nailed them during unexpected slides. Sometimes it was immediate hard braking and other times, I had to push hard into them, and then even harder to full stop before sliding off track. I think it varied based on abruptness, yaw and spin out speed. What you described is exactly what I experienced.
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12-09-2020, 11:50 AM | #15 |
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Excellent points KHAP13 . I’ve learned to drive around this by slowing my throttle to brake input as you’ve suggested. Combined with the higher torque of the PFC pads, that could be an interesting stacking effect.
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12-09-2020, 12:08 PM | #16 | ||
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12-09-2020, 02:13 PM | #17 | |
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How to get E-SYS varries as versions come out so you need to do some googling. My 2 cents find a forum member near you willing to code as a favour or check out you local BMW FB page for someone that can do it cheap. Its not hard just had learning curve and some hardware/software/time investment.
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12-10-2020, 12:38 PM | #18 |
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One other detail! I was running a set of track wheels and tires that do not have TPM sensors. So I had alerts on the dash saying that tire pressure was unknown etc. Is there any way that could have caused ABS to engage differently?
Based on the comments and link to the German site, it makes me wonder if all these safety systems are connected and without an accurate tire pressure and temp, the systems were more conservative. Thanks for all the input! |
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12-11-2020, 12:51 AM | #19 | |
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That said, I do vaguely remember some discussion of early cars having issues without TPMS sensors, but I thought the issues was that they couldn’t change drive modes or turn off DSC. Might be worth digging up to verify my recollection, but I thought that was a 2016 only thing. |
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01-31-2021, 12:51 PM | #21 |
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Look thru the postings on the 2'er forum. I recall somebody posting in fair detail about this. IIRC you can disable this, also related features that are trying to compensate for fade/boiling fluid. I think also some related TCS features that muck up the action of the aftermarket LSDs with high yaw (that may not apply to M2s).
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03-08-2021, 02:29 AM | #22 |
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I have developed and test a coding solution for your problem, to summarize I can disable all the brake electronic parameters that think you're going to crash and apply maximum braking force sending your car into abs zone, also I can reduce brake pressure-assist so you will be able to control the maximum brake pressure and therefore improve you braking on track, this will traduce into race car pedal feel and brake control, the problem is not abs maximum threshold as you suggest, PM me and will remote code your car if interested, I have tested this set up with different cars (M2-M3 M235 and M240i) and all of them owned by race drivers with amazing success and feedback.
I think I'm the first person to develop a solution for this problem, having a racing background and plenty of race driver friends we discuss how different race car brakes feel in comparison to our bimmers, so after many hours of testing and coding Development I finally ended with a solution which they have called "Gt4 coding for brakes. |
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