ABS Failure at the Track. Flat Spotted Tires :(

[Longboarder]

So I decided last minute to hit Auto Club Speedway this Saturday. Was a terrific day a bunch of bros there. Nice cool temps and dry track. Some high clouds to begin but gave way to sun. Temps probably 48 deg F in the morning rising to 60 deg F in the afternoon. Couldn't have been better conditions.

This was my first track day in the M3 in over two years. My track tires - NT05s were old, cracking and a little light on tread so I decided to pony up for some Bridgstone Potenza RE71R's. Good thing as when I had the wheels installed the front pads were really low so got some new pads as well. Good to go.

Everything was going well. First session just chilled getting the feel of the car and track and then was able to get into the groove session 2 and then I tried to push a little in session 3 as we were gridded by lap times and had a free track. Here's a vid of session 3 which unfortunately was short lived. I was getting ABS warning light all day which is fine if you aren't pushing it. But came in hot for turn 6 and that's all she wrote. Completely flat spotted both front tires which are now ruined. Expensive lesson. Rears are good to go.

Car is going to MRF tomorrow to see what's up with the ABS. First issue I've ever had with the car in over 3 years of ownership.

Anyway here's the vid if you have 10 minutes of boredom to kill. Lock up is at the very end of the vid if you want to see a one second lock up that will cost me $700.

[surlynkid]

ABS light on all day but you kept driving? Good thing I don't ever have to worry about you being behind me on track.

[Longboarder]

Originally Posted by surlynkid

ABS light on all day but you kept driving? Good thing I don't ever have to worry about you being behind me on track.

Coming to COTA this year check your rear view.

[surlynkid]

You won't be in my group or my wife's group. We are safe.

[Longboarder]

Originally Posted by surlynkid

You won't be in my group or my wife's group. We are safe.

Who knows I have a number of cars of varying performance haven't figured out which car/run group gonna bring yet.

[roastbeef]

i'm interested in hearing what could cause this. at least no one got hurt and you didn't crash!

[surlynkid]

Well you won't be instructing, so you won't be in my group. The car you bring does not matter. It is your skill and driving history that matter.

[roastbeef]

are you guys butting heads or something?

[Longboarder]

Originally Posted by roastbeef

are you guys butting heads or something?

I started messing with him but I'm think he's serious lmao.

Obviously with ABS light on I never pushed the car with someone right in front of me. I did when I had an open track no one in front as the vid clearly shows.

[M3 Number 86]

I've had the abs warning come on at buttonwillow before so I came in the hot pits and turned the car off and back on. Warning went away and it seemed fine. It I should get the code read I suppose. I thought I melted a cable or something and checked while swapping my oem pads back on and everything looked fine. I guess I should get it checked out but my braking seemed fine.

One of those exr cars that look like a baby m3 dtm car had horrible lock up in front of me - smoke flying everywhere. Kind of surprised me.

How'd you like the re71 initially though? My front right nt01 has a few slits of chording so will need to take an extra tire to the next track day just in case. I'll throw them on the rear right for buttonwillow cw and monitor. Everyone says they grip best just before chording so gotta keep them lol.

[RickyBobby]

Check your brake fluid level. If it's low, it can trigger abs warnings.

[Longboarder]

Originally Posted by roastbeef

i'm interested in hearing what could cause this. at least no one got hurt and you didn't crash!

Originally Posted by M3 Number 86

I've had the abs warning come on at buttonwillow before so I came in the hot pits and turned the car off and back on. Warning went away and it seemed fine. It I should get the code read I suppose. I thought I melted a cable or something and checked while swapping my oem pads back on and everything looked fine. I guess I should get it checked out but my braking seemed fine.

One of those exr cars that look like a baby m3 dtm car had horrible lock up in front of me - smoke flying everywhere. Kind of surprised me.

How'd you like the re71 initially though? My front right nt01 has a few slits of chording so will need to take an extra tire to the next track day just in case. I'll throw them on the rear right for buttonwillow cw and monitor. Everyone says they grip best just before chording so gotta keep them lol.

Yes guys will definitely post up what the cause of ABS failure is. While the light is not on now, it comes on intermittently so hopefully there is a stored code and a known easy fix.

So I did like the RE71's in the little time I used them. In the same category, I have tracked with PSS and NT05's. Also with RS3's and R888's but those are not really in the same category but still street tires. With 300 tread wear PSS aren't really good for the track, so I would compare RE71's with with NT05's. I didn't get enough seat time to figure out which are better for a stock suspension M3. I did notice a lot of road noise on the RE71's whenever I would drive over a less-than-perfect road surface. Would sound like I was driving through a rain puddle....kinda like the sound of tearing paper. Bugged me if I was using them as a street tire.

[Longboarder]

Originally Posted by RickyBobby

Check your brake fluid level. If it's low, it can trigger abs warnings.

Excellent thx for the tip...will have MRF check that out today for sure then.

[tdott]

Originally Posted by Longboarder

Excellent thx for the tip...will have MRF check that out today for sure then.

Probably not possible it's due to low fluid unless there is a leak in the system somewhere. If your pads were low you would be more likely to have the problem then, but when new pads are in the piston is compressed and that pushes all the fluid back into the reservoir. But still a good idea to check.

My guess would be a bad speed sensor or a broken connection somewhere. Either way MRF should be able to sort you out.

[dparm]

My advice would be to keep one of those $30 OBD2-wifi/bluetooth dongles in the car at all times and just pay the $50 for BMWhat/Carly. You could've easily pulled the code during a cooldown session to see if it was something serious or just a nuisance light.

[ban25]

Welcome to the club! Check your wheel bearing. Mine was going in and out, causing the wheel speed sensor to drop out, ultimately resulting in ABS going out right as I was about to turn onto the road course. I had to get a new hub and I'm replacing the others next month just to be safe.

[Longboarder]

Originally Posted by DrFerry

Longboarder,

Watched the video. A few things to consider and check are listed below:

1) The ABS is calibrated for the ~0.5inch difference in stock front and rear tire diameters. There is a tolerance built in, but do your new tires preserve the difference in front and rear tire diameters?

2) Occasional failure to invoke ABS cycling could be as simple as a bad sensor (or sensors).

3) Check both of the front wheel sensor wiring looms and plastic connectors for integrity or dirt.

4) If the tires are truly flat spotted and you are going to trash them, consider trying some full ABS stops in safe place such as a vacant parking lot, to exercise the ABS and replicate the problem, then immediately read the codes.

5) In the video it looked like you were slightly turned when the lock up occurred. As in 4) above try turning the wheel slightly, while trying to invoke the ABS, to see if there is a link.

Other than that, my guess is mild brake fade from hot brake fluid (like vapor lock) and/or a bad ABS sensor(s) are the culprits. Get some cool air (ducting) to your brakes, especially when running on banked tracks since the major braking zones are usually very high speed down to low speeds for the infield sections. Hence, the brakes can take a beating.

Also, when you run on oval tracks, be sure to run staggered and higher pressures than on a road course = right side >=+4.0psi over left side. This is because of the centrifugal loading caused by the banking angle. The right front tire takes a heck of a beating and right rear when running on a banked track in an anti-clockwise direction. Just keep that fact in mind when you set the cold tire pressures, as you want to be sure not to overload the right front of right rear on oval tracks. Some of that discussed in the attached.

Thanks for the analysis!

1) I assume the tire size did not cause the ABS issue. My new RE71R tires are 255 35 19 F and 275 35 19 R. These are the exact same tire size (Michelin PSS) that I use for daily driving.

2) I do hope it's just a sensor.

3) Excellent thanks for the tip.

4) Yes these tires are trash. But good idea, while the ride is rough they certainly could be used for some ABS testing at least.

5) Great point I didn't even notice that but entirely possible the wheel was turned a little.

Yes I was starting tire pressure lower on the passenger side and it worked. Ending tire pressures were the same. I have looked into brake ducting but understand there is no good easy solution. Maybe something has changed I'll ask around. One the Porsche platform everything is so easy. There is a race part for everything.

Cheers.

[M3 Number 86]

Originally Posted by Longboarder

Thanks for the analysis!

1) I assume the tire size did not cause the ABS issue. My new RE71R tires are 255 35 19 F and 275 35 19 R. These are the exact same tire size (Michelin PSS) that I use for daily driving.

2) I do hope it's just a sensor.

3) Excellent thanks for the tip.

4) Yes these tires are trash. But good idea, while the ride is rough they certainly could be used for some ABS testing at least.

5) Great point I didn't even notice that but entirely possible the wheel was turned a little.

Yes I was starting tire pressure lower on the passenger side and it worked. Ending tire pressures were the same. I have looked into brake ducting but understand there is no good easy solution. Maybe something has changed I'll ask around. One the Porsche platform everything is so easy. There is a race part for everything.

Cheers.

I left my pressures from when I dropped them at buttonwillow and ran. Pressures were 37 all around hot. But the right front outside got a handful of short slits of chording so I'll throw them on the rears for next time. Didn't take a picture but I drew one

[Longboarder]

Originally Posted by M3 Number 86

I left my pressures from when I dropped them at buttonwillow and ran. Pressures were 37 all around hot. But the right front outside got a handful of short slits of chording so I'll throw them on the rears for next time. Didn't take a picture but I drew one

You draw just like my 6-year old!

[M3 Number 86]

Originally Posted by Longboarder

You draw just like my 6-year old!

Was on my phone. It's hard to draw with a finger LOL

[Longboarder]

Originally Posted by M3 Number 86

Was on my phone. It's hard to draw with a finger LOL

[bigjae1976]

There's a ring on the bearing which is what the wheel speed sensor reads. Sometimes brake dust and other stuff will foul the sensor or the ring.

Hopefully it's just that.

Sucks.