Had trouble engaging ABS at the track this week; how come?

[SmoothIsSlow]

Originally Posted by strat61caster

The latter is a good sign, the former leads me to believe you can push the pedal harder, I've coached people before to perform a similar exercise, it usually takes three or four attempts before they understand how hard they need to push, like "I'm about to make the seat back break" hard.

Next time if you can ask the instructor to perform the exercise in your car it might be worth it, maybe I'm wrong, maybe there's something off about the pads or the brake system and having someone experienced feel it and confirm is worth it's weight in gold.

Thanks for the reply. I should add that when I switched the fluid, I was being a doofus and accidentally let the front half of the reservoir run very low (low enough for me to not be able to see the top of the liquid...)

I just tried pressing the pedal very hard again with the car off, the pedal gets firm quick but if I do press very very hard, the pedal will travel some more, I am guessing that’s not air but the master cylinder or brake lines flexing?

How would air in the MC or abs module feel like?

[SmoothIsSlow]

Originally Posted by NoHaveMSG

You must have been running with ProFormance. ATE Type 200 is plenty good if you are new to tracking. That's what I ran for a year. You could try bedding the pads but I don't think that is the issue. In those conditions ABS intervention is really not that severe, usually you will just get a little back and forth chirping out of the front end with a light tug at the wheel. Likely you are not being hard enough on it.

Thanks! There was no instructor with me in the car.

To be honest, I thought I had engaged ABS (I autocrossed a Miata for a season and the ABS in that car was very obvious), but the instructors outside said that they didn’t see it.

What G’s should I be pulling at threshold braking with PS4Ses?

[ZDan]

Originally Posted by NoHaveMSG

Type 200 is plenty good if you are new to tracking.

Indeed, parts store name-brand DOT4 has always been plenty good for me, even in a biggish horsepower RX-7, and I've been tracking for, well, for a while... ATE typ200 *underperformed* vs. off-the-shelf Castrol or Pennzoil DOT4 at the track for me. I think "normal" DOT4 should be sufficient for most who track these cars. Here and in other forums I see people are using harder-to-get, more expensive brake fluids even with street pads, which is pointless, the pads are going to give up long before standard DOT4 brake fluid...

[ZDan]

Originally Posted by SmoothIsSlow

To be honest, I thought I had engaged ABS (I autocrossed a Miata for a season and the ABS in that car was very obvious), but the instructors outside said that they didn’t see it.

How would they "see" ABS engaged? My impression is that ABS on this car doesn't give a low-cycle lock/unlock phenomenon that would give staccatto 16th-note smoke-signals from the tires. I would trust your feel at the brake pedal more than what an external observer could see.

I don't think you have a problem, but if you do think you want or need more braking from a given pedal effort, look into higher-coefficient track pads.

[Capt Spaulding]

I apologize if someone already asked this, but are/were you able to lock the brakes at all?

I don't track, but occasionally will find a deserted back road and practice threshold braking for 10 minutes or so. The car should be able to lock the wheels.

[strat61caster]

Originally Posted by SmoothIsSlow

I just tried pressing the pedal very hard again with the car off, the pedal gets firm quick but if I do press very very hard, the pedal will travel some more, I am guessing that’s not air but the master cylinder or brake lines flexing?

Yes, Firewall/MC flex is a thing, you can actually see it with the hood popped up since you can see the top of the reservoir cap and watch it move.

No real way to describe air in the system from me that hasn't been said before.

Originally Posted by SmoothIsSlow

Thanks! There was no instructor with me in the car.

To be honest, I thought I had engaged ABS (I autocrossed a Miata for a season and the ABS in that car was very obvious), but the instructors outside said that they didn’t see it.

What G’s should I be pulling at threshold braking with PS4Ses?

The pedal pulses and that's the biggest indicator, you're right, you feel it more than hear/see it usually, tire screech and pulsing is what usually tips me off, but not all tires are loud enough and not all surfaces grippy enough.

You might be surprised at what it takes to be an instructor, some groups let any old knucklehead right seat, that doesn't mean they don't have valuable things to teach you and help you with, but this might be a case where their expectation of 1/16th note tire chirps and puffs of smoke are outdated.

[SmoothIsSlow]

Originally Posted by strat61caster

Yes, Firewall/MC flex is a thing, you can actually see it with the hood popped up since you can see the top of the reservoir cap and watch it move.

No real way to describe air in the system from me that hasn't been said before.



The pedal pulses and that's the biggest indicator, you're right, you feel it more than hear/see it usually, tire screech and pulsing is what usually tips me off, but not all tires are loud enough and not all surfaces grippy enough.

You might be surprised at what it takes to be an instructor, some groups let any old knucklehead right seat, that doesn't mean they don't have valuable things to teach you and help you with, but this might be a case where their expectation of 1/16th note tire chirps and puffs of smoke are outdated.

In the case, I believe the pedal does pulse, just not very hard. I can experience some (for a brief period of time) pulsing if I jump on the brakes going 10 mph in the parking lot even).

I am hoping the fact that the ABS pedal pulsing feels weak is normal with this car and not indicating that I got air into the ABS system (which I believe would cause ESC to act funny? ESC seemed to have acted normal at the limit grip on track.)

[SmoothIsSlow]

Originally Posted by Capt Spaulding

I apologize if someone already asked this, but are/were you able to lock the brakes at all?

I don't track, but occasionally will find a deserted back road and practice threshold braking for 10 minutes or so. The car should be able to lock the wheels.

Per earlier reply, I believe I do feel pulsing, just not as hard as the NC Miata I am used to. I autocrossed the BRZ twice a while ago before I flushed the fluid and changed the pads myself. I recall getting into ABS then but I am not sure how “strongly” the pulsing felt.

FWIW, if I just jump on the brakes in the parking lot, I can actually smell my tires briefly (with the accompanying pedal pulsing)

The ABS light doesn’t go on when ABS is kicked in, right?

[NoHaveMSG]

Originally Posted by SmoothIsSlow

The ABS light doesn’t go on when ABS is kicked in, right?

Honestly, I have never paid attention but I don't think so. It's noticeable when ABS triggers. You can feel it through the wheel too. Pedal feel isn't too bad in the twins when ABS is active.

[wparsons]

The ABS light does not come on when ABS intervenes, it'll only come on if there's an issue with the ABS system.