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View Full Version : Ice mode--should I disable ABS at the track?



vtluu
08-31-2005, 11:22 AM
In at least two fairly recent track events, I had an off due to suddenly finding the brakes ineffective at the end of a fast straight section. Most recently this happened in turn 14 at Thunderhill; I had a racing datalogger recording and was able to verify afterwards that I used the same braking point as in previous laps, and furthermore that the amount of deceleration due to braking was about half of what it was in previous laps.

Until now I'd attributed this--brake pedal still felt firm but car just wouldn't stop--to "pad fade". However I'm starting to have my doubts. It seems to me that pad fade would be somewhat more gradual and predictable--braking would become less and less effective, it wouldn't just suddenly "go away". Furthermore, in subsequent laps (with very little time to cool the brakes--after the off I pulled back into the hot pits and was immediately waved back on to the track) braking felt "normal" again. Granted I did move my braking points forward a bit but I got pretty much the same deceleration force that I got prior to the brake failure.

I suspect now that the failures I experienced were actually due to ABS going into "ice mode". This is a notorious phenomenon well-known to Subaru STi drivers, where the ABS ECU will, upon experiencing sudden lockup, believe the car is sliding on ice and will modulate brakeforce to a fraction of the normal amount. I can't say for sure because when it happened I was a bit too "distracted"--if that's the word for the feeling one gets when one is hurtling towards the edge of the track at near-triple-digit-speeds--to notice if the ABS was pulsing or not. Also, I would imagine that with brakeforce reduced, ABS pulsing would have been much more difficult to feel in ice mode.

I'm usually a big fan of ABS--even on the racetrack--because except for a few special circumstances, locking up the wheels really doesn't do you any good. Moreover, ABS enables electronic brakeforce distribution, maximizing braking in situations where you have uneven traction on each corner. However I wonder (a) if I might be using it as a crutch for not threshold braking properly if it's subtle enough that I sometimes don't know that I locked up a wheel, and (b) if it's more of a liability than an asset if it's unpredictably going to do this "ice mode" thing. So far it's only happened at tracks where there was plenty of runoff for me to drive straight onto, but if it happened at a track like Infineon, I'd be screwed.

Maybe I should therefore disable ABS when driving at the track? Thoughts/comments?

methods4
08-31-2005, 11:34 AM
This is the first I've ever heard of ABS being "iced" on an Evo.

I vote no on disabling your ABS. I think your first guess of fade would be more conceivable. Does this ever happen in your first couple of sessions? ABS don't know how hot your brakes are.

earlyapex
08-31-2005, 11:34 AM
Get better pads, you are overpowering them now that you are running 275 wide race tires.

What you are describing is pad fade. Yes, it is sudden, and yes, cooling them off by going into the hot pits will fix it.

The EVO does not have the same problem as subarus do as far as "ice mode" you are describing. I only experienced that in my subaru if there was gravel or a large bump that only broke traction from one wheel, and just letting off the pedal fast and getting back on it solved it.

I have locked up the evo brakes a couple times for a split second, more so at buttonwillow since the track conditions are worse than thunderhill, and I have never had the "ABS ice mode" you speak of.

I really believe you need more aggressive pads now, you are going faster and running much grippier and larger tires.

What pads are you using now? Also, threshold braking will most likely help, what is your braking technique, do you just slam on the brake or?

chrisw
08-31-2005, 11:43 AM
I started experiancing the "ice mode" after installing the Quaife.

After the quaife was installed, I started to get the ABS reaction over the same bumps on my favorite back roads where my WRX experianced the same problem...

hell, I can get the ABS to cycle in a parking lot (not autocrossing) by getting on the brakes before the torque and power to the front diff has disipated.

Maybe that is what is happening to you.

vtluu
08-31-2005, 12:51 PM
I'm running Ferodo DS2500 pads--which Navid has used to some effectiveness (but he doesn't have ABS). I was using the brakes pretty well last event--smoke rising from the brakes after each session, slight glazing and surface cracking on the rotors.

Both times I remember it happening, it happened after the brakes were good and hot--fairly late in the day. Last time in turn 14 at TH on my 8th session of the day; previously in "Sunset" at BW on my 5th session or so.

I don't have any reason to believe the issue was related to the Quaife LSD--in both cases I can remember, the track was smooth and grippy and clear of oil or debris (as far as I could tell) and I was braking in a straight line, so traction should have been pretty even. Does anybody know if the ABS ECU is programmed differently for '05 Evos which have a front LSD? (And if so, if they're interchangeable with the '03-'04 ABS ECUs?)

earlyapex
08-31-2005, 01:12 PM
I'm running Ferodo DS2500 pads--

Does anybody know if the ABS ECU is programmed differently for '05 Evos which have a front LSD?

I would try some more aggressive pads. I mean, you are using 275 wide race tires but street/track pads. Try some race pads. I know methods4 didn't really like the DS2500's.

What pads are you using in the rear?

Yes, I heard the 05 ABS is a new variant of "sports-abs" by mitsubishi. What's different, I have no idea.

Navid@xperformance
08-31-2005, 04:04 PM
The DS2500's were good for 2:00 lap at TH with 285 R tires. They also held up for 30 minute straight hot sessions. Yes, they are street/track pads, but they are damn good ones. They are the only pads I have found that are equally good on track as they are on the street.

Do you get better grip with race pads? Yes, but at the cost of having to change pads every time you go to track and eating up your rotors more often.

--Navid

earlyapex
08-31-2005, 04:22 PM
The DS2500's were good for 2:00 lap at TH with 285 R tires. They also held up for 30 minute straight hot sessions. Yes, they are street/track pads, but they are damn good ones. They are the only pads I have found that are equally good on track as they are on the street.

Do you get better grip with race pads? Yes, but at the cost of having to change pads every time you go to track and eating up your rotors more often.

--Navid

Yes, but don't you have many years of racing under your belt? You probably have perfect proper braking technique down.

Also, your car is approx 2900 I think you said at one point. That's 300lbs less then we are lugging around.

For the average weekend open tracker, I honestly believe we need more brake or take a class on proper braking and technique.

I faded the PF street/ track pads this summer two times at two events, not as bad as Tam, but I am only running 255 RA1s. I know I have a bad habit of staying on the brakes too long or trail braking a bit too much but I acknowledge that and am working on it.

My red calipers are now dark dark rose red and the brembo lettering is brown from heat.

I have also heard that ABS is harder on pads, etc than non-ABS. Is that true Navid?

What speeds do you hit in the front straight at thill Navid? I was hitting 120+ counter-clockwise and 130+ clockwise. I know you are probably doing more than that if you are hitting 2:00 laps

Navid@xperformance
08-31-2005, 05:04 PM
Yes, but don't you have many years of racing under your belt? You probably have perfect proper braking technique down.

I'd like to think that, but Tam is not exactly a newby. I was very impressed by the way he handled my car without ABS. The difference should not be that much.


Also, your car is approx 2900 I think you said at one point. That's 300lbs less then we are lugging around.

I wish! At the last track day, my car weighed 3025. Right now, I'm at 2940. I ran the same pads on my e46 M3 during the first OTC. That car weighed in at 3300.


For the average weekend open tracker, I honestly believe we need more brake or take a class on proper braking and technique.

That may be true in some cases, but I would work on the latter rather than the former.


I faded the PF street/ track pads this summer two times at two events, not as bad as Tam, but I am only running 255 RA1s. I know I have a bad habit of staying on the brakes too long or trail braking a bit too much but I acknowledge that and am working on it.

That's because the 4s pads are crap on track, not the case with DS2500's.


I have also heard that ABS is harder on pads, etc than non-ABS. Is that true Navid?

I haven't heard this, but if it's true, it's because people who have ABS are more likely to jump on the brakes than people without it.


What speeds do you hit in the front straight at thill Navid? I was hitting 125+ counter-clockwise and 130+ clockwise. I know you are probably doing more than that if you are hitting 2:00 laps

Honestly, I have never looked down at the speedo there. I know I run out of 4th gear just before start/finish and have to shift to 5th. Maybe at the next track session, Tam will let me borrow his data logger. :lol:

--Navid

earlyapex
08-31-2005, 05:11 PM
I'd like to think that, but Tam is not exactly a newby. I was very impressed by the way he handled my car without ABS. The difference should not be that much.

Well, he is fading, to the point of not even working, the same DS2500's you have and you aren't fading them, running 10 secs faster than him. So what's the problem?


That's because the 4s pads are crap on track, not the case with DS2500's.

I'm not running the 4s. 8) Are you thinking of porterfields? I am running Performance Friction, sorry, that's what I meant when I said PF. :)

vtluu
08-31-2005, 05:19 PM
I'm tempted to disable ABS anyway if only so I can learn to brake better.

I wish I had a little indicator like in GT4 where a light would come on every time ABS kicks in. When the brakes are slightly faded/soft it gets harder to feel the ABS pulsing.

Navid@xperformance
08-31-2005, 05:35 PM
I'm tempted to disable ABS anyway if only so I can learn to brake better.

I wish I had a little indicator like in GT4 where a light would come on every time ABS kicks in. When the brakes are slightly faded/soft it gets harder to feel the ABS pulsing.

The ABS pump also acts as a proportioning valve on most cars. An ABS equiped car with the ABS disabled will not have the correct brake distribution. I experienced this both in my e36 M3 and Joe's Evo last year when we riped the wheel sensor out at the Nationals.

It's easy enough to try what earlyapex suggested. Just be prepared to change pads every time you go to track. Pagid orange or PF97's are both good options.

--Navid

vtluu
08-31-2005, 05:38 PM
Yeah, I can swap a set of front pads in about the same time as it takes me to put on race tires (about 15-20 minutes).

Pretty soon I'll just want to trailer the car and keep it in race trim all the time. :)

earlyapex
08-31-2005, 05:56 PM
I love my PF pads. I use them 100% on the car, track and daily driving. They work fine for my current level on the track when its not over 100 degrees. :?

They don't squeel on the street, but they do whine sometimes. They don't dust anywhere close to the carbotechs I used to use.

Best pads I have used so far on any of my cars. Great wear, and very easy on the rotors for how aggressive they are.

methods4
08-31-2005, 09:08 PM
I second the Performance Friction 95.7 pads. They are much better than the set of DS2500 I had. Much better pedal feel and initial bite. I haven't run into fade issues like Earlyapex has, but then again I've been running street tires most of the time. You should give them a shot some time. Actually soon because I think that pad is going to be discontinued. They are $60 cheaper than the DS2500, no orange dust and only slightly louder on the street.

Edit: Tam, you should try stepping up to a more agressive pad before you start disabling ABS n stuff. Maybe the DS3000 or PF97s.

vtluu
08-31-2005, 09:59 PM
Thanks, I have a set of the PFs; in fact I had them on hand at TH, but I wanted to wear down the Ferodos before trying the PFs. I'll try the PFs next time I'm at the track (which unfortunately won't be until after my October trip to Italy) and just keep the Ferodos as a spare set.

Question: the PFs seem to have built-in metal shims; do you still use the factory shims on top of them?

hagakure
08-31-2005, 10:24 PM
Get better pads, you are overpowering them now that you are running 275 wide race tires.

What you are describing is pad fade. Yes, it is sudden, and yes, cooling them off by going into the hot pits will fix it.

The EVO does not have the same problem as subarus do as far as "ice mode" you are describing. I only experienced that in my subaru if there was gravel or a large bump that only broke traction from one wheel, and just letting off the pedal fast and getting back on it solved it.

I have locked up the evo brakes a couple times for a split second, more so at buttonwillow since the track conditions are worse than thunderhill, and I have never had the "ABS ice mode" you speak of.



I really believe you need more aggressive pads now, you are going faster and running much grippier and larger tires.

What pads are you using now? Also, threshold braking will most likely help, what is your braking technique, do you just slam on the brake or?



I had serious braking problems as well last time out at T-hill. Not tot he degree Tam had, but I did have to brake MUCH earlier than I usually do. I run the aforementioned PF's as well. In all honesty, they were a bit worn, down to 1/3 by the end of the day. With my new tire and wheel set-up I am going with Carbotech XP-10's for the next few events and see how that goes. I've been told that the carbotechs can also hold up to driving to and from the track at least, with vastly improved braking. We'll see.

Percy

methods4
08-31-2005, 10:24 PM
Thanks, I have a set of the PFs; in fact I had them on hand at TH, but I wanted to wear down the Ferodos before trying the PFs. I'll try the PFs next time I'm at the track (which unfortunately won't be until after my October trip to Italy) and just keep the Ferodos as a spare set.

Question: the PFs seem to have built-in metal shims; do you still use the factory shims on top of them?

I do not.

earlyapex
08-31-2005, 11:29 PM
With my new tire and wheel set-up I am going with Carbotech XP-10's for the next few events and see how that goes. I've been told that the carbotechs can also hold up to driving to and from the track at least, with vastly improved braking. We'll see.

If they are anything like the carbotech panther plus Methods4 and I where running before, which are less aggressive than the XP10's, they squeel like a stuck pig, and I am NOT exageratting. But if you aren't using them on the street. who cares. :)

earlyapex
09-14-2005, 05:06 PM
I love my PF pads. I use them 100% on the car, track and daily driving. They work fine for my current level on the track when its not over 100 degrees. :?

Ok, I take this back. I destroyed my PF pads yesterday at thill running 2:05 laps. Time for some more aggressive pads.

Navid, are your 2:00 lap times with or without the bypass?

RonV
09-14-2005, 06:53 PM
Hey guys,
Has anyone factored in what Tam's tire temps were like at the end of the the "brake fade' runs? I wonder if his fronts were overheated. This might be causing some of the "ice mode" feeling Tam was experiencing.

Just wondering.....

dohcvtec
09-14-2005, 07:07 PM
I love my PF pads. I use them 100% on the car, track and daily driving. They work fine for my current level on the track when its not over 100 degrees. :?

Ok, I take this back. I destroyed my PF pads yesterday at thill running 2:05 laps. Time for some more aggressive pads.

Navid, are your 2:00 lap times with or without the bypass?
How about some Hawk Blues? Maybe you need to rig some air ducting to the center of your rotors.

earlyapex
09-14-2005, 07:13 PM
How about some Hawk Blues? Maybe you need to rig some air ducting to the center of your rotors.

I'm trying to stay away from Hawk Blues, they are caustic as shizzle. I like the paint on my car and wheels.

Cameron@xperformance
09-14-2005, 09:48 PM
Navid, are your 2:00 lap times with or without the bypass?
im pretty sure it was with the bypass, but let me double check....

are you thinking about changing pads or something?

zyounker
09-14-2005, 10:34 PM
Just pull the fuse and try it.. Actually i have had my ABS disabled for the last 8K miles and prefer it.. On rough roads i have always hated when ABS kicked in. I actually have always wanted to do a test, because i think i can brake harder without it, but without data, that don't mean shit :P

If you don't like it, turn the car off, put the fuse back in.. Its not hard, and its something you can still try..

What fluid are you running? when was it last changed?


Although on a smooth road course i really doubt the problem is in the ABS programming. I would change out your fluid and try changing out the pads like recommended earlier in the thread. Maybe try putting in some custom brake ducts for cooling?

methods4
09-15-2005, 12:39 AM
How about some Hawk Blues? Maybe you need to rig some air ducting to the center of your rotors.

Negatory. I faded my PFs at this past event as well, even with brake ducting. Bryan and I keep outgrowing the parts we have on our car. At this rate, I will be bankrupt by the end of the year.

dohcvtec
09-15-2005, 10:02 AM
How about some Hawk Blues? Maybe you need to rig some air ducting to the center of your rotors.

Negatory. I faded my PFs at this past event as well, even with brake ducting. Bryan and I keep outgrowing the parts we have on our car. At this rate, I will be bankrupt by the end of the year.
You pansy's just brake too much. :)
Maybe that bling Alcon brake kit is in your future? Tony, maybe you can get Sean to bet his brake kit in a game of hold em. ;)

methods4
09-15-2005, 12:40 PM
You pansy's just brake too much. :)
Maybe that bling Alcon brake kit is in your future? Tony, maybe you can get Sean to bet his brake kit in a game of hold em. ;)

I would love to, but I don't want to remove my calipers to change pads. :)

But if they are free from Sean, then maaayyybe. :P