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This makes sense to me...but, I am a bit slow. Why are there so many people that run a more aggressive pad on the front? For example, the Sector111 "hot set up" is Carbotech XP12 (front) and XP10 (rear). If you have ice mode issues, this would make it worse, right?.... and the opposite set up might help?
Maybe there's more than one cause which depends on car setup. I know that for me, the hotter pads in front, moving the brake bias forward, helped for sure. One of my local tracks, Thunderhill Raceway, has an uphill hard braking zone on a turn (T5, going up the crow's nest), where running the same pad in front and back got me ice mode every single time. With XP12F/XP10R, it happens once in a great while.

I'm running Nitron Singles, on Sector 111 "soft" springs, on Yokohama A005 slicks.
 

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Maybe there's more than one cause which depends on car setup. I know that for me, the hotter pads in front, moving the brake bias forward, helped for sure. One of my local tracks, Thunderhill Raceway, has an uphill hard braking zone on a turn (T5, going up the crow's nest), where running the same pad in front and back got me ice mode every single time. With XP12F/XP10R, it happens once in a great while.



I'm running Nitron Singles, on Sector 111 "soft" springs, on Yokohama A005 slicks.

Slicks are the answer here. ABS looks at both the slip and the rate of decel of the wheel. If you run a gripper tire plus grabbier pads, the decel on the rate of rotation isn't as hard to control as the stock combo. That's also why the initial bite of the pad can be a bigger factor than the dynamic coefficient of friction.


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Discussion Starter #23
Larger front brakes or "less grippy" rear pads will compound the problem. The base issue is that there is not enough rear brake. The evidence is overwhelming...if the car is going in to an ABS event because a front is starting to lock; there is far too much front brake bias. "Ice mode" is simply the ABS intervening as it would on any other vehicle equipped with ABS. It is far more annoying with the Elise as a result of a light front end with heavily front biased brakes.
This is incorrect. Ice mode is entirely different from simple ABS application. If it were simply a matter of the fronts hitting ABS and the rears having little to no influence on things, the car would still slow down plenty fast, just not as fast as optimal.

The "ice mode" event that everyone is really talking about is when the system locks up to a different kind of ABS, where all 4 wheels have drastically reduced pressure, and the car barely slows at all -- maybe 15-20% of usual braking force is being let through. This inevitably involves you flying off the end of a braking zone at a very high rate of speed, almost like you didn't slow down at all, as happened to me once this weekend, fortunately in a safe place.
 

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Jeff, going from XP10/8 to 12/10 resolved ice mode in 3d at BFR and as I think about it I don't think I've experienced it since making the pad compound change.

thanks for the tip Ken, that is pretty much the only corner I can regularly get ice mode, mostly due to the urge to start applying brake pressure before straightening the car out.

Looks like i'll be ordering an xp12 f at the end of this year :)
 

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As for the EBD description; the ABS system cannot determine the rate of pedal application-there is only an on/off input from the brake switch-there is no brake pedal position sensor. As for losing the brakes in "ïce mode", it is quite possible that the ABS HCU may have depleted all stored fluid during a particularly long ABS event. This system has no accumulator and once the quantity of fluid that is stored in the master cylinder(not the reservoir) and the small amount that resides in the HCU is depleted by the isolation and vent solenoids cycling it is quite possible that most of the brake pressure has been exhausted. Once again, this ABS system has no place in a competition environment, therefore avoiding the ABS event by maximizing brake balance and at the same time overall brake performance, is the best remedy (in my dopey opinion!).
 

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reading some of the comments here, it's important to point out that "ice mode" is not just the ABS working like it should.
ABS is not a bad thing, basically it lets you steer your car while being pretty close to maximum available braking friction.
when the car goes into "ice mode", the ABS system gets activated with no power on the brakes! it makes the same ABS noise and you're shut out of the braking system. You want to brake, but the system won't let you and you just keep on going full speed.
it's scary and, most of all, ridiculously dangerous and a serious flaw.
 

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I assume we all know that a quick release and re-application of the brake pedal will eliminate the "hard-as-a-brick" pedal and restore full braking. It may ruin the lap time but should help you avoid track-offs. ;)

"Ice-mode" is very scary when first experienced but once you know what's happening, you can anticipate the event and work around it with the stock braking system. As others have already commented, the best solution for a dedicated track car is the dual MC with bias bar. Having said that, some of the Lotus Cup guys have eliminated ice-mode by disconnecting the RF wheel speed sensor; and others just live with it and still turn some of the fastest lap times and get great results.
 

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Discussion Starter #28
Several times on Saturday, I fully released the brakes and got back into it, and it was still in Ice mode. I had to release a second time before I could get braking again. For whatever reason, it was particularly active on me, hence wanting to find a way to make it better. I know it'll never be completely eliminated unless I go with the Bosch system (not out of the question), but I'd like to at least make it less of an issue.
 

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Maybe there's more than one cause which depends on car setup. I know that for me, the hotter pads in front, moving the brake bias forward, helped for sure. One of my local tracks, Thunderhill Raceway, has an uphill hard braking zone on a turn (T5, going up the crow's nest), where running the same pad in front and back got me ice mode every single time. With XP12F/XP10R, it happens once in a great while.

I'm running Nitron Singles, on Sector 111 "soft" springs, on Yokohama A005 slicks.
I see what you are saying. Variables like the bias inherent to a particular car, or the shock/spring setup, ride height, wheel choice, etc... could mean the front or rear tend to lock up quicker. So what we are looking for is balance to minimize the incidents. I think that my fronts tend to lock up first, so I will try moving the bias back. If I am wrong, then I will have some barely used track pads for sale.
 

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Also, as others have said, let's be clear about what ice mode is.

What it feels like is that the brake pedal is much harder to press than normal and feels like it has less travel. No matter how hard you push, you have far less braking power than normal, the system is fighting you from applying full braking power because it thinks you're on ice or something. Letting go of the brakes and re-applying may fix it if you're going straight.

The normal ABS mode in this car is quite good, it's got far less "shimmy" than most other cars I've driven, and I've taken a whole bunch of students at the track out for a demo lap in their own cars when they've asked, so I'm drawing from a wide sample size here.
 

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Randomly brainstorming out loud, but the 2011s (Elises at least) got a new Bosch ABS module. Is that swappable to the older cars?
 

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Discussion Starter #32
I was also wondering if it'd be possible to dig into the unit and disable the EBD portion of it. The question is if there's a separate EBD for, for example, the rear line input, or if it's simply an EBD portion of the software that applies to the normal 2 independent rear channels via the individual pumps, which would be impossible to modify, given that you'd take down normal ABS with it.
 

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Discussion Starter #33
I did a swap of the ABS unit from an 04 Mazdaspeed Miata into a 91 car (the 04 one is a much newer Bosch unit that looks like the one in the 06 Elise), so the idea of swapping ABS units isn't too scary to me, especially if the newer one seems like it has fewer problems. :)
 

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Randomly brainstorming out loud, but the 2011s (Elises at least) got a new Bosch ABS module. Is that swappable to the older cars?

Probably not. The CAN spec on those is different, largely due to things like TC and those sorta things. My understanding is that the units try to determine the grip level partially by looking at how quickly the corners start to slow their respective rotational speeds. Too quickly, and it will think you are on ice and bleed off almost all the pressure.

I have the CAN spec somewhere and a friend is going to try to see if it is still useful on the earlier cars. I'd expect that there is a chance, but no guarantee


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Dude. Wait until you put some fat meats on the car and mess with the bias with pads. I've all but forgotten it was an issue.

For example, in Wilmington a couple weekends ago, there was a really fast section (65mph+) that ended in a mild offset right before a sharp turn. The braking zone was in a non-straight section. Add to that that the concrete slabs were very angled at this location for drainage. I was able to come flying into there, get some serious ABS action and still slow down enough for the turn. It was really hairy and would have cause ice mode in the past. Did not happen.

As seen here @ 0:39. The car is at 8k with the e153 in 2nd before I start breaking.

https://www.youtube.com/watch?v=XFJHYLcj73I
 

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Discussion Starter #36
Dude. Wait until you put some fat meats on the car and mess with the bias with pads. I've all but forgotten it was an issue.

For example, in Wilmington a couple weekends ago, there was a really fast section (65mph+) that ended in a mild offset right before a sharp turn. The braking zone was in a non-straight section. Add to that that the concrete slabs were very angled at this location for drainage. I was able to come flying into there, get some serious ABS action and still slow down enough for the turn. It was really hairy and would have cause ice mode in the past. Did not happen.

As seen here @ 0:39. The car is at 8k with the e153 in 2nd before I start breaking.

https://www.youtube.com/watch?v=XFJHYLcj73I
Yeah, for full disclosure, I just bought new offset bias pads to try that answer. The rest of this is going to be a longer term project if this doesn't fix it to my satisfaction.

I'm thinking about still running the car for track days periodically, so even if this solves it for autox, if it creeps up on the track, I may want to still do something more drastic.
 

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Yeah, for full disclosure, I just bought new offset bias pads to try that answer. The rest of this is going to be a longer term project if this doesn't fix it to my satisfaction.

I'm thinking about still running the car for track days periodically, so even if this solves it for autox, if it creeps up on the track, I may want to still do something more drastic.
What are your track tire sizes? That is going to come into play. When I was on 225/245, the pad install helped a bunch. When I went 275 square, there was no more issue.
 

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Also, as others have said, let's be clear about what ice mode is.

What it feels like is that the brake pedal is much harder to press than normal and feels like it has less travel. No matter how hard you push, you have far less braking power than normal, the system is fighting you from applying full braking power because it thinks you're on ice or something. Letting go of the brakes and re-applying may fix it if you're going straight.

The normal ABS mode in this car is quite good, it's got far less "shimmy" than most other cars I've driven, and I've taken a whole bunch of students at the track out for a demo lap in their own cars when they've asked, so I'm drawing from a wide sample size here.
Yep, it is exactly like having a brick under the pedal. I can usually just release and stab the brakes again to clear it up. So far, the worst it has meant for me was clinging to the outside of a corner instead of nailing the apex. Still, no fun.

My interest in better brakes was reignited this weekend by two things. First, I rode with an awesome Exige driver (60,000 track miles on his '06). He was really good in the braking zones. After that, a brand new Vette in our run group shot off a corner and flipped end-over-end into some trees. He should have used more brakes, but the driver was fine.
 

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Once again, this ABS system has no place in a competition environment, therefore avoiding the ABS event by maximizing brake balance and at the same time overall brake performance, is the best remedy (in my dopey opinion!).
Exactly. We had to use ABS (silly technical regs) in our Mini race car, and that was OK, except that it equalized the drivers rather than the cars. When we switched series/cars, we went with a driver-actuated bias/twin MCs. I can change bias nearly for every corner, uphill vs. downhill entry, etc., and most drivers don't do this. They are slow.

ABS can mess with your mind, in that "how" a driver gets on (and comes off) the brakes is masked (depending on the system), whereas you are naked without it, especially if you set it going into an uphill corner and forget to change it going into the next downhill one....don't ask how I know this.

One exception to this was a 24-hour endurance race, where it rained nearly the entire time. With four drivers, we agreed to set it and leave it, to avoid confusion on driver changes. Had it dried out, we planned to change it once and leave it, for the same reason.

ABS is fine for the street, but I wouldn't allow such a system on a race car unless the regs mandated it. Of course, I don't like TC/LC on a race car either. Driver aids make nearly anyone seem competent, kinda like marital aids, I suppose.


Stephen
 
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