I'm definitely generating too much heat in front brakes. Used a paint temp sensor kit from Stillen and found the max front rotor temp at the track today to be somewhere north of 560C. The caliper temp was much more reasonable, which is credit to the design and robustness of the AP Racing calipers. Time for some brake ducting!!!

What's the final word on the ABS fuse manipulation? Could be interested in doing this...

The ABS actuator fuse in on the 3-in-one fuse as described. Unfortunately I couldn't figure out where to buy one from, and I couldn't see how you could remove the center piece of the fuse without destroying it. You might be better off disconnecting a wheel speed sensor as that will shutdown the ABS computer.

Ya the wheel speed sensor sounds less complicated. So do you have any idea how to do this?

i believe its a simple plug in unit. find the sensor, trace the wire and unplug it.

Has anyone seen if disabling the ABS solves the icing issue? I was looking through the service manual to see where the speed sensor are located and of course ABS was in a nearby section.

If you disable the speed sensors, you'll be messing up the VDC/TCS system as well (possibly the icing problem, but maybe it's just the ABS system alone).

The manual also states the pulling the ABS harness will disable the system and then we can just threshold brake. Could be useful at the start of a track day, then just reconnect when done.

^ +1 REP

I'll try this next time when I'm on the track.

WHen this happens, are you guys progressively braking, or jam-braking?

Basically, are you loading the weight of the car on the front wheels progressively, or, are you slamming the brakes quickly?

The first is the correct way...and you're less likely to trip ABS in any instance. The front wheels are about 70% of your braking force, and by loading up the front suspension FIRST, then you end up with more downforce on those wheels, allowing them to do their work better without tripping ABS.

That said, perhaps the car is too soft in the front, and nose dives hard enough to allow the back wheels to trip into ABS. If you're turning a bit, perhaps it's enough to where ABS trips on one wheel, kicking off ice-mode?

It could also be related to the inertia sensors in the car - perhaps they are reaching their limits and not reading the car correctly.

don't think it is the inertia sensors, mine are disconnected

no. not 'slam braking'... controlled braking

yes, it is the differential wheel spin

Ok, so Semtex, StormCrow and Myself met up yesterday to do some braking tests and see what the stock 370z could do 60-0 and what a BBK 370z could do...

Well fully stock the 370z stops 60-0 in approximately 64 feet with no problems except brake fade after 3 stops. The third stop was about 68 feet.

so what does this tell us... Something we all already know the Magazines are full of $hit...

Now to the problem... The BBK 370z would redoubtably lock up the brakes faster and begin to slow faster than the stock Z then BAM "ice mode" would kick in and send the car an extra 40+ feet before allowing the brakes to reactivate. We tried several different processes to eliminate the problem but to no avail. We even disconnected the ABS harness and tried a test run at about 40mph and lets just say its was smokey!!! then we went for the 60-0 and with no speedo it was hard to gauge speed. At this point I decided not to lock the brakes but to progressively brake and it still locked the brakes to the point I said F' it and let off. I now have two flat spots on my right rear tire... :shakes head:

so all in all you need the ABS as you will lose your speedo and the intelligent key starts acting funny and will not turn off the car! It literally took me like a full minute of pressing the off button to get the car to shut down.

Now the question is... is there a way to dial back the abs? Giving us a larger margin for wheel speed deceleration?

but its gets even more weird... I took the car to a different road surface and the car did just fine...

a nissan test engineer warned me about unhooking ABS on this car - if you do, he said would need to add a bias adjustable master cylinder to tweak the rear brake force manually... you seem to have verified this

what else can we take away from your experiment?

thanks for doing the testing btw!

no problem...

Well, my theory is that with running my heavier 20" wheels and stickier tires than Semtex we will find that the icing effect will be magnified. We still have some testing to do with my car once I get it back from GTM. I hope to be back on 19's soon as 20's around Atlanta bend too easily... I believe that will solve some of the issue and save me some costs.

Some things I can think of that may be happening to you bullitt.

1. Your BBK comes with very grippy track pads. The ABS system doesn't seem to like these kind of pads because they are difficult to modulate, and the cycle time of the controller isn't allowing them to release which causes it to go into an ice mode where it releases the pressure for longer intervals.

2. The ABS system was designed with dynamic brake force distribution. Unlike a traditional brake system which is balanced with a front bias, the dynamic system can send a full 50% of the brake pressure to the rear. It then uses the ABS actuators to modulate the percentage of brake force to the rear depending on the input from the wheel speed sensors. So apparently when the ABS system is disabled it is locking in to a 50/50 split which is going to be pretty useless for manual braking.

3. This one I haven't been able to confirm, but the ABS system may be very sensitive to wheel diameter changes, and is unable to auto-calibrate. The people that are experiencing the biggest problems with the ice-mode effect seem to be running after market wheels and tires. When I asked my dealer mechanic (the GTR master mechanic) if the wheel diameter could be programmed, he said no. Now I'm not sure if that is no, there is no way to do it, or no, he has no clue how to do it.

Has anyone with stock tires experienced ice-mode? Please speak up!

That my car is awesome. :tup: (j/k)

Yes Ben we all know you got a Wed car freak of nature that powns all!!! Lol

in all seriousness. I believe I am running EBC Blue street pads. I will have to ask Mike @ blackline... Other than that I believe the larger wheel diameter and extra weight on each wheel are what's getting me. On certain road surfaces the car is a monster in braking while like our test arena it has an 80ft braking distance... Once again owned by Ben. Dangit ben if you go fi you better go epic big!!! That's one area I won't let you beat me hahahaha!

Very nice guys, good info. What kind of different surfaces are you talking about Bullitt? Grippier more even roads should minimize this problem.

Chris - I have experienced it on track (smooth, grippy surface) with stock wheels and tires.

This sucks, it's going to take someone getting into a serious accident for anyone to do anything...

What pads were you using at the time it happened?

On typical road surfaces that are fairly new and well still grippy the car does well. Places that are recently paved and haven't fully cured or concrete like surfaces that are smoother in nature tend to have a worse effect... I would really like nissan to come out with a patch to make the ABS a little less aggressive.

When I first installed the Carbotechs, every brake stop would activate the ice mode. On the track yesterday, more progressive braking didn't get a single icing incident (thank God). However, I was definitely not diving into corners given my apprehension for icing and just rolling right off the track. Every time ABS came on, I started to pucker and thought I was about to get ice'd. It sucks not being able to fully trust your brakes.

Stock everything Chris, except for fluid of course, but that made no difference.

I'm asking because with stock pads it may have been pad fade in that case. The pad fade feels almost identical to the ice mode except that it keeps getting worse as the heat builds.

I've had both so it was all that much harder to figure out what was going on.

maybe uneven fade is causing one wheel to slow down quicker than the rest causing ice mode?

stock pads and pad fade = total brake loss in about 4 applications.

I've never had the ice mode, even with the brembos. I think though, there is a big difference stopping from speeds in the 100s and even in the 60s with hot R-compounds than in the 40s-60s with street tires.

I'm pretty sure this is only an issue for autocross guys and not track guys.

Most of the ice mode are with autox guys. I hit it plenty of times during autox, almost never on the track.

I find the braking styles to be completely different between the two venues. On the track I never lock up the brakes as I am just slowing the car to entry speed where as in an autoX event you practically have to go from 60-0 to make some of those turns... In any case I am going to go back to 19's and see if that solves my issues.

Well they are completely different driving styles... You can tell immediately when someone who does auto-x goes to the track because their driving is very abrupt and violent vs someone who tracks and is smooth. People who track their car never slam on the brakes, it has to be gradual because of the higher speeds/ loads.

My icemode on the track happened at the end of a long braking zone though...I never went into ABS until I got ice mode

I am a road track guy so I am used to the 120-60 braking and I havent had ice mode in those type conditions... only in conditions where the car needs to stop at zero and that is only every now and then on certain road conditions.

Found this on the StopTech FAQ page and it seems to apply here.

StopTech : Balanced Brake Upgrades

Interesting. It helps to explain what's going on when this happens braking into a turn. But it doesn't explain why it happens when braking in a straight line. (Just making an observation, not knocking the FAQ or anything.)

good read but not the same thing...

What we are refering to is straight line braking. What that FAQ was talking about was corner entry braking or trail braking...

DAM you Ben always one step ahead!

:happydance:

I'm in the same situation. It really sucks when you can't trust your breaks on the track. when ever I want to do a hot lap and start diving in to corners, the ABS start kicking in and this grinding sound comes on (it sounds like the pads are grinding the disc).

I haven't expiration an ice mode yet. But if we can prevent the ABC from kicking in,That will be nice.

Edit: this only happens when the car is diving in to the corner(trail break), and not in a straight line.

Ironically the car does really well braking mid corner while unbalanced, it just can't brake in a straight line in certain conditions.

I think you got pad fade. Pad fade seems to really freak the ABS out because the rear brakes are working but the front brakes aren't at full capacity. End result is the ice-mode behavior but for different reasons.

As I recall you haven't had it since upgrading to track pads correct?

I haven't been to the track in a while so I'm not running upgraded pads at this time. I will be soon though if I don't get that S/C.

I am not to familiar with the 370z braking system yet but if the ABS functions anything like it does in my current and previous car, then if the car sense's that you are at a "high load of lateral force with out applying throttle it will initiate the brakes early, what i read in the OP was that you experiencing the abs activate when you are on the brake about 50% or less are you corner braking? Not to bash in anyway i noticed i did it a couple times and the ABS kicked in, i new i braked to late for a corner and it messed me all up, and i quickly learned to brake a second earlier and keep even on the throttle until you are ready to mash it again.

In my GTI and the current A4 the both do it, it is to makes sure they stop the situation from getting out of control, also keeping the throttle open and even or consistent tells the computer you are doing what you need to do, and doesn't allow the ABS to kick in.

Sorry for skipping the stuff in the middle, and jumping to the end but if anything i hope this is somewhat beneficial.

Ice Mode At Summit Point Main
 

I experienced the dreaded ice mode three times at the NASA Spring Slam on the Summit Point Main Circuit. I am running stock sport wheels with 265/35/19 front and 305/30/19 rear RE-11's. I was also running a custom made set of Porterfield R4 full race compounds (they are awful, noisy, grabby, hard to modulate, dirty...wanna buy my set cheap?) Here are my observations.

The ice mode always happened at the very end of large braking events (turn one and turn five) just before turn in. Before going into ice mode there was no perceivable warning.

It always happened when I came in to the braking zone too fast and needed to sharply increase braking force right before the corner.

By the end of my second day I could pretty much predict when my Z was going to go into ice mode.

Although the ice mode felt like there was no braking force being applied, my 370Z was still slowing.

Sounds like you were getting pad fade, which certainly does trigger the ice-mode in these cars. Despite the large rotors the heat seems to build up very quickly and there isn't adequate ventilation to dissipate it. But the real problem is something in the programming of the ABS controller isn't quite right, and when you do start to get a little bit of pad fade it steps in and makes things a whole lot worse.

I was getting some ice-mode myself the pass weekend at an auto-cross event. Conditions were pretty treacherous to start with, 40 degrees, drizzle, damp track. Everything started out fine, grip levels were obviously a little lower due to the conditions. But once the front brakes got up to a fairly average 400F I started to get some ice-mode behavior in the 5th, 6th and 7th runs of each session. An yes, this is with the Stillen AP Racing BBK installed.

I'm really beginning to wish that we could use the ABS controller out of the previous gen cars (350/G35) as I don't recall having an ABS issue in those.

The Porsche guys are experiencing the same thing even in the GT3's. Some have gone to a BMW ABS system that cures the problem. The only problem with that is.... it's 10K :eek:

Driving style or braking style seems to be the issue according to a response I received. It doesn't have to do with pads, brake fade etc. If someone would pm me their email address I will forward the response to this issue and perhaps it can be posted here.

To be continued...