Ice mode solution?

ChrisSlicks

I had it on the OEM setup at auto-x as well. It would only present itself towards the end of the session when things were warmed up. Everything in auto-x is much more deliberate and sudden that I think it was just easy to catch the ABS system off balance. When I went smoother on the brake pedal it was avoidable in this case.

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Hotchkis ARB | Stillen CAI | Art Pipes | Berk CBE | Stillen AP Racing Brakes | AE Performance Oil Cooler | BC Racing ER Coilovers | Doran Control Arms

clintfocus

so the trick is to not have the rear bias get to high?

travisjb

I'm running 18K springs up front and so load transition to front tires happens fast... would agree that soft springs also present a problem, as they can result in nose dive, which can shift the cg forward. My current thinking is that 16K/10K is just about right for this car.

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2009 370Z #104
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SPOHN

Good lord. I'm running 13K up front and I thought I was doing something. I know a lot of people love how planted my car is compaired to the rest.

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travisjb

18K is a little too twitchy!

16K is about right I think

I found 12K soft for track use, but it may be fine if you have high quality dampers and are running on tracks that favor a more compliant setup

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2009 370Z #104
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SPOHN

I have Stance true type coilovers. I know I like them. But I know they could be better. In the begining I didn't know the route I was heading and just settled. Only because I've ridden in a 370 with JRZ's. Mostly will be running at Road Atlanta.

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SPOHN

I have Stance true type coilovers. I know I like them. Only because I've ridden in a 370 with JRZ's. But I know they could be better. In the begining I didn't know the route I was heading and just settled. Mostly will be running at Road Atlanta.

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travisjb

^ I did the same... BC Racing are just fine, but not JRZ's... or Penske... etc

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2009 370Z #104
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wstar

Well I got to think on (and play with) this all day, and I think my initial reaction to "oh no I have to deal with ice mode" was overreaction. There's a few layers of analysis here, not sure what order to put it all in, and I'm trying to avoid my tendency to get really long-winded . But the bottom line in my case I think is:

An additional major contributing factor was front pad fade on the XP8s, even on my street tires. When the fronts start fading, of course the bias goes to the rear, which helps kick on the ice-mode.

Based on that alone, it would seem like it would be best to up the fronts to XP10 (at least) and get my brake ducts finished, which should lessen both the fade and bias contributing issues.

But, a major contributing factor to the pad fade (well, aside from lack of ducts) was that I was carrying around a lot more speed due to some skills improving, but I was abusing the brakes way more than I should have had to. We corrected some of this today, and I was able to make even faster lines with less brake abuse, and it helped a lot. I still got some ice-mode late in a hot session, but I was able to modulate through it and come out ok, and after pushing through that barrier for a bit, the XP8 front pad fade of course starting becoming increasingly obvious.

So really, learning to use the threshold better (so I'm not dipping into ABS in the first place), and not abuse my brakes in ways that aren't even warranted will go a long way towards fixing this for me on a practical level, although the ducts certainly can't hurt as well. Even then, I'm still going to be pushing the limits of the XP8's on street tires, but I think trying to upgrade the pads too far against these tires is probably a bad idea (just going to be a lot more touchy and sensitive on the ice-mode line when it does hit it), and I also think I haven't learned enough of the limits of these tires to consider upgrading to slicks either.

Really, where that leaves me for reducing the overheating problem is I need to not go balls out on the straights. If I held back at say 70% throttle on those long straights instead of flooring it, I wouldn't have as much speed to shed, and the braking system and the tires would all line up with my driving skill in the corners and work properly. In other words, even my lowly NA V6 really has a little too much power on tap for an ideal learning environment at my level of skill, if I want the rest of the system to hold up to a long session.

One way or another, I can play with modulating through the fade + ice mode and/or reducing my straight speeds and mitigate the ice-mode while continuing to learn how to push these tires to their fullest, and then consider further true tire+brake upgrades later when I'm ready, I think. The ducts will go on ASAP though

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clintfocus

well im going to buttonwillow sunday, stock suspension and wheels with RE11 street tires. I got DTC 60s for the front, was going to run the OEM pads in the rear. ill let you guys know how it goes

bullitt5897

What I found that was causing the ice mode was that the rear brakes were stopping the rear wheels/tires faster than the front. Because of that the car would release the brakes causing the "ice mode". This was from my brake test last year. I mean we tried everything from pulsing the brakes to me standing in the car on the mothers. Once the rear tires locked up or got really close to lock up "Ice Mode" came into affect. I think because of the bias in braking power from front to rear it causes this affect. we tried it on a stock car with upgraded pads and lines and my car with the alliance BBK. The BBK under the right circumstances was able to trigger it alot easier since we were running bigger rotors and calipers in the rear... This also depended on the ground composition as well... if it was dirty and sandy it happened a lot faster. If it was clean it didnt happen at all on the bbk and stock. With all the weight shifting forward under hard braking the rear end has less friction from the ground under braking thus allowing less effort to stop the rear wheels and causing Ice Mode...

My hypothesis on the solution is to run a stiffer front than rear bias and to run less aggressive pads for the rear.

Mike

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bullitt5897

Ohh and DO NOT DISABLE YOUR "ABS OR ABS MODULE" you will lock all four wheels up in an instant even at slow speeds like 35mph!!! Trust me I ruined a set of $1200 tires testing that theory out. The car went immediately sideways. I tried a modular increase in brake pressure and lock up. I also tried pulsing and with each pulse the wheels locked up. It is almost like an instant on/off switch with the abs disabled...

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wstar

Yeah, I meant to mention that in my above post. When I mentioned the idea of disabling ABS to a few others at the track event, the advice I got back was "Yeah that's great, except one little screw-up and you'll flat spot and ruin a tire, better to have the ABS as a backup at that point and not ruin tires."

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travisjb

You know what... I agree that it is "easy" to lock up and flat spot w/o ABS on... but that's the best training in the world and your ABS is only masking the situation... I was able to improve my setup a lot w/o ABS and then turned ABS back on, making the whole thing much smoother under braking

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2009 370Z #104
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wstar

Yeah but what's the practical difference between saying to yourself, "Oh I screwed up and managed to engage ABS" when you feel the pulsing, and saying to yourself, "Oh I just screwed up and now I need an expensive new tire?". Well, aside from the $$$

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