Ice mode solution?
 

I'm getting pretty sick of the ice mode on my car and have tried to try and fix it. Because of the SCCA rules Im pretty much limited to changing pads and fluid. Has anyone figured out a way to at least improve the braking performance with these restrictions?

Also FYI this is a daily street driven car and will only be used for autox. Please keep this in mind and don't bother recommending track-oriented solutions.

The grippier pads only make it worse.

I swear that ice mode actually kicked in while I was on ice this past winter and caused my fender bender. Hate it. I want a class action lawsuit.

I'm not familiar with this...?

Is this another VDC thing -- associated with the "icy" warning that comes on? :confused:

We don't get much ice in Floriduh, so... :D

If you get on the brakes HARD on bumpy pavement, or just pull any sudden decel, the brakes will actually release slightly. Imagine you hit the brakes and expect 100% braking power, the brakes actually let go and only give you 10-20%. It's a scary feeling, but it seems to be a common thing on newer cars now. The problem is mostly with people that races, shouldn't be a problem when you drive on the street. It's called ice mode because the car can do the same thing when you hit an ice patch (brakes release upon hitting ice quickly)

This is my theory, some people might disagree.

No it's a problem with the ABS computer. In heavy braking situations (tracking and autox) the abs wll engage early and limit the overall braking to maybe 30%. It seems to get worse with heat and "stabbing" the brakes.

It would make sense that pads with better bite would make it harder to be gentle on initial application and make ice mode happen more frequently. Maybe the solution is to use a less aggressive pad and give up some overall braking performance. I've also considered playing with dramatically different pads front and rear to change the brake balance.

Oh, okay -- can't you just disable the ABS?

Not allowed in the class I compete in.

Ergh... yeah, you'll probably have to play with pads then.

Well I don't think the computer is faulty, it is doing its job by throwing the car in ice mode under sudden decel on just one side. You are right, less aggressive pads seem to lessen the problem. Autozone pads might do the job for you. I had a tough time staying out of ice mode with my RE11 with my XP10 at the track

It's a common problem with the 350 and Corvette too.

So is there basically no fix for this (other than disabling ABS)?

I haven't yet faced "Ice Mode", but what exactly do you do when it happens? It sounds like it would cause a potential off-road/wall incident if you are braking at maximum threshold.

you can back off the brakes slightly and reapply or just pray that it will grip eventually. on the track you will notice it hit at roughly around the same spots, i sometimes go out of line just to avoid the bumps. at autox you just have to train yourself not to freak out and fight throgh it

Oh, so when you reapply the brakes, do you just apply less pressure than before?

It's good that it is somewhat predictable, since it would suck to be doing threshold braking on the same turn, and then all of a sudden the next time you take it and apply the same amount of braking you don't get what you expect. That could have some very bad end results.

Is it mostly bumps that cause this? Not that it matters for me, since the main track I do is Sebring, and that's probably the bumpiest track around.

The problem is the ABS controller. They added a two new features to the 370Z which don't really work properly, Dynamic Brake Proportioning and Brake Assistance.

The biggest problem is the Brake Assistance, this feature actively boost the brake pressure you apply when you hit the pedal suddenly but not hard enough to engage ABS. It boosts the pressure such that you immediately go into ABS. Auto-X drivers are always hitting the brakes suddenly because we always leave braking to the last possible second. The problem lessens if you get onto the brakes progressively but if you go into ABS manually you still have the issue.

The second problem is related to the Dynamic Brake Proportioning and the ABS programming, and to a certain extent, heat. It is very easy to overheat the front brakes on this car at Auto-X especially if co-driving, there is simply no airflow at all. The ABS controller loses it's mind when the front brakes start to lose effectiveness compared to the rear brakes, this is a severe programming problem. The solution I have found is to run a low bite, high temperature front pad, and a lesser rear pad. This combats the bias issue and the temperature issue.

thats what i do. lets say i am on the brake pedal hard at 95% at threshold braking, i just let off slightly to let say 90% to get rid of it and reapply hard again. the problem is worse with grippier pads, i dont know if slicks make the problem worse. i have re11, not sure if less grippy tires will do it easier or not.

one thing i know that is helpful is to hit the brakes slightly less hard. so instead of let say put 30 ft lb at the pedal, i would hit it with 20 ft lb of force. you still go all the way down on the brakes, you just have to hit it less hard initially to not flip the abs out. its the same reason why race pads hate the stock abs since they bite so hard and fast

i am with chris on the first point, but i am not sure if heat has anything to do with it ( i am not saying it doesnt, just saying i am not sure). you abuse the brakes way more at the track, you cant even compare a 135mph to 43mph turn to two 60 sec run to an autox.

this problem is not unqiue to the 370, 350 and corvettes have it too.

The heat issue is only really an issue on the hotter days and if you are co-driving. I've had my brakes hot enough to cause fluid fade in auto-x but that only happened once and that was after doing 3 back to back runs after several other runs (co-driving and then a re-run). The issue with heat is that it shifts the brake bias even more rearward which the ABS controller doesn't deal with very well.

So essentially still no fix guys?

Its interesting that you say that as my first run at SD NT I had no ABS Ice mode ISSUES, but after my co driver ran brakes were much warmer and then I got abs issue 2ND AND 3RD RUNS. I almost squirted the brake calipers and rotors. Wish I had tried that but I thought no heat wouldn't cause that!

I'm hearing that maybe changing proportioning more to the front and putting smaller calipers/pads on rear might be a solution. Its the issue with rears locking up that causes the computer to freak out. Less pad up front would be opposite of what you want to do if this is the case. Makes sense if you think about dynamics of braking on our cars. Weight shifts from rear where things are already light and those big rear calipers and rotors start to lock up rear wheels. Has anyone experimented with putting crappy pads on the back?

My class I have more options than stock guys. Has anyone in stock tried throwing terrible pads on the rear? Thats how I used to balance my race car sometimes. If issue is truly wheel speed problem because rears are locking up too easily why not put the worst pads ever back there. Or if you can down grade to base model rear brake - I dont know is there a difference? For my car we are going with old 350 Z Brembo caliper and rotor which is smaller. You poor stock class guys cant do that.

Man and I feel for you stock guys on oil temps. even with GTM cooler on my car we were seeing 220 oil temps and we were spraying the cooler.

I can throw my XP10 on in the front and leave the stock in the rears and try that

It's definitely heat related. With good 5 minute spacing between runs it will usually only happen when braking near or at the end of a run. However at local events when we end up lapping closer to 2 minutes apart it will happen during every major braking event.

You should be able to just pull the ABS fuse in SP or disable it in some other way.

For me it's time to start playing with pads. I'm thinking hawk hps may be a good starting point as people are always criticizing their initial bite characteristics.

Oh and don't spray your brakes with water between runs unless you want to crack and/or warp your rotors instantly. And for engine temps we leave the engine running with the defrost cranked at full heat and the hood open to cool the car. We can usually keep it 220-240 with no cooler

Just don't try the HP+, those were a dismal failure for me, even just front only. I think the problem with the HPS is that they will still be affected badly by heat. The Mintex Extreme has a reasonable heat rating (not as high as XP10) and not a very hard bite. It has worked well for me although I am no longer on stock calipers.

Heat was never an issue with me relating to ice mode. Ice mode occurs the harder/quicker I stab the brakes. I have done a few track events at the Z, the car will do it hot or cold or warm.

I'm curious if the issue has been experienced by anyone with the base brakes. I've obviously run into heat issues, but haven't yet experienced the reduced brake force the way you guys are describing. Might help narrow down the issue if it isn't being experienced on the base brakes.

Good point, but after pushing my base brakes to the point that Triple's could smell my brakes burning half a mile behind me with smoke billowing off them, I would not think they could last long enough or have enough bite to equal the conditions that trigger ice mode with the Akebonos.

Considering it happens to other cars too...I would imagine it has more to do with the programing of the ABS system. The worst part is that it's really only a matter of time before someone crashes on the track because of this. I've been really hesitant to get back out there and this is partly why. Even when the car was completely stock, I almost went off twice at a hairpin, if there had been anyone in front of me, it would not have been pretty. Maybe AM Racing has some kind of an answer for us considering they are building that gran-am 370z.

yup,corvettes, even 350 had it. my rx8 never had it, probably because it never went fast enough to have huge nose dives.

i just learn to modulate my pedals better.

now i wonder if the problem will get better or worse if i were to put a set of slicks on my car

I just got my Z and haven't experienced "ice mode" yet, but then again i've been going easy on it for the first 1200 miles. I plan to take it to the track in the future, so I'm curious what exactly you guys are talking about.

It sounds to me like people are simply describing brake fade. Or is there something different about "ice mode" that differentiates this from brake fade?

It is not brake fade as the brakes go from their full functions to having to braking power almost instantly. It is not a gradual decrease but a sudden loss of braking power.

Your pedal goes straight to the floor when your brakes fade, the car also won't stop. When you hit ice mode, brake pedal is as solid as ever. The ABS just pulsate and won't give you much braking power.

I understood it is not heat related, besides that, if you got to that point, you should have been hot enough to trigger the condition if it was.

From what I can tell, it's due to issues with the ABS controller. It may be worth looking into why it doesn't seem to occur on base setups.

cant you turn the ice mode off?

Wouldn't that be nice? No such luck.

I had it a little bit yesterday on my very last run. Once my front rotors got hot (I heard my 2-piece rotors clicking as they expanded while I was waiting in staging) that was when the problem started. Could have been a good thing though as it forced me to carry more corner speed and I picked up 1.5 seconds and the win!

Nice!^^ well in my 2011 model i can turn mine off in the dash. i dont know if it will be fully off though.

^So we should call it "autocross improvement mode"? :)

Uh? No you can't. Like every other 370Z, you can turn off VDC. Ice mode is neither recognized by the manufacturer or a user defeatable option.

I think you are looking at the VDC (traction control switch). It unfortunately has no effect on the ice mode ABS problem.

Just wondering if you've been able to test out this setup yet?

My garage is filled with junk thanks to some house construction, I will try it the next couple week or two as it only takes me 45 minutes to do the front brakes.

Cool, thanks cossie. I'd be curious to see if XP10/Stock would be a viable setup for the track. I normally run XP10/XP8.

I don't know what tires you run, but you are in a lot of trouble if you run XP10s with the V12s. The problem with the stock pad rear setup is that the Z cars have a lot of rear bias, I think the pads will overheat quickly if you do that. The solution is a low bite but high temperature resistance pad I think.