Ice mode solution?

travisjb

I just spoke with Bosch and with the head of their major west coast distributor

Not going to quote anyone directly but basically the theories discussed in this thread are correct. The DOT approved versions of Bosch ABS induce ice mode when the wheel rate sensors detect variation across the four sensors. I am not clear if it is front/rear overall or any one wheel or both, nor did I find out what % difference the computer looks for nor timing involved in the algorithms... but it is a safety mode designed to help in the majority of street situations... hard to blame them for that

There are two systems available for dedicated track vehicles. One produced by Bosch and one produced by Continental. These systems are only provided for vehicles not used on public roads and purchasers are required to sign a waiver that is kept on file with the mfgr. The systems are sold through distributors. The Continental system is apparently a modified BMW ABS that is not configurable. The Bosch system is a bottoms-up race ABS with config options. Bosch has two major US distributors, one east coast and one west coast. The west coast distributor is Brian Sekata with MS Electronics.

I realize this is not all that helpful for those of you that will keep your cars street legal. Sorry, I have nothing to offer you folks. The only possibility I can think of is to find someone that can crack the computer and re-write the code... but then there is an issue of liability and intellectual property

For anyone reading this that has a dedicated track Z (either 370 or 350), it may be possible for us to work out a group buy on Bosch Motorsports ABS systems. I have no commitment from Brian or from Bosch, but they are interested in starting the conversation with us and asked me to carry the idea forward. If there are enough of us willing to sign that waiver, there might be a break off the system price... as many of you know, it is $10K today ... but what if it were $6K ??? better braking performance and safe guard against ending up in a concrete wall... the system is also highly configurable - from the cockpit you can adjust proportioning and how the ABS reacts

In any event, please spread the word if you know anyone else with a dedicated track Z

Thoughts?

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2009 370Z #104
*For Sale*

travisjb

Here's the Bosch ABS race system overview FYI
Bosch Motorsport - Chassis & Brake Control

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2009 370Z #104
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Shamu

I think the Grand Am team found a differnt motorsports abs solution for around $7K. I can ask but they indicated it was one of the best race oreinted abs systems they have ever used.

The problem using the stock system on our cars on the track is that they have terrible rear brake bias. Just disable your abs and stopm on brakes and you'll understand issue that our system is dealing with when we get good pads and bigger tires on the front.

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Grant

travisjb

Suspect the Grand Am team got a killer deal on the Bosch system or more likely they bought the Continental system... anyone found a link to the Conti system?

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2009 370Z #104
*For Sale*

gomer_110

Not too sound like a noob but if the source of the problem is poor factory brake bias front to rear then wouldn't the simple and cost effective solution be to add a brake bias proportioning valve to the car. Yeah it might take a little trial and error to dial in but I would guess a hell of a lot cheaper than one of these ABS systems.

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'17 Titan Bone Stock

ChrisSlicks

Thanks for making the calls Travis!

I remember we all had discussions about the Motorsport version of the Bosch controller before. Looks really nice, just really expensive. Even at $6K it is a tough pill to swallow, more expensive than the entire BBK! If it were $2K or $3K it would be a no brainer.

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ChrisSlicks

If you did an ABS delete then that would be the best solution, but not sure how well that would work in conjunction with ABS.

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cossie1600

I have owned all the cars you mentoned. C6, 370, 350, elise. The problem is notiable on the 370 and c6, not so much on tje 350 or elise. while most believe the problem is likely due to the brake bias and abs on the 370, I personally dont believe they are the main reasons, definitrly a factor. Here is why

1. The 350 non brembo had way more rear brake bias than the 370, yet ice mode isnt quite as bad.

2. The corvette has way more front bias, the problem is as bad as the 370.

personally here are a few things I have learned on the 370

Almost all the ice mode occurance happened on bumpy area or low grip surfaces.

I have three set of pads and I have mix and match with different combo. Running oem fronts and xp10 didnt throw the car into ice mode frenzy and my datalogger showed a slightly better stopping distance. Thats why I still believe the brakes have too much front bite and it is flipping the system out. With all that said, I feel like the giant brakea and aggressive nature on race pads are locking the front wheels too easily and quickly, causing the ice mode. Of course that's just my opinion and I could be way wrong on it. It's just some of the things you guys are experiencing are different than mine. Btw I ran the 350 with the same pads and never really experiences ice mode. I am curious if nissan patched the abs software or maybe the little calipers I had didnt have the stopping power like my 370s akebono?

Sry typing on a phone

SPOHN

As little off topic but do you think the ABS is configured different from base model to sports?

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Shamu

That or smaller 350Z Bermbo caliper and rotor

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Grant

Shamu

I challenge you to unhook abs and see if you think its front bias. I dont see it. Niether did the Grand Am team. Its heavy rear bias. Most of us are dragging rears and system is releasing things to keep the car from spinning.

I originally thought it was front bias until I unhooked abs and tested the car with fast stabs and threshold braking on the track. And I have huge clampers in the front. Its lighter rear end with pretty aggressive rotors and calipers that cause rear to lock up from what I see.

Grant Am guys are pretty sure most of issues will go away with rear caliper change but I havent had a chance to make the change yet. Also have been waiting to see if there are any other solutions before I commit.

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Grant

ChrisSlicks

That is one of the most common triggers, pad fade is the other time I have experienced it but it feels slightly different in the way that it recovers.

Yes, I had the G35 with the crappy calipers like your 350 and never ever had a problem despite getting the brakes to the point of smoking. People were impressed with the stopping power. Did any 350 owners with the fixed caliper Brembo's experience ice-mode? I'm not sure if we can use their ABS controller however thanks to the newer sensors (yaw etc) and if it would be compatible with the ECU.

My brake pad experiments in the 370 have had the opposite results to yours though. I tried running the same compound front and rear for a session and it was pretty difficult. Minor ice-mode every time you stepped on the brake too hard too quickly. With a lesser pad in the rear it doesn't happen as much. Basically the same problem as the Corvette just in reverse.

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Shamu

How about this?

Turner Motorsport | Racing ABS Wiring Harness

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Grant

BGTV8

In August 2003, Stewart McColl died sa a consequence of an accident in the braking area into turn 4 at Philip Island whilst competing in the Australian Production Touring Car championship in a Volkswagen Golf (I think an R32 from memory, but I may be mistaken).

The coronial enquiry concluded (based on datalogging presented to the court by "specialist engineers" whose attribution does not appear in the court records) that the root cause of the incident leading to the driver death was small bumps in the circuit on drivers left (T4 is an 80kph right hand hairpin) approached at ~200kph that triggered the ABS in such a manner as to present a confusing set of circumstances the the electronic programming of the ABS controller "which were outside the paramaters for which the programming was created". The flag marshalls reported that the nose of the car dipped as the brakes were applied but once past the bumps, the car's rate of deceleration wsa not maintained. The vehicle impacted head-on into an earth filled tyre bank at relatively undiminished speed (data logging confirmed impact speed of 138kph - at whcih speed the driver suffered unspecified "internal injuries" which were the cause of death - such decsriptions are usual for a ruptured aorta).

There were 3 major consequences of the race incident:
1. Volkswagen withdrew their team from the championships forthwith (and have not re-entered as a distributor backed team in the Production Car championship since that date - and IMHO never will) given (my opinion) the issues associated using an OEM ABS system in a rce environment.
2. The circuit was modified to add large areas of gravel traps to pull cars up before they can impact the barriers, AND the earthen bank barriers have been moved further away from the race-track proper.
3. The sanctioning body removed the previously mandtory requirement for ABS-equipped cars to have the electrical system present in its entirety (which forced entrants to leave the ABS intact), by allowing the ABS to be "removed or disabled" provided that the brake lights must remain functional.

I make this comment only because the only time I have experienced "ice-mode" in my Z34 was at Philip Island on entry to T4 on literally "the perfect lap" where I got T2 and T3 absolutely right and and carried 9kph addiional speed thru T3 and kept the car all the way to the left and ran the left-hand side of the car down the LH edge of the track and hit the same bumps as in the McColl incident - about 12-15m into the braking area). I stood on the brakes - right the the threshold of lock-up, did not initially trigger ABS, but when the LH wheels hit the bumps, it this triggered the ABS and the pedal almost instantly went rock-hard and the ABS "went nuts" but the car did not slow. The situation was resolved by lifting off the brakes and re-applying with a shallow entry/deep trail brake and hard right to recover back onto the circuit when enough speed had washed. This was on the 4th lap of a 5lap run so everything was nice and hot. I run Endless 462TR pads front and rear and Direzza tyres (245/40R18 front and 275/35R18 rear). Pads give good initial bite, tolerate heat, have reasonable CoF and don't chew the rotors to death in road driving.

There is no doubt in my mind that "ice-mode" is an unintended consequence of an OEM requirement arising from the EBD implementation.

Whilst I run my Z34 on the track with VDC off, I have not bothered to disable the ABS but if I were to run the car in open competition (eg: full-on race champioships) then there is no doubt that I'd throw the standard brake setup away, go for ALCON/BREMBO/AP calipers and a stepper-motor driven balance bar assembly.

IMHO, the ABS/EBD logic works OK for the road, but is problematic on the track, and there is lots of good info inthe thread for how to best "manage" it - because that's the price of using a "road-car" in a track situation, the fact that it still needs to serve on "the road".

It is worth noting that the factory GT4 race-car (NISMO Fairlady Z RC) is Bosch MotorSport ABS equipped - details on the NISMO.CO.JP site.

For me, I know I have to stay off the bumps in braking areas on the track, and if not avoidable, I have to ease the brake pressure a little - might cost a tenth inlap times, but that is better than being in the fence.

I have my real race car for serious track work in any event.

Bottom line - everyone who tracks a Z34 needs to be aware of what ice-mode is (and this thread is as good a write-up of what it is I've ever seen) and how to react when it happens, andif serious about their track work, lots of ideas about brake balance that can/will help.

My thanks to the key contributors for an entertaining and informative read - a real gem of a thread ..........

RB

ChrisSlicks

Thanks you RB, an insightful commentary.

In addition to EBD I think Brake Assist is also a potential culprit. The brake controller can decide to boost brake pressure based on how sharply you stab the brake pedal regardless of how hard you pressed. Useful on the road but madness on the race track.

Interestingly enough though, the 350Z and G35 both had EBD and BA as well yet didn't seem to exhibit these problems. They used a slightly older revision of the Bosch brake controller.

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