Ice mode solution?

travisjb

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

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2009 370Z #104
*For Sale*

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*

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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SPOHN

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

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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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travisjb

I recall reading somewhere else today that there are no real experts posting on forums b/c they are all off doing what they do... well we have at least one here, so thanks RB for your thoughts!

(once I get a working engine!) I'm going to look into getting a proper proportioning valve setup... it'll be interesting to see what we learn about this issue by modulating bias

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2009 370Z #104
*For Sale*

cossie1600

I am with RB that I have just learned to accept the flaw and move away from the "hotspots" where I know the car will get into ice mode most of the time.

I still believe the 350Z I had didn't have the same problem as my 370 and Corvette is because I was riding on the smaller single piston caliper. Despite having nearly the same power, the 350 just didn't have the stopping power to lock up my RA1s where the Corvette and 370Z could. I have to look at the datalog to see exactly how many Gs as it happened.

I can say that whatever spots I hit ice mode with in the Corvette, I did the same exact thing in the 370.

wstar

Well what that site offers could amount to a complete ATE system for this car as well, but yes it does come out around 10K if you're not putting it in an appropriate BMW that already has some of the parts (sensors, etc) installed.

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Journal thread / Car setup details

Mike

So, in my C6 and this car, this really hasn't been an issue for me. I wonder why? I'm not the fastest out there, but far from the slowest. I run stoptech ST60 front and ST42 rear trophy calipers with equal compound pads front and rear. My only problem is getting more than a couple days out of a set of XP12s on the fronts.

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travisjb

Okay there's one vote for equal compound pads...

Mike, do the braking zones at your most frequented tracks have bumps or anything that would unsettle the rear? Also, do you tend to brake straight line only or use trail braking at all?

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2009 370Z #104
*For Sale*

Mike

I don't think that most braking zones at my tracks (VIR, Barber, Road Atl, Little talladega) have many bumps. Maybe at Roebling, but I've only been there the one weekend and don't think it did at all.

I do 90% of my braking in a straight line, stabbing the brakes hard and then trailing off into the turn. I used to street brake, but Sharif and Bryan Settle cured me of that. I actually think that I am only able to keep up with faster cars because I brake much later and make up lots of time there.

Cossie,
On the C6, I had a widebody conversion and ran Z06 brakes for 2/3rds of the time I owned it. On both the Z51 and Z06 calipers, I ran hawk HP+ pads, but until my last year in the C6, I was only doing 2 track days per year and not at the level I am now. 3 years ago, my last year in the C6, I started doing two per month for 6 months a year. The only brake issue I ever had on the Z06 is when ALSM driver Shields Bergstrom took me out for a session at VIR driving my car and he boiled the fluid, but had no ice or fade issues either.

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NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z
Porsche: 93 968 / 23 Macan GTS / 93 968

spearfish25

I did some hot laps with Shields at Autobahn in Joliet. We were in a race-spec Audi TT. That dude can drive...

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2013 Cadillac V-Wagon, RIP Z

Mike

He was about 30mph faster than me everywhere, but he gave me the confidence in my car that I picked up about 10mph throughout the track.

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NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z
Porsche: 93 968 / 23 Macan GTS / 93 968

cossie1600

T1 at VIR is bad. You get in at the wrong spot and you will get ice mode. I had a Z51 C6. The brake issues on that car is the same thing as my 370Z. The C6 did have more front bias and carried way more speed down the straight, it can be nerve racking going into T1 at 146mph! I have gone as deep as the 4 marker, but the brakes would burn right up and I would get nothing for the next corner.

I used the same Carbotechs on both the C6 and 370.

Speaking of EBD, I don't know if you guys had an issue with the car grabbing to one side under braking. For some odd reason, my car loves doing that at Watkins Glen. I am not sure why, but it sure flips me out to get the car grabbing right at over 100mph. 0411 370z WGI Unstable brakes.avi - YouTube