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Old 10-10-2014, 09:25 AM   #43
DougW
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These were OEM reverse engineering tools/scopes/sniffers....Pico? We needed the data for the traction control in the Hydra EMS. The CAN computer is like any other and it reports the data in a readable frequency and is typically averaged. We had to do exactly the same.

What we would like to know is "why" it does what it does under racing conditions. What is the trigger for ice mode or ABS shut down? It's all temporary and will reset immediately ornin case of the ABS just a key cycle. Even if we just knew the basic logic it would help without h a work around.

I just think the brake force distribution computing is too slow to deal with the fixed mechanical front bias inside the pump module.

It's all based on rate of change of wheel speed differential/brake applied pressure once these trigger then it uses G sensors to change the strategy.
You are probably pulling over 1 g and railing the sensors as well as unexpected rate of changes. you may need to switch to a Bosch motorsports ABS setup or try removing every other tooth on the rings to get the rates back in range ( speedo might be wrong). Brake bias without lockup or slip while an issue to the butt dyno shouldn't screw up the ABS obviously getting it balanced makes everything easier to control. Need some really got data logging to see where then we can look for the why.
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Old 10-10-2014, 12:42 PM   #44
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It's all based on rate of change of wheel speed differential/brake applied pressure once these trigger then it uses G sensors to change the strategy.
You are probably pulling over 1 g and railing the sensors as well as unexpected rate of changes. you may need to switch to a Bosch motorsports ABS setup or try removing every other tooth on the rings to get the rates back in range ( speedo might be wrong). Brake bias without lockup or slip while an issue to the butt dyno shouldn't screw up the ABS obviously getting it balanced makes everything easier to control. Need some really got data logging to see where then we can look for the why.
DougW
Yeah when I have run data under braking on the STi at least it's closer to 2G peak (we're on 325 width Pirelli Slicks on both cars). I agree something unexpected is happening to the system and it reacts by shutting down.

I can still log the CAN system with the Hydra EMS in there since that computer is also retained. I'm going to be working with someone to design an ideal brake kit for the car. We are going to first start with getting the mechanical bias without ABS close to ideal before turning the ABS back on. I'm hoping this could help prevent a rapid lock up of the fronts which may be causing the ABS to shut down.
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Old 10-10-2014, 01:44 PM   #45
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Yeah when I have run data under braking on the STi at least it's closer to 2G peak (we're on 325 width Pirelli Slicks on both cars). I agree something unexpected is happening to the system and it reacts by shutting down.

I can still log the CAN system with the Hydra EMS in there since that computer is also retained. I'm going to be working with someone to design an ideal brake kit for the car. We are going to first start with getting the mechanical bias without ABS close to ideal before turning the ABS back on. I'm hoping this could help prevent a rapid lock up of the fronts which may be causing the ABS to shut down.
Well if you need any electronics help let me know. We are all going to be where you are it's just a matter of time.
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Old 10-10-2014, 03:19 PM   #46
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Ok thanks. Typically I'm having this issue when speeds are in excess of 140 mph. Ya know when you need your brakes the most Toytoa/Subaru! LOL!

Maybe my XP12 are glazed over in the rear? I'm going to put all OEM pads on and the Prius tires for testing. LOL!
Yeah, my point is that a more aggressive rear may make a big difference. If I can get too much rear bias with a compound, maybe you can even it out enough to ease your issue. You, however, seem to like going all the way on solutions. Nothing wrong with that. If I'm going 140, I'd want to go all the way too. I've never been that fast on a track, though. Only 135.
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Old 10-10-2014, 04:44 PM   #47
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Is there any reason why you cant bypass the ABS module and plumb in a manual bias valve? Is it classing? Because, being a track beast, it seems like that would be the preferred setup.

Hell a quick valve with a lever in the cockpit like F1 uses might be pretty useful.
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Old 10-10-2014, 06:06 PM   #48
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This is a standard euro city car problem when running wide tyres & BBKs. Shut-off is basically the system going "I have no idea what's going on, I think I'm making things worse! Over to you & good luck". It was very important for this to happen quite early with euro city cars as if you tried braking hard on a surface with detached gravel you'd effectively have 0 braking with ABS on.

From the sound of it the system in your car is acting like a very early Bosch DBB system with seriously sticky tyres, in my case going from 145 wide eco tyres to 215 wide soft track day rubber (sticky enough to allow the car to endo!). I found someone with the kit to remap my ABS ECU which allowed me to keep it but input appropriate parameters for the brake & tyres I was running. I have no idea if this is possible with the BRZ system or not & what software is required.

The system I dealt with naturally had a brake bias of something ridiculous like a 95/5 F/R split without and DBB intervention. So when the system was disabled completely it'd become almost impossible to brake hard, thankfully when the system gave up it did at least leave the brake bias at a saneish setting. The two parameters that usually needed to be changed due to sticky tyres were the maximum wheel deceleration & the maximum pressure release cycle length. The latter is what caused the ECU to give up with sticky tyres. Because the wheels weren't really slipping the release values was way too low to reduce the braking enough so that the ECU thought everything was okay.

Sorry for the lack of useful info it's been so long since I dabbled in all this it's mostly been forgotten. I also doubt that most of what I knew is actually useful with modern ABS systems.
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Old 10-10-2014, 06:44 PM   #49
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Is there any reason why you cant bypass the ABS module and plumb in a manual bias valve? Is it classing? Because, being a track beast, it seems like that would be the preferred setup.

Hell a quick valve with a lever in the cockpit like F1 uses might be pretty useful.
That would assume I'm a good enough driver. LOL! For the record this car has AC and electric windows and I do drive it on the street In all seriousness ABS can be totally superior especially at a track like VIR where you are turning while braking and even cresting hills. All of that lightens up one or two wheels and without ABS you need to release pressure on more wheels to stop locking than a 4 ABS channel system would (when it works).

I do run cockpit Tilton bias valves on my STi so I can fine tune my brake bias even with the ABS. This is what I plan to do with the FRS (tame the fronts). Keep the ABS but plumb in driver adjustable valves. First however we need to fix or get much closer with the bias via the rotor/caliper.

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Yeah, my point is that a more aggressive rear may make a big difference. If I can get too much rear bias with a compound, maybe you can even it out enough to ease your issue. You, however, seem to like going all the way on solutions. Nothing wrong with that. If I'm going 140, I'd want to go all the way too. I've never been that fast on a track, though. Only 135.
Even though I set a new lap record this past weekend you can't go fast when you don't have 100% confidence in your car with brakes being the number one scariest thing to fail. Without ABS you need to get your brakes balanced and feeling just right. When you get there you can push the car and you'll have better feel for lockup. Right now I can't feel or hear the lockup with the tires I race until it's way too late.

That is why I'm going all the way vs. just swapping compounds around. Also keep in mind I trashed over $2k in tires in two weekends so while I do agree I could probably get something OK with pad compound swaps I feel like it's not a real fix for my level of racing. For you track day guys it's probably all you need until you go with a front BBK to help with brake fade. It's at that point you're going to want to make sure those rears are doing their share of the workload.
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Old 10-10-2014, 06:49 PM   #50
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This is a standard euro city car problem when running wide tyres & BBKs. Shut-off is basically the system going "I have no idea what's going on, I think I'm making things worse! Over to you & good luck". It was very important for this to happen quite early with euro city cars as if you tried braking hard on a surface with detached gravel you'd effectively have 0 braking with ABS on.

From the sound of it the system in your car is acting like a very early Bosch DBB system with seriously sticky tyres, in my case going from 145 wide eco tyres to 215 wide soft track day rubber (sticky enough to allow the car to endo!). I found someone with the kit to remap my ABS ECU which allowed me to keep it but input appropriate parameters for the brake & tyres I was running. I have no idea if this is possible with the BRZ system or not & what software is required.

The system I dealt with naturally had a brake bias of something ridiculous like a 95/5 F/R split without and DBB intervention. So when the system was disabled completely it'd become almost impossible to brake hard, thankfully when the system gave up it did at least leave the brake bias at a saneish setting. The two parameters that usually needed to be changed due to sticky tyres were the maximum wheel deceleration & the maximum pressure release cycle length. The latter is what caused the ECU to give up with sticky tyres. Because the wheels weren't really slipping the release values was way too low to reduce the braking enough so that the ECU thought everything was okay.

Sorry for the lack of useful info it's been so long since I dabbled in all this it's mostly been forgotten. I also doubt that most of what I knew is actually useful with modern ABS systems.
Thank you, that was actually very useful to hear. The FRS/BRZ truly does feel like when the ABS is off the bias "unsafe" meaning the fronts lock up too easily and provide very little deceleration for the car. I know this really well because I had been driving without a working yaw sensor for a few months on the street and therefore no ABS.

We need a computer hack ASAP over here
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Old 10-13-2014, 03:20 PM   #51
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VSC yes. ABS no. Feels just like my other Subarus, non STIs. Slow, clunky and rough. I've had 5 Toyotas, none of them feel like the FRS or my Subarus. Toyota ABS is more refined feeling in my experiences. Historically Toyota usually has done well with brakes up and down the lineup compared to other Japanese car companies. The shitty stopping distance and crap brake pedal feel on the FRS is all Subaru again.
The brake system is Subaru/Hitachi/Tokico but the ABS unit is Toyota/Bosch. The stock rotors and pads are Toyota/ADVICS.
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Old 10-13-2014, 03:43 PM   #52
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The brake system is Subaru/Hitachi/Tokico but the ABS unit is Toyota/Bosch. The stock rotors and pads are Toyota/ADVICS.
Seems like a common issue in the Bosch ABS units. I'm wondering if it's already been hacked?
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Old 10-13-2014, 04:08 PM   #53
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The brake system is Subaru/Hitachi/Tokico but the ABS unit is Toyota/Bosch. The stock rotors and pads are Toyota/ADVICS.
Seems more complicated than that. Looks like ADVICS was only established in 2001. So it's likely my prior Toyotas didn't use ADVICS at all. Denso seems to fit into the mix too. I have noticed Toyota braking distances creeping up over the years so I wouldn't doubt the possibility of a correlation.

Since you pointed it out, I decided to do some digging and it looks like the crap Subaru brakes I was referring to, are also made by ADVICS. So the Subaru brakes I hate are made by a company partially owned by Toyota. Toyota is also part owner of Fuji Heavy who own Subaru. So yeah, all the incest is complicated and difficult to sort through these days.

Point is, the modern Subaru brakes feel like shit to me compared to the older Toyota brakes I was used to. When I first test drove the FRS and got on the brakes, the first thing I thought about were the brakes in my Subaru which I hated till I swapped out for Hawks.

Any idea which Toyotas used to have Akebono pads?

http://www.autonews.com/article/2009...ness-to-advics

http://www.advics.co.jp/eng/company/enkaku.html

https://www.google.com/search?q=advi...cs+subaru+pads
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Old 10-13-2014, 05:01 PM   #54
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Seems more complicated than that. Looks like ADVICS was only established in 2001. So it's likely my prior Toyotas didn't use ADVICS at all. Denso seems to fit into the mix too. I have noticed Toyota braking distances creeping up over the years so I wouldn't doubt the possibility of a correlation.

Since you pointed it out, I decided to do some digging and it looks like the crap Subaru brakes I was referring to, are also made by ADVICS. So the Subaru brakes I hate are made by a company partially owned by Toyota. Toyota is also part owner of Fuji Heavy who own Subaru. So yeah, all the incest is complicated and difficult to sort through these days.

Point is, the modern Subaru brakes feel like shit to me compared to the older Toyota brakes I was used to. When I first test drove the FRS and got on the brakes, the first thing I thought about were the brakes in my Subaru which I hated till I swapped out for Hawks.

Any idea which Toyotas used to have Akebono pads?

http://www.autonews.com/article/2009...ness-to-advics

http://www.advics.co.jp/eng/company/enkaku.html

https://www.google.com/search?q=advi...cs+subaru+pads
Before ADVICS, it was just AISIN, which is still Toyota's brand. But the OEM parts used can vary from model to model over the years. ADVICS only fairly recently started doing discs and pads. The increased braking distances likely have to do with the ever-increasing weight of the vehicles.

The pads are usually the biggest factor in brake feel. Fortunately, pads and discs are not that big of a deal to swap out. There are lots of options out there for these cars.
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Old 10-14-2014, 04:18 PM   #55
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So the car pretty much has front wheel brakes until it's decelerating very hard.

That would explain why my car understeers under braking in the canyon, but nowhere else: no grip.
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Old 10-28-2014, 12:45 AM   #56
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It's quite possible that what happened to me was just a case of me kicking up a bunch of dirt, temporarily messing with the wheel speed sensors and throwing, but if that's the case I don't see anything like that in my wheel speed data. I only see a lot of inside wheel spin (clutch type LSD is planned for next year) in that turn:

{Green=Front Left, Brown=Front Right, Blue=Rear Left, Orange=Rear Right}

Turn 2 is right around the 1500ft mark and then you can see the fronts lock up going into turn 5 around 4100ft
t's worth posting this data here because its data It's hard to tell what actually triggers the ABS off mode as I am seeing some front wheel speed differential prior to the lock up. In my car I'm wheels up all the time so it's possible excessive front wheel speed differential triggers ABS Off mode prior to actually braking.

In any event it was good to see someone else experience the extreme front bias when the ABS fails. Click on the link in the quote to watch his video and see how he struggles to stop even at relatively slow speeds.

The key is going to balance the brakes without the ABS on.
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