follow ft86club on our blog, twitter or facebook.
FT86CLUB
Ft86Club
Speed By Design
Register Garage Members List Calendar Search Today's Posts Mark Forums Read

Go Back   Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB > Technical Topics > Tracking / Autocross / HPDE / Drifting

Tracking / Autocross / HPDE / Drifting What these cars were built for!


User Tag List

Reply
 
Thread Tools Search this Thread
Old 09-16-2020, 05:13 PM   #15
ZDan
Senior Member
 
ZDan's Avatar
 
Join Date: May 2011
Drives: '23 BRZ
Location: Providence, RI
Posts: 4,567
Thanks: 1,368
Thanked 3,879 Times in 2,024 Posts
Mentioned: 85 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by rice_classic View Post
I'm operating under the assumption that the ABS block is also responsible for brake bias. By pulling the big fuse, did you notice your front:rear bias to be any different? Easier to lock up one end vs the other than before?
With the fuse pulled there's enough front bias to ensure thhe fronts lock first, at least with the pads I'm running (CSG Spec C2 front, Winmax W5 rear). I didn't note any loss of overall braking so the built-in mechanical bias/balance must be pretty decent, i.e. forward-biased but not *too* forward-biased...
ZDan is offline   Reply With Quote
The Following 4 Users Say Thank You to ZDan For This Useful Post:
CSG Mike (09-17-2020), JesseG (09-22-2020), NoHaveMSG (09-16-2020), rice_classic (09-16-2020)
Old 09-16-2020, 08:37 PM   #16
Evan55
Member
 
Join Date: May 2013
Drives: 06 Exige, 17 BRZ PP
Location: VA
Posts: 92
Thanks: 30
Thanked 42 Times in 24 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Well this is terrifying.


And at the Glen no less. Probably the last track Id want to have a wheel randomly lock up
Evan55 is offline   Reply With Quote
Old 09-16-2020, 11:24 PM   #17
ZDan
Senior Member
 
ZDan's Avatar
 
Join Date: May 2011
Drives: '23 BRZ
Location: Providence, RI
Posts: 4,567
Thanks: 1,368
Thanked 3,879 Times in 2,024 Posts
Mentioned: 85 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by Evan55 View Post
Well this is terrifying.


And at the Glen no less. Probably the last track Id want to have a wheel randomly lock up
Just take it *super* easy on brakes if you ever see the VSC light come on!

I went out a few times and was able to reproduce the problem. Brakes operated fine until the VSC light came on. After that the brakes went psycho next time the brakes were applied somewhat hard (like 80% max), aggressively and asymmetrically locking the fronts.

I put the 40A fuse back in for the trip home today and the light never came on. I don't know if there really is a yaw sensor problem or if track usage made the car think there's a problem there. Anyway, I'll probably just pull the fuse for next track event. I get -1 points for that so can run 42 lb. lighter so why not...
ZDan is offline   Reply With Quote
Old 09-17-2020, 03:52 AM   #18
churchx
Senior Member
 
churchx's Avatar
 
Join Date: Mar 2015
Drives: 2014 GT86
Location: Latvia, Riga
Posts: 4,333
Thanks: 696
Thanked 2,085 Times in 1,436 Posts
Mentioned: 53 Post(s)
Tagged: 1 Thread(s)
Not much related with yaw sensor glitch, but when few times ago i got handbrake signal on dash from time to time on track, first thing i'd check would be brake fluid level. Pads wear > fluid level dropped below normal > that light lit. Simple fillup to normal level to compensate pad wear "fixed", just had to remove excess when changing new full thickness pads and pushed pistons in, to not overflow.
churchx is offline   Reply With Quote
Old 09-18-2020, 12:13 PM   #19
ZDan
Senior Member
 
ZDan's Avatar
 
Join Date: May 2011
Drives: '23 BRZ
Location: Providence, RI
Posts: 4,567
Thanks: 1,368
Thanked 3,879 Times in 2,024 Posts
Mentioned: 85 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by timurrrr View Post
Do you have any data acquisition system?
Can you log what you're getting from CAN PID 0xD0?
https://github.com/timurrrr/RaceChro...86.md#pid-0xd0
Don't have any CAN data. Deep-dive my bud did after the incident showed these codes:
C1234 Yaw Rate Sensor
C1237 Speed Sensor Rotor Faulty
C1464 Front Speed Sensor RH Circuit
C1465 Front Speed Sensor LH Circuit

Went back out with no changes, after a few laps the light came on again and again at the very next braking zone, taking it easy (early braking at ~70%) the same early and asymmetrical front lockup happened. But no crash this time! Brought it in, plugged in and this time it only showed the "Yaw Rate Sensor" code. We think the speed sensor codes from the first occurrence might have been triggered by the massive front lockups and impact.

Went out again with "pedal dance" instead of 5-sec hold on VSC "OFF" button, again fine for a few laps, then VSC warning light on and insane front brake behavior.
ZDan is offline   Reply With Quote
Old 09-18-2020, 12:15 PM   #20
ZDan
Senior Member
 
ZDan's Avatar
 
Join Date: May 2011
Drives: '23 BRZ
Location: Providence, RI
Posts: 4,567
Thanks: 1,368
Thanked 3,879 Times in 2,024 Posts
Mentioned: 85 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by churchx View Post
Not much related with yaw sensor glitch, but when few times ago i got handbrake signal on dash from time to time on track, first thing i'd check would be brake fluid level. Pads wear > fluid level dropped below normal > that light lit. Simple fillup to normal level to compensate pad wear "fixed", just had to remove excess when changing new full thickness pads and pushed pistons in, to not overflow.
Yep, I checked that too tho I knew it was fine (recently bled/filled). Red "BRAKE" light went back to sleep after 40A ABS fuse was re-installed for trip home.
ZDan is offline   Reply With Quote
Old 09-21-2020, 12:03 PM   #21
redlined600
Senior Member
 
redlined600's Avatar
 
Join Date: Nov 2014
Drives: Fr-s
Location: MN
Posts: 731
Thanks: 122
Thanked 492 Times in 266 Posts
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
When I bought my car it had a bad clockspring/steering angle sensor(long story). it showed bad wheel speed sensor as well but once I replaced the clockspring/angel sensor the wheel speed sensor error went away.

You mentioned you have(or have a friend with) techstream, have you tried to do the calibration?
__________________
redlined600 is offline   Reply With Quote
The Following 2 Users Say Thank You to redlined600 For This Useful Post:
JesseG (09-22-2020), ZDan (09-22-2020)
Old 09-22-2020, 01:30 PM   #22
ZDan
Senior Member
 
ZDan's Avatar
 
Join Date: May 2011
Drives: '23 BRZ
Location: Providence, RI
Posts: 4,567
Thanks: 1,368
Thanked 3,879 Times in 2,024 Posts
Mentioned: 85 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by redlined600 View Post
When I bought my car it had a bad clockspring/steering angle sensor(long story). it showed bad wheel speed sensor as well but once I replaced the clockspring/angel sensor the wheel speed sensor error went away.

You mentioned you have(or have a friend with) techstream, have you tried to do the calibration?
When I called Subaru parts, when I told them the error I was seeing and asking for price on a "yaw sensor", the parts guy suggested that what I really wanted was the steering angle sensor. So yeah if I get the opportunity I might try that. Friend who did deep-dive at the track is a guy I haven't seen in years who happened to be there, but I think I could track him down, see if he can do dis...
ZDan is offline   Reply With Quote
Old 09-22-2020, 01:42 PM   #23
rice_classic
Senior Member
 
rice_classic's Avatar
 
Join Date: Jun 2012
Drives: Nevermorange FRS
Location: Seattle, WA
Posts: 4,160
Thanks: 755
Thanked 4,200 Times in 1,803 Posts
Mentioned: 77 Post(s)
Tagged: 1 Thread(s)
I think you have a failed part. Unlike many other Toyota's and subarus, the Yaw Sensor isn't external and easily replaceable like on other cars but these yaw sensors do fail. In our case the Yaw Sensor is integrated into the Speed Control Computer which is integrated into the ABS Block (Brake Actuator Assembly).

Ideally, you have a wheel speed sensor that is faulty (or getting a dirty signal) and it can be cleaned/replaced. Another ideal scenario is that the calibration is off and a recalibration with Techstream will set you straight (pun).
Quote:
Diagnostic codes
DTC detecting conditions
Faulty part
C1234
Skid control computer (brake actuator ASSY) internal error (yaw rate sensor)
Skid control computer (brake actuator ASSY)
C1419
Skid control computer (brake actuator ASSY) internal error (G sensor)
C1472
Skid control computer (brake actuator ASSY) internal error (lateral G sensor)
C1474
Skid control computer (brake actuator ASSY) internal error (longitudinal G sensor)


Recommends checking wheel speed sensors for damage or foreign material

Check speed sensor with techstream (think you have that) should be equal

1. VDC sensor midpoint setting mode
CAUTION: ·When the skid control computer (brake actuator ASSY) has been replaced, make sure to perform VDC sensor midpoint setting.
·Make sure to perform [VDC sensor midpoint setting mode] on a level surface (grade of 1 % or less). While centering, do not shake the vehicle or open/close a door.



NOTE: When performing [VDC sensor midpoint setting mode], make sure to set zero point of yaw rate sensor & G sensor (brake actuator ASSY is integrated) and steering sensor.


(1) Turn the ignition switch to OFF.

(2) Shift into neutral and apply the parking brake.

(3) Connect the SSM3 to the DLC3.

(4) Turn the ignition switch to ON.

(5) Set the steering wheel in a straight position.

(6) On the SSM3 screen, select [ABS/VDC System]→[Work Support]→[VDC sensor midpoint setting mode].

(7) Following the SSM3 screen, perform [VDC sensor midpoint setting mode].
If you DO have a failed Yaw sensor, then you'll have to replace your ABS block so you may want to start looking on Ebay or your local salvage yards for one instead of paying $1500-2k on a new one.
__________________
SCCA T4 - FRS
rice_classic is offline   Reply With Quote
The Following 2 Users Say Thank You to rice_classic For This Useful Post:
JesseG (09-22-2020), ZDan (09-22-2020)
Old 09-22-2020, 01:50 PM   #24
rice_classic
Senior Member
 
rice_classic's Avatar
 
Join Date: Jun 2012
Drives: Nevermorange FRS
Location: Seattle, WA
Posts: 4,160
Thanks: 755
Thanked 4,200 Times in 1,803 Posts
Mentioned: 77 Post(s)
Tagged: 1 Thread(s)
Quote:
Originally Posted by ZDan View Post
When I called Subaru parts, when I told them the error I was seeing and asking for price on a "yaw sensor", the parts guy suggested that what I really wanted was the steering angle sensor. So yeah if I get the opportunity I might try that. Friend who did deep-dive at the track is a guy I haven't seen in years who happened to be there, but I think I could track him down, see if he can do dis...
Did you ever remove your steering wheel or install an aftermarket wheel? If so it's very possible you reinstalled things without your clock spring perfectly center. I reinstalled mine enough off center that when I turned the wheel to full lock I broke the damn thing but I got the C1231 code, not the C1234 code you have for Yaw.

Obviously you want to eliminate this as a possibility which means you do need (and should have) techstream and checking/resetting the calibration should be considered if you've ever had your steering wheel off. If you've never removed your steering wheel I think the likelihood of your Steering Angle Sensor (clock spring) being the culprit is low.
__________________
SCCA T4 - FRS
rice_classic is offline   Reply With Quote
The Following User Says Thank You to rice_classic For This Useful Post:
ZDan (09-22-2020)
Old 09-22-2020, 01:52 PM   #25
ZDan
Senior Member
 
ZDan's Avatar
 
Join Date: May 2011
Drives: '23 BRZ
Location: Providence, RI
Posts: 4,567
Thanks: 1,368
Thanked 3,879 Times in 2,024 Posts
Mentioned: 85 Post(s)
Tagged: 0 Thread(s)
Given that the problem does give warning (VSC warning light), and given that the car performs great at the track with the ABS fuse pulled, and that pulling the ABS fuse gains me a classification point (42 lb. lower weight allowed), and that the failure doesn't happen on the street (not so far anyway), and that I'm about to be $$$$ out for body repairs, I think I'ma leave ABS module as is for now...

Quote:
Originally Posted by rice_classic View Post
I think you have a failed part. Unlike many other Toyota's and subarus, the Yaw Sensor isn't external and easily replaceable like on other cars but these yaw sensors do fail. In our case the Yaw Sensor is integrated into the Speed Control Computer which is integrated into the ABS Block (Brake Actuator Assembly).

Ideally, you have a wheel speed sensor that is faulty (or getting a dirty signal) and it can be cleaned/replaced. Another ideal scenario is that the calibration is off and a recalibration with Techstream will set you straight (pun).


If you DO have a failed Yaw sensor, then you'll have to replace your ABS block so you may want to start looking on Ebay or your local salvage yards for one instead of paying $1500-2k on a new one.
ZDan is offline   Reply With Quote
The Following User Says Thank You to ZDan For This Useful Post:
JesseG (09-22-2020)
Old 09-22-2020, 02:30 PM   #26
Icecreamtruk
Senior Member
 
Join Date: Dec 2015
Drives: Track preped NA FRS
Location: Montreal, Canada
Posts: 987
Thanks: 1,056
Thanked 680 Times in 405 Posts
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
@ZDan a bit of topic, but would you say the car was better or worse to brake with after pulling the 40A ABS fuse pulled? Im doing a swap next season and car will be ABS-less and I had to return the nanny86 that I had borrowed so Im considering this option for my last TT this season. Thoughs?
Icecreamtruk is offline   Reply With Quote
The Following User Says Thank You to Icecreamtruk For This Useful Post:
NoHaveMSG (09-22-2020)
Old 09-22-2020, 02:37 PM   #27
NoHaveMSG
Senior Member
 
NoHaveMSG's Avatar
 
Join Date: Jan 2018
Drives: Crapcan
Location: Oregon
Posts: 11,088
Thanks: 18,059
Thanked 16,224 Times in 7,328 Posts
Mentioned: 106 Post(s)
Tagged: 0 Thread(s)
Garage
Quote:
Originally Posted by Icecreamtruk View Post
@ZDan a bit of topic, but would you say the car was better or worse to brake with after pulling the 40A ABS fuse pulled? Im doing a swap next season and car will be ABS-less and I had to return the nanny86 that I had borrowed so Im considering this option for my last TT this season. Thoughs?
I'm wondering the same thing for the same reason
__________________
"Experience is the hardest kind of teacher. It gives you the test first and the lesson afterward." -Oscar Wilde.
NoHaveMSG is offline   Reply With Quote
The Following User Says Thank You to NoHaveMSG For This Useful Post:
Icecreamtruk (09-22-2020)
Old 09-22-2020, 03:36 PM   #28
ZDan
Senior Member
 
ZDan's Avatar
 
Join Date: May 2011
Drives: '23 BRZ
Location: Providence, RI
Posts: 4,567
Thanks: 1,368
Thanked 3,879 Times in 2,024 Posts
Mentioned: 85 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by Icecreamtruk View Post
@ZDan a bit of topic, but would you say the car was better or worse to brake with after pulling the 40A ABS fuse pulled? Im doing a swap next season and car will be ABS-less and I had to return the nanny86 that I had borrowed so Im considering this option for my last TT this season. Thoughs?
Before this event, I'd say I could more reliably hit threshold utilizing the ABS, which has previously always worked great for me, but for lap times (as opposed to being able to out-brake someone into a corner), I don't think there's much in it time-wise.

At this event, before the light came on, it seemed to me that the *outside* left front was kinda being overworked going into turn one, which struck me as odd. Then light came on and next brake zone left front, then both fronts dead LOCKED, quite prematurely at a much-lower-than-expected force applied at the pedal.

With the 40A fuse removed, no ABS, braking was quite good and predictable, and modulatable up to and after front lockup (i.e. easy recovery and no wacky darting left or right during lockup).

Without ABS, front/rear brake pad selection is going to be more important for ultimate braking and controllability. Again, I'm on CSG Spec C2 fronts and Winmax W5 rears. My impression is that this is somewhat front-biased but not excessively so. I wouldn't be averse to trying C2 rears with the C2 fronts, which has been recommended by the experts (i.e., CSG). But for sure I'd keep the W5s on hand just in case it got squirrelly under braking.

I'd recommend having same/same front/rear brakes with no ABS but maybe have a lower-coefficient rear set on hand just in case...

I have zero qualms about running without ABS for the last two events of the year and definitely *prefer* this to taking chances with malfunctioning sensors when the now KNOWN failure mode (excessive, premature, and asymmetric front lockup) is pretty dangerous!
ZDan is offline   Reply With Quote
The Following User Says Thank You to ZDan For This Useful Post:
Icecreamtruk (09-22-2020)
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Instability under hard braking on track, rear cross camber, road undulation, or toe? SmoothIsSlow Suspension | Chassis | Brakes -- Sponsored by 949 Racing 11 06-26-2019 02:58 AM
Had trouble engaging ABS at the track this week; how come? SmoothIsSlow Suspension | Chassis | Brakes -- Sponsored by 949 Racing 23 06-04-2019 08:54 AM
Trouble at Track, Need Help Lunatic Scion FR-S / Toyota 86 GT86 General Forum 43 07-20-2014 07:12 PM
Braking system concern after track incident SubiePig Tracking / Autocross / HPDE / Drifting 22 01-22-2014 07:35 PM
Help me track down my braking problem :( #87 Other Vehicles & General Automotive Discussions 32 09-26-2011 12:49 PM


All times are GMT -4. The time now is 02:30 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
User Alert System provided by Advanced User Tagging v3.3.0 (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.

Garage vBulletin Plugins by Drive Thru Online, Inc.