Front Left (Driver) Brake Lockup - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

B T · 01-23-2018, 03:45 PM

Under hard braking in a straight line, my driver's side front brake always locks up long before any others. In fact, I'm not sure I've ever locked up any other wheel at all. I've tried multiple sets of tires, track brake pads, ABS off, and finally moved to a 4 corner big brake package moving bias slightly to the rear, always with the same outcome.
I've had this issue since new under hard braking and have tried to single it down without too much success. All I can think it maybe there's a problem at the central split to each wheel. Has anyone else encountered the same issue?

churchx · 01-23-2018, 06:07 PM

If tires (multiple sets, and i guess that pressures were even) & brakes (misc pads & no abs & BBK) & diff (as front) are out of picture, what's left .. alignment?

cjd · 01-23-2018, 06:18 PM

Corner balanced?

strat61caster · 01-23-2018, 06:59 PM

How do you know it's doing that?

x808drifter · 01-23-2018, 07:21 PM

Quote:

Originally Posted by cjd

Corner balanced?

All else being equal I'd go with that.
My miata did the same until I corner balanced the car.
It was way off before that though.

B T · 01-25-2018, 01:16 PM

Someone else has suggested corner balance as well, so maybe I'll go that route. It was having the same issue on stock suspension and coilovers.
Different sets of tires have been tested also. Alignment has been done several times due to various circumstances and doesn't seem to have made a difference.

x808drifter · 01-25-2018, 03:22 PM

Did you buy the car new?

B T · 01-25-2018, 05:01 PM

had it since new

cjd · 01-25-2018, 10:11 PM

What do you have done suspension-wise? It strikes me as really odd behavior, but I can concoct a possible way if the balance is messed up and the front swaybar is stiff enough relative to everything... I'm still skeptical. It brings me back to the question, how do you know that's the wheel locking up?

ls1ac · 01-25-2018, 11:59 PM

Hold on, you are able to "lock up" the front tire and get blue smoke with the ABS unit turned on? If so it is not working. Or are you hearing the ABS kicking in? Is it the ABS unit that you are hearing as it applies and releases the brakes to keep from locking up? That sound comes from the unit not the tires, and is located in front of the brake master cylinder.

Tcoat · 01-26-2018, 10:32 AM

Quote:

Originally Posted by ls1ac

Hold on, you are able to "lock up" the front tire and get blue smoke with the ABS unit turned on? If so it is not working. Or are you hearing the ABS kicking in? Is it the ABS unit that you are hearing as it applies and releases the brakes to keep from locking up? That sound comes from the unit not the tires, and is located in front of the brake master cylinder.

This ^ makes the most sense.

B T · 01-26-2018, 12:41 PM

yeah, it'll smoke the front tire until I back off the brakes. I've felt ABS on plenty of cars in the past as well as on this car back when I first acquired it. I'm pretty sure the ABS isn't functioning correctly. There doesn't seem to be any ABS intervention at the point the tire locks up. I'm taking it in sometime soon to have the module replaced by subaru.

churchx · 01-26-2018, 01:29 PM

Wait a sec. In OP there was mentioned among tried out things ABS off. Now it'a about ABS not functioning correctly. Was it switched back at all?

ls1ac · 01-26-2018, 02:36 PM

OK, first you say it happened when you got the car and now you say you were aware of the ABS working when you got it???

This is interesting as you describe left front locking up first, the steering wheel would pull hard left and the car would try to go left when ever the brakes were used hard. Not a good car to drive.

(In a race car left front first is either a balance/bias issue or the right front caliper is sticking and is slow to engage and will not release as quickly as the left. Pulling first left then right. Should not admit it but have tried to finish a race like this, not fun in traffic.)

01-23-2018, 03:45 PM	#1
B T Senior Member Join Date: May 2015 Drives: 15 BRZ, 2003 MR2, '70 Elky, 06 TBSS Location: Mobile, Alabama Posts: 510 Thanks: 194 Thanked 200 Times in 142 Posts Mentioned: 7 Post(s) Tagged: 0 Thread(s)	Front Left (Driver) Brake Lockup Under hard braking in a straight line, my driver's side front brake always locks up long before any others. In fact, I'm not sure I've ever locked up any other wheel at all. I've tried multiple sets of tires, track brake pads, ABS off, and finally moved to a 4 corner big brake package moving bias slightly to the rear, always with the same outcome. I've had this issue since new under hard braking and have tried to single it down without too much success. All I can think it maybe there's a problem at the central split to each wheel. Has anyone else encountered the same issue?

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01-23-2018, 06:07 PM	#2
churchx Senior Member 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)	If tires (multiple sets, and i guess that pressures were even) & brakes (misc pads & no abs & BBK) & diff (as front) are out of picture, what's left .. alignment?

01-25-2018, 01:16 PM	#6
B T Senior Member Join Date: May 2015 Drives: 15 BRZ, 2003 MR2, '70 Elky, 06 TBSS Location: Mobile, Alabama Posts: 510 Thanks: 194 Thanked 200 Times in 142 Posts Mentioned: 7 Post(s) Tagged: 0 Thread(s)	Someone else has suggested corner balance as well, so maybe I'll go that route. It was having the same issue on stock suspension and coilovers. Different sets of tires have been tested also. Alignment has been done several times due to various circumstances and doesn't seem to have made a difference.

01-25-2018, 03:22 PM	#7
x808drifter LMGTFY Join Date: Mar 2016 Drives: 13 FRS, 91 Miata Location: Lava Town, HI Posts: 2,776 Thanks: 5,561 Thanked 3,646 Times in 1,625 Posts Mentioned: 15 Post(s) Tagged: 0 Thread(s)	Did you buy the car new?

01-25-2018, 05:01 PM	#8
B T Senior Member Join Date: May 2015 Drives: 15 BRZ, 2003 MR2, '70 Elky, 06 TBSS Location: Mobile, Alabama Posts: 510 Thanks: 194 Thanked 200 Times in 142 Posts Mentioned: 7 Post(s) Tagged: 0 Thread(s)	had it since new

01-26-2018, 12:41 PM	#12
B T Senior Member Join Date: May 2015 Drives: 15 BRZ, 2003 MR2, '70 Elky, 06 TBSS Location: Mobile, Alabama Posts: 510 Thanks: 194 Thanked 200 Times in 142 Posts Mentioned: 7 Post(s) Tagged: 0 Thread(s)	yeah, it'll smoke the front tire until I back off the brakes. I've felt ABS on plenty of cars in the past as well as on this car back when I first acquired it. I'm pretty sure the ABS isn't functioning correctly. There doesn't seem to be any ABS intervention at the point the tire locks up. I'm taking it in sometime soon to have the module replaced by subaru.

01-26-2018, 01:29 PM	#13
churchx Senior Member 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)	Wait a sec. In OP there was mentioned among tried out things ABS off. Now it'a about ABS not functioning correctly. Was it switched back at all?

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