Important warning / notice: 100% brake system failure lexus sc430
07-05-18, 12:05 PM
#31
Driver School Candidate
Thread Starter
07-05-18, 12:37 PM
#32
Instructor
Guys
Over the years, I have owned 4 SC 430s ranging from 2002( current SC) to an 03 and 04
To an 06. I am no expert but I know our ABS/Brake Boosyer is
one unit. All 4 of my SC had mileage ranging from 28K to 78K
As you can tell, I am a big SC fan. I do notice all my SC
have the ABS pumping continuously. I brought two SC to
the dealer and each time, they diagnosed it is normal operation
Other than the ABS pumping for pressure, all the SCs have been
whisper quiet. I wondered if over time the pump
Leak pressure due to age and or mileage.
Regardless, I don’t agree any car should lose 100% brake
pressure with or without warning or because it is X year old
. It is possible from what I understand, the VSC and the ABS lights
all go off as your ABS pump loses pressure which would be
a sign your SC ABS/Brake booster is going out.
Even if there were only “1 “ incident where someone could
Fatually get hurt is 1 too many.
Glad to hear MJN was safe and not hurt but for domeone
who is less experienced or don’t know about the dienshift
option could be more than 1 fatility.
Over the years, I have owned 4 SC 430s ranging from 2002( current SC) to an 03 and 04
To an 06. I am no expert but I know our ABS/Brake Boosyer is
one unit. All 4 of my SC had mileage ranging from 28K to 78K
As you can tell, I am a big SC fan. I do notice all my SC
have the ABS pumping continuously. I brought two SC to
the dealer and each time, they diagnosed it is normal operation
Other than the ABS pumping for pressure, all the SCs have been
whisper quiet. I wondered if over time the pump
Leak pressure due to age and or mileage.
Regardless, I don’t agree any car should lose 100% brake
pressure with or without warning or because it is X year old
. It is possible from what I understand, the VSC and the ABS lights
all go off as your ABS pump loses pressure which would be
a sign your SC ABS/Brake booster is going out.
Even if there were only “1 “ incident where someone could
Fatually get hurt is 1 too many.
Glad to hear MJN was safe and not hurt but for domeone
who is less experienced or don’t know about the dienshift
option could be more than 1 fatility.
The following users liked this post:
jszachar (12-11-20)
07-05-18, 12:45 PM
#33
I would expect Lexus to handle this in pretty much the same way Pontiac handled my situation. I had a 90 Grand Prix . While going down a two lane country road I lost all steering. You could spin the steering wheel freely like a toy wheel. A car was coming the other direction, but my car was drifting to the right towards the ditch. So I didn't touch the brakes because I didn't want the car to maybe head into the oncoming car. The car landed safely in a rather deep ditch. Come to find out, the rear engine cradle bolts snapped. This snapped the steering shaft. The car was like six years old. Pontiac covered everything about eight grand in parts and labor. There wasn't any body damage miraculously. Later that year a recall came out for the engine cradle bolts. I had to take it back in to get the updated bolts installed. I can't see Lexus taking this brake problem any less serious than Pontiac took my situation.
The following users liked this post:
jszachar (12-11-20)
07-05-18, 04:31 PM
#34
Driver School Candidate
Thread Starter
Guys
Over the years, I have owned 4 SC 430s ranging from 2002( current SC) to an 03 and 04
To an 06. I am no expert but I know our ABS/Brake Boosyer is
one unit. All 4 of my SC had mileage ranging from 28K to 78K
As you can tell, I am a big SC fan. I do notice all my SC
have the ABS pumping continuously. I brought two SC to
the dealer and each time, they diagnosed it is normal operation
Other than the ABS pumping for pressure, all the SCs have been
whisper quiet. I wondered if over time the pump
Leak pressure due to age and or mileage.
Regardless, I don’t agree any car should lose 100% brake
pressure with or without warning or because it is X year old
. It is possible from what I understand, the VSC and the ABS lights
all go off as your ABS pump loses pressure which would be
a sign your SC ABS/Brake booster is going out.
Even if there were only “1 “ incident where someone could
Fatually get hurt is 1 too many.
Glad to hear MJN was safe and not hurt but for domeone
who is less experienced or don’t know about the dienshift
option could be more than 1 fatility.
Over the years, I have owned 4 SC 430s ranging from 2002( current SC) to an 03 and 04
To an 06. I am no expert but I know our ABS/Brake Boosyer is
one unit. All 4 of my SC had mileage ranging from 28K to 78K
As you can tell, I am a big SC fan. I do notice all my SC
have the ABS pumping continuously. I brought two SC to
the dealer and each time, they diagnosed it is normal operation
Other than the ABS pumping for pressure, all the SCs have been
whisper quiet. I wondered if over time the pump
Leak pressure due to age and or mileage.
Regardless, I don’t agree any car should lose 100% brake
pressure with or without warning or because it is X year old
. It is possible from what I understand, the VSC and the ABS lights
all go off as your ABS pump loses pressure which would be
a sign your SC ABS/Brake booster is going out.
Even if there were only “1 “ incident where someone could
Fatually get hurt is 1 too many.
Glad to hear MJN was safe and not hurt but for domeone
who is less experienced or don’t know about the dienshift
option could be more than 1 fatility.
07-05-18, 04:32 PM
#35
Driver School Candidate
Thread Starter
I would expect Lexus to handle this in pretty much the same way Pontiac handled my situation. I had a 90 Grand Prix . While going down a two lane country road I lost all steering. You could spin the steering wheel freely like a toy wheel. A car was coming the other direction, but my car was drifting to the right towards the ditch. So I didn't touch the brakes because I didn't want the car to maybe head into the oncoming car. The car landed safely in a rather deep ditch. Come to find out, the rear engine cradle bolts snapped. This snapped the steering shaft. The car was like six years old. Pontiac covered everything about eight grand in parts and labor. There wasn't any body damage miraculously. Later that year a recall came out for the engine cradle bolts. I had to take it back in to get the updated bolts installed. I can't see Lexus taking this brake problem any less serious than Pontiac took my situation.
07-05-18, 06:46 PM
#36
Driver School Candidate
Some History:
At least 4 occurrences of what could be a catastrophic failure. that the SC's are older models, 16 or so years, does not absolve LEXUS or TOYOTA from potentially ignoring what may be a systemic design issue that could result in fatalities
From OWALI (7/15/2011)
Pretty scary... driving along the other night and my dash lights up like a Christmas tree. A minute later my brakes are 95% useless. Luckily I made it to the side of the road without hitting anything. I need some help determining what the cause is though. I have been reading other peeps stories on the forum and at first it sounded like a brake master cylinder/booster failure, but I need to make sure before I drop all that cash on a new part.After reading here, I was almost positive it was the BMC/booster. But my mechanic said it was an electrical problem. He said the brakes were electronically assisted and they were not getting power. He said the BMC looked fine. He said I would need to go to Lexus Dealer to get fixed. Now I am really confused
Lexus dealer is 3 hours away so I cant just stop by for a diagnosis. I am wondering if the BMC is fine but the attached booster is bad, but I don't want to pay for a new one on a hunch.
Symptoms: Strange continuous buzzing alarm from dash, Brake light, ABS and VSC lights on. Almost no braking power left. Pedal is stiff as a rock. It is mostly pressed down and wont budge. When I start the car with the pedal pressed the pedal does not sink. I have not seen any brake fluid leaking, still looks full.
FROM RUNYUN (7/15/2011)
Ton's of threads here about it. It's common on the 98-00 year models.
Best bet would to find one used
Exact same symptoms:
Buzzing sound (intermittant) typically last about 6-8 seconds
Then, one day no power assist in braking. Your brake pedal barely moves and the car doesn't stop anywhere close where it needs to. (I almost wrecked on my previous GS because of it)
From JRyan (2/15/2012)
this happened to me two times. I took it to my mechanic who used to be a senior mechanic for Lexus but now has huis own shop. He knew immediately when I called him what the problem was. He has seen it many times. The electric pump motor on the master cylinder failed. The entire master cylinder does not have to be replaced. Only the pump motor. Unfortunately the part is not sold seperately. Lexus will sell the master cylinder for around $2500. My mechanic removed the motor and sent it to a shop to have it rebuilt. This cost me $400. He tells me that there are only like three places in the in tire country that will rebuild them. He said replacing the motor only takes 20 mins. My first motor failed after several months. It is back at his shop awaiting the rebuild once again. Covered under warranty so, no out of pocket.
From: KYLex42701 (2/262012)
I have a 99 gs300 that has the same problem..my mechanic says its the abs system that has gone out. Does anyone know where i can buy an aftermarket or used one?
At least 4 occurrences of what could be a catastrophic failure. that the SC's are older models, 16 or so years, does not absolve LEXUS or TOYOTA from potentially ignoring what may be a systemic design issue that could result in fatalities
From OWALI (7/15/2011)
Pretty scary... driving along the other night and my dash lights up like a Christmas tree. A minute later my brakes are 95% useless. Luckily I made it to the side of the road without hitting anything. I need some help determining what the cause is though. I have been reading other peeps stories on the forum and at first it sounded like a brake master cylinder/booster failure, but I need to make sure before I drop all that cash on a new part.After reading here, I was almost positive it was the BMC/booster. But my mechanic said it was an electrical problem. He said the brakes were electronically assisted and they were not getting power. He said the BMC looked fine. He said I would need to go to Lexus Dealer to get fixed. Now I am really confused
Lexus dealer is 3 hours away so I cant just stop by for a diagnosis. I am wondering if the BMC is fine but the attached booster is bad, but I don't want to pay for a new one on a hunch.
Symptoms: Strange continuous buzzing alarm from dash, Brake light, ABS and VSC lights on. Almost no braking power left. Pedal is stiff as a rock. It is mostly pressed down and wont budge. When I start the car with the pedal pressed the pedal does not sink. I have not seen any brake fluid leaking, still looks full.
FROM RUNYUN (7/15/2011)
Ton's of threads here about it. It's common on the 98-00 year models.
Best bet would to find one used
Exact same symptoms:
Buzzing sound (intermittant) typically last about 6-8 seconds
Then, one day no power assist in braking. Your brake pedal barely moves and the car doesn't stop anywhere close where it needs to. (I almost wrecked on my previous GS because of it)
From JRyan (2/15/2012)
this happened to me two times. I took it to my mechanic who used to be a senior mechanic for Lexus but now has huis own shop. He knew immediately when I called him what the problem was. He has seen it many times. The electric pump motor on the master cylinder failed. The entire master cylinder does not have to be replaced. Only the pump motor. Unfortunately the part is not sold seperately. Lexus will sell the master cylinder for around $2500. My mechanic removed the motor and sent it to a shop to have it rebuilt. This cost me $400. He tells me that there are only like three places in the in tire country that will rebuild them. He said replacing the motor only takes 20 mins. My first motor failed after several months. It is back at his shop awaiting the rebuild once again. Covered under warranty so, no out of pocket.
From: KYLex42701 (2/262012)
I have a 99 gs300 that has the same problem..my mechanic says its the abs system that has gone out. Does anyone know where i can buy an aftermarket or used one?
Last edited by Bre88; 07-05-18 at 06:58 PM.
The following users liked this post:
jszachar (12-11-20)
07-05-18, 07:12 PM
#37
Driver School Candidate
Thread Starter
Some History:
At least 4 occurrences of what could be a catastrophic failure. that the SC's are older models, 16 or so years, does not absolve LEXUS or TOYOTA from potentially ignoring what may be a systemic design issue that could result in fatalities
From OWALI (7/15/2011)
Pretty scary... driving along the other night and my dash lights up like a Christmas tree. A minute later my brakes are 95% useless. Luckily I made it to the side of the road without hitting anything. I need some help determining what the cause is though. I have been reading other peeps stories on the forum and at first it sounded like a brake master cylinder/booster failure, but I need to make sure before I drop all that cash on a new part.After reading here, I was almost positive it was the BMC/booster. But my mechanic said it was an electrical problem. He said the brakes were electronically assisted and they were not getting power. He said the BMC looked fine. He said I would need to go to Lexus Dealer to get fixed. Now I am really confused
Lexus dealer is 3 hours away so I cant just stop by for a diagnosis. I am wondering if the BMC is fine but the attached booster is bad, but I don't want to pay for a new one on a hunch.
Symptoms: Strange continuous buzzing alarm from dash, Brake light, ABS and VSC lights on. Almost no braking power left. Pedal is stiff as a rock. It is mostly pressed down and wont budge. When I start the car with the pedal pressed the pedal does not sink. I have not seen any brake fluid leaking, still looks full.
FROM RUNYUN (7/15/2011)
Ton's of threads here about it. It's common on the 98-00 year models.
Best bet would to find one used
Exact same symptoms:
Buzzing sound (intermittant) typically last about 6-8 seconds
Then, one day no power assist in braking. Your brake pedal barely moves and the car doesn't stop anywhere close where it needs to. (I almost wrecked on my previous GS because of it)
From JRyan (2/15/2012)
this happened to me two times. I took it to my mechanic who used to be a senior mechanic for Lexus but now has huis own shop. He knew immediately when I called him what the problem was. He has seen it many times. The electric pump motor on the master cylinder failed. The entire master cylinder does not have to be replaced. Only the pump motor. Unfortunately the part is not sold seperately. Lexus will sell the master cylinder for around $2500. My mechanic removed the motor and sent it to a shop to have it rebuilt. This cost me $400. He tells me that there are only like three places in the in tire country that will rebuild them. He said replacing the motor only takes 20 mins. My first motor failed after several months. It is back at his shop awaiting the rebuild once again. Covered under warranty so, no out of pocket.
From: KYLex42701 (2/262012)
I have a 99 gs300 that has the same problem..my mechanic says its the abs system that has gone out. Does anyone know where i can buy an aftermarket or used one?
At least 4 occurrences of what could be a catastrophic failure. that the SC's are older models, 16 or so years, does not absolve LEXUS or TOYOTA from potentially ignoring what may be a systemic design issue that could result in fatalities
From OWALI (7/15/2011)
Pretty scary... driving along the other night and my dash lights up like a Christmas tree. A minute later my brakes are 95% useless. Luckily I made it to the side of the road without hitting anything. I need some help determining what the cause is though. I have been reading other peeps stories on the forum and at first it sounded like a brake master cylinder/booster failure, but I need to make sure before I drop all that cash on a new part.After reading here, I was almost positive it was the BMC/booster. But my mechanic said it was an electrical problem. He said the brakes were electronically assisted and they were not getting power. He said the BMC looked fine. He said I would need to go to Lexus Dealer to get fixed. Now I am really confused
Lexus dealer is 3 hours away so I cant just stop by for a diagnosis. I am wondering if the BMC is fine but the attached booster is bad, but I don't want to pay for a new one on a hunch.
Symptoms: Strange continuous buzzing alarm from dash, Brake light, ABS and VSC lights on. Almost no braking power left. Pedal is stiff as a rock. It is mostly pressed down and wont budge. When I start the car with the pedal pressed the pedal does not sink. I have not seen any brake fluid leaking, still looks full.
FROM RUNYUN (7/15/2011)
Ton's of threads here about it. It's common on the 98-00 year models.
Best bet would to find one used
Exact same symptoms:
Buzzing sound (intermittant) typically last about 6-8 seconds
Then, one day no power assist in braking. Your brake pedal barely moves and the car doesn't stop anywhere close where it needs to. (I almost wrecked on my previous GS because of it)
From JRyan (2/15/2012)
this happened to me two times. I took it to my mechanic who used to be a senior mechanic for Lexus but now has huis own shop. He knew immediately when I called him what the problem was. He has seen it many times. The electric pump motor on the master cylinder failed. The entire master cylinder does not have to be replaced. Only the pump motor. Unfortunately the part is not sold seperately. Lexus will sell the master cylinder for around $2500. My mechanic removed the motor and sent it to a shop to have it rebuilt. This cost me $400. He tells me that there are only like three places in the in tire country that will rebuild them. He said replacing the motor only takes 20 mins. My first motor failed after several months. It is back at his shop awaiting the rebuild once again. Covered under warranty so, no out of pocket.
From: KYLex42701 (2/262012)
I have a 99 gs300 that has the same problem..my mechanic says its the abs system that has gone out. Does anyone know where i can buy an aftermarket or used one?
07-05-18, 07:25 PM
#38
Instructor
Guys that was exactly my point from my first reply to this issue.
I have an 85 SL and a 96 Mercedes C280 ( it has its own issues)
And no where would I hear anywhere of my other cars ever have
a critical part failed. These are cars that are even older and not known
for strong reliability like the Toyota or Lexus we own.
Anytime you hear loss of control of a car due to a factory part
potential defect is a concern for all parties involved . I really think
if this part could potentially failed without true warning, it is a serious lisbility
to the auto manufacturer. Because we love the SC and we know so much
about these cars, we might at least know how to stop the car with downshifting etc
but to someone who does not know about the signs of a failed
booster or know how to downshift , it is a serious accident
waiting to hapoen
I have an 85 SL and a 96 Mercedes C280 ( it has its own issues)
And no where would I hear anywhere of my other cars ever have
a critical part failed. These are cars that are even older and not known
for strong reliability like the Toyota or Lexus we own.
Anytime you hear loss of control of a car due to a factory part
potential defect is a concern for all parties involved . I really think
if this part could potentially failed without true warning, it is a serious lisbility
to the auto manufacturer. Because we love the SC and we know so much
about these cars, we might at least know how to stop the car with downshifting etc
but to someone who does not know about the signs of a failed
booster or know how to downshift , it is a serious accident
waiting to hapoen
07-05-18, 07:39 PM
#39
Instructor
What every SC owners need to know regardless where we are
and hopefully the SC driver is not in the middle of the dessert
is if you see any warning lights suddenly light up you have to immediately
pull to the side of the road.
Of course that is assuming you are not going down hill
Man, this is troublesome..
and hopefully the SC driver is not in the middle of the dessert
is if you see any warning lights suddenly light up you have to immediately
pull to the side of the road.
Of course that is assuming you are not going down hill
Man, this is troublesome..
The following users liked this post:
jszachar (12-11-20)
07-06-18, 10:44 AM
#41
Driver School Candidate
Thread Starter
Guys that was exactly my point from my first reply to this issue.
I have an 85 SL and a 96 Mercedes C280 ( it has its own issues)
And no where would I hear anywhere of my other cars ever have
a critical part failed. These are cars that are even older and not known
for strong reliability like the Toyota or Lexus we own.
Anytime you hear loss of control of a car due to a factory part
potential defect is a concern for all parties involved . I really think
if this part could potentially failed without true warning, it is a serious lisbility
to the auto manufacturer. Because we love the SC and we know so much
about these cars, we might at least know how to stop the car with downshifting etc
but to someone who does not know about the signs of a failed
booster or know how to downshift , it is a serious accident
waiting to hapoen
I have an 85 SL and a 96 Mercedes C280 ( it has its own issues)
And no where would I hear anywhere of my other cars ever have
a critical part failed. These are cars that are even older and not known
for strong reliability like the Toyota or Lexus we own.
Anytime you hear loss of control of a car due to a factory part
potential defect is a concern for all parties involved . I really think
if this part could potentially failed without true warning, it is a serious lisbility
to the auto manufacturer. Because we love the SC and we know so much
about these cars, we might at least know how to stop the car with downshifting etc
but to someone who does not know about the signs of a failed
booster or know how to downshift , it is a serious accident
waiting to hapoen
07-06-18, 10:50 AM
#42
Driver School Candidate
Thread Starter
It sure does -- the dealer's had the car since Monday and the Lexus corporate case worker was on it the next day. So far, no answers on anything and do know the case manager relayed they're pulling in their factory reps (or whatever). Obviously, this doesn't feel like a situation where it's the customer's fault and/or your car suffered from wear and tear.
07-06-18, 12:54 PM
#43
Driver School Candidate
A reposting of BGW 70 concern:
Sounds like the brake booster motor failed or the accumulator lost pressure.
the Brake Master Cylinders (BMCs) on the GSs are the same as ours and they sold thousands more in the model which means there are more failures.
https://www.clublexus.com/forums/sus...-help-bmc.html
The brake system unit is one assembly, the BMC, booster and ABS.
they will most likely want to replace the BMC...usually no big deal except on our cars. $2500-$3000.
Plenty of info on this subject...please let us know what happens.
https://www.justanswer.com/lexus/1xa...ard-press.html
Sounds like the brake booster motor failed or the accumulator lost pressure.
the Brake Master Cylinders (BMCs) on the GSs are the same as ours and they sold thousands more in the model which means there are more failures.
https://www.clublexus.com/forums/sus...-help-bmc.html
The brake system unit is one assembly, the BMC, booster and ABS.
they will most likely want to replace the BMC...usually no big deal except on our cars. $2500-$3000.
Plenty of info on this subject...please let us know what happens.
https://www.justanswer.com/lexus/1xa...ard-press.html
07-07-18, 04:26 AM
#44
MJN your car most definitely does have a brake booster, so your mechanic must know this part by another name... but having worked as a mechanic myself I can’t imagine what other name this would be.
Either way, as others have said, it’s either a failure of the master cylinder/booster/some other type of loss of power assist. As someone else stated above, all cars on the road have hydraulic brakes which are assisted by vacuum created by the engine. If you lose this power assist, it will feel like your brakes aren’t working. You say in your title “100% brake system failure” but then say that you still had about 3%-5% braking power. That means you didn’t quite have 100% brake failure. Yes, I understand having even 5% braking power is far too little braking power for just about every situation, but it isn’t 0% braking power/100% braking failure. This again reinforces the notion of loss of power assist. Pushing your brakes with what is normally ‘100%’ effort which would normally resulting 100% stopping power of vehicle, feels like basically 0% when you lose power assisted brakes. I’m having trouble putting into words what I’m trying to say.... let’s try it this way. When your brakes are working properly, let’s say you only need to apply 7lbs of pressure on the brake pedal for them to go to the floor and active ABS fully. Now, you’re used to that amount of pressure (7lbs) being needed for full stopping pressure and full stopping power. However, after losing power assisted brakes, you basically can’t apply the required amount of pressure to recieve the same full ABS stop - you’d have to apply 150-250lbs of pressure on the brake pedal to achieve the same full ABS stop. So, with that in mind, you’re hitting the brakes with the same amount of force that you’re used to (7lbs) and getting all of 3-5% stopping power from them. Meanwhile, had you pulled on the bottom of the steering wheel with both hands to brace yourself in place while standing with both feet on the brake pedal like you were trying to rip off the steering wheel, you would have likely seen 30-70% stopping power, depending on how strong your legs, arms, and back were.
So, it’s not that there was a 100% brake failure, more that you were unaware that a malfunctioning component required you to apply 20-30x more effort to the brake pedal to have the desired stopping power. Granted, this is obviously far from safe, but I wanted to clear up the thought that you experienced “100% brake system failure”.
To try this out yourself as I have done many times in the last 15+ years of driving, find a small hill in a large, empty parking lot. Turn the engine off (just to accessory) with the transmission in neutral, then turn the key back to “on” but don’t engage the starter. Make sure your emergency/parking brake is working and adjusted properly since this will be what ultimately stops you at the end of this test unless the hill you chose is very, very slight (otherwise you might end up pulling a muscle or two lol). Pump the brake pedal 4-6 times until the brake pedal gets rock hard... you’ll notice the car is starting to roll down the hill even with you pushing the brake pedal quite hard. Push harder and harder on the brake pedal using the steering wheel and seat back as bracing to give you more leverage to push on the brake pedal. You’ll notice the braking of the car does increase, but the amount of effort required on the pedal is substantially more than you would expect.
Either way, as others have said, it’s either a failure of the master cylinder/booster/some other type of loss of power assist. As someone else stated above, all cars on the road have hydraulic brakes which are assisted by vacuum created by the engine. If you lose this power assist, it will feel like your brakes aren’t working. You say in your title “100% brake system failure” but then say that you still had about 3%-5% braking power. That means you didn’t quite have 100% brake failure. Yes, I understand having even 5% braking power is far too little braking power for just about every situation, but it isn’t 0% braking power/100% braking failure. This again reinforces the notion of loss of power assist. Pushing your brakes with what is normally ‘100%’ effort which would normally resulting 100% stopping power of vehicle, feels like basically 0% when you lose power assisted brakes. I’m having trouble putting into words what I’m trying to say.... let’s try it this way. When your brakes are working properly, let’s say you only need to apply 7lbs of pressure on the brake pedal for them to go to the floor and active ABS fully. Now, you’re used to that amount of pressure (7lbs) being needed for full stopping pressure and full stopping power. However, after losing power assisted brakes, you basically can’t apply the required amount of pressure to recieve the same full ABS stop - you’d have to apply 150-250lbs of pressure on the brake pedal to achieve the same full ABS stop. So, with that in mind, you’re hitting the brakes with the same amount of force that you’re used to (7lbs) and getting all of 3-5% stopping power from them. Meanwhile, had you pulled on the bottom of the steering wheel with both hands to brace yourself in place while standing with both feet on the brake pedal like you were trying to rip off the steering wheel, you would have likely seen 30-70% stopping power, depending on how strong your legs, arms, and back were.
So, it’s not that there was a 100% brake failure, more that you were unaware that a malfunctioning component required you to apply 20-30x more effort to the brake pedal to have the desired stopping power. Granted, this is obviously far from safe, but I wanted to clear up the thought that you experienced “100% brake system failure”.
To try this out yourself as I have done many times in the last 15+ years of driving, find a small hill in a large, empty parking lot. Turn the engine off (just to accessory) with the transmission in neutral, then turn the key back to “on” but don’t engage the starter. Make sure your emergency/parking brake is working and adjusted properly since this will be what ultimately stops you at the end of this test unless the hill you chose is very, very slight (otherwise you might end up pulling a muscle or two lol). Pump the brake pedal 4-6 times until the brake pedal gets rock hard... you’ll notice the car is starting to roll down the hill even with you pushing the brake pedal quite hard. Push harder and harder on the brake pedal using the steering wheel and seat back as bracing to give you more leverage to push on the brake pedal. You’ll notice the braking of the car does increase, but the amount of effort required on the pedal is substantially more than you would expect.
Last edited by Mbodall; 07-07-18 at 04:36 AM.
07-07-18, 06:20 AM
#45
Instructor
The question then is can one stop the car fully with both legs
with 90-95% loss of brake hydraulics?
Not to say anyone of us would want to ever had to test
this theory going downhill but I still think the likelihood of
A serious accident is imminent.
Most drivers will not know about this approach let along
be fast enough to even remember to downshift as your mind
is probably in a state of sudden shock to react fast enough
with 90-95% loss of brake hydraulics?
Not to say anyone of us would want to ever had to test
this theory going downhill but I still think the likelihood of
A serious accident is imminent.
Most drivers will not know about this approach let along
be fast enough to even remember to downshift as your mind
is probably in a state of sudden shock to react fast enough