Brake Issue
Thread Starter
Heel & Toe
Joined: Jul 2014
Posts: 18
Likes: 0
From: Graham NC
Brake Issue
Hi everyone. My 1991 Coupe had a brake issue yesterday. I was backing out of my garage and had to do some maneuvering. I put her in drive and pulled forward just a bit. As I was about to put her back into reverse (With foot firmly on the brake peddle) she lunged forward and hit my garage! 
Fortunately only scuffed her a bit. What could this be??? I heard a noise in front of me and then I felt the brake peddle vibrate and heard the rotters and pads chatter then the lunge. All of this happened very quickly with no time for me to react. 
Thank you for any help in figuring this issue out.
Fortunately only scuffed her a bit. What could this be??? I heard a noise in front of me and then I felt the brake peddle vibrate and heard the rotters and pads chatter then the lunge. All of this happened very quickly with no time for me to react. Thank you for any help in figuring this issue out.
Thread Starter
Heel & Toe
Joined: Jul 2014
Posts: 18
Likes: 0
From: Graham NC
Thank you guys for your input on this.
You guys Rock!!
Thread Starter
Heel & Toe
Joined: Jul 2014
Posts: 18
Likes: 0
From: Graham NC
Safety Car
Joined: Aug 2009
Posts: 3,745
Likes: 275
From: Melbourne, Victoria, Australia
Hi everyone. My 1991 Coupe had a brake issue yesterday. I was backing out of my garage and had to do some maneuvering. I put her in drive and pulled forward just a bit. As I was about to put her back into reverse (With foot firmly on the brake peddle) she lunged forward and hit my garage! Fortunately only scuffed her a bit. What could this be??? I heard a noise in front of me and then I felt the brake peddle vibrate and heard the rotters and pads chatter then the lunge. All of this happened very quickly with no time for me to react.
Thank you for any help in figuring this issue out.
Fortunately only scuffed her a bit. What could this be??? I heard a noise in front of me and then I felt the brake peddle vibrate and heard the rotters and pads chatter then the lunge. All of this happened very quickly with no time for me to react. Thank you for any help in figuring this issue out.
Did you hear a hiss? the brake booster is plastic and can crack which limits braking and need more pedal effort. The booster diaphragm leak is usually heard in the car, the external booster needs to be checked run the engine and turn it off listen for any hiss noise.
Also how long did you run the engine, it should develop enough vacuum so check your oneway valve that should hold vacuum for a few brake pedal applications.
I have no problem keeping the car stopped, even if i rev her a little and slam it into reverse or drive.
(Mechanical or pilot error), leaning to mechanical if your booster is leaking or check valve.
Team Owner
Joined: Dec 2000
Posts: 21,094
Likes: 282
From: Phila., PA burbs
My car did the same exact thing several times and I believe on mine it was an issue with a bit of air somewhere in the system. When it happened to me it was also while pulling into the garage. I was inching forward, foot on the brake, trying to get to a certain point within the garage. Suddenly it felt as if the ABS kicked on and the car surged forward, probably 10 inches or so. This happened on two occasions. Both did, however, occur after washing the car, so I guess wet brakes could have been an issue also.
Even though I had a firm pedal, I decided to bleed the brakes, as I needed to flush the system anyway. I flushed the everliving snot out of the brakes (at least 5-10 times for each corner) ensuring I got out all the old fluid and any potential air. The car has never done it since.
Even though I had a firm pedal, I decided to bleed the brakes, as I needed to flush the system anyway. I flushed the everliving snot out of the brakes (at least 5-10 times for each corner) ensuring I got out all the old fluid and any potential air. The car has never done it since.
Thread Starter
Heel & Toe
Joined: Jul 2014
Posts: 18
Likes: 0
From: Graham NC
Hi we feel for you.
Did you hear a hiss? the brake booster is plastic and can crack which limits braking and need more pedal effort. The booster diaphragm leak is usually heard in the car, the external booster needs to be checked run the engine and turn it off listen for any hiss noise.
Also how long did you run the engine, it should develop enough vacuum so check your oneway valve that should hold vacuum for a few brake pedal applications.
I have no problem keeping the car stopped, even if i rev her a little and slam it into reverse or drive.
(Mechanical or pilot error), leaning to mechanical if your booster is leaking or check valve.
Did you hear a hiss? the brake booster is plastic and can crack which limits braking and need more pedal effort. The booster diaphragm leak is usually heard in the car, the external booster needs to be checked run the engine and turn it off listen for any hiss noise.
Also how long did you run the engine, it should develop enough vacuum so check your oneway valve that should hold vacuum for a few brake pedal applications.
I have no problem keeping the car stopped, even if i rev her a little and slam it into reverse or drive.
(Mechanical or pilot error), leaning to mechanical if your booster is leaking or check valve.
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Thread Starter
Heel & Toe
Joined: Jul 2014
Posts: 18
Likes: 0
From: Graham NC
Hi we feel for you.
Did you hear a hiss? the brake booster is plastic and can crack which limits braking and need more pedal effort. The booster diaphragm leak is usually heard in the car, the external booster needs to be checked run the engine and turn it off listen for any hiss noise.
Also how long did you run the engine, it should develop enough vacuum so check your oneway valve that should hold vacuum for a few brake pedal applications.
I have no problem keeping the car stopped, even if i rev her a little and slam it into reverse or drive.
(Mechanical or pilot error), leaning to mechanical if your booster is leaking or check valve.
Did you hear a hiss? the brake booster is plastic and can crack which limits braking and need more pedal effort. The booster diaphragm leak is usually heard in the car, the external booster needs to be checked run the engine and turn it off listen for any hiss noise.
Also how long did you run the engine, it should develop enough vacuum so check your oneway valve that should hold vacuum for a few brake pedal applications.
I have no problem keeping the car stopped, even if i rev her a little and slam it into reverse or drive.
(Mechanical or pilot error), leaning to mechanical if your booster is leaking or check valve.
My car did the same exact thing several times and I believe on mine it was an issue with a bit of air somewhere in the system. When it happened to me it was also while pulling into the garage. I was inching forward, foot on the brake, trying to get to a certain point within the garage. Suddenly it felt as if the ABS kicked on and the car surged forward, probably 10 inches or so. This happened on two occasions. Both did, however, occur after washing the car, so I guess wet brakes could have been an issue also.
Even though I had a firm pedal, I decided to bleed the brakes, as I needed to flush the system anyway. I flushed the everliving snot out of the brakes (at least 5-10 times for each corner) ensuring I got out all the old fluid and any potential air. The car has never done it since.
Even though I had a firm pedal, I decided to bleed the brakes, as I needed to flush the system anyway. I flushed the everliving snot out of the brakes (at least 5-10 times for each corner) ensuring I got out all the old fluid and any potential air. The car has never done it since.
Thanks to all you guys who have given input on this.
Safety Car
Joined: Aug 2009
Posts: 3,745
Likes: 275
From: Melbourne, Victoria, Australia
Ok some insight, i was backing my company car in the garage looking to clear the door and went a little to close to my vette. hitting the brake pedal sharply activated the ABS brakes. (almost backed the towbar into the front of my corvette) 
The concrete floor doesnt have the grip of bitumen, there was some sawdust on the concrete (courtesy of next door neighbour chopping down trees) the garage door was up a bit and quite a bit blow in with the wind.
So there you have it, nothing wrong with your brakes as a similar thing has almost happened to me.
(very similar of what happended to you)
You may have a dusty surface and no matter how hard you hit the brake pedal the abs will just keep locking and releasing rapidly due to the slipery surface. Handbrake may have helped?
This may be problem solved for you as your abs did activate in similar circumstances.
What do you think?
The concrete floor doesnt have the grip of bitumen, there was some sawdust on the concrete (courtesy of next door neighbour chopping down trees) the garage door was up a bit and quite a bit blow in with the wind.
So there you have it, nothing wrong with your brakes as a similar thing has almost happened to me.
(very similar of what happended to you)You may have a dusty surface and no matter how hard you hit the brake pedal the abs will just keep locking and releasing rapidly due to the slipery surface. Handbrake may have helped?
This may be problem solved for you as your abs did activate in similar circumstances.
What do you think?