braking system Helppp!!
Thread Starter
Intermediate
Joined: Mar 2015
Posts: 48
Likes: 1
From: Beirut
braking system Helppp!!
Hi all
My braking system failed on me today. I took my 86 vette out for a ride today and in about 30 min through it, I ve noticed that the brake pedal became soft and spongy until it sank in all the way down. I had to decompress it a couple times till I gained a bit of braking force.
I pulled over and let the car cool down a bit as it was too dangerous to drive it. I tried to get bk on the road after cool down but the symptom stayed the same. I am aware that my front and rear pads needs replacement but I doubt that is the problem? I have replaced my master cylinder few years ago so im not sure if that caused the pedal to sink in?
what should I check?
Any help or advice is appreciated
Thank you in advance
My braking system failed on me today. I took my 86 vette out for a ride today and in about 30 min through it, I ve noticed that the brake pedal became soft and spongy until it sank in all the way down. I had to decompress it a couple times till I gained a bit of braking force.
I pulled over and let the car cool down a bit as it was too dangerous to drive it. I tried to get bk on the road after cool down but the symptom stayed the same. I am aware that my front and rear pads needs replacement but I doubt that is the problem? I have replaced my master cylinder few years ago so im not sure if that caused the pedal to sink in?
what should I check?
Any help or advice is appreciated
Thank you in advance
Last edited by eliebarcham; May 8, 2015 at 05:23 AM.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
A failed power booster doesn't create the symptom that the OP is describing. His symptom is:
"the brake pedal became soft and spongy until it sank in all the way down"
That is a leak in the system....not a booster.
OP check level in reservoir as HRR pointed out, then look for leaks.
"the brake pedal became soft and spongy until it sank in all the way down"
That is a leak in the system....not a booster.
OP check level in reservoir as HRR pointed out, then look for leaks.
Racer
Joined: Oct 2012
Posts: 265
Likes: 5
From: Phoenix AZ
A failed power booster doesn't create the symptom that the OP is describing. His symptom is:
"the brake pedal became soft and spongy until it sank in all the way down"
That is a leak in the system....not a booster.
OP check level in reservoir as HRR pointed out, then look for leaks.
"the brake pedal became soft and spongy until it sank in all the way down"
That is a leak in the system....not a booster.
OP check level in reservoir as HRR pointed out, then look for leaks.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Your symptoms describe either bad seals inside the master cylinder or water in the brake system that is boiling in the calipers.
Bleed the brakes first and see if that affects your problem.
Bleed the brakes first and see if that affects your problem.
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
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Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
Good grief...That is EXACTLY what happened to me on the way home from work. Try it some time. It was...drum roll...THE POWER ASSIST. OP, go to your car, press your brake pedal repeatedly. If you hear hissing your power assist is bad. If you don't, then look elsewhere. Eliminate the obvious first, right captain obvious?
The pedal moves a rod that goes thru the booster and meets the piston in the master cylinder. In order for the pedal to go down the piston in the master cylinder has to move. How far the piston in the master cylinder moves determines how far the pedal can go down.
The booster simply applies pressure to the rod where it attaches to the master cylinder. There is no internal travel in the booster that can allow the pedal to go down and not push the piston in the master cylinder.
So for the pedal to go "to the floor" the master cylinders piston must go in all the way. Thus either the master cylinder is bad or the system needs bleeding. If this happens with no brake work being done and no external leaks then the master cylinder is bad not the booster.
Thread Starter
Intermediate
Joined: Mar 2015
Posts: 48
Likes: 1
From: Beirut
I really appreciate everyone's help.
I will first of all check for leaks then go ahead and bleed/top up the system with some fluid as advised.
If that didnt help then im gonna have to replace my master cylinder as you guys assured.
Im not aware of any hissing sound but I will check for that too.
I will post any updates when i get on it.
Thank you all again. Really helped me
I will first of all check for leaks then go ahead and bleed/top up the system with some fluid as advised.
If that didnt help then im gonna have to replace my master cylinder as you guys assured.
Im not aware of any hissing sound but I will check for that too.
I will post any updates when i get on it.
Thank you all again. Really helped me
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
So "Good grief" back at ya.
Last edited by Tom400CFI; May 8, 2015 at 10:41 AM.
Melting Slicks
Joined: Jan 2001
Posts: 2,996
Likes: 304
From: MOORESVILLE NC
Hi all
My braking system failed on me today. I took my 86 vette out for a ride today and in about 30 min through it, I ve noticed that the brake pedal became soft and spongy until it sank in all the way down. I had to decompress it a couple times till I gained a bit of braking force.
I pulled over and let the car cool down a bit as it was too dangerous to drive it. I tried to get bk on the road after cool down but the symptom stayed the same. I am aware that my front and rear pads needs replacement but I doubt that is the problem? I have replaced my master cylinder few years ago so im not sure if that caused the pedal to sink in?
what should I check?
Any help or advice is appreciated
Thank you in advance
My braking system failed on me today. I took my 86 vette out for a ride today and in about 30 min through it, I ve noticed that the brake pedal became soft and spongy until it sank in all the way down. I had to decompress it a couple times till I gained a bit of braking force.
I pulled over and let the car cool down a bit as it was too dangerous to drive it. I tried to get bk on the road after cool down but the symptom stayed the same. I am aware that my front and rear pads needs replacement but I doubt that is the problem? I have replaced my master cylinder few years ago so im not sure if that caused the pedal to sink in?
what should I check?
Any help or advice is appreciated
Thank you in advance
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 79
From: Monroe OH
NCM Sinkhole Donor
Scooter, the booster doesn't have any control or affect on pedal travel. All it does is make the pedal easier to push. When you lose your booster, you get a hard pedal. Pedal has the same range of motion, brakes still work....but it's much harder to push. OP's pedal is going to the floor which is a leak. Either you had other, undiagnosed issues that you apparently fixed while changing the booster, or your memory of your particular symptom is off...but a bad boost can NOT, in any way, cause the pedal to go to the floor. Can't do it. If you understood how the stuff works, you'd agree. You're giving the OP bad advice.
So "Good grief" back at ya.
So "Good grief" back at ya.
I'm with Tom on this one. If the op was on track then I would suspect boiled brake fluid, but since he wasn't it is either low on fluid, got air in the system, or the fluid in the system is expended.
Thread Starter
Intermediate
Joined: Mar 2015
Posts: 48
Likes: 1
From: Beirut
Hello everyone
I Done all the checks that you guys advised and turned out to be my master cylinder was at fault.
Had to replace it then top up/bleed the system. My brake pedal is now back in shape.
Thank you all for you help, saving my time and money.
I Done all the checks that you guys advised and turned out to be my master cylinder was at fault.
Had to replace it then top up/bleed the system. My brake pedal is now back in shape.
Thank you all for you help, saving my time and money.