Brake pedal almost to the floor
09-21-2018, 08:07 PM
#1
8th Gear
Thread Starter
Brake pedal almost to the floor
Bled the system, both power vac and human method. Pedal is not mushy, just doesn't start stopping til the pedal is way down. Had a local shop tell me it needs a master cylinder and the GM house wants big $$. I've looked here and there on line, local parts stores, some rebuilt and some called new. Any advice on best place to purchase for cost and quality.?
Also, I've read some posts where they mention the sequence left rear, right rear (inner, outer), left front,right front. I did it RR, LR, RF, LF. Only saw one bleeder screw on the back...did I miss something important.
Like this site..Thanks to all for the assistance.
Also, I've read some posts where they mention the sequence left rear, right rear (inner, outer), left front,right front. I did it RR, LR, RF, LF. Only saw one bleeder screw on the back...did I miss something important.
Like this site..Thanks to all for the assistance.
09-22-2018, 04:44 PM
#3
Le Mans Master
Was any previous work done to car or parts replaced before this problem as you describe it?
Having said that, sounds like the booster actuator rod might be way out of adjustment. This normally would not happen just over night and usually the adjustment never changes due to the lock nut system.
I would remove the 2 bolts for the master and pull it back and get a look between the master and booster. See if the rod looks OK and the top should be (ball park) just above the surface of the booster (far as I remember).
As far as master causing this problem, usually not…..anything is possible
Having said that, sounds like the booster actuator rod might be way out of adjustment. This normally would not happen just over night and usually the adjustment never changes due to the lock nut system.
I would remove the 2 bolts for the master and pull it back and get a look between the master and booster. See if the rod looks OK and the top should be (ball park) just above the surface of the booster (far as I remember).
As far as master causing this problem, usually not…..anything is possible
09-22-2018, 04:51 PM
#4
Le Mans Master
the old school test for a bad or going bad Master cyc. is to have the car running and like at a red light, foot on the brake, if it slowly starts sinking towards the floor, the cups inside the MC are worn and fluid is getting past them. Time for a rebuild or rplacement
Last edited by ghoastrider1; 09-22-2018 at 04:52 PM.
09-22-2018, 09:43 PM
#5
Le Mans Master
the old school test for a bad or going bad Master cyc. is to have the car running and like at a red light, foot on the brake, if it slowly starts sinking towards the floor, the cups inside the MC are worn and fluid is getting past them. Time for a rebuild or rplacement
And is correct. But it does not sound like he is indicating a sinking pedal. Let's see what he says in response.
09-22-2018, 10:56 PM
#6
Team Owner
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Depending on the year, the bleeding sequence is different than normal because of the location of the ABS unit behind the driver. IIRC, for the C4 it is RR-RF-LR-LF, but that might not be correct either.
09-23-2018, 01:48 AM
#8
8th Gear
Thread Starter
This is a 96 base rag top with 130 k miles. No history on previous work, but anything done was probably at a local small town garage with very little vette experience.
When I got it, it had ABS/TCS code, and I thought that was part of poor braking. I found a bad fuse, that cleared the code. (that was thanks to a forum member here) but still not good stopping.
Previous owners said they didnt think it stopped very good:. Pedal has always been close to the floor. The car sat in driveway most of the time.
I've put more miles on it in a year than previous owner in 5 years.
Is there a method of eliminating either master or booster. I have read other forums where they talk about pumping to get a good pedal, and starting car. If the pedal goes down a lot the booster may be issue. If pedal never goes solid, then bleed all wheels. So, with pedal solid almost on the floor, and others suggesting master, I guess thats where I'll go. Besides. Its most likely original.
Where is best source, and after replace, any special method or corcern on bleeding...like ABS system.
When I got it, it had ABS/TCS code, and I thought that was part of poor braking. I found a bad fuse, that cleared the code. (that was thanks to a forum member here) but still not good stopping.
Previous owners said they didnt think it stopped very good:. Pedal has always been close to the floor. The car sat in driveway most of the time.
I've put more miles on it in a year than previous owner in 5 years.
Is there a method of eliminating either master or booster. I have read other forums where they talk about pumping to get a good pedal, and starting car. If the pedal goes down a lot the booster may be issue. If pedal never goes solid, then bleed all wheels. So, with pedal solid almost on the floor, and others suggesting master, I guess thats where I'll go. Besides. Its most likely original.
Where is best source, and after replace, any special method or corcern on bleeding...like ABS system.
09-23-2018, 10:30 AM
#9
Le Mans Master
So the car has had a low pedal for some time now.
When you shut the engine off and then pump the pedal 4 times does the pedal get harder and hardness seem to rise higher with hardness.
If a shop had replaced the booster and never adjusted the actuator rod, a master replacement will not help you. You got to get in there and get a look at it.
When you shut the engine off and then pump the pedal 4 times does the pedal get harder and hardness seem to rise higher with hardness.
If a shop had replaced the booster and never adjusted the actuator rod, a master replacement will not help you. You got to get in there and get a look at it.