Question concerning brakes
Thread Starter
3rd Gear
Joined: May 2009
Posts: 3
Likes: 0
Question concerning brakes
My Dad and I have just finished rebuilding the calpiers on an '82 (did a very clean job), and after bleeding the brakes multiple times, we are still confused.
When the car is turned off, it has pretty good pressure with the brake pedal, but as soon as the car is turned on, I am able to push it to the floor, and braking is very spongy while on the road.
He seems to think it could be something with the master cylinder or the brake booster. The car has been sitting for about 6 months. Does anyone have any ideas as to what we could try or what might be the problem?
When the car is turned off, it has pretty good pressure with the brake pedal, but as soon as the car is turned on, I am able to push it to the floor, and braking is very spongy while on the road.
He seems to think it could be something with the master cylinder or the brake booster. The car has been sitting for about 6 months. Does anyone have any ideas as to what we could try or what might be the problem?
Melting Slicks
Joined: Dec 2006
Posts: 2,669
Likes: 3
From: Kingston Ontario
You need to bleed all air from the system. Make sure you maintain fluid at all times in the reservoir. Continue to bleed until all air is removed. Not uncommon to pump a quart through the system in order to complete. Have patience; you'll get there. You may have to recenter the combination valve if your brake light is illuminated on the dash.
Le Mans Master
Joined: Aug 2006
Posts: 7,426
Likes: 1,559
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Bad Brakes!
To test the power booster: Step on the brake pedal 4 or 5 times and continue to push down on the pedal and start the motor. The brake pedal should go halfway to the floor, if it does than the booster is good.
To test the Master Cylinder: With the motor off, step on the brake pedal 4 or 5 times and continue to hold the pressure for about 30 seconds, if the M/C is bad the pedal will slowly go to the floor. If the pedal stays in the same place the M/C is good.
Sounds like you still have some air in the system. Question: When you rebuilt the calipers did the M/C go dry? If so you will have to bench bleed the M/C to make sure there is no air traped in it and then bleed the entire system again.
When bleeding the rear calipers do the inner first than the outer. PG.
To test the Master Cylinder: With the motor off, step on the brake pedal 4 or 5 times and continue to hold the pressure for about 30 seconds, if the M/C is bad the pedal will slowly go to the floor. If the pedal stays in the same place the M/C is good.
Sounds like you still have some air in the system. Question: When you rebuilt the calipers did the M/C go dry? If so you will have to bench bleed the M/C to make sure there is no air traped in it and then bleed the entire system again.
When bleeding the rear calipers do the inner first than the outer. PG.
Thread Starter
3rd Gear
Joined: May 2009
Posts: 3
Likes: 0
We bench bled the master cylinder yesterday, and that yielded slightly better pressure, but it still feels rather spongy. We also bled the brakes multiple times afterwards. Maybe we still need to bleed the brakes more?
Also, thanks for all of the replies. I really appreciate the help.
Also, thanks for all of the replies. I really appreciate the help.
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