Brake Master Cylinder not functioning
Thread Starter
1st Gear
Joined: Nov 2009
Posts: 1
Likes: 0
Brake Master Cylinder not functioning
I recently purchased a 1975 Corvette coupe. It was barn stored for the last 10 years or so. One of my big concerns with getting the car back on the road was making sure the brake system worked.
I planned to take care of that this weekend. I ordered a new master cylinder, lines, hoses, calipers, ect. All of wich I installed over the weekend. Everything went smoothly until I started to bleed the system. I did not bench bleed the mc knowing that would make bleeding the system take longer. The rears filled with fluid and worked fine. When I went to work on the front my friend and I worked and worked and worked at bleeding the brakes only to decide that the front system was not working. We checked everything for leaks and found no signs that there were any. We eventually disconnected the line out of the mc that runs down to the proportioning valve. When we pumped the pedal there was no fluid that came out. Is there something that we missed in the assembly? did I receive a bad new mc? Any advice or guidance would be appreciated. Thank you.
I planned to take care of that this weekend. I ordered a new master cylinder, lines, hoses, calipers, ect. All of wich I installed over the weekend. Everything went smoothly until I started to bleed the system. I did not bench bleed the mc knowing that would make bleeding the system take longer. The rears filled with fluid and worked fine. When I went to work on the front my friend and I worked and worked and worked at bleeding the brakes only to decide that the front system was not working. We checked everything for leaks and found no signs that there were any. We eventually disconnected the line out of the mc that runs down to the proportioning valve. When we pumped the pedal there was no fluid that came out. Is there something that we missed in the assembly? did I receive a bad new mc? Any advice or guidance would be appreciated. Thank you.
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
You will most likely have to rebuild or replace all of your calipers also if the car has been sitting for 10 years. If you have the $ I'd recommend either rebuilding with O-ring seals or buying calipers with o-ring seals installed.
Rick B.
Rick B.
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Bench "bleeding" is just a test of the master cylinder to make sure that it is pumping fluid out both outlets at the same time. It sounds like you have a bad M/C...it happens...just return the M/C for an exchange. The very first thing you need to do with a brake system is remove the M/C and bench bleed it. It only takes a few minutes to do and can save you hours if you don't.
Burning Brakes
Joined: Mar 2010
Posts: 803
Likes: 4
From: Christchurch, New Zealand
Hi guys!
Grant's the name, and I bought my 1st Vette, a 1974 L48 convertible to restore, late last year. I've just just rebuilt my brakes after searching these forums for all the help I could get, and I found that you could bench bleed the M/C on the car by disconnecting the brake lines, holding your fingers over the holes, and have someone pump the pedal. We then gravity-bled the lines with great success. We then went around the car, bleeding the normal way just to be sure all the air was out. Went really well! BTW, I'm a complete novice when it comes to these cars. My car restoration experience is limited to 1930's cars. If anyone needs a hand with their staight 8........!
Cheers
Grant
Grant's the name, and I bought my 1st Vette, a 1974 L48 convertible to restore, late last year. I've just just rebuilt my brakes after searching these forums for all the help I could get, and I found that you could bench bleed the M/C on the car by disconnecting the brake lines, holding your fingers over the holes, and have someone pump the pedal. We then gravity-bled the lines with great success. We then went around the car, bleeding the normal way just to be sure all the air was out. Went really well! BTW, I'm a complete novice when it comes to these cars. My car restoration experience is limited to 1930's cars. If anyone needs a hand with their staight 8........!
Cheers
Grant
