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Has anyone found and/or done a conversion over to a 7/8" dual master cylinder to replace a C2 single outlet master cylinder? . . If so, what parts were used?
If your going to change from a single to a dual, looks like you will need to change both lines and junction blocks. Also if you have don't have a big block hood and thinking about adding the booster, I read about issues of it hitting the hood.
I have the same setup as you and thought about doing the conversion last year.
I understand you may "feel" safer with a dual master, but the reality is the single master cylinders don't just fail out of the blue. You will know if the CYLINDER is leaking before it fails. The failures I have experienced (and the ones you should be worried about) are from a burst brake line or hose (those can be scary). So, if you have replaced or serviced the lines and cylinders, what's all the worry about?? These cars are for the most part garaged and out of the weather these days. I just don't see all the fuss as necessary. I drove GM DD's for years with single masters in the snow and weather parked outside all the time and that was the reality. Pilot Dan
While all brake parts, hoses, etc. have been replaced I was thinking of doing the conversion to dual outlet as a safety margin mainly because of the 50 year old steel brake lines.
The steel brake lines still look good - no rust issues, etc. .. For as much as the car sees the open road, roughly 3K miles a year, I'm considering going this route over replacing the steel brake lines.
Has anyone found and/or done a conversion over to a 7/8" dual master cylinder to replace a C2 single outlet master cylinder? . . If so, what parts were used?
Many years ago, I converted my '65 to a dual master cylinder using the '67 corvette dual master cylinder for standard disk brakes which has a 1" bore. (The '65 corvette standard disk brake master cylinder also had a 1" bore.)
The brake feel is great, the pedal feels solid, the forces and pedal travel are normal. If I had used a 7/8 bore MC, the pedal forces for any given deceleration rate would have been lower, but the travel would have been increased - something I would not have liked.
BTW, I did not find it necessary to use the junction block - I didn't feel that I needed a warning light to tell me that half of my braking system was not working. Braking without it has been fine.
Note: With my '78 vette, I removed the 1 1/8" bore power brake system and went to manual brakes due to low engine vacuum by using a 1" bore corvette master cylinder. I also removed the junction block and preferred braking without the block compared to braking with it. (Braking usage included competitive autocrossing.)
While all brake parts, hoses, etc. have been replaced I was thinking of doing the conversion to dual outlet as a safety margin mainly because of the 50 year old steel brake lines.
The steel brake lines still look good - no rust issues, etc. .. For as much as the car sees the open road, roughly 3K miles a year, I'm considering going this route over replacing the steel brake lines.
Thanks for the replies.
Going to a dual master because your steel lines are 50 years old to me is flawed logic not safety. Why not just replace all the brake lines if they are suspect with new steel ones instead of using a crutch to compensate and be done with it? On a garged car, they will outlast all of us and you will have confidence in your system.
Going to a dual master because your steel lines are 50 years old to me is flawed logic not safety. Why not just replace all the brake lines if they are suspect with new steel ones instead of using a crutch to compensate and be done with it? On a garged car, they will outlast all of us and you will have confidence in your system.
I agree.
My car was garaged and for all practical purposes, not driven between 1973 and 2001. I got the car out to clean it up and drive it a little. Found one front caliper leaking so I replaced it and bled the brakes. After bleeding, I checked for a firm pedal and it went to the floor. Seems the main brake line (front/rear) had corroded underneath the clips that hold the line to the frame. Even if you could see that line on a '65, you wouldn't have seen the corrosion under the clips.
One other thing. I've had three total brake failures with dual master cylinders. Total means no brakes at all. I remember two of them were rusted lines. Don't remember the third cauase. Dual cylinders are no guarantee.
I converted to a dual master cylinder a few years ago as well. I am using a 1" bore with manual brakes. On the HRPT I was glad I did. I kept loosing the front brakes. By the way we were a 1000 miles from home. No leaks but kept getting enough air in them to make them basically non-functional. We were bleeding them at every stop with the GM Performance techs.
We replaced the master cylinder but that did not fix it. I didn't find the root cause until I got home. Front calipers were sucking air. Braking was compromised to say the least but thanks to the dual master we did not loose all braking. We made it home safe and sound.
I converted to a dual master cylinder a few years ago as well. I am using a 1" bore with manual brakes. On the HRPT I was glad I did. I kept loosing the front brakes. By the way we were a 1000 miles from home. No leaks but kept getting enough air in them to make them basically non-functional. We were bleeding them at every stop with the GM Performance techs.
We replaced the master cylinder but that did not fix it. I didn't find the root cause until I got home. Front calipers were sucking air. Braking was compromised to say the least but thanks to the dual master we did not loose all braking. We made it home safe and sound.
Oooookaaaaay.
I re-read post #7. I agree. If there is concern about the reliability of the hard lines it would be prudent to replace them. That does not however negate that fact that there are lots of components in the braking system and even new parts can fail. I am far from an expert but I'm pretty sure most, if not all, automobile manufacturers went to divided brake systems long ago with a dual master cylinder for safety reasons. The scenario in post #9 was my personal experience in which a dual master cylinder saved the day, so to speak.
If I misinterpreted something please let me know.
Tom
Going to a dual master because your steel lines are 50 years old to me is flawed logic not safety. Why not just replace all the brake lines if they are suspect with new steel ones instead of using a crutch to compensate and be done with it? On a garged car, they will outlast all of us and you will have confidence in your system.
Replacing the steel brake lines - no disagreement there. . It will likely happen at a future point in time. Changing over to a dual outlet master cylinder for the time being may be putting the cart before the horse but looks easy doable to get the ball rolling. .. Not looking forward to the under car gymnastics involved on the 'ol bod (65) .
12-18-2014, 07:17 PM
C2 7/8" dual master cylinder - revisited
Pilot Dan
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