Old Shep

Several questions:
1) The replacement master cylinder for my 1967 with manual (no power) brakes did not come with a firewall gasket. Will this be something that I can get from a local parts store?
2) After filling the cylinder with DOT 3 fluid (same as in the vehicle now) and replacing the cover, is the first step to bleed the master cylinder using the two bleeding valves above the brake line ports before bleeding each caliper in the correct sequence and is it necessary to bleed both master cylinder compartments at the same time?
3) Should I reconnect the brake lines to the master cylinder before or after bleeding the master cylinder?
4) If I decide to purge the system of all old brake fluid and replace with new fluid does that change the procedure I should follow and how much DOT 3 fluid would be necessary?

JohnZ

1. You might be able to find the master cylinder-to-dash gasket locally, but I doubt it - you could probably make one in about 5 minutes.

2. You should bench-bleed the master cylinder before installing it (see photo below) - the "Help" section at your auto parts store will have a $5.00 kit with plastic fittings and hose. Ignore the bleeders on the master cylinder - they don't do anything (which is why they were removed three years later).

3. Connect the lines after bench-bleeding the master cylinder; keep an eye on the fluid level in the reservoirs, or you get to start all over again from scratch.

4. Good idea to flush the existing system while bleeding it - should take about a quart. I use a Motive Power Bleeder - whole job takes one person ten minutes, and you don't have to watch the master cylinder.

00fxd

You know John, I'm gonna order one of those ... You just pressure up the master with the hand pump and away you go?

vetsvette2002

Thats it. It takes me more time to jack it up and remove the wheels than it does to do the actual bleeding.

You will need to use the same clamping method as shown in John's photo as the mfg supplied system just doesn't cut it.

Rons65

I got some gasket material and made my own firewall/MC gasket. Not that hard at all - and yes, I do have one of those Motive bleeder's - only way to go!

JohnZ

Yup - put fresh fluid in the bottle, pump it up to 5-10 psi, and you're in business; they also make handy vented bleeder bottles with a tether wire for hanging them.

Diablo427

Thanks John for the picture of doing this on our Vettes. Here is a picture of a bleeder that I made for my Tundra and it uses a compressor set at 6 lbs. I had an attached bottle to keep fluid up but it didn't work that well right off the bat. So, I just used it like shown and checked it often. I actually worked so well, that I had really good brakes for the first time in about 7 years as 1st gen Tundras are notorious for bad brakes.

Looking forward to making something for the 67 Vette when I do brakes on it and I'm sure that I will be looking at your picture to do that. How is the underside of the cap on yours? I don't see two lines going to each reservoir, so I guess that you have two holes in the top plate for the dual zones on the MC.

JohnZ

Yup - there's a single inlet that has two outlets, one over each reservoir.

Diablo427

Thanks for the tip John. I'll be sure to make a cool part like yours for my setup in the future. What is that top made of? Rubber, a piece of plastic of some sort, wood, etc.? I love how you were able to C clamp it on like that. I may try my original thing out again too to let it pull fluid from a separate vessel. Love this forum! Learn something everyday.

JohnZ

The Motive adapter plate is hard molded plastic with a soft gasket on the bottom; the bar is a 7"-long piece of 1-1/2" square aluminum tubing.

Diablo427

Thanks again John! I'll make some kind of adapter plate for mine when they need bleeding again. I didn't know if that was a Motive product or something that you had made yourself to make it work better for your situation. I was actually thinking that I might take the calipers and MC off and paint them sometime. Seeing your setup makes the thought of bleeding them much more palatable.

Old Shep

To JohnZ:
You said: Good idea to flush the existing system while bleeding it - should take about a quart. I use a Motive Power Bleeder - whole job takes one person ten minutes, and you don't have to watch the master cylinder.

I am ready to begin the cylinder bleeding process after bench bleeding the Master using the same kit you used and mounting a model 0105 Motive Power Bleeder to the master cylinder in the vehicle in a manner similar to the way you did. I have 32 ounces of Dot 3 in the Motive container and want to purge the old fluid in the process. There is not a noticeable difference in the color between the old fluid and new fluid so I won't be able to go by that.

Stupid Question: Can I purge all the old fluid from a single caliper bleeder valve (left rear inner bleeder valve for example) or do I have to purge a certain amount from each of the six bleeder valves separately and if so, without being able to recognize a color difference in fluid how can I determine when the old fluid is removed?

JohnZ

Two or three seconds of flow from each bleeder will work fine.