The Stovebolt Site Forums The Parking Lot '60-'66 Trucks master cylinder and brake questions

long story short, I need a new master cylinder and I don't have the old one for a guide.

Was about to click buy on a dual resevoir and noticed at least 2 different bore sizes available...

If I don't have the original, which one do I get? Does it matter? Currently have drums all the way around with no intention (in the near future) to convert to disc.

Do I need a proportioning valve?

Couldn't find much on a quick search, sorry if this is already out there somewhere.

You won't be needing a proportioning valve. Here's an excellent thread I stumbled upon many years back that contains a wealth of information related to a dual reservoir master cylinder upgrade. Good luck to ya and be sure to share how your conversion works out http://67-72chevytrucks.com/vboard/showthread.php?t=460791

I also have a printed copy of a thread from here on the Stovebolt from May 2009 entitled "brake...master cylinder" where dave64 states the following:

"I just changed my 66 over to a manual (no power) 4 wheel drum dual master cylinder a few weeks ago. Running the lines was the toughest part.

Go to Partsource and ask for a master cylinder from a 68 1/2 ton chevy (Impala etc. is the same one) It bolts right up exactly the way your old one did. I just had to grind the shoulders of the bolts slightly. Uses the same rod from the pedal - you don;t even have to adjust it."

Related question, How to U determine the proper
activation rod length on a all new system?

I did a similar conversion on my 65 a few years back. I took a dual reservoir from a 67, and it installed with no problems. The rod from the petal works with no adjustments. It mounted up the same as the single reservoir. Rerun the brake lines and it doesnt get easier than that.

I just finished replacing my master cylinder, all brake lines, junction tees and drum components. Kept everything original.

I was able to buy all of the pieces at local auto parts stores. I gotta warn you, the junction tees made in China will probably not work, mine all leaked. They were not milled correctly. Then I bought junction tees made by Edelmann and they worked great. The single chamber reservoir was only $18 plus tax. It was cheaper than the rebuild kit!

I seem to have good brakes up to a point I get about 80% until the pedal seems to bottom out. (its not the pedal)that is adjusted ok.

I am not a brake expert, that's for sure, but I do read a lot. Make sure you have properly bench bled the master cylinder. The lines must be properly bled as well. If it were me, after making sure all the stuff was properly bled, I'd jack up the truck and have someone else hand spin the front wheels and then see at what pedal depth the front brakes engage. The factory service manual should be able to tell you if you're close to specs or not.

I agree with lugnutz, make sure that the reservoir was bench bled. In addition, if you ran new lines, the rears can be a pain. I had to bleed the rears multiple times even after letting them gravity bleed for several hours. Eventually I got the air out and had a good petal.

probably in over my head, but got the 1" dual chamber and ordered lots of crap from inline tubing and waiting on some hardware from Tony... I guess there's a first time for everything, gonna run lines, fittings, rubber hoses, all new everything, so we'll see...

finished overhauling the front drums... everything new except the drum itself... parts for both drums about $80 (pads, cylinders, spring kit, and adjusters), probably gonna have to do same on rears
http://www.tj-mac.com/images/drum_before.jpg
http://www.tj-mac.com/images/drum_after.jpg

I sent you a PM.

Having just completed my 1965 brakes, new lines and junctions, I know you can do it too. I have NEVER done brakes before, or lines, or anything of this sort and with careful attention to the process, I did it all myself. You can too.

sounds like lugnutz and I were on a similar plan. i had never done brakes before. it was time consuming learning as
I went, but I learned a lot. continue to lean on the forums on this site and you will make it through.

Getting all the air out of new lines to the rear with a small bore m/c is very difficult. All you do is move the air bubble(s) back and forth in the line. We always start the bleed process at the furthest brake and evacuate the lines with vacuum.

What system or tool do you use to bleed the lines with vacuum? I think HF has a tool for that, but I don't want to waste money if you have a DIY method.

HF brake bleeder - but is it junk or good?

Thanks