Manual to power brakes on 1961 Apache

[tchevs]

Hoping to get some help from you guys. I don’t know how to navigate to find the information that I need. I have looked online but i really can’t find the information. My son and i are working on a 1961 Apache 40. We cleaned up a 1980 2wd frame. Mounted 73-87 front suspension from a c30 dually. Added a 2006 Silverado 3500 rear with disc brakes. Installed the cab forward from the c40 on it. Cut the bed from 12’ to 6 feet. Lowered the stance a little. Dropped an 04 LQ9 in it. Installed new brake calipers, brake lines, hoses, booster and master cylinder. I bleed the brakes, no air left but yet the pedal doesn’t firm up. I thought it was the master so I picked another at the local junk yard. Still the same. Questions I have are is if the master we used does not push enough volume to those big calipers? Is there a chance that the pedal ratio doesn’t let the piston push in enough in the master?

[whateverpratt]

If you are using the original master that was meant for drums, I would swap that out with a bigger master that will push more volume like you said. It was easy for me to do that on my '63 because the firewall bolt pattern for the master was the same from '63 through at least the early '90's; however, '60-'62 trucks had the hydraulic clutch/brake brake master cylinder combo, so I don't know that you will have a bolt in option unless you order a setup from captainfab

[tchevs]

I actually bought a booster/master set up intended for 60-62. It bolted right up. I have captains adapter but when I ordered from him I got the he one for manual transmission. This truck is running an automatic transmission so I didn’t use it. Im thinking those big brake calipers might need a bigger trucks master cylinder?

[whateverpratt]

That's what I was trying to say was that the original master isn't going to have the volume needed for your calipers. I was able to install an '85 master on my '63 without any modifications or adapters, so I sufficient flow to my calipers

[Captainfab]

How does the bore of the master you are using compare to the 2006 C3500 master? I would have used a booster, master and prop valve for the 2006 C3500. You could use the booster bracket you bought from me with an auto trans or simply purchase the booster bracket that I make for the '60-'62's with an auto trans. When you bled the brakes did you use the tool to hold the prop valve in center so it didn't slide one way and block off one circuit?

[tchevs]

Originally Posted by Captainfab

How does the bore of the master you are using compare to the 2006 C3500 master? I would have used a booster, master and prop valve for the 2006 C3500. You could use the booster bracket you bought from me with an auto trans or simply purchase the booster bracket that I make for the '60-'62's with an auto trans. When you bled the brakes did you use the tool to hold the prop valve in center so it didn't slide one way and block off one circuit?

I don’t know how it compares to the master on the 3500. All I had and used was the rear end. I did not use that tool to hold the prop valve in the center. I’ll have to take those lines apart and set that back in the center, next time a get a chance to work on it. I didn’t want to hack your bracket because I figured I can use it on something else later, plus I didn’t want the clutch master going to waste.

[tchevs]

Just another question though, if that prop valve was stuck on one side, would I still be able to get fluid to bleed out of front and back? It does go through all wheels, just the pedal never gets hard.

[Captainfab]

If you are getting good fluid flow out of all 4 calipers, the valve should be in the center. Are the rear calipers dual piston?

[tchevs]

Originally Posted by whateverpratt

That's what I was trying to say was that the original master isn't going to have the volume needed for your calipers. I was able to install an '85 master on my '63 without any modifications or adapters, so I sufficient flow to my calipers

Ok misunderstanding because I didn’t explain well. The booster/ master is 78 corvette for disc/disc. The piston bore is 1-1/8” I believe.

[64shortbox]

Tony,
One other thing - I also was NEVER able to get my brakes to bleed on my 64 C-10 after swapping to front Disc brakes & I used EVERYTHING off the 73 donor truck. Gravity bleeding, having my wife pump up the brake pedal & hold it as I bled the brakes, I used a Mighty Vac to try & draw the brake fluid through. That didn't work either. My proportioning valve is also located in the 73 stock location under the radiator. Since my master cylinder is a 73 & cast iron I ended up making a cover plate from some 1/4" aluminum plate we had at the shop and added a 1/4" ball valve and a pressure gauge, I used some small chain to wrap around the master & plate. I ended up having to use around 15 PSI air pressure over the brake fluid filled master to finally push the brake fluid through master & all 4 wheel cylinders. That finally got them to bleed correctly and I had pedal pressure. I was later told that 7 or 8 LBS of air pressure should have done it but it took a good 15 LBS on my home made contraption to get them to bleed. If you have a friend that has access to a real brake pressure bleeder - see if you can borrow it and give that a try. I'll see if I can find some pictures of my home made pressure bleeder contraption but I did all this probably about 7 or 8 years ago.

[1968C30]

I had the same problem on my 64. I installed 95 Impala rear disk brakes and could not get a firm pedal. I bought one of these and set the booster pin depth and it fixed my problem. I now have a firm pedal and great brakes.
https://www.ebay.com/itm/power-brake...-/232919566152

[tchevs]

Originally Posted by 1968C30

I had the same problem on my 64. I installed 95 Impala rear disk brakes and could not get a firm pedal. I bought one of these and set the booster pin depth and it fixed my problem. I now have a firm pedal and great brakes.
https://www.ebay.com/itm/power-brake...-/232919566152

I had seen that tool. I adjusted the pin using the ruler off a micrometer. Should be pretty close. The adjustment that has me more worried is the one from the pedal to the booster. Did you move the location of where that rod attaches to the pedal? Our pedal is about 12.5 inches long, the rod attaches about 2 inches down from where it hinges. Thats about a 6 to 1 ratio. In order to get a 4 to 1 ratio, I need to drill a hole about an inch lower and attach the rod there. Am i to worried about this? does it really matter? Thanks for your help

Tony

[64shortbox]

Tony,
I found my original post with pics of my home made pressure bleeder. And YES! as I'm sure you can tell by the pics I've got Okie blood running through my veins but it got the job done and it's what I could get my hands on without spending any money. I used what we had lying around at my work. Scroll down to post #6.

http://67-72chevytrucks.com/vboard/s...d.php?t=633937

[tchevs]

I would try that right now if I had that little tool for the prop valve

[tchevs]

Originally Posted by 64shortbox

Tony,
One other thing - I also was NEVER able to get my brakes to bleed on my 64 C-10 after swapping to front Disc brakes & I used EVERYTHING off the 73 donor truck. Gravity bleeding, having my wife pump up the brake pedal & hold it as I bled the brakes, I used a Mighty Vac to try & draw the brake fluid through. That didn't work either. My proportioning valve is also located in the 73 stock location under the radiator. Since my master cylinder is a 73 & cast iron I ended up making a cover plate from some 1/4" aluminum plate we had at the shop and added a 1/4" ball valve and a pressure gauge, I used some small chain to wrap around the master & plate. I ended up having to use around 15 PSI air pressure over the brake fluid filled master to finally push the brake fluid through master & all 4 wheel cylinders. That finally got them to bleed correctly and I had pedal pressure. I was later told that 7 or 8 LBS of air pressure should have done it but it took a good 15 LBS on my home made contraption to get them to bleed. If you have a friend that has access to a real brake pressure bleeder - see if you can borrow it and give that a try. I'll see if I can find some pictures of my home made pressure bleeder contraption but I did all this probably about 7 or 8 years ago.

That is pretty crafty. On my research through the web, came across a reverse bleeder, also a good idea. Ill see what i can come up with. I know im going to be messing with these old trucks the rest of my life.

[chev-obsession]

What size brake lines did you run from master to the calipers? How long of flexible lines from hardline to calipers?

[tchevs]

Originally Posted by chev-obsession

What size brake lines did you run from master to the calipers? How long of flexible lines from hardline to calipers?

Fronts are 3/16 rear is 1/4. Flexes are new. I did not measure them but they are around 18" long.

[tchevs]

As an update i was able to work on it a little yesterday. Separated the master from the booster to take some measurements of the pushrod. Turns out that with the pedal to the floor, the pushrod travels about 1 inch. With some measurements at the pedal, I figured that the rod will travel more if the rod was set lower at a 4:1 ratio. I drilled a hole 3-3/4" center to center from the upper pivot. The pedal now travels 1-5/8".
I was looking at the cutaway for the prop valve and got to thinking, since its a little difficult to get to, why not just test the switch for continuity to see if the valve has moved to one side? Isnt that what that valve and switch do? If the valve moves to one side the switch closes and sends a ground to the brake light on the dash right? If theres no continuity the valve is centered.

[tchevs]

I was able to get my brakes working. Thanks for all your replies. Brainstorming and previous experience is always helpful. It turns out in my case that the master was not pushing enough fluid as captain fab pointed out. I had to swap to a 2500 silverado master, which is meant for disc/disc application and i also had to change the booster because the master would not mate to the booster I was using. For a booster I used a vacuum type booster out of 2004 tahoe. I did not use the booster out of the silverado because it was a hydro booster, didnt want to add more hoses in the compartment and change the power steering pump.