Master Cylinder Conversion - Upgrade

[Kaiserjeeps]

The way I have always read and heard, the rear brakes get pressure first...once there is resistance at the rear...pressure starts to build up because the slack is taken out back there with the shoes or pads making contact with the drum or disc...then the front starts to get fluid. This way, since most of the braking is done up front anyway, at least the rears are in the system and active by the time the fronts kick in...

I think I remember that also Jon. I edited the post above. Seems like I can't remember everything anymore. Can't wait for 10 more years to pass by.

[eightydeuce]

I used the 1331 MC for disc Dana 60 front, and 14 bolt rear disc without any problems as long as you keep an eye on the fluid level. Granted with the 1.125" bore you have to push hard on the pedal if you're sticking with the manual brakes. Al, I have a used hydroboost set-up that I'd donate to you if you're interested. It's probably going to collect dust in my garage.

[Kaiserjeeps]

Well hey! I just sent you an email before reading this. That taps in to the power steering correct? I should do that. I will think on it today and send you an email on that. Gotta go poke some more holes in your top.

[Kaiserjeeps]

I forgot to mention the hydroboost in our phone call. I was going to try non power brakes. But I suspect such a heavy truck and bigger bore master, I may need to address that later if the pedal pressure needs are to much. I am getting older and loosing muscle tone.. I shall keep that in mind and thank you.

[Kaiserjeeps]

Just FYI.. I found the answer to the front and rear port question regarding the master cylinder in question. The 13-1331 chevy master. The ports are front to front and rear to rear. I found this in a couple places looking the other night. I get that the reservoirs are the same size and can be hooked up either way. I am just posting what I found for this master.

https://www.lmctruck.com/1967-72-che...brake-line-set

Onward.

[eightydeuce]

I forgot to mention the hydroboost in our phone call. I was going to try non power brakes. But I suspect such a heavy truck and bigger bore master, I may need to address that later if the pedal pressure needs are to much. I am getting older and loosing muscle tone.. I shall keep that in mind and thank you.

Not a problem Al. My 4 wheel disc with the 13-1331 chevy master worked fine. I had a few (maybe a little more) hundred bucks burning a hole in my pocket so I went with the hydroboost. I also live in the burbs and sometimes deal with a decent amount of traffic and had a couple of "oh crap" moments when someone pulled out in front of me. I definitely feel a little safer now. It's here if you want it in the future.

[Kaiserjeeps]

I have been thinking about my brakes here and there. Then while looking at my firewall arrangement I see that my clutch master cylinder is right next to my brake master. I possibly have ruined any booster possibilities later because it is so close. I know the FSJ brake booster most likely won't fit now. I have not checked to verify.

The one glaring question that has been crossing my mind, when you stall an engine, do you loose boost assist right away on a hydroboost system? Where as a power brake using a vacuum can has one or two brake pumps before stored vacuum is gone. I was kind of wondering about that.

[Barrman]

Al,
The gold cylinder on a Hydroboost is a 2-3 pedal push reserve pressure holder. So, yes you get a little bit more than vacuum after the engine turns off.

I put a Hydroboost on my M715 and on the one for Sermis mounted upside down at the firewall. Lots of engine room then.

[Kaiserjeeps]

Al,
The gold cylinder on a Hydroboost is a 2-3 pedal push reserve pressure holder. So, yes you get a little bit more than vacuum after the engine turns off.

I put a Hydroboost on my M715 and on the one for Sermis mounted upside down at the firewall. Lots of engine room then.

Ah, I see. Thank you for that Tim. I am pretty darn sure I could not fit a small FSJ power brake booster with my clutch master so close. I should get a
hold of eightydeuce and see if he could take a pic to see if the hydroboost would fit. I wanted to keep it all simple, but the more I think about it, power brakes would be nice. Age has not made me stronger.
I just finished all my brake lines today.

Thanks again barrman.

[kwai]

Here is the hydroboost I used. Bracket is angled to work with our trucks. Tell him it is for a M715. He also makes them with a bigger reservoir.

https://www.ebay.com/itm/NEW-74-91-A...cAAOSwBahVTe6x

If you get a CUCV power steering pump/reservoir it already has all the fittings for the hydroboost.