master cylinders

[bippy93]

I know this subject has been beat to death, but just curious what
the experts would recommend for a master cylinder. Just did the
disk brake f-150 conversion and have manual brakes. Can I use
the factory master with the residual valve removed or go with
a 77 master for a bronco. It sounds like some of you are using
an f-250 master, but I also read that this makes a very hard pedal.

HELP!!!!!

 

[SaddleUp]

I would go with the 77 one. The original ones don't have the right capacity in the reservoirs for disk brake calipers. Removing the valve may make it work but I personally wouldn't do it. (Master cylinders are inexpensive so I would just go with a replacement instead)

 

[bippy93]

Any difference in the 77 vs. the 78 big bronco master?????

 

[SaddleUp]

I think the lines come out on opposite sides.

 

[bippy93]

Are the 77 lines on the correct side or the 78??? I thought I saw a
picture on jeffs site for a 77 with them on the pass side.

 

[Brewbro21]

Hey bippy I got off the phone yesterday with Lonnie from Tom's Bronco Parts, is pretty much the disc brake guru over there, very nice guy to do business with as well as get info from.

Lonnie said to just use your old one and you'll be fine. If you do experience front brake drag then remove your check valve out of the front port of the M/C. He said he has done this countless times and even has this setup on his rig with no problems. Unless you have a leaking M/C I wouldn't change until you upgrade to power brakes.

I plan to do this when I put on my disc brakes in a week or two.

 

[bippy93]

So is there any advantage if I use the F-150 master??? Will it work.

 

[SaddleUp]

Hey bippy I got off the phone yesterday with Lonnie from Tom's Bronco Parts, is pretty much the disc brake guru over there, very nice guy to do business with as well as get info from.

Lonnie said to just use your old one and you'll be fine. If you do experience front brake drag then remove your check valve out of the front port of the M/C. He said he has done this countless times and even has this setup on his rig with no problems. Unless you have a leaking M/C I wouldn't change until you upgrade to power brakes.

I plan to do this when I put on my disc brakes in a week or two.

I would question any shop that suggests using a drum/drum master cylinder on a disk/drum setup. Mods like that are better left to the backyard mechanics. Can you get by with it? Probably. Will it be right? No, for the reason I mentioned above. It isn't just a matter of the only difference being a residual pressure valve. The disk calipers have larger pistons than the wheel cylinders in them which require more fluid to operate than them. While the drum/drum ones will work it puts them close to their capacity which gives less leeway if a leak develops before they completely fail. Having rolled 2 vehicles that were directly the result of losing the brakes I will not mess around with them. I.E. Brakes are something that you want to do right. BTW, rebuilt master cylinder usually cost around $12 to $15 so it isn't as though the cost is really a big issue.

 

[cynrays]

Auto Zone for less than 15 dollars..

 

[Skuzzlebutt]

With the '77 MC, it depends on if it's from and if you have power assist. Most '77 had power assist and ergo, the lines are on the passenger side. If you don't have power you need the lines on the drivers side.
I don't know about '78s.

 

[jbeyer]

check out that beat the disk mc into the ground thread. lots of options. the 77 bronco mc has a 1 inch bore. but the line on the pass side will be a problem unless you have that offset mount for the mc with the vacumm booster. some guys think you need a bit more. the f250 is the 1.25 bore. i just put that on, and you do need to be a real man to use those brakes. but they work.

 

[Brewbro21]

Just remember Lonnie has done more disc conversions then everyone on this board combined, plus he/Toms Bronco parts have the liability should the brakes fail. If he says it works then I'd believe him.

He said if I wanted to he'd sell me his M/C that cost $59 but it would just be overkill. People like him are what make the Early Bronco World the most exciting.

I'm going to try it and I'll let everyone know how it works. Remember this is only for the manual front disc setup not power.

 

[SaddleUp]

Just remember Lonnie has done more disc conversions then everyone on this board combined, plus he/Toms Bronco parts have the liability should the brakes fail. If he says it works then I'd believe him.

He said if I wanted to he'd sell me his M/C that cost $59 but it would just be overkill. People like him are what make the Early Bronco World the most exciting.

I'm going to try it and I'll let everyone know how it works. Remember this is only for the manual front disc setup not power.

Just because something works 99 out of 100 times doesn't make it right nor does it make it the safest. Power brakes doesn't effect the fluid requirements of the calipers so it has very little to do with it. When rebuilt master cylinders can be had for so little it just seems pretty stupid to me for someone not to go ahead and do it right. It's just plain irresponsible for someone in a position such as Tom's Bonco Parts to advise others in this manner. (You are welcome to tell them I said so) If your really curious go into a parts store and have them show you a master cylinder for a 68 Bronco, a 78 Bronco, and a 78 Lincoln Mark VII. (drum/drum, disk/drum, and disk/disk) You will see that each one has one larger reservior than the previous one. If it wasn't relavant then the 78 Mark VII with it's 4 wheel disks would still be using the same one found on the 68.

 

[bippy93]

Thanks for all the replys guys.