4 Wheel Drums are killin me!

[Neto]

I'm not sure where I saw this link, but there's some possibly helpful info at:
http://www.markwilliams.com/braketech.aspx

Here is an exerpt of the info there:

The goal ... is to balance the entire system. Pedal force, system pressure and lever travel all need to be taken into account.
A balanced system includes the following things:
1) A lever that moves the entire stroke of the master cylinder
2) A Lever that moves comfortably in the confines of a car
3) Uses a reasonable amount of force to reach the desired system pressure
4) Is aligned well enough to minimize lever travel.

There are also charts & formulas for figuring optimal MC bore size, lever ratios, etc.

 

[smallfoot]

My start on pedal and bracket might be overkill but I have plenty to play with. I'm starting with an 18" total lever length and 2" distance on actuator rod from pivot. That'll start it out at 9/1. Mounting the bracket as high as I can and using up every bit travel to the floor. Should have left the MC attached but here's a pic of the bracket roughed out. I expect to do some reshaping and some length changes until it feels good to me.

 

[31ModA]

Still fighting with my starter hope to get back on brakes issues.

 

[401ton]

I just got my ride on the road a few weeks ago and have good stopping, lock the wheels and sequel the tires.
I wouldn't guarantee my front to back bias is perfect, but seems to panic stop good on old crappy brake shoes.

My setup is:
1954 Chevy car front wheel cylinders (1 1/8" bore)
1975 ish Ford f-150 rear wheel cylinders (15/16" bore)
1968 Ford Mustang manual drum/drum master cylinder (1" bore)
I have about 5 1/2:1 or so pedal ratio. I would have made it 6:1 but didn't plan ahead far enough.

First thing I would do is measure your pedal ratio, because if that is off, changing the master might not fix everything.
Measure length of where you foot pushes on pedal to pivot point, then length of pivot point to master cylinder rod if pivot is under master cylinder.
If your master is under your pivot, you will need to measure from pedal to master rod-then master rod to pivot.
Divide long by short measurements to get ratio.
As stated before, 6:1 is recommended for manual brakes.

Starting with the pedal ratio is usually only a time thing as opposed to spending money for a new master on a possible fix.

Hope this helps.

 

[401ton]

My start on pedal and bracket might be overkill but I have plenty to play with. I'm starting with an 18" total lever length and 2" distance on actuator rod from pivot. That'll start it out at 9/1. Mounting the bracket as high as I can and using up every bit travel to the floor. Should have left the MC attached but here's a pic of the bracket roughed out. I expect to do some reshaping and some length changes until it feels good to me.

This should give superior leverage with probably more pedal travel than most would want.

 

[smallfoot]

The way I'm setting the lever up shouldn't have excessive travel. I'll take some better pix when the deal is all set up in there. The MC rod is adjustable and heimed and I'm sure there will be some length adjustments on the lever. But I know from past experience, that it doesn't hurt to set it up with all the extra you can gather to start with and take only what you need to as it's adjusted. I've got 6 working master cylinders on vehicles around here and I've checked into the action on the rod in several. Can't find a one around here that travels more than an inch and a half before it piles up pressure. The old dj5 MC had a frame mount with a limiter built into it that could adjust upward limits. I'ts a pretty simple set up that could be moved.