I have a ‘66 F250 2wd V8 Camper Special with drums and manual brakes. My next project is to upgrade to power brakes with a brake booster. I’ve read a lot of posts and have read a lot of recommendations and cautions. I am taking these items in pieces to spread out some cost and to evaluate each step to see if I need to keep going farther. Eventually I may go to ’74 dual piston discs up front, but that may or may not happen depending on how the rest of this project goes. I have a few questions before I get started.

My first thought is to just get just the booster. Napa has a ‘66 booster that is 7” for $114. They also have a ‘74 booster that is 9” for $134. My thought is to go to the ‘74, but here are my questions.

Will the ‘74 require an adapter plate to the firewall?
Will the ‘74 require some kind of rod change to the brake pedal?
Will the ‘74 work with my ‘66 master cylinder in the meantime?

My second thought is to do both the booster and master cylinder. Napa has them as a package, but I’ll list some items here separately, so I can keep my questions straight. Napa has a ‘66 rebuild that has a 1” bore for $70. When you get into the ‘74 the options change significantly. There is a 1” bore and a 1.25” bore. The larger bore seems to be for dual piston calipers only. The 1” bore is available for manual or single piston calipers. The 2wd trucks seemed to have all been discs where the 4wd trucks had an option for discs or drums. And then there are different line thread sizes available (3/8 vs 9/16) which is tied to the bore size (1” bore = 9/16 line thread, 1.5” bore = 3/8” line thread). These master cylinders range from $36-56 depending on the configuration and if new or remfd.

Will either bore size matter if I stay with drum/drum for a while?
If staying drum/drum for a while would the manual, single piston and the dual piston caliper m/c work ok? Or would the dual or even the single cause the fronts to lock up too fast?
If staying drum/drum for a while, which one of the master cylinders would work without adding a separate proportioning valve?
I saw a post for a T-fitting to use the stock brake light switch with a dual pot m/c. Has anyone tried it successfully?

The project…

• I want to get just a booster to add to what is stock, so I don’t have to worry about a brake light switch and a plethora of other parts.
• I want to get a dual pot master cylinder for just drum/drum, so I don’t have to worry about all the front disc setup yet.
• I may, down the road, go to a ’74 dual piston front disc setup.

 

First of all, you cannot add just the booster. There is a bracketry support that bolts to the firewall for the booster, and sits between the pedal and the booster. You will need acquire this from a donor truck.
There are several types out there. I recommend you look for the one with a flat rod that connects the brake pedal to the booster. It is easy to redrill the hole for the brake pedal bolt. (The distance between the brake pedal and the firewall in the '70s trucks is longer than in your '66. That rod - or flat blade has to be shortened.)

You can use the '66 master cylinder on the later booster IF you can remove the brake pedal rod and use the pushrod in the front of the booster, the one between the booster and the master cylinder. It will require some adjustment and testing to get it right, though.

The Feds required all cars and trucks (with some few exceptions) to have front disc brakes in '73, so you will not find F-100/250s with front drums.
As for the NAPA master cylinders, the larger bore is indeed for larger volume, to activate the dual front piston calipers. You will definitely need that if you go to the heavier duty disc brakes.
You should be able to use the larger bore master cylinder with drums, but your pedal travel will be less, and will sit up quite high.
You MUST use a master cylinder for drums with drum brakes. You must also use a disc master cylinder with disc brakes - do not mix and match drum-disc parts.

I hope this helps.

 

Thanks for the extra info.
For the firewall bracket, is it something like in the picture of mine or is it more of a riser?
For boosters with a flat rod (and others) I have found some boosters with a threaded rod on the booster side and a threaded banjo bolt that threads in or on to the booster rod. This would give some adjustment in throw, although I am not sure by how much. With that said, there are two full setups on ebay (not that I’m a big ebay buyer) that I’m wondering if they will work pretty easy. One is an 8” dual diaphragm booster and the other is a 7”. The 8” setup is for a ’61-’72 Galaxie and the 7” is for a ’64-’66 Mustang. They are from Nelcohotrods. It says they can do any brake configuration with the right prop valve. Ah… just found one of theirs for ’57-’72 F100 with 7” booster 1 1/8” bore and says to bolt right up. What are the thoughts and experience with these?
http://www.ebay.com/itm/1957-1972-Ford-F100-7-Brake-booster-1-1-8-Bore-Master-cylinder-w-brackets-/331436129190?pt=Vintage_Car_Truck_Parts_Accessorie s&hash=item4d2b21fba6

 

This is what you need:



(Let me know if you cannot see the picture.)

I bought a donor truck, and harvested all the parts to do the upgrade from it, and that is my recommendation as well. It really saves a lot of frustration, money and time, especially looking for the little piece you really really need that cannot be obtained from the parts store.
With the donor truck, you get the spindles, brake lines for templates to make your own, and you can use the calipers for cores if they are no good.
(Then, part out the donor truck for parts you do not or cannot use, and get a good amount of your money back!)

As to the other options, unfortunately I have no experience with them, so I cannot speak to them.

 

Ok, I see what that plate is now. That helps. I posted a question to the seller on the F100 setup and I'll see what he comes back with.

 

There are several different kinds of booster support brackets. This one came off a '78 F-250. You cannot see it in the picture, but there is a pivoting lever inside the brackets, between the brackets' supports. Not sure what the purpose for that is, but it is what came with the donor, so I used it. I think the purpose was to raise the booster up higher, so it didn't interfere with the valve overs of the engine, which was a 400.
Other supports are different. Some do not have the pivoting lever, some have a round rod instead of a flat pushrod, but any of them '68-'79 will bolt up to the firewall on your '66.

 

You wrote: For boosters with a flat rod (and others) I have found some boosters with a threaded rod on the booster side and a threaded banjo bolt that threads in or on to the booster rod. This would give some adjustment in throw, although I am not sure by how much.

The booster side adjustments are not for adjusting the throw of the brake pedal rod. They are instead for minimizing the slack between the booster and the master cylinder.
Too much slack and your pedal will go to the floor with little or no braking, for example.

The banjo bolt at the brake pedal allows of a very small adjustment of pedal travel, but less than an inch, based on my experience.
It is best to set the pedal rod to its optimum length first, and then use the banjo bolt to make fine adjustments.