I have a work in progress, and the story behind it is it was built from about 4 different trucks but I don't think I have the proper equipment for the power braking system. The brakes work well now, but if I want to try to lock them up, the pedal just feels really hard, and the brakes feel like about 75%. The system is bled and slave cylinders seem good, proportioning valve seems OK, master cylinder I believe is good, Front calipers are nice, dual piston units, front dana 60, lines might need replaced, drums and rotors are wonderful.

Here is what I am working with. The truck (chassis) is a 78 f250 4x4 custom. original was 400 and 4 spd. Now, 545 and c6. no cruise, dual piston calipers. The cab was a 79 f250 2wd 460 ranger With Cruise, c6, camper special. Not sure of caliper orientation. I feel that the booster and pedal are wrong for my application for sure, maybe even my master cylinder. There is a number on the pedal but not on the booster that I can find. Is there a parts manual out there that will enlighten me on this system so that I can verify the correct components?

 

This is what the parts catalog shows as fitting your '78 F250 chassis. There should be an ID number stamped on the booster, it may be hard to see/read because of rust and dirt/grease.
Brake booster
Fits 77-79 F250 4WD and dual piston disc brakes w/ booster before s/n DJ00,001
D7TZ-2005-B
Marked D7TA-2005-ADA, D8TA-2005-JA, 12288
Master Cylinder D7TZ-2140-B. This has an 1 1/16" Bore. If your cab came from a truck w/ single piston calipers, it will have a 1" bore master cylinder.
Brake pedal
Fits 78-79 F250 w/ power brakes w/o speed control before s/n DJ00,001
D7TZ-2455-B
marked D7TA-2455-LA

 

Thanks Mike! On the road to success already! My pedal is a F8 something, obviously wrong. Booster, well looked and no luck. Might be an aftermarket or something. Master cylinder, I will verify the bore from the back side.

 

There could be one of three different booster / MC combos on there.

The F150 and the F-250 with single piston calipers used a single diaphragm booster and MC had ports on engine side.

(Cardone # 503703 w/MC & it uses # 131854 MC for reference)



F-250s with dual piston calipers used a single diaphragm booster as well, but their MC had ports on fender side.

(Cardone 509335 w/MC & it uses # 131676 MC for reference)



And then you could upgrade to F-350 dual diaphragm booster and MC combo (which is what I used on my '77 F-150 as part of my brake upgrade.)

(Cardone 503311 w/MC & it uses # 131682 MC for reference)



It has larger bore to fill larger pistons in the calipers and rear wheel cylinders and dual diaphragm booster adds mucho boost ..... huge change on my '77 F-150. Either way, I suspect the F-350 parts will help a same year F-250. If by chance you used a booster and MC from a truck that had single piston calipers, you have the same stuff my F-150 had OEM and I lived with that since it had just 35K in 1986, never was a lot of assist. Boster was "operating properly" too ..... the F-350 parts just work "more better". Even the booster as provided on a F-250 with dual piston calipers is a single diaphragm unit.

https://www.ford-trucks.com/forums/1...e-upgrade.html

Besides, the F-350 booster and MC will give more room over that left valve cover area.

 

Well, that explains why my 2 79 f350 4x4 brake way better than my other trucks. It is in my dual diaphragm booster. What parts are required to properly set up a dual diaphragm booster? My f250 has the front 60, so it is essentially a f350, if it matters which I believe it does not, but that is probably what I want to do. Is the pedal special? Mine was all 2wd cruise control equipped stuff, camper special 460. I would love to get that firm brake in this truck like the f350s have.

 

I used a 79 2wd cab(pedals) on a 79 chassis. The F350 upgrade stops extremely well with 37's.

One thing I remember was the stock bracket between the booster and firewall aimed the master up towards the sky. I just happened to have another bracket from god knows what truck but it straightened it right out.

 

You have dual piston calipers you said .... I'ld start with just the same year F-350 dual diaphragm booster and it's matching master cylinder and see how that does. The F-350 MC will have no problem filling those dual piston calipers. For the rear, you might look at differences between the F-250 and F-350 wheel cylinders, there may be no difference.

Bench bleed the new MC before you install, then simply bleed the brakes starting at farthest and work to shortest. Don't forget bleed valve on proportioning valve. Also a perfect time to replace any questionable rubber lines .... and braided SS hoses will make for a harder pedal.

 

what would it take to put the F350 booster on a 73 f100? and how well would it stop

 

I believe my MC is 79 f350 4x4 equipment now, but booster is what ever was on there since moses and the crusades. My 2wd cab might have single piston booster, so I guess a booster is in order first. If that does not correct anything, pedal will be next. I hope the pedal will work, but if not I still entertain the theory that the pedal/booster combo I have now is maybe not compressing the MC far enough. With the old cab the brakes were better and I kept the same entire system other than pedal and booster. If I could get my old brakes bake, or even better brakes, that would be cool.