Truck: "79" F-250 4x4 400cid running 35" tires. Power Brakes not working too good. I have looked at some of the post about installing a f-350 power brake booster and M/C. Is this a straight bolt on option? Had trouble understanding this question. I have already added a vacuum pump and new canaster., and front and rear brakes are good, so says the shop I trust. I thought I read about some of you doing this upgrade. Thanks for the help

 

I heartily recommend it to people who pull heavy Holiday or Work trailers.

For a daily driver truck with front discs already I consider it a waste of money

 

Does this mean it is a straight bolt on? Or are there other things i need to know

 

Well you have to choose the correct booster for your application.
w/ or w/o cruise control. The Vin# also makes a difference on the Booster application.
Plus having the proper proportioning valve

Post the Last 6 digits of your Vin.

IMO, The tech article is pretty extensive so no real need to elaborate on it.

 

Thanks for the help. we are doing the upgrade now. well let you know how well it works

 

Make sure to put some lube on pins on pivot points on the fulcrums on booster.

 

i have a 84 with really huge wildwood brake calipers. i am junking the truck will the brakes bolt on my 73 f 250 it has 16.5 rims. what woould ineed to take with the claipers? rotors of course or i might buy new. lines? in fact i am taking the rims from this truck too. what else might i take from it to go on my truck?

 

I don't think the brakes would fit your truck. try posting in a new thread in this forum.

 

Help, any ideas? Have put on the f-350 m/c and booster, new f-350 proportioning valve. Also have installed a vacuum pump. we can not get the brakes to lock up. They will stop the truck. It would not be any fun in an Emergence. you can not get the truck to stop as it should.

 

Did you not do the rest of the necessary swap over ?

Calipers/Rotors ?

 

Are bleeder valves on front caliper facing up?
Did you flush out the brake fluid from system?
Try adjusting the rear brakes?

Upgrading the front calipers.

 

Would this have anything to do with the proportioning valve? This valve is meant to distribute power to a bigger front and rear brake system. Is everyone doing this swap also changing the valve or just the booster? I was under the impresion that when swapping in the bigger booster from the 350, that was all, because you were keeping everthing else stock.
My reasoning is if the f350 is meant to haul and load heavier it would need something heavier duty to prevent lock up when empty. I'm thinking maybe the valve. This is just a thought.
Everthing else mentioned would also need to be checked, residual air in system. MC's aren't always the easiest to bleed, and does the proportioning valve have a bleeder?

Madmike33

 

Was M/C bench bled thoroughly, could be allowing air to be trapped in brake lines and brake calipers and brake cylinders.

Check the rubber brake line on the rear axle, from frame to axle.
Check the rubber brake line on the front axle, from frame to axle.
Check the ruber brake line from the caliper to brake line bracket on front axle.

buck

 

There is a difference with the master cylinder piston size.

You need to change the calipers accordingly to allow the different pressure handling ability from the F-350 MC.

I was sure the article mentioned that

EDIT:
From the tech article

Now let's discuss the master cylinder. The Bronco master cylinder has a narrower bolt pattern, thus will not fit the F350 booster. We will be using the matching F350 master cylinder. The increased 1 1/16" bore will be beneficial to us when we install the larger front disc brake calipers (later). The F350 master cylinder locates the brake lines toward the fender rather than the engine, which provides more room around the engine and looks neater. Simply twist the lines over to the opposite side of new master cylinder. The only change needed here is replacing the line nut fitting on the chamber for the front brakes. The Bronco master cylinder uses a 9/16"-18 threaded nut and the F350 master cylinder uses a 3/8"-24 threaded nut. The line nut fitting for the rear brakes is the same on both at 7/16"-24. This is a simple task with a double flaring tool kit.

A quick tip; when bench bleeding your new master cylinder, the lines must be submerged in the brake fluid chambers in order to effectively remove all air. Allow me to clear up a common misconception about master cylinders. A larger bore provides more volume but less pressure.

A smaller bore provides less volume but more pressure. So you should never increase master cylinder bore diameter unless you're also installing larger brake calipers to accept it. If you do, your brakes will only feel better because the added volume shortened your pedal stroke and made it more firm. In reality however, the same calipers are receiving less pressure which just made your brakes worse. I purchased a new master cylinder, Wagner part #F97938.

The front brake calipers on our Broncos are weak because of their small 2 7/8" pistons. The phenolic (plastic) piston is also undesirable. These calipers are another major factor of our Broncos poor braking. The brake calipers we want are off of '73-'78 Ford fullsize cars.
For the sake of arguing, I will be calling these fullsize car calipers the Thunderbird calipers. These calipers have a thicker casting, a huge 3 3/32" steel piston and are a direct fit replacement on our Dana 44 axles! The Thunderbird calipers even use the same brake pads. What will amaze you more is the clamping force of these calipers. In order to put its power in proper perspective, we need to understand what's called a caliper's piston area. Caliper piston area is the measure of a brake calipers clamping force. It is found by first finding the decimal equivalency of the piston diameter and multiply it by itself to find its "squared" value. Then multiply that figure by .785 and the result is the caliper piston area. Let's first compute the Bronco's caliper piston area. 2.875 X 2.875 X .785 = 6.48 square inches of clamping force. If we compute the dual piston caliper of an F350, the only difference is finding the piston area and multiply it by 2, because this dual piston caliper uses two smaller 2 3/16" pistons instead of one large one. 2.187 X 2.187 X .785 X 2 = 7.50 square inches.

As you can see, the F350 dual piston caliper has over one square inch of piston area and in terms of hydraulic pressure, one square inch is a very potent difference in clamping force. Now let's compute the Thunderbird caliper with its 3 3/32" piston. 3.094 X 3.094 X .785 = 7.51 square inches of clamping power! Remarkably, we have just swapped in a brake caliper equal in strength to an F350 dual piston caliper and it fits inside the 5 lug, 15" wheel! The only implication is plumbing the Thunderbird caliper. It has a 7/16"-24 inlet hole as oppose to a Bronco caliper having a 3/8"-24 hole. The Thunderbird caliper also never used a banjo bolt, the hose itself threaded into the caliper with a crush washer. We need the ninety degree angle a banjo bolt provides, in order to clear the upper ball joint on our Dana 44 axle. Since a banjo bolt was never used and 7/16"-24 is unusual, we need to convert to a #3 AN fitting. Aeroquip part #FCM2929 is the fitting adapter you'll need along with the aluminum crush washer part #FCM3513. Now you need a #3 AN stainless steel flex hose with a real tight ninety degree bend on one end and straight on the other. I chose Earl's Performance part #630117-14 because it met the criteria and is 14" long. On the opposite end of the flex hose you'll need Aeroquip part #FCM2936 to adapt it to the 3/16" inverted flare steel line. Both Thunderbird and Bronco calipers use the same bleeder screws and brake pads. I purchased a set of rebuilt calipers, King part #6083 & #6084.

 

For FTE members and entusiasts wondering what article https://www.ford-trucks.com/article/...d_Broncos.html