I have four wheel drums with a 7" booster and a 1" bore master cylinder. The lines have 10psi check valves. What needs done to install discs up front?

 

Need more info. F100 F250? What are these 10 psi valves you talk about? Are you looking at a kit or Factory from a later year?

 

The vehicle is a 1969 f100. The valve is called a residual check valve. They're used to keep a slight bit of pressure in the wheel cylinder for faster brake response. Normally drum brakes use a 10lb valve and discs use a 2lb. My question is does anything need done other than switching the front to a 2lb valve and adding a adjustable proportioning valve?

 

For best results, you will want to change the master cylinder to a larger bore. A common upgrade is the early 90s explorer/ranger master cylinder.

Personally, when I upgraded to disc brakes I kept them as manual (no booster). I like the feel of the pedal more, and have plenty of leg power to lock them up.

 

Larger than an inch? This is not the factory MC.

 

Did I stutter?

Yes. 1" is the minimum considered acceptable with boosted discs. Even then, you'll have very touchy brakes. What you have will work, but you might not be happy with it.

1-1/16 or 1-1/8" result in a better feeling pedal.

 

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There are numerous threads here as well as other information all over the Internet on what needs to be done.

Fordification has a very well documented procedure on how to swap and what to get

 

You're new here, you'll figure it out....

 

@351Cleveland C4 Did you change the Brake Proportioning Valve and if so, who's did you use? I have read a lot of the aftermarket ones leak.

 

I used Wilwood

 

F100's with four wheel drums didn't come with a proportioning valve, just a differential valve. Until now I haven't needed a proportioning valve (combination valve). That was the crux of the question. Looks like I need to switch out the 10lb check valve up front with a 2lb and add an adjustable proportioning valve to the rear. May try and find a combination valve off a disc brake truck though.

 

what check valves are you talking about? I've never seen any.

 

Also known as residual pressure valve. A number of old masters has RPV's in the outlet ports and the new and/or rebuilts often do not have them. They are also used in applications where the master sits below the wheel cylinders - some kit cars, or older cars where the master was below the floor. They can also be helpful when you have a large system volume and a relatively small master cylinder. It ensures that the wheel cylinders are full of fluid and ready to react. I needed to put in a 10psi valve in the rear circuit when I installed the Sterling rear.

What you may want or need in addition to what you have pieced together is a brake metering valve that is used in some Ford disc/drum applications. This is sometimes called and anti-dive valve. It ensures that the discs and drums apply at about the same time. Since there is more mechanical movement in the drums, they react a little slower than discs. To avoid the fronts hitting hard all at once causing a potential loss of control, the metering valve slows down the fronts a bit. Here is a better description https://www.freeasestudyguides.com/b...ing-valve.html . My 1970 F-250 has this valve. They are available today from some sources and there is a Chrysler version that seems to be easy to find. Ideally they are tuned to the vehicle where more or less pressure on the front brake circuit is required for the valve to open. You may or may not need one of these depending on how your truck reacts to braking. A sudden hard application is where it provides a factor of safety. In normal driving you may not know it was even there.

 

I am going back to the '78 f150 I pulled the front from. Would the combination valve from that truck do truck?