How hard should manual brakes be?

[cancow]

Should it take every ounce of your leg strength to wait for a light to turn green? That is what mine is like, but if this is normal why they heck is the brake peddle made for only one foot?

[70_F100]

Well, it depends on how strong your leg is... LOL

Seriously, it shouldn't be really hard to stop a vehicle with manual brakes.

It sounds as if you may have some sticking wheel cylinders, worn out brake linings, grease/brake fluid on your linings, pinched lines or a combination of these.

How long has it been since you've had the brake drums off?

How long since you've done a complete brake job, including rebuilding/replacing the wheel cylinders and master cylinder?

Give us that information and I'm sure someone can give you a pretty accurate diagnosis, or at least help you to better troubleshoot the problem

[jzjames]

Well my 67 w/automatic transmission is like that. The C4 transmission wants to pull at idle, and if I let off the brake it will travel at 3-4 mph. My brakes take alot of pressure, possibly because the 67 had smaller front brake linings than 68-72 F100s.

[cancow]

I had the rear brakes replaced a couple years ago and they have less than 1000 miles since then. The front I have not done yet. Any way to tell if the master or wheel cylinders are bad?

[fordman]

to check the wheel cylinders. jack up each wheel. have someone step on the brake and you see if you can turn the wheel that is off of the ground.

[cancow]

Yeah, that is how it is with my Cruise-O-Matic camper special. I find it hard to believe old men went to the mountains with campers and brakes like these... Can I put bigger brake linings on?

Well my 67 w/automatic transmission is like that. The C4 transmission wants to pull at idle, and if I let off the brake it will travel at 3-4 mph. My brakes take alot of pressure, possibly because the 67 had smaller front brake linings than 68-72 F100s.

[70_F100]

The front brakes provide a larger percentage of total braking force than the rear. That's why the front shoes on 99% of drum brake systems are wider than the rear. The front wheel cylinders also have a larger bore.

Since you haven't done the front, I would at least pull the drums and check them. You may have some wheel cylinders that are sticking.

I've driven MANY vehicles with non-power brakes, and it shouldn't be that much harder to stop your truck than one with power assist. My 70 F100 wasn't nearly as hard to stop before I upgraded to PB as you say yours is.

Even if you don't find problems, the fact that you replaced your rear and not the front makes them suspect. The linings could be crystallized, which can make it nearly impossible to stop since crystallization of the linings greatly reduces the coefficient of friction between the linings and the drums.

[FordTruck]

When I was drivin my 70 around before I put a booster on it it would take both feet on the pedal to keep it from creeping at a stop light because it had a proporating valve on it still. I put a booster on it and now it isn't as bad but it still wants to creep sometimes.

[FordTruck]

When I was drivin my 70 around before I put a booster on it it would take both feet on the pedal to keep it from creeping at a stop light because it had a proporating valve on it still. I put a booster on it and now it isn't as bad but it still wants to creep sometimes so you might wanna check that if it used to have power brakes.

[Bullitt390]

I swapped from power brakes to manual and hardly notice any difference, especially at slow speeds and stoplights.

What is your idle set at, 1200?

Josh

[fordman]

yea something doesnt sound right.

[jzjames]

All I can think is the vacuum signal to the modulator valve is too high (too much vacuum), at idle. The idle rpms is correct, yet it really pulls and tries to move at idle. You've got to keep the foot on the brake. Alot of times I throw it into neutral at a stop light.
The other thing is the shift points feel like theyre too early when accelerating at normal speed. It shifts to 3rd at 18 mph. I thought this could also be a vacuum issue, but Ive come to think this is how this tranny runs.

[70_F100]

The modulator has no effect on transmission operation when the vehicle is stopped.

You say the idle speed is correct. What is the RPM in drive with vehicle stopped?

As for the shift points, going into 3rd gear at 18 MPH is about right under light acceleration.

[convincor]

something else to look at with heavy pedal effort would be the bore size of the master.
Went through this building my car.
A master that's to big makes for short pedal travel and very hard pedal and no stopping.
Smaller bore master makes for longer pedal and light pedal effort but stops like power brakes.

[70_F100]

Convincor, you are correct.

It seems as if it would work the other way around, but anyone who knows about hydraulics or fluid dynamics understands that you can build higher pressures with less effort through a smaller actuating cylinder. A good example of this is a bottle jack -- slow, but powerful.

On the other hand, a larger wheel cylinder will provide better stopping power. That's one reason (but not the only reason) that disc brakes are more effective than drums. There is more surface area on a disc brake piston than on the two pistons/cups in a conventional wheel cylinder, resulting in substantially more force being applied to the pads. That's also one of the reasons (again, not the only reason) why there is less surface area required on disc brake pads than on drum brake shoes.