I am trying to find information or diagrams for the brakes of a '85 F-700. Either brake scymatic or wiring diagram. I know it has elec over hydro assist brakes, w/ 2 master cylinders. Does anyone know where I can get information on this. I have been searching all over and I am still not able to find anything.

Thank you,
see ya in the funnies .....
fozzy

 

Welcome to the site.

The Title should read: F700 Brake Schematic

as that is the topic.

Unless you have a used book store that may have an old Ford,Motor,Chilton Medium/Heavy Duty Truck manual you may have to go to the library.

There isn't much on the net for these trucks.

 

I'll look up what they are called tomorrow when I'm in the shop but the name of them should be cast into the rear spring brake slave cylinder. Sometimes it is on the front service brake cylinder as well.

I want to say their name starts with a W or an M but I'm not positive right now. I did a set two or three weeks ago and can probably answer some questions.

Basically when you press on the pedal to stop, both slaves are actuated at the same time and the brake pads expand tword the drums on both sides. The front slave acts pretty much like a slave cylinder from any other vehicle.

The rear is pretty screwy though. It has three pistons inside, two wedges and two rollers. One system in that slave actuates the service brakes like I said, the third piston inside is actuated by the wedges and rollers which are actuated by the spring can. The spring can is released by the spring brake fluid, the spring brake fluid is pressurized by one of two pumps.

When the engine is running and the brake switch is pushed in, the main pump which looks like a power steering pump supplies pressure to release the spring brake.

If the engine isn't running, the switch is pushed in and the brake pedal is touched lightly an electronic pump should come on and release the emergency brake.

Don't worry though, they are every bit as screwy as I make them sound. That was the first time I had ever run across them and no parts people or other tech's had ever seen them either. Once I figured out their name I was able to find some info online. I'll let you know once I get to my PC in the shop tomorrow.

I'll try to answer specific questions if I can also.

 

Ok, it's a Lucas Girling heavy brake system. Try searching "girling f-700" on Google and without the quotes.

Here is another short thread on this sitwe that says a little about them. https://www.ford-trucks.com/forums/3...ng-brakes.html

I wouldn't recommend rebuilding the slaves, they are very difficult to keep from leaking but as the other thread says all the parts are available at Napa.

Don't hesitate to ask questions, if I can help I will.