Hi there,

When I bought my 66 mustang it came with SSBC disc brake kit and a master cylinder. How do you tell the difference if its a power brake or manual brake cylinder? After I put it all together and drove it the pedal requires serious effort to stop the car. But then again I'm not used to old cars and my friends tell me that's how old manual brakes are.


Since I don't know what master cylinder is in there what would happen if I added the power brake booster? Like a 7" or 8" booster. If it was a manual brake cylinder with the booster would it be too much and cause instant lock up?

Thanks

 

With manual brakes you do have to apply more force to stop the car then if you had power brakes.

 

If it has a booster behind the master cylinder then it is power. No booster non-power.

You could try bleeding the brakes. Or maybe when the master was put in the push rod was a different length.

 

All else equal, a manual brake MC will probably have a smaller piston(s) than a power MC. Remember, pressure = pounds per square inch: the pounds come from your foot (plus the booster force for power brakes), while the square inches come from the MC piston area.

(Of course, the other way to make up the difference is with the piston sizes at the wheels.)

The tradeoff is with pedal travel. Manual brakes require more pedal travel because of their smaller MC pistons (or larger wheel cylinders).

You might want to call SSBC and ask them. Maybe they can tell you how to identify it.

 

I understand that...I am trying to identify the master cylinder because I want to add a brake booster..it doesn't have one right now. When the previous owner bought the kit I am not sure if he purchased a master cylinder made for power booster but just never bought that last piece or was going the manual route. It's going to be tough to identify because there are no markings on the MC.

Well I guess I could always buy the booster and see what happens if the brakes are super touchy and lockup easily it must mean I have the manual MC.

 

Well you are lucky that on '65/'66 the manual/power pedals are the same, '67> had different pedals. The MC for manual vs. PB should be different as the rods are different and the piston in the MC is different.

With PB the pushrod goes through the booster and is longer if I remember right. I don't know if a manual MC pushrod would reach the pedal and if it did it may pull it against the floorboard. I would go with an 8" booster at least, from what I've read the 7" run out of vacuum quicker being smaller so multiple uses may use up your available vacuum.

Here's some pedal/booster info.
http://www.mustangsteve.com/fyi_brak...akepedals.html

http://www.mpbrakes.com/technical-support/overview.cfm

Jon

 

All you should have to do is change the push rod to an adjustable one.

 

Hi,
It sounds like you need go in another direction. I would suggest you replace, both the Master cylinder and the booster as a unit. be sure to identify to the vendor whether you have discs/drums, drum/drum, or disc/disc.
happy Motoring!

 

Do you currently have disc brakes now? On my '66 GT (disc/drums) I had put on a '67 power brake disc/drum mc with a 1" bore and it was a bear to stop. It took all the effort to come to a normal stop. I changed over to a '74 Maverick manual disc/drum mc and it has a 15/16" bore. Wow, what a difference. Stops easily with much less effort. The Mustang mc for this year with disc/drum is 15/16" bore size.

 

Hi,
First, not doubting your results but am amazed how "1/16"th can make a dis-earnable difference. Hydraulics can do powerful things. But then, pressure vs. volume are powerful forces!