Brakes 101

[Don Dulmage <big-d@xxxxxxxxxxxx>]

Ok now that i have  vented i have twice help fellows sort out disc brake conversion. !st most ARE NOT MOPAR stufff but chevy truck. If you want more brake pressure in relation to pedal effort you need a smaller bore master cylinder. 
Because we are so conditioned to thinking bigger is always better we get in trouble this way and so do the people aho make the kits. If you have a 1 inch bore cylinder try a 7.8 bore. pedal travel will increase a bit not not much but hydraulic pressure will be higher for the same effort.  if we could bigger pistons in the calipher would do the trick but since wecant a smaller n bore inthe master must be used.  Put crudly it iwroks like a lever with mechanical advantahe. If for instance the master could have the same bore as the cliphers then the only mutiplication would be the machanical advnate in the pedal assembly.   It is complicated but  the smalker the master bore the higher the pressure acting on the calipher but also te more travel. Last one I fixed had been supplied with a 1 (might have been 1 1/16th even)inch bore GM cylonder and was alsost undrivable as it required too uch pedal effort. I recognized the forighnn cylinder right away havinfg installedseveral hundred in my carreer. We went to the local UPS (napa) Store andbought a mopar one with a 7/8 bore and the brakes worked perfectly ever since. That was Bill Parsons car and some of you met him at carlise I believe. (Black 64 dodge)
The other was a duster conversion and for the life of me I dont understand why they didnt just order the duster caliphers and rotors and master and such rather than buy some foreign born Chvy truck red calipher piece of crap. Anyway i explained the stituation onthe phone to the shop. They didntbelive me and gave up on the car and it never did get fixed.(I dont think it got driven either as it wasto sacry i heard. ) Anyway. That is how it works. The biggir the diffeence between the area of the  slaves pistons s and the master;s piston area with the slave being the bigger  the higher the mechanical advanyage but the greater the pedal travel at the master.
 
Have you air in the lines? How do you tell. 
Pedal is always the same when you stroke it if the system has only fluid. If it has air you can pump it up. 
A pro mechanic will bleed the brakes then get a good pedal then release and count to 30. it should be right there again on the first stroke. if not you have air. 
Don   
Author of
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Old Reliable (Mopar)
http://altonapublicschool.faithweb.com/

http://seniordragster.bravehost.com/index.html
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