brake update

[reborn55]

Pulled rear drums and got very little cylinder movement applying th brakes--cylinders appear to be free. Went to pull pressure switch and hook up a guage of sorts and broke the fitting going into valve(murphy back again). Hooked a makeshift pressure gauge into line coming from master cylinder that went to residual valve-pressure switch--Wilwood valve. After several pumps--getting some of the air finally got a reading. about 25psi. few more pumps and pressure went up to about 150 at the end of pedal travel. harder push on pedal--could hear master cylinder piston move and pressure shot up. Using more force was able to push needle past 300 psi(trans gauge). New master cylinder----lines etc. also took alot of force to get brake light to come on. Is this pressure normal or do I need to start looking elsewhere..Will put back to gether tomorrow-hopefully and try to get a better pressure reading.  let it set for awhile--has probably got osme air int eh system and hit pedal a few times and got 75 psi on initial pump.

[Fat Cat]

Pulled rear drums and got very little cylinder movement applying th brakes--cylinders appear to be free. Went to pull pressure switch and hook up a guage of sorts and broke the fitting going into valve(murphy back again). Hooked a makeshift pressure gauge into line coming from master cylinder that went to residual valve-pressure switch--Wilwood valve. After several pumps--getting some of the air finally got a reading. about 25psi. few more pumps and pressure went up to about 150 at the end of pedal travel. harder push on pedal--could hear master cylinder piston move and pressure shot up. Using more force was able to push needle past 300 psi(trans gauge). New master cylinder----lines etc. also took alot of force to get brake light to come on. Is this pressure normal or do I need to start looking elsewhere..Will put back to gether tomorrow-hopefully and try to get a better pressure reading.  let it set for awhile--has probably got osme air int eh system and hit pedal a few times and got 75 psi on initial pump.

The pressure value at output is related to the ratio of the pedal length from pivot to end and pivot to mounting for the pushrod. The accepted value that works in most cases is 6 to 1. So if the pedal is in the 5 to 1 range it will take more force from your leg to equal the output pressure of a 6 to 1 pedal.

[Bruce Dorsi]

.... few more pumps and pressure went up to about 150 at the end of pedal travel. harder push on pedal--could hear master cylinder piston move and pressure shot up. Using more force was able to push needle past 300 psi(trans gauge).

I have seen specs calling for a minimum fluid pressure in the disc circuit of 700psi, and a minimum of 400 psi in the drum circuit.

My small Wilwood calipers (single piston) specify a maximum of 1000psi.

You may need to get a higher pressure gauge to really know what is happening in your brake system!

[wayne petty]

the drums were back on and the shoes adjusted properly when you tested...  

the rear half of the master for the front brake system pushes on the front half with pressure not mechanical force as i understand it...

the trans testers long hose might also be expanding..   possibly give you an incorrect reading by taking the fluid volume...   you might try to find a brake hose.. with 1/8 pipe fittings or get the inverted flair adaptors to make it work... brake hoses don't expand a lot..

i sure hope you washed it out with several washes of brake fluid... so no atf remained... might contaminate the fluid to the wheel cylinder or where ever you hooked it up to...    flush the system ... several times...    water washes the fluid up off the various car parts... and floor...  alcohol and glycerine is what is it made up from..


one might take a look at this link from classic industrys

http://www.classicindustries.com/images/ProductImg/A/A1704.jpg

it is a set of brake pressure gauge adaptors with a 3,000 psi gauge that screw into the the bleeder screw holes....

buying a spare bleeder screw... drilling it through the end... the hole is on the side normally.. brazing on an 1/8" female pipe adaptor will allow you to screw a gauge into it.. then thread it into the back of the wheel cylinder...  to check pressure...  only draw back.. finding a gauge that will handle the pressure cheeply...


i know that you have gotten something to work .. but a lot of people read this...