master cyl question

[57larry]

I got another question guys.....have a 40 Ford sedan with a chevy 350/350 disc brakes, fron & rear.  master cyl under the floor 1" bore has 2 residual valves, 6 inch power booster with a vacuum canister.

problem: brake pedal goes to the floor, car stops but I don't like the feel. disc brakes are wilwood, master cyl setup from ECI

thanks for any advice

[chimp koose]

soft pedal?

[57larry]

yes, soft pedal, bled many times

[chimp koose]

Do all the calipers have the bleeder screws right at the top? Do you have any of those through the frame brake line fittings ? Those 2 things can cause 'air pockets' in the system . Master was bench bled ? What is the pedal ratio?

[57larry]

yes, no yes

[chimp koose]

Fully bled and pedal goes to the floor . Is the volume of your master cyl able to supply the volume used in the calipers ?I would think with 1" bore it would . Does your pedal allow for a full stroke in the master cyl before it gets to the floor ?

[phat46]

Any chance the MC is bad. Not uncommon nowadays to be bad out of the box.

[slocrow]

57Larry; As much as I relent from responding with advice, based upon my limited knowledge, I remember back 20 years ago when a member had a similar problem. He resolved his issue and a second members same problem by replacing the power booster canister with, in their cases a used Astro van unit, from the boneyard. They wanted one that was working hense the used boneyard part. Solved both issues quickly from soft to lock-up. I believe if the residual valves are holding then the booster canister is your issue. Hope I'm correct and your issue gets resolved. Let us know, Frank

[Bruce Dorsi]

Does the pedal go to the floor on a quick double-pump?

[57larry]

I'm done! taking out the master cyl & booster, going back to manual brakes. thanks  for all the advice

[GPster]

Are the master cylinder and the booster a factory pair? Maybe the rod between the two is too long and not letting the brake cylinder retract all the way and letting the master cylinder re-fill with fluid. GPster

[57larry]

master cylinder, pedal, booster are from a kit from ECI

[chimp koose]

Go to the HAMB and look up a thread called " BRAKE BLEEDING!? " it was posted by ' Jaw 22 ' .  On the 8th page of the thread he finds the problem . It caught me by surprize but would be worth a look on any system , especially those with under floor m/c .

[57larry]

thank you for the link, chimp

[chimp koose]

you are welcome . Those are the threads I like to read as a guy can usually learn something.