"low pedal" brake situation

[sellersrodshop]

hello everyone, have a real headscratcher here. i just built a complete brake system on my 69 mustang & cant seem to get a good pedal feel. all the brake action is on the lower third of the pedal travel.

the system;

rebuilt bendix booster correct for the 69
2000 mustang v6 master with 1" bore
12.5" front disc setup from 2008 mustang gt
11.3" lincoln mark VII rear disc setup
wilwood distribution block with built in prop valve.
all new stainless hardlines, braided stainless flex lines up front & new rubber hoses in rear

the master was bench bled & the booster to master pushrod adjusted to fit the m/c bore before installing. the rear calipers with the screw in pistons were adjusted before installation to the ford/lincoln tech manual & seem to be correct as the internal parking brakes work fine. the system was gravity bledfirst, them vacuum bled with a mityvac & after that coventionally bled with the old foot to pedal method. calipers are all mounted correctly with the bleeders at the top & i get NO air bubbles when bleeding. i even opened up the prop valve to full pressure while bleeding to make sure that wasn't causing a problem, then readjusted valve afterwards. car seems to stop fine, but havent done much yet but a couple test runs around the block to bed the pads.

anyone have any ideas what i've missed or why i have no/soft pedal until its pushed 2/3 of the way down?

[Apogee]

You're correct to think that it's a air issue, the question is where? I would start by plugging one port at a time on the master cylinder to see if you can isolate which end of the car the issue is on...if that doesn't work, it means the air is in the MC. When you bench bleed the master cylinder, did you confirm it was fully bleed by blocking both outlet ports and testing to see if it would hydraulically lock?

Tobin
KORE3

[sellersrodshop]

thanks tobin!

no, i didn't check to see if it would lock. i lost my good bleeding tools in the fire a while back, so used a combination of a hard line i made up with one of the cheap $9 bleeder kits. the bleeder kit only had one metric fitting the size i needed so had to find a fitting & make up a bleeder line for the other port. i bled it until no more bubbles were present, then pumped it about 10-15 more times to make sure. had fits with this new style master. most of the old style masters i've bench bled over the years were fairly easy to install without a mess. i would only get a trickle of fluid out in changing from the bleeders to the hard lines. these new ones flood when the ports are open. had to keep a bottle of fluid handy & add as i installed. i hope i dont have to pull the master again. its such a tight fit that in order to remove, the pedals have to be loosened & the booster loosened up also just to get the master on & off...

you can see how close a fit the front of the master is to the shock tower..
https://static1.pt-content.com/images/pt/2012/07/IMG_3164-1.jpg