Brake pedal issue, diagnosis

[zintrex]

My bronc has always had a rather big area on the pedal where theres has been no effect.

so today i decided id take a look at the brake system to see if i coud figure out why the brake pedal has that 1 1/2 inch dead area/area w next to no effect.

i cheked all the hoses while i had my bro press the pedal, and none of the hoses seem to have any flex or weak spot in them. and they where new last yr.

i dont loose any brake fluid. and theres no fading of the effect once it bites properly.

i also bled the brakes on all 4 wheels, just to be shure it wasnt a air pocket, and in the same prosess "flushed" the brake system w new fluid to be shure.

i checked with my hand to feel if there was any play, and it seems like there are no play.

so i have come the conclusion it most likely is a worn out master cylinder.

but before i go and order a new master cyl, i want to ask if theres something else i have forgotten to check?

after all i hate replacing parts just to learn that the part i replaced wasnt defect.

what ya guys think?

shoud i just order a new master cylinder?

and if so whitch one of theese 3 shoud i go for:

Dorman M97934

A-1 CARDONE 100-101854

Raybestos master cylinder

i live in Norway, and parts for 80s American trucks are hard to get here since their more of a enthusiast car than something thats common

so i am pretty much stuck with either summit racing, JBC or some greedy bastard shop specializing in american cars.

 

[Bully Bob]

I would check the rod that runs fr. the pedal arm thru the firewall (booster) assuming it has pwr. brakes.

That rod is adjustable but., it should have some play.

There should be no "hissing" coming from that area around the floorboard. A hiss would indicate a leaky booster.

If the M/C will hold foot pressure with eng. running i.e. not creeping down.., then M/C is prob. still good.

Is that disc brakes..?

 

[Rons beast]

Your rear brakes could be out of adjustment. Too much clearence between the shoes and drum will result in a low pedal, as the combo valve will allow fluid to be pushed to the rear before the front brakes.

 

[zintrex]

lol i totally forgot about those darn rear drums.

gonna try to adjust the rear drums, but its gonna be a bitch to do since i run a spool in the rear.

cant wait till i get a proper diff back there tough, the bronc has been very tail happy this winter,

EPIC fun on the ice tough, darn thing wags its ass like a happy dog.

@ bully bob:

took an another look at the system today, and i have a sligth hiss from the pedal area when the truck is running.

but the hiss is gone when i apply the brakes, so i hope the booster will last a bit longer.

and yeah, disks in front, drums in the rear

 

[Bully Bob]

Hi Zen..,

"...and i have a sligth hiss from the pedal area when the truck is running, but the hiss is gone when i apply the brakes,"

As you may know., this is a vacuum leak that leans the rear cylinder(s).

Some boosters are rebuildable with a gasket kit.

Might want to deal with that in the near future.... /emoticons/[email protected] 2x" width="20" height="20" />

& ya.., like Ron said...the rear brakes need to be kept to spec as well.

 

[Rons beast]

Gotta fix that booster.....and with a relative short wheelbase, the back end will wag BAD! on acel/decel, with low gears it's worse. Are you running an auto or manual trans? (not related to the brake problem, just curious.)

good luck.

 

[zintrex]

Gotta fix that booster.....and with a relative short wheelbase, the back end will wag BAD! on acel/decel, with low gears it's worse. Are you running an auto or manual trans? (not related to the brake problem, just curious.)

good luck.

c6 auto tranny and 3,55 gearing. running on 32" bf at ko tires that has been siped, and slightly modified engine,

(mostly polished and ported intake ports and exhaust ports, 115 octane lpg kit, and a full engine overhaul last summer)

cant push it to far due to the speed densety efi system on it. so im planning a maf convertion and possibly the explorer intake mod.

but i have to say its a lot of fun on the ice, but on normal roads its quite a hand full especially now that we have hot weather in the day and cold in the night.

black iced roads. so 90% of the time its safely in 4high, running it w rear wheels only is just to ask for the back end to come flying.

over to the brake issue.

im going to take the time to re adjust the rear brakes, i replaced all the guts in there last summer, so il take a look at it today.

when it comes to the booster, im prob just gonna end up buying a booster, mc combo. who'd look horrible with a old rusted mc on a shiny new booster.

but it got to wait a month or so, just payed some plane tickets so im broke..

------ Edit (dun see the need for an new post) ------

spent about 1 hr looking a lot closer at the entire brake system today.

Rear drums:

neither of the drums where really out of adjustment, but i did tighten them with 2 clicks on the self adjuster.

and the pedal still has that 1 to 2 inch area with little / no brake effect.

rest of the brake system:

i tried something new when it comes to testing for pedal movement,

i took a piece of wood and wedged it between the seat and the pedal with the engine running, and let it sit there for 3 minutes, and i think it maybe have moved just a tiny bit.

nothing close to something i whoud call a critical thing tough.

but together with the slight hiss in the booster, i think its better to just swap both as soon as i get money to, instead of waiting until the issue develops further.

i also noticed a tiny bit of rust on the pipe going to the front drivers side. so when its time to mount the new mc and booster il just go over the entire brake system agean

and make my own new pipes, if i find the smallest issue with any of the pipes.

i plan on keeping my bronco for as long as i can, so i dun have any issue replacing things if they are on the way out anyways.