72 pickup brake pedal goes to floor - The 1947 - Present Chevrolet & GMC Truck Message Board Network

swiny20 · 08-14-2007, 02:02 PM

Ok,(72 disk/drum) try to make this short, bought truck knowing it had rear wheel cylinder leak, assuming this was also related to pedal, I have since replaced rear wheel cylinders and brake shoes. I have bled and bled these things (all 4 corners), but no change in pedal, with little resistance it just goes to the floor. I'm new to this site, but I would appreciate any advice. Things I have checked from reading other post. Brakes are adjusted so drums barely go on, combo/poportioning valve button(?) pushed in., and bled the @#it out of them.

**truckdude239** · 08-14-2007, 02:26 PM

master cylider has gone bad

Chevyholic · 08-14-2007, 03:08 PM

I recently had a similar problem. No leakage anywhere, but the brakes just kept getting worse. Finally pulled the MC and found that it was leaking back into the booster. Replaced the MC and all is well again.

Good luck!

**truckdude239** · 08-14-2007, 11:16 PM

if it is leaking into the booster always replace the booster

swiny20 · 08-15-2007, 12:00 PM

Thanks guys, I put it on yesterday and their is a difference now I just need to re-bleed all four corners.

cdowns · 08-15-2007, 12:51 PM

just clamp the pin on the combination valve like it says in the service manual and the bleeding will go smoothly

**WorkinLonghorn** · 08-15-2007, 02:57 PM

Make sure you bleed the new M/C as per the instructions that usually come with one. There's a cheap little kit you can buy for like $4 with hoses and clips that make it really easy too.

retodd7711 · 08-15-2007, 06:11 PM

good luck and WELCOME to the board. Remember WE LIKE PICTURES !!

08-14-2007, 02:02 PM	#1
swiny20 Registered User Join Date: Apr 2007 Location: Alabama Posts: 35	72 pickup brake pedal goes to floor Ok,(72 disk/drum) try to make this short, bought truck knowing it had rear wheel cylinder leak, assuming this was also related to pedal, I have since replaced rear wheel cylinders and brake shoes. I have bled and bled these things (all 4 corners), but no change in pedal, with little resistance it just goes to the floor. I'm new to this site, but I would appreciate any advice. Things I have checked from reading other post. Brakes are adjusted so drums barely go on, combo/poportioning valve button(?) pushed in., and bled the @#it out of them.

08-14-2007, 02:26 PM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,238	Re: 72 pickup brake pedal goes to floor master cylider has gone bad __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

08-14-2007, 03:08 PM	#3
Chevyholic Will it run today? Join Date: Feb 2007 Location: DFW, Texas Posts: 272	Re: 72 pickup brake pedal goes to floor I recently had a similar problem. No leakage anywhere, but the brakes just kept getting worse. Finally pulled the MC and found that it was leaking back into the booster. Replaced the MC and all is well again. Good luck! __________________ Jaws, the 1971 Chevy Cheyenne Longbed. She's big, grey, and has an insatiable appetite!

08-14-2007, 11:16 PM	#4
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,238	Re: 72 pickup brake pedal goes to floor if it is leaking into the booster always replace the booster __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

08-15-2007, 12:00 PM	#5
swiny20 Registered User Join Date: Apr 2007 Location: Alabama Posts: 35	Re: 72 pickup brake pedal goes to floor Thanks guys, I put it on yesterday and their is a difference now I just need to re-bleed all four corners.

08-15-2007, 12:51 PM	#6
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: 72 pickup brake pedal goes to floor just clamp the pin on the combination valve like it says in the service manual and the bleeding will go smoothly __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

08-15-2007, 02:57 PM	#7
WorkinLonghorn Senior Member Join Date: Dec 2006 Location: Studio City, Calif. Posts: 2,886	Re: 72 pickup brake pedal goes to floor Make sure you bleed the new M/C as per the instructions that usually come with one. There's a cheap little kit you can buy for like $4 with hoses and clips that make it really easy too. __________________ '69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme.

08-15-2007, 06:11 PM	#8
retodd7711 chrome makes it go FASTER! Join Date: Feb 2007 Location: Cleveland Tennessee Posts: 2,884	Re: 72 pickup brake pedal goes to floor good luck and WELCOME to the board. Remember WE LIKE PICTURES !! __________________ She can't cook and she won't clean. But she looks good in a skirt and she brings me beer. She can stay for now. EDIT:: But she left me anyway, So forget her. 1962 GMC Stepside V6 4 speed My rolling resto thread http://67-72chevytrucks.com/vboard/s...d.php?t=324226 My old farm truck http://67-72chevytrucks.com/vboard/s...=1#post3465005



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