The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 07-06-2016, 10:09 PM   #1
1972GMCsierra4x4
Registered User
 
Join Date: Feb 2013
Location: Winchester Kansas
Posts: 145
Spongy Brakes, can't fix issues

Hey guys, I'm having some very frustrating issues with the brakes on my '72 K-2500. The truck has a Dana 60 with the big 12" drums. No matter what I do, the brakes are extremely spongy. I've had a complete brake job done, replaced the master cylinder, bled the lines several times and they still feel like I'm stepping on a plum when I try to stop. All tips and suggestions are greatly appreciated. Thanks!
1972GMCsierra4x4 is offline   Reply With Quote
Old 07-06-2016, 10:40 PM   #2
Zoomin
Man of Mini-Talents
 
Zoomin's Avatar
 
Join Date: Sep 2009
Location: Oklahoma City, OK
Posts: 4,295
Re: Spongy Brakes, can't fix issues

Did you replace the flex lines?
Have you tried to pressure bleed the brakes using air to force fluid from the master out?
Did you bench bleed the master cylinder?
Zoomin is offline   Reply With Quote
Old 07-06-2016, 10:46 PM   #3
LockDoc
The Older Generation


 
LockDoc's Avatar
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,779
Re: Spongy Brakes, can't fix issues

Quote:
Originally Posted by 1972GMCsierra4x4 View Post
Hey guys, I'm having some very frustrating issues with the brakes on my '72 K-2500. The truck has a Dana 60 with the big 12" drums. No matter what I do, the brakes are extremely spongy. I've had a complete brake job done, replaced the master cylinder, bled the lines several times and they still feel like I'm stepping on a plum when I try to stop. All tips and suggestions are greatly appreciated. Thanks!

First off bench bleeding the master cylinder is important, so if you had the old one off or installed a new one make sure to do that....

Also make sure that the proportioning valve is centered as it should be.

On the drum rear brakes, one thing I found on mine is when you put everything back together and adjust the brake shoes you can’t just adjust them out until they start rubbing and quit. You have to adjust them out as far as they will go and you cannot turn the wheel or drum at all. This centers the whole assembly in the drum. (I even tap around the drum as I tighten them to help them center themselves) Then you back them off until the wheel just turns, and stop. If you only adjust them out until they start rubbing and quit, the first time you press on the brake pedal the brake shoe assemblies will center themselves and you will have too much clearance between the shoes and the brake drum. I also put three lug nuts on backwards to hold the drum tight against the axle on the rear.

I know it is a pain in the butt to try and hold the self adjusters off of the adjuster wheel while you back them off, but this is the only way I could get my drum brake shoes adjusted correctly.

LockDoc
__________________
Leon

Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles

(My Dually Pickup Project Thread)

http://67-72chevytrucks.com/vboard/s...d.php?t=829820

-
LockDoc is offline   Reply With Quote
Old 07-06-2016, 11:09 PM   #4
1972GMCsierra4x4
Registered User
 
Join Date: Feb 2013
Location: Winchester Kansas
Posts: 145
Re: Spongy Brakes, can't fix issues

Thanks for the tips guys. I couldn't tell you if the master was bled, I didn't install it. I need to replace my flex lines on the rear. I'll also try adjusting the brakes again
1972GMCsierra4x4 is offline   Reply With Quote
Reply

Bookmarks

Tags
1972, gmc, k-2500, spongy brakes


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 10:28 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com