![]() |
Register or Log In To remove these advertisements. |
|
|
![]() |
|
Thread Tools | Display Modes |
![]() |
#1 |
Registered User
Join Date: Jan 2011
Location: Townsend MT
Posts: 1,725
|
NEED Help! Front disc brakes won't release!
My 1972 GMC 3/4 ton 4X4 brakes won't release. The original brake booster went bad so I installed a NAPA brake booster. They worked fine before but now the brakes won't release all the way. They just drag and over heat the brakes (600 degrees F in 5 minutes on the rotors
![]() Any help is greatly appreciated. |
![]() |
![]() |
![]() |
#2 |
Registered User
Join Date: Feb 2009
Location: Jefferson City, MO
Posts: 83
|
Re: NEED Help! Front disc brakes won't release!
Did they ever work correctly after the new booster?
If not, of course the problem is likely in the booster or the rods going to it - there are adjustments - look for a jamb nut on a threaded rod. Next things to suspect are the rubber lines to the brakes - sometimes they can look fine, but collapse on the inside. If you replace one, always do both. The proportioning valve - if the valve inside gets "slid" too far to one side, you can sometimes loosen the line to the opposite brakes & press the pedal & slide it back. Hope this helps & post what you find out. |
![]() |
![]() |
![]() |
#3 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
|
Re: NEED Help! Front disc brakes won't release!
doubt both rubber lines fail at exact same time
push rod adhustment should solve problem
__________________
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 |
![]() |
![]() |
![]() |
#4 |
Registered User
Join Date: Aug 2009
Location: Alden NY
Posts: 2,705
|
Re: NEED Help! Front disc brakes won't release!
There is a small adjustable rod in the front of the booster that contacts the piston in the master cylinder. If it is too long it will preload the MC, and if it is too short it won't feel like the booster is working. You can adjust it by unbolting the MC from the booster and carefully moving the MC with lines attached forward. Don't let the MC stand on the brakelines alone for support - use a bungie to the hood hinges while you are adjusting it. Sometimes it takes a few tries.
__________________
1961 C1 Corvette 1959 El Camino 350 TPI, 9" 4 w disc 69 Blazer K5 - sold July '20 2021 Durango RT 5.7 Last edited by rsavage; 04-11-2011 at 06:50 AM. |
![]() |
![]() |
![]() |
#5 |
Registered User
Join Date: Apr 2010
Location: Boise, ID
Posts: 1,280
|
Re: NEED Help! Front disc brakes won't release!
Probably unrelated but don't foget the white lithium on the caliper bolts. Believe it or bot, this was why my disc brakes would not release. Your problem sounds differetnt but just wanted you to know.
|
![]() |
![]() |
![]() |
#6 | |
Senior Member
![]() Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,903
|
Re: NEED Help! Front disc brakes won't release!
Quote:
If you don't have the instructions, here's a link: http://www.cardone.com/english/club/...s/93039354.asp Last edited by truckster; 04-11-2011 at 11:12 AM. |
|
![]() |
![]() |
![]() |
#7 |
Registered User
Join Date: Jan 2011
Location: Townsend MT
Posts: 1,725
|
Re: NEED Help! Front disc brakes won't release!
I just pulled the master cylinder off last night. It is a solid rod between the MC and booster. I put 3 flat washer on each stud, bolted the master cylinder on and it works fine. Is there anything wrong with leaving it this way? I saw no adjustment.
Thanks |
![]() |
![]() |
![]() |
#8 |
Registered User
Join Date: Aug 2009
Location: Alden NY
Posts: 2,705
|
Re: NEED Help! Front disc brakes won't release!
Here is a photo of the rod that comes out of the front of the booster and goes into the back of the MC. It takes a 5/16" wrench. I have never had a booster without one. You can see that the end is threaded out some on mine.
![]()
__________________
1961 C1 Corvette 1959 El Camino 350 TPI, 9" 4 w disc 69 Blazer K5 - sold July '20 2021 Durango RT 5.7 |
![]() |
![]() |
![]() |
#9 |
Registered User
Join Date: Jan 2011
Location: Townsend MT
Posts: 1,725
|
Re: NEED Help! Front disc brakes won't release!
Mine is just a solid 3/8 rod.
|
![]() |
![]() |
![]() |
#10 |
Registered User
![]() Join Date: Sep 2010
Location: Formerly MD and San Diego, now loving life in Arizona
Posts: 1,636
|
Re: NEED Help! Front disc brakes won't release!
Is the rod from your old setup still available? If so, try to swap the "new" rod with the old one. I am not a fan of adding shims (washers) to the setup but that is me.
Another possibility would be to shorten the new rod by the thickness of the washers that were installed. Al '69 GMC 2500 Custom Camper '69 Chevy C10 396 (engine in machine shop) |
![]() |
![]() |
![]() |
Bookmarks |
|
|