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#1 |
Registered User
Join Date: Jun 2009
Location: Arlington Texas
Posts: 602
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trouble shooting drum brakes
I have an issue of the brake peddle moving too far when I hit the brakes and the truck doesnt brake very well. I have replaced the master cylinder, wheel cylinders, new brake hardware, new adjusters, I have replaced everything in the brake system but the drums. Bled the crap out of the brakes but nothing seems to help. I have no idea if the drums are original or not so they may be way out of spec but I need some ideas before I throw more money at it.
I have no signs of the wheel cylinders leaking either. Im thinking a bad master cylinder or drums too far out of spec. Any other ideas would be appreciated.
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1970 GMC truck ![]() 1988 Harley 1200 Sportster ![]() |
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#2 |
the boat guy
Join Date: Jul 2007
Location: springfield mo
Posts: 2,339
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Re: trouble shooting drum brakes
Sounds like they need to be adjusted.
Posted via Mobile Device
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67, swb, fleet, tach, throttle, 5.3, 4l60e, 3.73's, fuel cell, 5 lug, p.d.b., 4-6 drop. great little truck 66, stevens drag/ski 18' silouette, 350, 2.02 doublehump heads. comp extreme marine 278 cam, vette 7 fin valve covers, old polished edelbrock intake, velvetdrive, casale v-drive, adj cavitation plate. 28, model a rpu project, |
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#3 |
Registered User
Join Date: Apr 2000
Location: Bonne Terre, Mo
Posts: 3,005
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Re: trouble shooting drum brakes
Agreed. If the drums are true then adjust them out more. Also insure the drums are clean where they make contact with the shoes. Sometimes they shoes need to seat for the drums after replacement.
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'69 Chevy Long Fleet & '71 GMC Short Step & Project "ODD BALL" "You can wash a pig, soak it in most expensive perfume. In the end it is still just a pig." ODD BALL build thread http://67-72chevytrucks.com/vboard/s...d.php?t=478629" |
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#4 |
Registered User
Join Date: Jun 2009
Location: Arlington Texas
Posts: 602
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Re: trouble shooting drum brakes
They are adjusted. They feel better since I added the new hardware and adjusters but not good enough. Also this is something I have been dealing with since I got the truck in 2009.
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1970 GMC truck ![]() 1988 Harley 1200 Sportster ![]() |
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#5 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: trouble shooting drum brakes
Did you replace the m/c with one the same bore?
Do you have the brake rod that attaches to the pedal in the upper hole? |
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#6 |
Registered User
Join Date: Jun 2009
Location: Arlington Texas
Posts: 602
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Re: trouble shooting drum brakes
I have another MC laying around. I am going to swap them and see if it makes a difference.
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1970 GMC truck ![]() 1988 Harley 1200 Sportster ![]() |
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#7 |
Registered User
Join Date: Jan 2012
Location: Clarksville TN
Posts: 32
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Re: trouble shooting drum brakes
I Had alot of trouble with mine as well. Did you bleed the brakes in the sequence the books say. Plus what helped as well I made a bleeder bottle out a 1liter soda bottle and put some fluid in the bottle and a tube running from the bleeder into the fluid. It worked for me.
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#8 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,594
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Re: trouble shooting drum brakes
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#9 |
Registered User
Join Date: Jun 2009
Location: Arlington Texas
Posts: 602
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Re: trouble shooting drum brakes
Forgot to say I have a booster on it. All I did was swap masters on the booster.
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1970 GMC truck ![]() 1988 Harley 1200 Sportster ![]() |
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#10 |
Registered User
Join Date: Jun 2009
Location: Arlington Texas
Posts: 602
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Re: trouble shooting drum brakes
Also checked the brake rod. Its in the only hole in the brake pedal.
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1970 GMC truck ![]() 1988 Harley 1200 Sportster ![]() |
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#11 |
Registered User
Join Date: Sep 2012
Location: San Antonio, TX
Posts: 1,026
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Re: trouble shooting drum brakes
I am wondering about this too. My pedal seems to go to far and I am thinking the drums need to be adjusted more or brake pedal needs adjusting.
Posted via Mobile Device
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Jeff 1972 Cheyenne Super SWB 350, Auto, Bucket Seats w/Console, Tach, Factory A/C, P/S ,P/B, Tilt 1998 Chevy 1500 Ext Cab 5.7, Pewter w/blue interior |
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#12 |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,197
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Re: trouble shooting drum brakes
If the truck was like this when you bought it maybe it had the wrong master cylinder on it at that time. The drum/drum master cylinders are different than the disc/drum master cyls.
Excessive pedal travel is most usually caused by brake shoes not adjusted close enough to the drums. Even if the drums are worn past spec adjusting the shoes out to it will compensate for the extra travel. I adjust the shoes until the wheel stops turning to seat them then back off until the shoes just barely touch the drum.
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Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
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#13 | |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: trouble shooting drum brakes
Quote:
it is not a just boltup a new cylinder repair
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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 |
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#14 | |
Registered User
Join Date: Jun 2009
Location: Arlington Texas
Posts: 602
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Re: trouble shooting drum brakes
Quote:
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1970 GMC truck ![]() 1988 Harley 1200 Sportster ![]() |
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#15 |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,197
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Re: trouble shooting drum brakes
Well moving backward and hitting the brakes hard is supposed to ratchet them up but as we all know self adjusters don't always work. The surest method is remove a drum adjust the shoes out to where the drum just drags when pushed back on then install the wheel. Now turn the wheel by hand and listen for the dragging sound. With a tool make any further adjustment through the slot in the backing plate. Move onto the next wheel.
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Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
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#16 |
Registered User
Join Date: Dec 2012
Location: Altoona Iowa
Posts: 481
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Re: trouble shooting drum brakes
I am glad you mentioned your Booster. Pull your vac hose attached to your booster and look for fluid inside it. It sounds like your booster has a bad seal and is not performing well enough.
I had the same issue right after installing a new master, and bleeding them. |
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#17 |
Registered User
Join Date: Jun 2009
Location: Arlington Texas
Posts: 602
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Re: trouble shooting drum brakes
I should have mentioned I had this problem before I installed the booster.
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1970 GMC truck ![]() 1988 Harley 1200 Sportster ![]() |
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#18 |
Registered User
Join Date: Mar 2012
Location: New Orleans, La
Posts: 406
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Re: trouble shooting drum brakes
I doubt this is the culprit, but I've heard of MC's being tempermental if you don't bench bleed them. Apparently, they can even be next to impossible to completely bleed if not done on the bench first.
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It's not that I am apathetic, I just don't care. If your life is a joke, it appears death will be your punchline. |
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#19 |
Registered User
Join Date: Jun 2009
Location: Arlington Texas
Posts: 602
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Re: trouble shooting drum brakes
I bench bled it correctly. I may have time tomorrow to work on it after work so I will swap the masters then and see if that makes a difference.
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