All drums and no hope. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ChevyGearHeads · 01-08-2019, 06:21 PM

I have a '68 C10 with an all manual drum set-up. I have tore down and replaced every piece of the system (including two master cylinders) and I get some pressure but not for long and the pedal works its way to the floor. The only existing original part is the proportioning/combination valve/distribution block. I have tried to bleed this truck about 4 times for hours on end with the same bleak result. Any guidance would be great.

68Stepbed · 01-08-2019, 06:25 PM

Sounds like bad wheel cylinders.

demian5 · 01-08-2019, 06:28 PM

Quote:

Originally Posted by 68Stepbed

Sounds like bad wheel cylinders.

Sounds like you did miss something. List out what you replaced with something new.

68Gold/white · 01-08-2019, 06:32 PM

You need to make darn sure the brakes are adjusted. If in doubt adjust the shoes to where the drum/spindle or axle is tight, and barely turns. You can back the shoes off later....to operate vehicle...

Fill the M/cylinder, let each wheel gravity bleed, one wheel at a time, of course do both rears or both fronts together...THEN have someone help you pressure bleed the brakes...DO NOT LET THE MASTER CYLINDER RUN DRY!!! the master cylinder needs to be bench bled first...

I use 1/4" I.D. clear vinyl tubing, I loop it a foot or two above the bleeder screw, so I can wattch for fluid and/or bubbles...I use an empty 16 oz or larger plastic pop bottle to catch the excess fluid. I drill a hole just slightyl smaller than the OD of the hose, so the tubing stays in the bottle. and you need another small hole in the bottle cap for pressure relief...

ChevyGearHeads · 01-08-2019, 06:41 PM

-Master Cylinder (bench bled twice)
-Both 3/16th lines to the front.
-Both front hoses.
- All 4 wheel cylinders, shoes, springs, drums, self-adjusters
- 5 foot section of line going to the rear hose.
- Rear hose
- Both 3/16th lines going to the rear.

I seem to keep getting air in the system so I installed 4 speed bleeders.
The pedal will start to get firm and just go away.
I can hear the shoes hitting the drums..both front wheels you can hear the shoes dragging the drum very slightly. I never considered adjusting them?

**WorkinLonghorn** · 01-08-2019, 09:26 PM

Quote:

Originally Posted by 68Gold/white

You need to make darn sure the brakes are adjusted. If in doubt adjust the shoes to where the drum/spindle or axle is tight, and barely turns. You can back the shoes off later....to operate vehicle...

^^^^ This^^^^

burnin oil · 01-08-2019, 10:11 PM

The others are on the track. One more thing you may try is breaking loose the lines and reseating them. I have seen some where they didnt 100% line up and leaked. Reseating the line squarely and retightening solved the issue.

If you do need to replace the proportioning valve I would suggest digging through Summit Racing. They are one of the few places that really stock them and have many combinations/options available. I have an old Dodge 2500 that I fought the brakes on and replaced it all. Brakes were still crap and you never knew if it would stop. I ended up getting the proportioning valve for a 70s chevy and swapped it in. That truck stopped in half the distance as it did new! It is amazing how much fluid can actually bypass inside those things.

68Gold/white · 01-09-2019, 11:30 AM

Remove the 4 speed bleeders, and install the regular bleeders, then bleed brakes as in post 4, after adjusting shoes...

With shoes that are at least a little out of adjustment, the pedal can feel exactly like what you have...

The pistons in the wheel cylinder move very little to make the shoes contact the drums. It's a fine line deal. I am sure you are very close to making the deal done!!!

Are the drums new??? or in spec??? If they are out of spec, it will contribute to the problem...slightly...

I hate drum brakes, especially on the front!!!

ChevyGearHeads · 01-09-2019, 11:38 AM

Re: 68Gold/White

The drums are brand new and I'm assuming in spec.
I haven't attempted to adjust them because I figured they would self adjust?
The shoes just barely contact the drum with the brakes disengaged.

ChevyGearHeads · 01-09-2019, 11:51 AM

Can the distribution block be causing an issue?
they seem to be surrounded by mystery if its not a disc/drum setup.

*randy500* · 01-09-2019, 01:04 PM

Standard brake procedure....adjust the shoes! You will never get a good pedal until it’s done properly. It’s loose shoes you can get a pedal for a short while and it will bleed down to no pedal.

Your problem is not the distribution block.

RustyBucket · 01-09-2019, 02:59 PM

MAYBE your new master cylinder is enough different that the push rod is a little short.

cypressbog · 01-09-2019, 03:11 PM

Make sure the shoes are adjusted then bleed brakes. First RR then LR, then RF and finally LF.

rpmerf · 01-09-2019, 03:28 PM

Quote:

Originally Posted by ChevyGearHeads

I haven't attempted to adjust them because I figured they would self adjust?

The brakes self adjust when you firmly apply the brakes while the vehicle is moving backwards.

After checking adjustment, I would check over every junction and wheel cylinder to look for any signs of leakage. Check rubber lines also.

I've had issues with air being sucked around the bleeders while attempting to bleed. You can either wrap the bleeders in teflon tape, or:
Start pressing the pedal
Open the bleeder
Press the pedal down to about 75%
Close the bleeder
Release the pedal

01-08-2019, 06:21 PM	#1
ChevyGearHeads Registered User Join Date: Jul 2010 Location: Anne Arundel County, MD Posts: 108	All drums and no hope. I have a '68 C10 with an all manual drum set-up. I have tore down and replaced every piece of the system (including two master cylinders) and I get some pressure but not for long and the pedal works its way to the floor. The only existing original part is the proportioning/combination valve/distribution block. I have tried to bleed this truck about 4 times for hours on end with the same bleak result. Any guidance would be great. __________________ Paul '68 C10 327/TH350 LWB

01-08-2019, 06:25 PM	#2
68Stepbed Registered User Join Date: Mar 2005 Location: 10-Uh-See Posts: 5,609	Re: All drums and no hope. Sounds like bad wheel cylinders. __________________ Matt 68 C10 stepside, LS1/700R4, TCI Engineering suspension system

01-08-2019, 06:32 PM	#4
68Gold/white Registered User Join Date: Sep 2011 Location: Ark City, Kansas Posts: 3,409	Re: All drums and no hope. You need to make darn sure the brakes are adjusted. If in doubt adjust the shoes to where the drum/spindle or axle is tight, and barely turns. You can back the shoes off later....to operate vehicle... Fill the M/cylinder, let each wheel gravity bleed, one wheel at a time, of course do both rears or both fronts together...THEN have someone help you pressure bleed the brakes...DO NOT LET THE MASTER CYLINDER RUN DRY!!! the master cylinder needs to be bench bled first... I use 1/4" I.D. clear vinyl tubing, I loop it a foot or two above the bleeder screw, so I can wattch for fluid and/or bubbles...I use an empty 16 oz or larger plastic pop bottle to catch the excess fluid. I drill a hole just slightyl smaller than the OD of the hose, so the tubing stays in the bottle. and you need another small hole in the bottle cap for pressure relief...

01-08-2019, 06:41 PM	#5
ChevyGearHeads Registered User Join Date: Jul 2010 Location: Anne Arundel County, MD Posts: 108	Re: All drums and no hope. -Master Cylinder (bench bled twice) -Both 3/16th lines to the front. -Both front hoses. - All 4 wheel cylinders, shoes, springs, drums, self-adjusters - 5 foot section of line going to the rear hose. - Rear hose - Both 3/16th lines going to the rear. I seem to keep getting air in the system so I installed 4 speed bleeders. The pedal will start to get firm and just go away. I can hear the shoes hitting the drums..both front wheels you can hear the shoes dragging the drum very slightly. I never considered adjusting them? __________________ Paul '68 C10 327/TH350 LWB

01-08-2019, 10:11 PM	#7
burnin oil Registered User Join Date: Jan 2013 Location: Eastern TN Posts: 1,921	Re: All drums and no hope. The others are on the track. One more thing you may try is breaking loose the lines and reseating them. I have seen some where they didnt 100% line up and leaked. Reseating the line squarely and retightening solved the issue. If you do need to replace the proportioning valve I would suggest digging through Summit Racing. They are one of the few places that really stock them and have many combinations/options available. I have an old Dodge 2500 that I fought the brakes on and replaced it all. Brakes were still crap and you never knew if it would stop. I ended up getting the proportioning valve for a 70s chevy and swapped it in. That truck stopped in half the distance as it did new! It is amazing how much fluid can actually bypass inside those things.

01-09-2019, 11:30 AM	#8
68Gold/white Registered User Join Date: Sep 2011 Location: Ark City, Kansas Posts: 3,409	Re: All drums and no hope. Remove the 4 speed bleeders, and install the regular bleeders, then bleed brakes as in post 4, after adjusting shoes... With shoes that are at least a little out of adjustment, the pedal can feel exactly like what you have... The pistons in the wheel cylinder move very little to make the shoes contact the drums. It's a fine line deal. I am sure you are very close to making the deal done!!! Are the drums new??? or in spec??? If they are out of spec, it will contribute to the problem...slightly... I hate drum brakes, especially on the front!!!

01-09-2019, 11:38 AM	#9
ChevyGearHeads Registered User Join Date: Jul 2010 Location: Anne Arundel County, MD Posts: 108	Re: All drums and no hope. Re: 68Gold/White The drums are brand new and I'm assuming in spec. I haven't attempted to adjust them because I figured they would self adjust? The shoes just barely contact the drum with the brakes disengaged. __________________ Paul '68 C10 327/TH350 LWB

01-09-2019, 11:51 AM	#10
ChevyGearHeads Registered User Join Date: Jul 2010 Location: Anne Arundel County, MD Posts: 108	Re: All drums and no hope. Can the distribution block be causing an issue? they seem to be surrounded by mystery if its not a disc/drum setup. __________________ Paul '68 C10 327/TH350 LWB

01-09-2019, 01:04 PM	#11
randy500 Account Suspended Join Date: Jul 2016 Location: Tacoma, WA Posts: 6,873	Re: All drums and no hope. Standard brake procedure....adjust the shoes! You will never get a good pedal until it’s done properly. It’s loose shoes you can get a pedal for a short while and it will bleed down to no pedal. Your problem is not the distribution block.

01-09-2019, 02:59 PM	#12
RustyBucket Registered User Join Date: Jul 2009 Location: Space Coast, Fl. Posts: 1,055	Re: All drums and no hope. MAYBE your new master cylinder is enough different that the push rod is a little short. __________________ Dad always said, "Son, WISH IN ONE HAND, and ......." -------------------------------------- -------------------------------------- Current toy trucks: '71 GMC 1500 SUPER CUSTOM short/step, orig. dk. blue, 350/700r, ps,pb, A/C '72 Blazer 2wd, ochre & white, 454, tremecTKO 500 5spd. ps, pb, A/C, tilt Last 10yrs of hobby vehicles, had a FEW more in the 50yrs. before these: '66 Plymouth Belvedere City of Miami cop car clone. '70 Nova 406"sb, 13.5-1, solid roller, Brodix, p.glide/t.brake, back halved, 9" Ford, spool 4.88, cage,ladder bar/coilover, 10.5 tire....... SOLD!! '67 C10 short/step side mount spare -- SOLD!! '72 Jimmy 2wd, 350/350, ps, pb, fun driver, lots of bondo & a shiny red paint job..... SOLD!! '69 Nova 350, 4spd, A/C, ps, p.b, ...SOLD!!

01-09-2019, 03:11 PM	#13
cypressbog Go Pack Go! Join Date: Nov 2005 Location: Green Bay Posts: 2,669	Re: All drums and no hope. Make sure the shoes are adjusted then bleed brakes. First RR then LR, then RF and finally LF.



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