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#1 |
Registered User
Join Date: Apr 2004
Location: Clanton, AL
Posts: 1,253
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Continuing the saga of disc brakes up front... I think the brakes are bled thoroughly. In fact, they won't release. What is wrong!?.
When I bleed the brakes at the MC, they get harder. When I bleed them at the wheels, they get all soft like there is lots of air in the lines. Either way, they don't stop the truck worth $%#t. I can't possibly lock up a single wheel, even though the pedal is hard. I even unhooked the brake booster b/c of how slow they are to come back up. They won't stop grabbing the wheel, yet they won't stop it either. I'm to the point of fixing my brakes with my SKS.
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85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! ![]() 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal! ![]() Last edited by grayw0lf; 08-18-2007 at 08:30 PM. |
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#2 |
Sleep-Deprived
Join Date: Sep 2002
Location: Tulsa, Oklahoma
Posts: 445
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Re: More brake troubles...
Are the rubber lines new? If they're old, they can deteriorate to the point of acting like a one way valve and lock the brakes.
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1971 K/10 Long Fleetside 350/350 - 6" Lift 1969 C/10 SWB 292 - Sold It |
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#3 |
Registered User
Join Date: Apr 2004
Location: Clanton, AL
Posts: 1,253
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Re: More brake troubles...
The front is all new 6 lug conversion, new rubber lines. I also bent new 3/16" lines from the MC to PV & the 3 way T up front, leaving 1/4" in the back.
The back lines were never a problem before. I'm at my wit's end here.
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85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! ![]() 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal! ![]() |
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#4 |
Registered User
Join Date: Apr 2004
Location: Clanton, AL
Posts: 1,253
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Re: More brake troubles...
Here's a pic to go along... tell me if you see anything
.
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85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! ![]() 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal! ![]() |
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#5 |
67-72 Addict!
Join Date: Feb 2002
Location: The TAX State!
Posts: 7,857
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Re: More brake troubles...
I recently did the disc conversion also and that prop valve in your pic looks like a 3/4 ton (not positive but it's different than mine) and the MC you have looks like a drum version but not 100% sure. Mine looks different in shape and mine has 2 clips to hold the cap on. I used a 71' prop valve off a 1/2 ton truck and a 71' MC. This is what mine look like.
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Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads Last edited by 70c10; 08-19-2007 at 01:07 AM. |
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#6 |
Registered User
Join Date: Mar 2004
Location: CA
Posts: 2,057
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Re: More brake troubles...
on my truck the lines are reversed from your pic, the front MChole goes to the rear PV hole, and the rear MC hole to the front PV hole
not sure if it matters, and im having brake probs of my own but maybe that will help |
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#7 | |
Sierra Grande Club
Join Date: Jan 2007
Location: New Mexico USA
Posts: 2,433
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Re: More brake troubles...
Quote:
s/t
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1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe. ![]() |
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#8 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: More brake troubles...
i'd think its a bit difficult to switch those 2lines since they're different sizes
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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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#9 |
Registered User
Join Date: Mar 2004
Location: CA
Posts: 2,057
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Re: More brake troubles...
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#10 |
Registered User
Join Date: Apr 2004
Location: Clanton, AL
Posts: 1,253
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Re: More brake troubles...
Here's the setup. The PV is apparently a 3/4 ton & came attached to a 3/4 ton MC. On the 3/4 ton MC, the lines were crossed back to front as the rear chamber was the larger for discs.
It is a 71 1/2 ton MC (large front chamber) & going front to front, back to back. Do I need to get a 1/2 PV? The output lines from the PV are front to front, back to back.
__________________
85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! ![]() 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal! ![]() |
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#11 |
Registered User
Join Date: Apr 2004
Location: Clanton, AL
Posts: 1,253
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Re: More brake troubles...
A little update. I think I resolved the brakes locking problem. The pushrod in the booster was adjusted too far out.
I'm still stuck wondering why my pedal is hard & I have no stopping power.
__________________
85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! ![]() 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal! ![]() |
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#12 |
Registered User
Join Date: Jun 2006
Location: Indiana
Posts: 4,859
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Re: More brake troubles...
Here's a "This happened to me" story. Short version.
Pulled engine -- rebuilt -- reinstalled. Maybe two months during the summer. After rebuild-- VERY hard brakes. After much fighting, bleeding, replacing M/C, PV, Vac Booster, Still Hard peddel. Started to pull the Vac Booster again, yanked out the check valve thingy and saw the problem. MUD DOBBER NEST IN MY CHECK VALVE! ![]() It's the little things that get ya.
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'70 GMC C1500 LWB Power disc brakes. WooHoo! Posi 6 Lug Dana 60 |
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#13 |
67-72 Addict!
Join Date: Feb 2002
Location: The TAX State!
Posts: 7,857
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Re: More brake troubles...
Just curious, where is the adjustment to the pushrod made?
__________________
Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads |
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#14 |
Registered User
Join Date: Apr 2004
Location: Clanton, AL
Posts: 1,253
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Re: More brake troubles...
There are 2 places, at the back of the pedal, which seems fine. The second, which I just changed is on the rod coming out of the power booster, going into the receiving end of the MC.
__________________
85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! ![]() 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal! ![]() |
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#15 |
To The Levy
Join Date: Jan 2007
Location: california
Posts: 391
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Re: More brake troubles...
not sure if you mentioned you had changed master, but I remember that if you stay with the same master you need to pull the residual check valve out of the port just under the tapered fitting under the line (I screwed a metal screw into it and pulled out with vise grips and wulla , pull out and discard the valve) I have done conversions on rear discs on other vehicles and using the same master was ok, but had to remove this check valve. I may have missed in your postings, that you already changed master to proper disc/drum combo, if so , sorry and disregard my post, good luck
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#16 |
Sleep-Deprived
Join Date: Sep 2002
Location: Tulsa, Oklahoma
Posts: 445
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Re: More brake troubles...
My "rebuilt" vacuum booster was bad and I had to stand on the brakes as hard as I could to brake and could not lock up the brakes for anything. Much worse than having drum brakes without vacuum assist. Well, I put a hand vacuum pump on the booster to check it and could not pull a vacuum. Tried another rebuild and it was a night and day difference.
Also look at anything that might obstruct the engine from pulling vacuum on the booster - hose, check valve or the engine condition. I checked the vacuum the engine was producing with the hand pump and showed 18-19 inches of mercury at idle.
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1971 K/10 Long Fleetside 350/350 - 6" Lift 1969 C/10 SWB 292 - Sold It Last edited by 69_hafton; 08-20-2007 at 09:08 PM. |
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