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#1 |
computer illiterate
Join Date: Jan 2001
Location: Des Moines, IA
Posts: 6,446
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brakes
i am kinda stumped here i put 72 axles in my 70 k20. i rebuilt wheel cylinders and installed new shoes on the rear and i replaced the calipers and pads on the front. i also replaced the brake hoses with braided stainless ones from inline tube as well as a new booster and master cylinder but the damn thibg still wont stop very well you have to reall mash the ppedal like it has manual brakes and it still doesnt stop very well and the brake light is on. does anyone have any ideas?
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72 2wd blazer 72 swb 4x4 |
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#2 |
Spanked once
![]() Join Date: Oct 2006
Location: Intheshop, Indiana
Posts: 969
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Re: brakes
Does it have good vacuum and does it have reset on the proportional valve?
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#3 |
Registered User
Join Date: Jan 2007
Location: Topeka,KS
Posts: 778
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Re: brakes
If the brake light is on they probably need bled. You have to bench bleed a new master cyl. Then bleed all the brakes at the wheel.
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#4 |
computer illiterate
Join Date: Jan 2001
Location: Des Moines, IA
Posts: 6,446
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Re: brakes
yes it has good vacuum. what do you mean reset on the prop valve? i figure that thing may be my problem.
no they dont need bled i did that 3 times to make sure. and yes i bench bled the mc.
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72 2wd blazer 72 swb 4x4 |
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#5 |
Spanked once
![]() Join Date: Oct 2006
Location: Intheshop, Indiana
Posts: 969
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Re: brakes
On the front of the proportioning valve there is a black button , either clamp it or get help to hold it in while you depress the pedal slowly and the let off easily then let off the button.
I ask about the vacuum because the vac check can or could be backwards or clogged or history . HTH |
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#6 |
Registered User
Join Date: Nov 2005
Location: VIRGINIA
Posts: 905
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Re: brakes
check your adjusters on the back>?? make sure there not all the way out, if so u may need drums? i had that problem but mines all drums just waiting on the new ones
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1969 rs 1966fastback 1969swbc/10 2006gt 1972swb4x4 |
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#7 |
computer illiterate
Join Date: Jan 2001
Location: Des Moines, IA
Posts: 6,446
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Re: brakes
adjusters are fine and drums are like brand new. ill try the prop valve trick
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72 2wd blazer 72 swb 4x4 |
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#8 |
Registered User
Join Date: May 2003
Location: Englewood, CO
Posts: 146
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Re: brakes
IMO needs bled, vacuum to the booster is low, or the booster is bad. Possibly bad master that has happened to me twice.
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#9 |
Senior Member
Join Date: Jun 2001
Location: Shelbyville, KY
Posts: 3,269
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Re: brakes
ACcording to the factory manual, you are supposed to have a special tool that holds the proportioning valve pin "IN" when you bleed the brakes. You can probably use a large C clamp. I have also discussed this with a very experienced mechanic that says his best results is by holding the pin "out" verses pushing it in. Either way---if the proportioning valve is not functioning correctly or positioning it's piston in the wrong place, you can't get proper fluid flow against the front caliper pistons or the rear wheel cylinder pistons. That will give you that hard pedal with little to no braking.
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#10 |
Registered User
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
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Re: brakes
If brake light is on, one side of brakes are not working. See if this will help:
http://www.classicperform.com/TechBo...t.htm#testprop
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56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer |
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#11 |
computer illiterate
Join Date: Jan 2001
Location: Des Moines, IA
Posts: 6,446
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Re: brakes
i think you hit it right on huck my rear brakes when being bled squirt the fluid out pretty well. but the front ones do not. so i am going to use the link jhow posted on trying to reset the prop valve and see if it works. if not ill just buy a new one.
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72 2wd blazer 72 swb 4x4 |
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#12 |
Registered User
![]() Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 1,176
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Re: brakes
This may sound stupid and Im not sure you could mak this mistake on a truck but many years ago I did a disk brake conversion on my 69 camaro and put the new calipers on the wrong sides the bleeders were down instead of up and you could bleed it all day and it still wouldnt work for crap. sounds dumb but it bolted right on like it belonged that way. I only figured it out after talking to an older chevy guy!
Last edited by old Chevy guy; 04-27-2007 at 01:09 PM. Reason: misspelled |
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#13 |
computer illiterate
Join Date: Jan 2001
Location: Des Moines, IA
Posts: 6,446
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Re: brakes
they are on right lol...........
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72 2wd blazer 72 swb 4x4 |
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#14 |
Senior Member
Join Date: Mar 2007
Location: VANCOUVER ISLAND, B.C., Canada
Posts: 1,602
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Re: brakes
With vice grip's go from one brake rubber line @ each wheel. Squeeze it off until you have pressure @ the pedal. Now you will have found the brake that is causing you the problem. I did this on a 67 BB Vette and found that the s/s caliper that had been rebuilt had some crap in the fluid port I believe that is what it is called and it was not allowing enough fluid through and as a result sponge pedal. Took the caliper a part inspested and cleaned it, reinstalled & went cruzin.
esll. This is why I don't like s/s line here as they look good but who want's to do the above to there lines once they are running s/s. esll. ![]()
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Tomorrow is for doing today's stuff. ![]() ************************************* This truck has just the right amount of energy for me! ![]() Author: Warren Lake .... (member) Last edited by EAST SIDE LOW LIFE; 04-27-2007 at 10:12 PM. |
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#15 |
Registered User
Join Date: Mar 2005
Location: San Bernardino, CA
Posts: 57
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Re: brakes
Put on a good pair of work boots and by opening the door you can assist with your feet. Also having a friend with an old beater in front of you can help.
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#16 |
computer illiterate
Join Date: Jan 2001
Location: Des Moines, IA
Posts: 6,446
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Re: brakes
lol thats funny. my pedal isnt spongy it just feels like manual brakes that dont work very well i think it is the prop valve when i bleed the rear brakes it squirts fluid out the bleeders pretty good but when i bleed the front it just rolls out of the bleeder im going to try and reset it today and if that doesnt work ill order a new one
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72 2wd blazer 72 swb 4x4 |
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#17 |
Senior Member
Join Date: Jul 2005
Location: Winters Ca. 95694
Posts: 4,843
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Re: brakes
Have you checked to make sure your MC push rod is adjusted right? It should have about a 3/32 gap bafore making contact with the bore cap. Also have you tried running the engine then after you turn it off pull out the one way vac valve from the booster to make sure it is holding psi. I agree your light is on because the PV is not centered but you should still have an assited pedal just with out much action but you said it feels like MB not PB and that tells me their is another problem.
For checking Vac in the booster do what I said above. For checking push rod depth in the MC just loosen the two nuts holding the MC in place and it should stay in place. If it has psi against it and pushes out a bit then your rod needs to be adjusted in untill it just makes contact then turn it in another few turns. Hope this helps, I know how frustrating brakes can be but their are only so many possible things to go wronge. Your truck was power brakes to start with right or did you just convert it over? Kevin LFD Inc. |
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#18 |
computer illiterate
Join Date: Jan 2001
Location: Des Moines, IA
Posts: 6,446
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Re: brakes
i have already checked the push rod length and it is correct. the truck was power brakes before. i havent checked the booster to see if it is holding psi yet. i will do that tomorrow
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72 2wd blazer 72 swb 4x4 |
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#19 |
computer illiterate
Join Date: Jan 2001
Location: Des Moines, IA
Posts: 6,446
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Re: brakes
ok here is where i am at. i took the prop valve off of my 2wd blazer because i know it is good. i put it on the truck and bled the brakes and the fluid in the rear bleeders was great. the fluid in the front was just shy of fair. so i get in still no brake light on yet. so i pull out of the garage and they feel better but still i cannot pull my tractor like this. so i drive down the road 1/2 a mile and back and ill be damned the brake light comes back on. so now i know the prop valve is good maybe the pushrod coming out of the booster needs to be lengthened to get more pressure on the front calipers? what do yah think?
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72 2wd blazer 72 swb 4x4 |
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