brakes

[meathead95]

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?

[Richard H.]

Does it have good vacuum and does it have reset on the proportional valve?

[airdale94]

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.

[meathead95]

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.

[Richard H.]

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

[va_tlc]

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

[meathead95]

adjusters are fine and drums are like brand new. ill try the prop valve trick

[pharcydekm]

IMO needs bled, vacuum to the booster is low, or the booster is bad. Possibly bad master that has happened to me twice.

[Huck]

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.

[jhow66]

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

[meathead95]

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.

[old Chevy guy]

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!

[meathead95]

they are on right lol...........

[EAST SIDE LOW LIFE]

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.

[Geno]

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.

[meathead95]

Originally Posted by Geno

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.

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

[Rokcrln]

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.

[meathead95]

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

[meathead95]

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?