Was reading a post about brake problems??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sam's 72 · 05-17-2003, 12:15 AM

I didn't want to steal some one else post so I started this one, I redid all my brakes on my 72, every thing new! When I benched bled the master cylinder, after I was done, and while it was still in the vice, I hooked up the propotionate valve to it, then I benched bled the master cylinder and the propotionate valve together. Was this a good thing to do or not? My brake are really stiff like the power booster is not working, but it is new also. I seen on another post about clamping the reset button on the valve then hitting the brakes hard. Do you think it could be the valve makeing the brakes stiff? My truck will not lock up the brakes, no matter how hard you hit them. But it stops it good, when you have to get on the brakes hard, and it comes to a stop, there is only about an 1/8" to 1/4" of peddal left. And when I said I replaced everything, the only thing that I did not replace was the brake pedal, every thing else has been replaced. This has been bothering me for a while now. Don't have a clue on what to check, or hell it all might be right, but it just don't seem right. When I drive my other truck, as soon as I touch the brakes, I can feel them start to grab, but then again, this truck is a 97'. So do I have a problem, or is this how it is supose to be? If I have a problem, what do I check out?
Help me out guys.
Sam

73stepside · 05-17-2003, 12:34 AM

sounds like you still have air in your brake lines. might try bleeding them again

sam's 72 · 05-17-2003, 12:54 AM

73,
I have all the air out, I have bled these brakes over and over again, when I bleed them, it is all liquid not even bubbles!
But, just for grins, I will do it again and see what happens, it make me think I might have done something wrong when I bench blde the propotionate valve, I am not sure if you are suppose to do this or not?
Sam

Blue68 · 05-17-2003, 12:59 AM

The fact that they don't lock up leads me to agree that there is air in the system. Also, make sure the brake lines are not close to the exhaust, it will boil the fluid and you won't have brakes there as well.

jimfulco · 05-17-2003, 04:52 AM

Sometimes it takes a while for the air to collect in the calipers & wheel cylinders.

Blue Beard · 05-17-2003, 08:17 AM

Had my brake line on the right side touching the exhaust.............real bad situation.........

Gordo · 05-17-2003, 09:47 AM

Usually air in the lines gives you a low "spongy" peddle. A low hard peddle would tell me it needs a brake shoe adjustment (in your case the rear only) and/or improper brake linkage/adjustment (push pin) and/or insuffient vaccum supply to the booster. Pull the vaccum supply hose that feeding the booster off at the engine while the engine is running, it should stall or damn near stall the engine if you have a good vaccum. A power brake system with out the power booster working properly, it would be very difficult to lock up the brakes even with the rest of the system in good working order.

05-17-2003, 12:15 AM	#1
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	Was reading a post about brake problems??? I didn't want to steal some one else post so I started this one, I redid all my brakes on my 72, every thing new! When I benched bled the master cylinder, after I was done, and while it was still in the vice, I hooked up the propotionate valve to it, then I benched bled the master cylinder and the propotionate valve together. Was this a good thing to do or not? My brake are really stiff like the power booster is not working, but it is new also. I seen on another post about clamping the reset button on the valve then hitting the brakes hard. Do you think it could be the valve makeing the brakes stiff? My truck will not lock up the brakes, no matter how hard you hit them. But it stops it good, when you have to get on the brakes hard, and it comes to a stop, there is only about an 1/8" to 1/4" of peddal left. And when I said I replaced everything, the only thing that I did not replace was the brake pedal, every thing else has been replaced. This has been bothering me for a while now. Don't have a clue on what to check, or hell it all might be right, but it just don't seem right. When I drive my other truck, as soon as I touch the brakes, I can feel them start to grab, but then again, this truck is a 97'. So do I have a problem, or is this how it is supose to be? If I have a problem, what do I check out? Help me out guys. Sam __________________ 72 LWB chevy truck. Pasadena, Texas

05-17-2003, 12:34 AM	#2
73stepside Registered User Join Date: Feb 2002 Location: Moore OK 73160 Posts: 974	sounds like you still have air in your brake lines. might try bleeding them again __________________ 04 GMC Sierra RCSS 70 CST LWB 04 HD Sportster 1200 Custom

05-17-2003, 12:54 AM	#3
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	73, I have all the air out, I have bled these brakes over and over again, when I bleed them, it is all liquid not even bubbles! But, just for grins, I will do it again and see what happens, it make me think I might have done something wrong when I bench blde the propotionate valve, I am not sure if you are suppose to do this or not? Sam __________________ 72 LWB chevy truck. Pasadena, Texas

05-17-2003, 12:59 AM	#4
Blue68 Registered User Join Date: Apr 2000 Location: Frisco, Tx, USA Posts: 606	The fact that they don't lock up leads me to agree that there is air in the system. Also, make sure the brake lines are not close to the exhaust, it will boil the fluid and you won't have brakes there as well. __________________ http://home.comcast.net/~r.landrum/w...tos.html-.html '68 C-10 LWB, '98 Z-71 350 w/accessories (Serpentine), Edelbrock Performer, Edelbrock 1405 (600cfm) carb, GM HEI, CompCam Extreme 4x4 roller cam, Thorley Headers, Carter Electric Fuel Pump, Vintage Air, 700r4, 3.73, disc brakes and power steering upgrades.

05-17-2003, 08:17 AM	#6
Blue Beard Registered User Join Date: Jan 2003 Location: Washington State Posts: 8,831	Had my brake line on the right side touching the exhaust.............real bad situation......... __________________ 1970 Chev CST 2003 Harley Fatboy 1975 Chevrolet Step Van 1956 Chev Bel Air 1977 Blazer 2WD For Sale $3000.00 1978 Blazer 2WD For Sale $7000.00 1978 Silverado 2005 Monte Carlo

05-17-2003, 04:52 AM	#5
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	Sometimes it takes a while for the air to collect in the calipers & wheel cylinders.

05-17-2003, 09:47 AM	#7
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	Usually air in the lines gives you a low "spongy" peddle. A low hard peddle would tell me it needs a brake shoe adjustment (in your case the rear only) and/or improper brake linkage/adjustment (push pin) and/or insuffient vaccum supply to the booster. Pull the vaccum supply hose that feeding the booster off at the engine while the engine is running, it should stall or damn near stall the engine if you have a good vaccum. A power brake system with out the power booster working properly, it would be very difficult to lock up the brakes even with the rest of the system in good working order. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist. Last edited by Gordo; 05-17-2003 at 09:50 AM.



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