Brake bleeding question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

minibike · 01-23-2003, 11:50 PM

When bleeding brakes, what needs to be done to the proportioning valve? There is a little pin in the end of it that I have heard has to be pushed in or something...is this true? I have 71 discs/master cylinder/proportioning valve.

'72 Shorty · 01-24-2003, 12:28 AM

I've never done anything special and it always works fine. Now, if I could just get the rears to stop locking...(90 wt in drums)

-Jesse

Low68 · 01-24-2003, 12:33 AM

I have never heard anything about that. You are talking about the stock type (non adjustable) right? If it is stock, I don't think you have to do anything special.
Low68

MR. GOODWRENCH · 01-24-2003, 01:43 AM

you do nothing to the proportioning valve,it is factory preset,make sure the matercylinder is full and the lid clipped on,get someone to pump the brake petal 6 or 7 times,and on the last pump hold the petal to the floor,someone else needs to loosen the bleeder screw on the caliper and let the air out,but do not let off the brake petal until the bleeder screw is tightened or it will suck in air,do this until you get a steady stream of brake fliud out of the bleeder screw,do the same on the back wheelcylinders,and your done,it may sound hard from what I have wrote here,but it is a very easy job to do.

Hooter · 01-24-2003, 03:17 AM

I never had to do anything with the proportioning valev when I bleed brakes. I know what you are talking about my factory service manual shows the same thing for my Monte

minibike · 01-24-2003, 09:12 AM

Thanks guys...I have all new lines, wheel cylinders, calipers and master cylinder. I have been getting a lot of air out of it, but I guess it is to be expected. I'll just keep bleeding...

cacauba · 01-24-2003, 12:20 PM

go to the parts store, i got mine from NAPA. there called speedbleeders. they are about 10.00 for a pair and they have a check valve in them. they replace the bleeder screw in the wheel cylinder. they work awsome for one man operations.
chris

SWINGSAX68 · 01-24-2003, 01:12 PM

It is not too necasary, but did you bench bleed the master cylinder????I did and it helped a bit!! But when I did that I had very bad dirty brake lines and clogged front hoses so I never got to bleed them correctly my self.

Stout72 · 01-24-2003, 03:47 PM

Bench bleeding the master cylinder is real important. It saves you from continuing to pump air thru the system. I had a problem with mine, I didn't bench bleed it enough so I just couldn't get rid of the air. Bench bled it again and I finally got straight fluid.

As for the prop valve, the book says you have to depress the pin on the end of it to properly bleed the back brakes, and to bleed the back brakes first. Mine wouldn't depress, so I just bled them in order from furthest to closest to the master cyl. Seemed to work for me.

Good luck!

Hey, this is my 100th post! Finally!

minibike · 01-24-2003, 08:12 PM

Thanks guys...in my haste, I did not bench bleed the master cylinder. Pretty stupid. It's time to slow down and take a deep breath. This is the most important system on the truck, and I rushed it...

Oborny71 · 01-25-2003, 12:24 PM

Yeah like mentioned before, make sure you start with the farthest wheel away from the master cylinder ( the right rear) and work to the closest ( the left front)

01-23-2003, 11:50 PM	#1
minibike Registered User Join Date: Jun 2002 Location: Lafayette, LA Posts: 500	Brake bleeding question When bleeding brakes, what needs to be done to the proportioning valve? There is a little pin in the end of it that I have heard has to be pushed in or something...is this true? I have 71 discs/master cylinder/proportioning valve. __________________ 69 SWB LT1/4L60E www.classicplace.com

01-24-2003, 12:28 AM	#2
'72 Shorty I finally got an avatar Join Date: Jan 2003 Location: Cheney, WA Posts: 180	I've never done anything special and it always works fine. Now, if I could just get the rears to stop locking...(90 wt in drums) -Jesse __________________ -72 C-10 short step (straight line only) 12.922/102.28 -69 C-20 on Propane (DD) -69 C-10 -56 Mack B-753LS (tow rig) -94 Chev K2500 Short Ex-Cab -89 Isuzu Trooper...Kinda -03 Kawasaki KFX-400 -05 Suzuki DRZ-400S

01-24-2003, 12:33 AM	#3
Low68 Registered User Join Date: May 2001 Location: Arizona Posts: 758	I have never heard anything about that. You are talking about the stock type (non adjustable) right? If it is stock, I don't think you have to do anything special. Low68 __________________ Build Thread

01-24-2003, 01:43 AM	#4
MR. GOODWRENCH Registered User Join Date: Jan 2003 Location: Maryville,TN Posts: 402	you do nothing to the proportioning valve,it is factory preset,make sure the matercylinder is full and the lid clipped on,get someone to pump the brake petal 6 or 7 times,and on the last pump hold the petal to the floor,someone else needs to loosen the bleeder screw on the caliper and let the air out,but do not let off the brake petal until the bleeder screw is tightened or it will suck in air,do this until you get a steady stream of brake fliud out of the bleeder screw,do the same on the back wheelcylinders,and your done,it may sound hard from what I have wrote here,but it is a very easy job to do. __________________ 68 CST SWB,full off frame restoration,72 GMC Sierra Grande SWB,72 Cheyenne 30 long wheelbase flatbed,2000 4door Chevy Dually bought new,2002 SS Camaro with 600 miles,bought it to put up,72 Monte Carlo,it was my first car,69 Impala with 50,000 miles,it was my dads,89 Dodge diseal 3/4 ton 4 wheel drive,my dad bought it new,68 Camaro RS dragcar,97 United Transporters 25 foot enclosed trailer,58 Oliver Super 77 Diseal,my grandfather bought new fully restored,55 Oliver Super 66 Diseal my uncle bought new,49 Oliver Rowcrop 88,51 Farmall H,51 Farmall Super C,81 Ford 3600,89 Ford 6610,49 Allis Chalmers WD45,81 Allis Chalmers 7060 my dad bought new,Allis Chalmers 175.

01-24-2003, 03:17 AM	#5
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	I never had to do anything with the proportioning valev when I bleed brakes. I know what you are talking about my factory service manual shows the same thing for my Monte __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

01-24-2003, 09:12 AM	#6
minibike Registered User Join Date: Jun 2002 Location: Lafayette, LA Posts: 500	Thanks guys...I have all new lines, wheel cylinders, calipers and master cylinder. I have been getting a lot of air out of it, but I guess it is to be expected. I'll just keep bleeding... __________________ 69 SWB LT1/4L60E www.classicplace.com

01-24-2003, 12:20 PM	#7
cacauba STL-KKN Join Date: Aug 2001 Location: Tomball, Tx Posts: 182	go to the parts store, i got mine from NAPA. there called speedbleeders. they are about 10.00 for a pair and they have a check valve in them. they replace the bleeder screw in the wheel cylinder. they work awsome for one man operations. chris __________________ 1969 C10 350/POWERGLIDE 1991 1500 EXTCAB 350 Formally: collegeK5er

01-24-2003, 01:12 PM	#8
SWINGSAX68 Now the others dig........ Join Date: May 2002 Location: San Antonio, TX Posts: 1,520	It is not too necasary, but did you bench bleed the master cylinder????I did and it helped a bit!! But when I did that I had very bad dirty brake lines and clogged front hoses so I never got to bleed them correctly my self. __________________ 68 Chevy C10 Stepside Black Primer 78 GMC Longbed White 09 Chevy Silverado Shortbed Granite Blue *LOOKING FOR A 67 4 DOOR IMPALA!!!Just like Sam and Dean Winchester!! 'Cause Mustangs are for p^#$ and you can fit a body in the trunk of a 67 Impala* MEMBER OF THE DRUM BRAKE CLUB Bachelor of Music in Jazz Studies Texas State University-San Marcos, TX Certified Music Educator I hope Mom is up there watching and being my Guardian Angel "I've got a fever.....and the only prescription.....IS MORE COW BELL" -The Legendary: Bruce Dickenson "F#$@ 'em up!!!!!!" -The Legendary: Rogelio Escobar TRUCKY LINKS** http://67-72chevytrucks.com/vboard/s...d.php?t=457750 http://67-72chevytrucks.com/vboard/s...d.php?t=461184 http://67-72chevytrucks.com/vboard/s...d.php?t=472848 http://67-72chevytrucks.com/vboard/s...d.php?t=417541 http://67-72chevytrucks.com/vboard/s...d.php?t=477788

01-24-2003, 03:47 PM	#9
Stout72 Not my good side. Join Date: Mar 2002 Location: Fairfield, California Posts: 222	Bench bleeding the master cylinder is real important. It saves you from continuing to pump air thru the system. I had a problem with mine, I didn't bench bleed it enough so I just couldn't get rid of the air. Bench bled it again and I finally got straight fluid. As for the prop valve, the book says you have to depress the pin on the end of it to properly bleed the back brakes, and to bleed the back brakes first. Mine wouldn't depress, so I just bled them in order from furthest to closest to the master cyl. Seemed to work for me. Good luck! Hey, this is my 100th post! Finally! __________________ 72 Chevy K20 Custom Camper, 350/350, 4" lift, dual shock suspension front & rear. Daily driver and a work in progress. 00 Suburban LT 90 Camaro RS 79 Yamaha XS1100 Special (Ol' Reliable)

01-24-2003, 08:12 PM	#10
minibike Registered User Join Date: Jun 2002 Location: Lafayette, LA Posts: 500	Thanks guys...in my haste, I did not bench bleed the master cylinder. Pretty stupid. It's time to slow down and take a deep breath. This is the most important system on the truck, and I rushed it... __________________ 69 SWB LT1/4L60E www.classicplace.com

01-25-2003, 12:24 PM	#11
Oborny71 Registered User Join Date: Apr 2001 Location: Lincoln, Nebraska Posts: 587	Yeah like mentioned before, make sure you start with the farthest wheel away from the master cylinder ( the right rear) and work to the closest ( the left front) __________________ 67 Chevy SWB - goal of a 1,000 hp weekend cruiser



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