76 GMC k1500, have replaced calipers, drums.

GADMAN

MEMBER
1976 GMC TRUCK

76 gmc k1500, have replaced calipers, drums, master cyl & factory perportioning valve. Have no front brakes & rears lock up. After repeated checks it appears the perportioning valve is not centered? Is there a way to reset it? Other ideas? Could the lines in be swapped &

5 Replies

JDL

MECHANIC
16,098 POSTS

Did you bleed the brakes? The pin on the proportioning vavle should be held open during bleeding.

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Wednesday, October 17th, 2012 AT 4:54 PM

GADMAN

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3 POSTS

Yes, how do you hold the pin open? Have never heard of that before & can it be reset at this point?

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Wednesday, October 17th, 2012 AT 5:53 PM

JDL

MECHANIC
16,098 POSTS

You can have a helper hold it open. There is a tool for that, use to be a tool. I believe in the past, I have used a small vice-grip to hold the pin. It's been a while since I worked on that model year.

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Wednesday, October 17th, 2012 AT 6:43 PM

GADMAN

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3 POSTS

Is the pin in the center of the brass plug on the lft side? There is not enough to get ahold of. If I were to loosen the plug & pull it will it center the valve? They have been bled several times & all lines are fresh fluid & no apparent air in system, just no pressure to the fronts. Does the valve need pwr? I dont care about the light, hasnt worked in years.

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Wednesday, October 17th, 2012 AT 7:03 PM

JDL

MECHANIC
16,098 POSTS

It's been a while, I'd have to look at it. That little pin, you either push it in or pull it out. I can't remember? I tried looking up that valve on an inline partsbook, couldn't find it. I thought maybe looking at the valve would jog my memory.