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Topic: 1977 Proportioning Valve

in Forum: C3 Engines, Driveline and Handling


1977 Proportioning Valve

Posted: 11/12/07 5:41pm Message 11 of 12
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Badin Lake, NC - USA
Joined: 4/21/2004
Posts: 101
Vette(s): 1979 Red L-48 Corvette with Doeskin interior, 3-speed automatic, 3.55 rear; 1986 L-98 Coupe, 4+3 Manual - Satin Black and Purple (SCCA TT/Hillclimb Car); 1993 White LT-1 Coupe, Black Interior, 6-speed
yup - replaced the rubber with SS. The primary hard lines were in good shape, but I may replace with SS just for appearance - but the steel ones are still good.  It really helped the feel to go with SS flex lines instead of rubber and it gives you a lot of confidence not having 30 year old rubber holding your brake system together.


C3: 1979 Corvette Coupe, Auto, L-48, Red/Doeskin (my wife's fave);
C4s: 1986 C4 coupe (SCCA road race car), satin black, 4+3, Z51 package, L-98;  & 1993 C4 coupe, white, 6-speed, LT-1.
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1977 Proportioning Valve

Posted: 11/12/07 6:39pm Message 12 of 12
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
The filter that was in the vacuum line does not affect the brake operation at all if it's working properly.
 
It is there as a moisture filter.   In the 70's GM found moisture was getting through the vacuum line and into the power booster.   The moisture would freeze on a cold day, and the driver would come out and step on the pedal and the pedal would not move.   After the car ran awhile, the heat from the engine would warm the booster, melt the ice, and the brakes would work again.
 
I installed a LOT of them as a mfg recall.   Granted, if they went bad or clogged it really made the brake operation suffer.
 
The rough point for bleeding si the line to the right rear, where it crosses the back of the frame.    The line goes up, and back down, and creates an air pocket.   It can make you nuts getting it out.   Proper bleeding or a power bleeder will cure the problem.    Follow Joels procedure.
 
If you do pump the brakes, pump gently.  A solid thump causes the air bubbles to break up into tiny bubbles, and then they won't come out until they recollect and form larger bubbles again.
kstyer2007-11-12 18:39:56


in Forum: C3 Engines, Driveline and Handling


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