For Firebirds Trans Ams & Camaro & most all GM Front Disc /drum rear cars from 69-85, Camaro, Firebird, GTO, Chevelle, Nova.. Carby (not for 80-81 Turbo).. with drums on the rear end.. fits all the engine sizes.

• This is NOT for the Disc brake rear OR for the 80-81 Turbo Trans Am - that is listed elsewhere.

   

  What does a proportioning valve do?	A proportioning valve is used in the rear to decrease the rate of pressure rise to the drums relative to the pedal force as weight is shifted to the front during braking. This prevents the rear from locking up under hard braking conditions.
  What are the symptoms of a bad proportioning valve?	If your prop valve has gone bad your rear wheels will lock up easily, especially on wet surfaces.

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