brake booster check valve

[Tom Cloud]

>  <<<
>  >There is a check valve in the brake booster to prevent pressure from entering 
>  the booster on many cars.  Under boost >you loose all effects of   >>>
>  
>  On the plus side these valves are just inexpensive plastic valves available 
>  anywhere; they go inline with the hose to the booster (at least on GM- don't 
>  know about other) so really ought to be easy to have one... 

same on Ford -- and if you don't know what to look for, you'll
not know they're there .... they're shaped about the size of 1-1/5
nickels together with a go-zinga and a go-zouta tube in the
center on each side.

Tom Cloud <cloud at peaches.ph.utexas.edu>