Neutral safety switch on a 57?

[Philippe Courant <accf-club@xxxxxxxxxxxxxxxx>]

>
>
>but does the 1957 even have a neutral safety switch?  I don't think so.  It 
>has a neutral starter switch which is not the same thing.  
>
In fact ther're 2 "neutral safety" switches !
- One on the intake manifold which opens the starter wiring when ther's 
vacuum so when the engine is running you don't worry to push "N" button 
all the way. This switch is closed when engine is off and if this switch 
is bad you can't start (except if you shorts the two prongs)  .. I call 
it the "neutral vacuum safety switch"
- One at transmission which closes to ground the starter relay wiring 
(coming from the previous switch) when the trans. is in N . It's a 
mechanical device between trans. manual valve and switch : when you put 
the trans. in N on transmission (w/o cable attached) you're sure this 
neutral switch is closed. It's the "trans. neutral safety switch".
If you've these 2 switches, you can't start the engine except in N. But 
if someone has removed the trans. sfty switch (i.e leaking switch) and 
put a plug rather replaced it (and grounded the wire) you can start the 
engine in D or R (the 2 adjacent positions to N in trans.) if the cable 
is misaligned.

Wiring of the starter system:

+ 12 ------ "N" push button ----- Neutral vacuum sw ----- starter relay 
("ign" pin) ---- starter relay ("ground" pin) --- trans. neutral sw  --- 
ground

About the '57 which has the problem (drive R in all positions ) i've 
told to the mechanic to see if the "trans. neutral safety switch" is not 
bypassed. He hasn't check at this time but he told me that the problem 
arrived when he drove the car (in R) from the service lift. After he 
need to go forward, pushed D button (or 1 or 2 or N) but the car went 
always in R ! Since this time the car drives (or start) only  in R ; he 
told me also that the dash unit works perfectly and that the cable goes 
in and out . I think that the cable unkookeds itself (bad installation 
of the previous mechanic ? ) so it can push (when it went to R) but he 
can't pull (to go from R to other positions). The R position is the last 
rear detent on trans. Then you've N, D, 2 ,1 which is the last forward 
detent.
I'll see the car at end of next week. Hope that is an unhooked cable ..

-- 

Philippe COURANT (Pau, France)- Webmaster des sites ACCF et C-I-F
Imperial 1957 Crown convertible
Buick 1996 Roadmaster wagon

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