B&M Shifter

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B&M Shifter

Postby pcguy » Fri Sep 07, 2012 8:43 am

Some of you have helped with this 75 Vega project I'm working on - appreciate all the help.

Getting close to having this thing ready for the track, at least for a trial run - going to run it with the 2.73's it came with for starters. Have an Eaton posi in the mail with 3.73's.

Anyway, something is bothering me about the B&M shifter neutral safety contact switch - the contact switches (neutral & safety) were absent when I got the car) and the engine starts in any gear. I traced the starter solenoid activation wire (purple & 12ga stranded) to the firewall and I can not locate it under the dash. Removed the driver's seat so I could get under the dash and I even put a tone generator on it - nothing.

What I don't understand is what happens between the key on the column and the wire in the engine bay on the other side of the firewall. That wire is energised when the key is turned to the start position, but there are no 12ga wires going into the column.

Is there some sort of relay under the dash that I need to connect the neutral safety switch to? I don't believe B&M contacts are rated for enough amps to power the starter solenoid, or what am I missing here???

Nick
2009 Corvette ZR1 - bone stock
1975 Vega Hatch - Built 350/TH350/3000 Stall - 400ish HP
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Re: B&M Shifter

Postby stage169 » Fri Sep 07, 2012 6:08 pm

I'll try and help, going by the 77 schematic ( I would bet it is the same for the 75 Vega ) the two terminals on the Neutral safety switch for the starting circuit are numbered 5 & 6.

Wire number 5 is purple with a double white stripe (12ga) and it goes to the ignition switch on the SOL terminal. If you aren't familar with the ignition switch it is mounted to the steering column. When you turn the key there is a rod that goes down the steering shaft to the ignition switch. If you would like a picture I'll post one?

Wire number 6 is purple (12ga) and it goes through the firewall in the wire harness to the starter solenoid and the oil pressure switch.

So basically the power should come from the ign switch through the NSS and then to the starter solenoid.

I have a Megashifter and the switches are Omron with 15 amp contact ratings. The instructions show a Radio Shack DPST normally open relay part# 275-206 to be used for the NSS circuit. The Omron switch turns on the relay and uses the relay contacts to energize the solenoid. It is for 82 -92 Camaro but any 12vdc coil relay with contacts rated for 20 amps or more would work.

Spence will probably chime in he has done a ton of wiring on the H body. Hope this helps, Brian
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