Changing neutral safety switch
- Thread starter 6T9QDA
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You'll get a fair amount. Quart-ish. Jack the rear of the car to try and prevent some of tge spillage.
I just did mine. Timing is everything. If you are prepared to insert the new one quickly, you won’t loose much. Have a catch pan.
I raised the rear and put the rear end on Jack stands.
Little to no fluid loss
Little to no fluid loss
Well that was frustrating. I replaced the switch (Standard Motor Products NS-11) without much fuss but still no backup lights, which was the problem. The NSS function of the original switch was ok. I had jumpered the two outer pins of the wiring connector and had backup lights, so it had to be either the switch or the actuator inside the transmission, which seemed unlikely.
The old switch bench-tested bad and the new one good. The backup function is a normally-closed switch that has continuity when the plunger is extended, and the actuator pushes it in for all shift positions except Reverse. But installed in the trans, the switch had no continuity in any shift position, which suggested a misadjusted actuator or the switch extends too far into the transmission.
So I unscrewed the switch a little at a time, checking for continuity. At two full turns out the switch closed. I removed it and compared it to the old one, and the plastic/metal plunger assembly is 0.08" longer than the old one, preventing it from fully extending when installed. I added a 0.1" O-ring between the switch body and the seal, but it compressed enough that there was still no continuity when installed. Adding a second O-ring allowed the switch to close, but that seems sketchy. I'll look for a single, thicker O-ring. I don't know if all NS-11s are made this way, or if I got one out of spec. Not stocked locally, so I can't measure before I buy.
Sorry for the long-windedness on something so simple. "New doesn't mean good."
The old switch bench-tested bad and the new one good. The backup function is a normally-closed switch that has continuity when the plunger is extended, and the actuator pushes it in for all shift positions except Reverse. But installed in the trans, the switch had no continuity in any shift position, which suggested a misadjusted actuator or the switch extends too far into the transmission.
So I unscrewed the switch a little at a time, checking for continuity. At two full turns out the switch closed. I removed it and compared it to the old one, and the plastic/metal plunger assembly is 0.08" longer than the old one, preventing it from fully extending when installed. I added a 0.1" O-ring between the switch body and the seal, but it compressed enough that there was still no continuity when installed. Adding a second O-ring allowed the switch to close, but that seems sketchy. I'll look for a single, thicker O-ring. I don't know if all NS-11s are made this way, or if I got one out of spec. Not stocked locally, so I can't measure before I buy.
Sorry for the long-windedness on something so simple. "New doesn't mean good."
what year is your 904 / Car
your avatar is a 68, in 68 the backup light switch was still on the column or on the floor shifter.
the stock NSS for a 68 would be a single pin
Neutral Safety Switch 1966-1968 A-Body B-Body C-Body
Backup light switch - Console
Back up light switch Column
your avatar is a 68, in 68 the backup light switch was still on the column or on the floor shifter.
the stock NSS for a 68 would be a single pin
Neutral Safety Switch 1966-1968 A-Body B-Body C-Body
Backup light switch - Console
Back up light switch Column
Last edited:
Inertia
Well-Known Member
I don't follow. Normally closed has back up lights on. Open switch is open circuit / no reverse lamps
The switch in its "normal" or relaxed position is closed between the two backup light pins. The actuator in the transmission pushes the plunger in, opening the circuit, in every shift position except Reverse.
Inertia
Well-Known Member
Occasionally, I've run across this issue, whether parts in wrong box, wrong comb, whatever.
I discovered that by spacing the incorrect 3 pin switch out from the case, there wasn't a need to wait for another, or argue with a parts guy, this was an immediate solution.
Power valve gsk was right thickness .
I discovered that by spacing the incorrect 3 pin switch out from the case, there wasn't a need to wait for another, or argue with a parts guy, this was an immediate solution.
Power valve gsk was right thickness .
Inertia
Well-Known Member
Lol. . .
Sorry. I can't answer that.
I'm often at odds between theory and actuality . lol
I know how you guys like follow-ups and closure. The new NSS started slow-dripping, so I replaced it with the original. With lube and moderate exercise I was able to get it going again, working reliably on the bench and in the car.
I think the lesson is to make sure your replacement matches your old one. The difference may be small, but it matters.
I think the lesson is to make sure your replacement matches your old one. The difference may be small, but it matters.
Inertia
Well-Known Member
A pan gasket, fibre or copper would be my choice, o--ring might be too soft, jmo
Thanks for following up,
Cheers
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