What the heck did I break now.

[So.Cal.Super]

Sometimes you know you should just go to bed and get some sleep.
But, noooo... just one more thing to try and take apart..
I think its the neutral safety switch? Can someone tell me.

Thanks.

[SS Tim]

Actually that looks like the stop lamp switch. It has orange and white wires. The two purple wires in the picture are the neutral safety switch and the two greens are the reverse lamps in a combo boxy half round switch housing. Get some sleep. Tired and upsidedown don't work.

[So.Cal.Super]

Thanks Tim!

Your right not a good combo, 4hrs of sleep, coffee and some breakfast later I get to go see what I break today

[BadaSs_Cal]

Neutral safety switch? I guess mine was supposed to have one.. is it weird that i dont?
I pinned my father in law against a Honda when I first got the truck, anyone know why an Sm420 wouldnt have one?

[SS Tim]

Generally only auto trans. vehicles have neutral safety switches to prevent the engine from being started in a gear other than neutral or park. Manual transmission vehicles for the most part do not have such a starter interlock, at least not a gear position specific device. Later/newer vehicles usually have instead a clutch switch to prevent motion during start up. But this is not without problems. Off-road vehicles with a clutch switch can be a real pita under some conditions. Worse is the fact that during start up a dry thrust bearing is taking the clutch clamping pressure until the oil lubes it up regardless of the transmission gear selected. So when you are thinking about a used engine think about that. I have personally seen engine crankshafts of otherwise great running engines so worn that the factory thrust face was gone due to dry start up re-machining.

[camrycurt]

Originally Posted by SS Tim

Worse is the fact that during start up a dry thrust bearing is taking the clutch clamping pressure until the oil lubes it up regardless of the transmission gear selected.

OK, wait. I'm relatively new to older trucks and don't quite follow all of the terminology here but think I might be doing something wrong.

With my SM465, I leave my truck in gear when it's parked. Then on start-up I put my foot on the clutch, leave it in gear, and start the truck. Is this wrong?

Should I be putting the truck in neutral before I start it and then start it in neutral with my foot off the clutch?

Thanks for the help!

[SS Tim]

Originally Posted by camrycurt

OK, wait. I'm relatively new to older trucks and don't quite follow all of the terminology here but think I might be doing something wrong.

With my SM465, I leave my truck in gear when it's parked. Then on start-up I put my foot on the clutch, leave it in gear, and start the truck. Is this wrong?

Should I be putting the truck in neutral before I start it and then start it in neutral with my foot off the clutch?

Thanks for the help!

Good question Curt. I try really hard not to use too much terminology in my posts but sometimes they read like a service manual. With a manual trans. and no clutch switch the decision is really yours in your truck. Either way "works" I was just trying to point out a specific issue that is the result of pushing the clutch. But the transmission should be in neutral for safety reasons, again either way. Cranking with the clutch pushed only rotates parts forward of the clutch throwout bearing (other than the disc). As a result starter loads can be lower and the motor might spin a little faster. Cranking with the clutch out and the trans. in neutral results in more spinning parts like the imput shaft and a couple of gears. The engine might turn a little slower with higher starter loads. The advantage is there are no thrust loads on the engine thrust bearing. Plus it frees up a foot so starting is an easy "one on the brake and one on the gas".

[camrycurt]

Cool, got it. Thanks for the help!

[OJ1988]

Did the stick trucks not have a saftey switch?

I know my three on the tree truck did, its up in the column.

I find it hard to believe the trucks with floor shift manula trans had no safty to prevent the truck from starting in gear.

[SS Tim]

OK, specifically what "truck" are we talking about? If it was your '69 step and stock then it is probably the reverse lamp switch with a light green and a dark green wire connected to it. Not to sure why you find this "hard to believe" though.

[OJ1988]

Lets say 1967-1972.

You mean all these trucks that had manual transmissions could be started with the transmission in gear and the clutch not engaged?

[So.Cal.Super]

To clarify my original post yes, Tim was correct it was the brake light switch. I could see it better when I pulled the column out the next day.

[SS Tim]

Yes, Things change over time. During the '67-72 period alone many things changed due to mandate. Defrosters, starter/shift interlocks for automatics, marker lights, evap emission control, NOX controls, seatback latches all come to mind.

[OJ1988]

Originally Posted by SS Tim

Yes, Things change over time. During the '67-72 period alone many things changed due to mandate. Defrosters, starter/shift interlocks for automatics, marker lights, evap emission control, NOX controls, seatback latches all come to mind.

So a 1967 chevy c 10 with a manual transmission could in fact in factory form be started by the key with the trans in gear and the clutch pedal not depressed?

[SS Tim]

Yes, the starter would bump. Now if the engine would actually start depended on a number of factors like if the park brake were engaged, the transmission gear engaged and the gradient it was parked on. Don't you ever remeber hearing or reading about someone cranking their way off railroad tracks because the engine would not start. My 2 ton Dodge is very happy, due to the gear rations, doing a rolling start empty.

[vern650]

i had a 71 and a 73 Chevy 4x4s with manuals and neither one had a clutch safety switch, i also had a few buddys with 70's chevs ranging all the way up to 79 and none of them had them either. my experience it wasn't til around the 80's the clutch switches became standard in the chevs unless everyone i ever seen had been disabled. as long as u pay attention its no problem, but i'll admit there was a curb or two jumped in my day from spacing out and hitting the key.

[OJ1988]

You guys blew my mind. Guess most the old stuff I've had have been autos, thought it'd been like that forever.
Posted via Mobile Device