Clutch Switch Bypass For Big Blue

[Gary Lewis]

Bob/Nothing Special has suggested that I put a bypass switch for the clutch switch in the starter circuit so I can start with the clutch engaged should I need to do so while on the trail. So this thread is to work through my plans to do just that.

All I have to do is to simulate the clutch switch with a closed switch of some kind, but since it is pulling in the fender-mounted starter relay I'm thinking a mechanical switch or relay would be better than something solid state.

My first thought was to use a simple pushbutton, but Bob suggested that I use something that doesn't require you to hold the switch on as I might need to be using that hand to steer. So he suggested I just put an on/off toggle switch on it. But knowing that my kids and grandkids are going to drive the truck I don't want something that could easily cause a problem by being left on. So my plan right now is to use a relay with a 10 second engagement time, and trigger it with a momentary pushbutton switch.

There are a lot of relays available that delay before coming on, but these two come on for a specified length of time:

• Module: This is the thing on the left, below, and it has a variable delay up to 10 seconds. It comes with the pushbutton switch as well as an "on" LED. However the LED is on the board so my plan is to determine the voltage supplied to the LED and get a panel mount one to put beside the switch. I have one of the relay units on order as well as a small project box in which to mount it.

• Cube Relay: I've ordered the cube relay on the right with a 10 second engagement period, and it would be the easiest to use given the 1/4" connections. However it is apparently literally coming from China as it might not be here until April Fools Day. Seriously. But I could epoxy a tab on it and tie it under the dash and wiring would be easy.

[BigBrother-84]

So he suggested I just put an on/off toggle switch on it. But knowing that my kids and grandkids are going to drive the truck I don't want something that could easily cause a problem by being left on.

Which would be exact same situation than Big Bro, living without a clutch safety switch.

So my plan right now is to use a relay with a 10 second engagement time, and trigger it with a momentary pushbutton switch.

I like the idea!

An adjustable delay would be great too.

[Gary Lewis]

So he suggested I just put an on/off toggle switch on it. But knowing that my kids and grandkids are going to drive the truck I don't want something that could easily cause a problem by being left on.

Which would be exact same situation than Big Bro, living without a clutch safety switch.

So my plan right now is to use a relay with a 10 second engagement time, and trigger it with a momentary pushbutton switch.

I like the idea!

An adjustable delay would be great too.

Doesn't Big Bro have a safety switch? I thought they were introduced in '84.

The relay unit I have on order adjusts from 0 to 10 seconds, but the adjustment will be way up under the dash in a project box. I thought about using a 555 timer and with it I could put a dial on the dash to adjust it, but I think 10 seconds will be about right. And if it isn't the instructions say I can change out a capacitor and extend it a bit.

The idea is to allow starting in gear when in low range, and probably 1st gear, without having to push in the clutch and potentially rolling backwards. The PMGR starter is quite capable of moving the the truck in about any situation, and if I need a bit more power I can parallel the batteries with the push of another button.

[viven44]

So he suggested I just put an on/off toggle switch on it. But knowing that my kids and grandkids are going to drive the truck I don't want something that could easily cause a problem by being left on.

Which would be exact same situation than Big Bro, living without a clutch safety switch.

So my plan right now is to use a relay with a 10 second engagement time, and trigger it with a momentary pushbutton switch.

I like the idea!

An adjustable delay would be great too.

When I had “Big Red” which was a 460/T19/4x4 the clutch safety was removed by prior owners or not sure if it came with one. There was no provision to add one.

I needed a Robust neutral safety switch with easily available parts.

I came up with this solution below which used a firewall mount push switch (capable of 20A) from a 90s accord or Camry. A clutch pedal mounted L bracket would push it when the clutch was depressed all the way down. I specifically had it this way so the switch worked only during start ups.

Pic below just shows the initial version. I cleaned it up to look better.

[viven44]

Thanks for sharing Gary. Looks like the most optimal solution. I would think the probability is low for someone to unintentionally activate the switch and try to start the vehicle within 10 seconds.

[Nothing Special]

.... The idea is to allow starting in gear when in low range, and probably 1st gear, without having to push in the clutch and potentially rolling backwards....

And if anyone wants a visual of why that might be important or how it works...

Here is a Jeep going up a VERY steep hill (I "put tires on it" in 2022, but chose not to actually try driving up it). He stalls the engine near the top and the Jeep comes to a safe stop with the engine holding it from rolling back down. He's given the advice to "crank yourself over" but chooses to hold the brake and push the clutch in to restart the engine. This could've gone VERY badly, but don't worry, the video is still rated G (or maybe a weak PG). (the applicable stuff starts at 9:11, the link should start you there)

And here's a time where the driver did follow the advice. It was a much easier situation (I'm not sure the guy in the first video COULD have cranked it over), but it shows the concept at work. (starting at 15:08)

Both of these vehicles are under-powered, and have carbs that aren't working well. And at least the second Jeep doesn't have very low gearing. Those are definitely factors that make this more necessary. And in all likelihood Big Blue, with his fuel injected 460 and granny-low 5 speed, won't have any need of this. So (as I told Gary already) it isn't strictly needed for this trip. But it is a nice tool to have in the toolbox, just in case.

[viven44]

.... The idea is to allow starting in gear when in low range, and probably 1st gear, without having to push in the clutch and potentially rolling backwards....

And if anyone wants a visual of why that might be important or how it works...

Here is a Jeep going up a VERY steep hill (I "put tires on it" in 2022, but chose not to actually try driving up it). He stalls the engine near the top and the Jeep comes to a safe stop with the engine holding it from rolling back down. He's given the advice to "crank yourself over" but chooses to hold the brake and push the clutch in to restart the engine. This could've gone VERY badly, but don't worry, the video is still rated G (or maybe a weak PG). (the applicable stuff starts at 9:11, the link should start you there)

And here's a time where the driver did follow the advice. It was a much easier situation (I'm not sure the guy in the first video COULD have cranked it over), but it shows the concept at work. (starting at 15:08)

Both of these vehicles are under-powered, and have carbs that aren't working well. And at least the second Jeep doesn't have very low gearing. Those are definitely factors that make this more necessary. And in all likelihood Big Blue, with his fuel injected 460 and granny-low 5 speed, won't have any need of this. So (as I told Gary already) it isn't strictly needed for this trip. But it is a nice tool to have in the toolbox, just in case.

Thanks for sharing this idea. With a 460 and granny low, My truck "Big Red" would literally 'take off' the couple of times I forgot to press the clutch.. there was so much torque (Still scares me to this day!!). I can see it working a lot better on Big Blue vs. these videos.

 

[Gary Lewis]

.... The idea is to allow starting in gear when in low range, and probably 1st gear, without having to push in the clutch and potentially rolling backwards....

And if anyone wants a visual of why that might be important or how it works...

Here is a Jeep going up a VERY steep hill (I "put tires on it" in 2022, but chose not to actually try driving up it). He stalls the engine near the top and the Jeep comes to a safe stop with the engine holding it from rolling back down. He's given the advice to "crank yourself over" but chooses to hold the brake and push the clutch in to restart the engine. This could've gone VERY badly, but don't worry, the video is still rated G (or maybe a weak PG). (the applicable stuff starts at 9:11, the link should start you there)

And here's a time where the driver did follow the advice. It was a much easier situation (I'm not sure the guy in the first video COULD have cranked it over), but it shows the concept at work. (starting at 15:08)

Both of these vehicles are under-powered, and have carbs that aren't working well. And at least the second Jeep doesn't have very low gearing. Those are definitely factors that make this more necessary. And in all likelihood Big Blue, with his fuel injected 460 and granny-low 5 speed, won't have any need of this. So (as I told Gary already) it isn't strictly needed for this trip. But it is a nice tool to have in the toolbox, just in case.

Yikes! I do NOT want to "put tires on" that! But I sure get the reason why I want/need to be able to "crank it over."

However, as you said, the EFI is going to make a world of difference. Those Jeeps were pig-rich, maybe from altitude and maybe from angle, but Big Blue won't be. And he's got low enough gearing to make cranking it easy, peasy.

So while I don't think I need to be able to crank it over, I sure want to be able to. If I can I won't need to.

[Gary Lewis]

Thanks for sharing this idea. With a 460 and granny low, My truck "Big Red" would literally 'take off' the couple of times I forgot to press the clutch.. there was so much torque (Still scares me to this day!!). I can see it working a lot better on Big Blue vs. these videos.

Trust me, when the engine cranks and you are in 1st, even in 2Hi, the truck MOVES. I had Big Blue connected to the trailer with the trailer's jack down hard, and accidentally hit the key. It started and took off, trailer, jack, and all. That's when I discovered that someone had bypassed the clutch safety.

Up through 83, I think, there was no clutch safety switch. But when it was introduced in '84 people got used to having it and didn't think about the consequences of starting in gear. Years ago one guy hit the key on Dad's truck and almost went through the garage door - into Janey's GLK. People don't understand that with low gearing things are going to GO someplace.

[viven44]

Thanks for sharing this idea. With a 460 and granny low, My truck "Big Red" would literally 'take off' the couple of times I forgot to press the clutch.. there was so much torque (Still scares me to this day!!). I can see it working a lot better on Big Blue vs. these videos.

Trust me, when the engine cranks and you are in 1st, even in 2Hi, the truck MOVES. I had Big Blue connected to the trailer with the trailer's jack down hard, and accidentally hit the key. It started and took off, trailer, jack, and all. That's when I discovered that someone had bypassed the clutch safety.

Up through 83, I think, there was no clutch safety switch. But when it was introduced in '84 people got used to having it and didn't think about the consequences of starting in gear. Years ago one guy hit the key on Dad's truck and almost went through the garage door - into Janey's GLK. People don't understand that with low gearing things are going to GO someplace.

I can believe all that. Mine was an 85 but rigged up so the clutch safety was gone entirely including harness. Yes it is probably the most terrifying thing I have seen with these Granny low/460 setups. I still have compulsive thoughts every so often from recalling the couple of times this happened (what if someone were in front of the truck, like a child)... It is a risk beyond anything else owning these trucks, so I had to immediately address that.

So I think you will really enjoy taking advantage of it on the trail (literally the one time you REALLY need it !!).