Gary Lewis Posted February 3 Share Posted February 3 My 'special' mind has a filing system of its own..... It could have been ANY of the section drawings. Maybe it's the one on Keith's forum? Maybe it's the drawing of one of the aftermarket ones I tried to show that member who wanted to gut his???? I am NOT good at knowing exactly where I come up with the minutiae I have in my head. Just yesterday I was driving to my brothers and we saw a purple fence. I turned to him and said it was OSHA Safety Plum. He was incredulous.... (until I looked it up on my phone and showed him!) Then he said "You are a (explitive) retard." Yeah, I'm THAT GUY! And I'm that guy that goes into a room, stops to ask "why did I come here", and then goes on his merry way oblivious to the fact that he's just forgotten to do something important. I'll look around a bit, but I don't know where to look. Link to comment Share on other sites More sharing options...
85lebaront2 Posted February 3 Share Posted February 3 In stock form the vacuum dump also shut down the servo, so there were three things. But since the later system doesn't use vacuum you'd only have two ways to kill it - the brake light system and the Off switch. And if the fuse blows on the brake lights then you won't have that. Ok, first item, I believe on all of the speed controls a blown brake light fuse will keep the speed control form activating. I still stand by the need for a "safety kill" in case the nice hefty stepper motor and it's affiliated gear train jams. Brake light switch will tell the electronics to let go of the cable - gears are jammed - no clutch magnet release - throttle is now stuck at whatever opening you were at! Link to comment Share on other sites More sharing options...
Tarheel Blue Posted February 3 Author Share Posted February 3 Ok, first item, I believe on all of the speed controls a blown brake light fuse will keep the speed control form activating. I still stand by the need for a "safety kill" in case the nice hefty stepper motor and it's affiliated gear train jams. Brake light switch will tell the electronics to let go of the cable - gears are jammed - no clutch magnet release - throttle is now stuck at whatever opening you were at! My truck is an F150 SB The MC that I installed I know is an’87, just don’t know if it was for a 1/2/or 350. I can’t imagine that I would have selected a 250 or 350 version. There is a boss in the casting, just not drilled/ tapped for the fire hazard switch. The plastic reservoir has a “low level” switch that I never hooked up. My proportioning valve (original from factory) has a switch in the middle on the top. Two P/W wires lead into a harness going to . . . Not a clue! Brake Light Switch Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 3 Share Posted February 3 My truck is an F150 SB The MC that I installed I know is an’87, just don’t know if it was for a 1/2/or 350. I can’t imagine that I would have selected a 250 or 350 version. There is a boss in the casting, just not drilled/ tapped for the fire hazard switch. The plastic reservoir has a “low level” switch that I never hooked up. My proportioning valve (original from factory) has a switch in the middle on the top. Two P/W wires lead into a harness going to . . . Not a clue! Brake Light Switch 3/4 ton and up have wider stud attachments. You need to slot these to put an 1 1/8 bore MC on a lighter truck. Link to comment Share on other sites More sharing options...
Tarheel Blue Posted February 3 Author Share Posted February 3 Ok, first item, I believe on all of the speed controls a blown brake light fuse will keep the speed control form activating. I still stand by the need for a "safety kill" in case the nice hefty stepper motor and it's affiliated gear train jams. Brake light switch will tell the electronics to let go of the cable - gears are jammed - no clutch magnet release - throttle is now stuck at whatever opening you were at! Bill, I hear ya. But splain me the difference in your hypothetical if it was the pressure switch that went bad. Gears are still frozen and throttle cable can’t move. If the gears freeze up, 20 redundant switches won’t return the throttle to idle. Not bustin on ya, just trying to understand. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 3 Share Posted February 3 My truck is an F150 SB The MC that I installed I know is an’87, just don’t know if it was for a 1/2/or 350. I can’t imagine that I would have selected a 250 or 350 version. There is a boss in the casting, just not drilled/ tapped for the fire hazard switch. The plastic reservoir has a “low level” switch that I never hooked up. My proportioning valve (original from factory) has a switch in the middle on the top. Two P/W wires lead into a harness going to . . . Not a clue! Brake Light Switch I'm not talking about the switch threads, I'm talking about removing a line nut and making up a line with a banjo fitting, so you can use one of those pressure switches without switching master cylinders (again) Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 3 Share Posted February 3 Bill, I hear ya. But splain me the difference in your hypothetical if it was the pressure switch that went bad. Gears are still frozen and throttle cable can’t move. If the gears freeze up, 20 redundant switches won’t return the throttle to idle. Not bustin on ya, just trying to understand. I think his argument is for a vacuum servo over a stepper motor..... 🧐 Link to comment Share on other sites More sharing options...
Tarheel Blue Posted February 3 Author Share Posted February 3 I'm not talking about the switch threads, I'm talking about removing a line nut and making up a line with a banjo fitting, so you can use one of those pressure switches without switching master cylinders (again) Jim - I’m pickin up what your layin down. It’s an interesting solution that could be made to work. I’m just not interested in adding to my to do list if I don’t have to. Installing an engine that I rebuilt AND converting from an NP435 to a 4R70W that I rebuilt has created an ever increasingly long list of things to do! I’m just hoping that something that someone says makes that lightbulb in my head shine and I say “Ah Ha! NOW I understand!” Right now I’m not convinced of the need for more than the stop switch or the horn pad switch to disengage the speed control. But don’t take that statement the wrong way, I’m VERY open to being convinced. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 3 Share Posted February 3 Jim - I’m pickin up what your layin down. It’s an interesting solution that could be made to work. I’m just not interested in adding to my to do list if I don’t have to. Installing an engine that I rebuilt AND converting from an NP435 to a 4R70W that I rebuilt has created an ever increasingly long list of things to do! I’m just hoping that something that someone says makes that lightbulb in my head shine and I say “Ah Ha! NOW I understand!” Right now I’m not convinced of the need for more than the stop switch or the horn pad switch to disengage the speed control. But don’t take that statement the wrong way, I’m VERY open to being convinced. Believe me, I'm not trying to sell you anything. You gave me a list and I'm trying to come up with expedient solutions that can work with what you already have. A $15 switch isn't going to break you, but I totally understand where you're at (look at my rear end! 😳) Link to comment Share on other sites More sharing options...
85lebaront2 Posted February 4 Share Posted February 4 Bill, I hear ya. But splain me the difference in your hypothetical if it was the pressure switch that went bad. Gears are still frozen and throttle cable can’t move. If the gears freeze up, 20 redundant switches won’t return the throttle to idle. Not bustin on ya, just trying to understand. Under the drum the cable goes around is an electromagnetic clutch powered through the hydraulic switch on the master cylinder. If the switch is opened by hydraulic pressure in the brake system, the clutch releases the drum and the throttle return springs do the rest. Link to comment Share on other sites More sharing options...
Recommended Posts