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I’m presently refurbishing my gauge clusters and at the moment replacing the tach and speedo in my ‘68.
I’m upgrading to a speedo with the speed-minder option.
I’ve passed that anxiety filled portion of drilling the hole for the adjustment cable and thankfully got that right on the first (only) shot. Get that wrong and your kinda screwed.
Now before I get it all together I need to figure out how the speed minders plug exits the gauge pod . Comparing the photos of the standard and speedo-minder pod backs the only difference I see is the addition of the adjustment cable hole and a button of sorts.with only the photo to go by I can’t figure out how this works or how the wiring is supposed to exit .
Can anyone help me with that ?
How my speedo cup was standard..
How it is now with the adjustment cable hole added. (Not mine pictured, this is presumably factory piece).
Only thing I see different is the button (?) on the left….
Looking at the wiring harness the two clips obviously don’t directly connect together . I’m thinking that button I see in the photo is an isolator they connect together either side of. Am I right ? That little part looks impossible to get.
Looking at the wiring harness the two clips obviously don’t directly connect together . I’m thinking that button I see in the photo is an isolator they connect together either side of. Am I right ? That little part looks impossible to get.
I can’t tell you what the connector on the inside of the housing attaches to, but the “button” on the outer housing is the attaching point to the external harness for the U-15 option. One connector (single) of the harness goes to this button, one connector goes to the fuse box, the last connector (triple) goes to the relay.
I’m with you that the internal connector probably attaches to the other side of that button.
Cruise control is a whole lot better than having a "reminder" that you are going faster than you intended....
My car has a 4 speed and its ‘68 tech so it’s not the place for a cruise control.
I’ve got this going in for two reasons, first the odometer hasn’t worked since I’ve owned the car and it’s easier to replace the whole speedometer than repair what I have. Second it was either a standard speedo or this and it was available as an option in ‘68 so why not ?
Rather than just install the speedo and be a dummy gauge for just show its my intent to make it work. The wiring harness, buzzer and long adjustment cable were harder to find than the gauge. The speedo is the easy part. The rest is in very short supply if you search “ 68 Corvette, cable, buzzer, harness, etc…” and if you do find it theres a significant “Corvette tax” put on it by the seller. Not one to accept that I did a workaround. I found the parts in the AIM manual and used their GM part numbers to search. Turns out 68-69 Camaros use the exact same part and being sold as a part for a Camaro the asking price is a fraction of what it would be as marketed for a Corvette.
Ok, it’s apparent the pin these use connect to are not available unless you can source the gauge cup from a unit that had the speed minder speedo and thats highly unlikely as well. My plan B would be replace the two connectors with a round pin style connector (used with car stereo speaker connections) and drill the cup for a rubber grommet to pass the connector thru. I’ll make a quick search for the factory parts but from what I’ve seen I expect to move ahead to plan B.
Nothing wrong with what you are doing. Electronic cruise controls are readily available with 'drop' switches on both clutch pedal and brake pedal. They work exactly like modern cruise units. I put one on my '71 (auto) just after I purchased it 20 years ago. Worked flawlessly and saved my old legs on several long excursions.
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Originally Posted by Lt.Mike
Looking at the wiring harness the two clips obviously don’t directly connect together . I’m thinking that button I see in the photo is an isolator they connect together either side of. Am I right ? That little part looks impossible to get.
Interesting project you are working on.
Here's the only schematic I could find. Do you have or need the electromagnet?
Interesting project you are working on.
Here's the only schematic I could find. Do you have or need the electromagnet?
The schematic that you posted is interesting. The relay (the “electromagnet”) for this application is different compared to the (very similar) horn relay in that it has three terminal blades instead of four. I always thought that the terminal connector also had three terminal blades, but according to your schematic, one of the isn’t used. I’ll have to verify the wiring harness only has two blades in the connector that goes to the relay. My 1969 that I’m turning into a tribute car originally came with the U-15 option… The only part on the car when I purchased it was the speedometer. I tracked down the remaining “special” parts for the option; the wiring harness came from Lectric Limited, but the rest (relay, reset cable/****, and cable mounting bracket) were excellent used original or NOS. Not sure that I’m going to use it, so it will go to the next owner along with all of the other original parts.
Again, thanks for posting the schematic… Interesting stuff.
My car has a 4 speed and its ‘68 tech so it’s not the place for a cruise control.
I’ve got this going in for two reasons, first the odometer hasn’t worked since I’ve owned the car and it’s easier to replace the whole speedometer than repair what I have. Second it was either a standard speedo or this and it was available as an option in ‘68 so why not ?
Rather than just install the speedo and be a dummy gauge for just show its my intent to make it work. The wiring harness, buzzer and long adjustment cable were harder to find than the gauge. The speedo is the easy part. The rest is in very short supply if you search “ 68 Corvette, cable, buzzer, harness, etc…” and if you do find it theres a significant “Corvette tax” put on it by the seller. Not one to accept that I did a workaround. I found the parts in the AIM manual and used their GM part numbers to search. Turns out 68-69 Camaros use the exact same part and being sold as a part for a Camaro the asking price is a fraction of what it would be as marketed for a Corvette.
Ok, it’s apparent the pin these use connect to are not available unless you can source the gauge cup from a unit that had the speed minder speedo and thats highly unlikely as well. My plan B would be replace the two connectors with a round pin style connector (used with car stereo speaker connections) and drill the cup for a rubber grommet to pass the connector thru. I’ll make a quick search for the factory parts but from what I’ve seen I expect to move ahead to plan B.
Mike,
Any chance you could post the part numbers for some of these parts?
I have speed minder on a car I'm going to be restoring and would like to start rounding up some of the parts
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I had a write up about this and someone deleted it from out server...dont know how or why. It also had a odometer repair part and how to rebuild your odometer....
Anyway the proper case has an insulted post the connectes the inside with the outside, nothing special. I will look for pics and post them if i can find them.
And yes, the camaro relay is the same...i noticed that as well
Last edited by Rescue Rogers; May 27, 2025 at 09:05 PM.
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Just so you know...the relay is the speedwarning buzzer, if it has power to one of the blades but nothing off the other it buzzes, the needle has a spring that when it contacts the pointer that you set at a certain speed, creates the ground through the case and closes the circuit...dont break the speedometer needle, they are super hard to come by
Not mine, but have been tempted, maybe someone here could use it.
Thats actually a pretty good deal as it includes the cup/back with the pin and the cable bracket which no one sells.
One thing though, what is this that I’ve circled ? Can’t find it in the AIM manual page on this .
Mike,
Any chance you could post the part numbers for some of these parts?
I have speed minder on a car I'm going to be restoring and would like to start rounding up some of the parts
And here are part numbers on the AIM manual page that I searched. These numbers for the above parts are the same for other Chevy’s from the era. Camaro, Chevelle, etc..
Just so you know...the relay is the speedwarning buzzer, if it has power to one of the blades but nothing off the other it buzzes, the needle has a spring that when it contacts the pointer that you set at a certain speed, creates the ground through the case and closes the circuit...dont break the speedometer needle, they are super hard to come by
Wondering if the body of the buzzer needs to be grounded to work properly. I’m going to make a point of adding a wire to a known ground to an attachment screw .
2020 Corvette of the Year Finalist (performance mods)
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Mine was hard mounted to the birdcage. I tested everything before the install. YOu can get a spare battery or a 12vdc power supply and bench test everything ....thats what I did so I wasnt suffering under the dash trying to troubleshoot anything
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Speed-minder speedometer conversion
Get that wrong and your kinda screwed.
