I'm getting some help this weekend in wiring my 48 Plymouth from a friend and we noticed the old cloth wrapped wiring coming out of the gauge cluster. I'm sure the original is 6 volt. Other than buying after market 12v gauges, can anyone step me through on how to wire the stock gauges up? Speedometer, fuel, temp, etc. I've searched the message board and haven't found much. I assume I can buy a resistor, transformer, flux capacitor, etc. setup to help? I'm sure this is a newbie question, so please go easy on me. I just want to make sure it gets done right and safe. I know little to nothing about wiring (hence using my buddy who does, but has only wired newer 12v systems), but hope to learn about it. So please talk slow and pretend that I'm a child when you respond. And yes, pictures would be nice too.
Uh when I was still building cars back in the 90's , I used to go to N A P A and use their Volt- A - drop resistors . Generally , one resistor will do fine for what you need as all you're going to do is power guages . Replace the lights to illuminate the guages to a 12 volt bulb though . Oh , you can P- M me if ya run into any trouble too...... scrubba
That 48 Ply has a very odd gas gauge setup; 2 sender wires from tank to dash gauge. Also has 3 wires at the dash gauge; power and 2 sender terminals. I plan on using a tech thread from hamb, using early 70s Ford truck dash gauge guts and senders in a 46-48 cluster.
A couple of thoughts: 1) You could possibly use one of those Ford instrument voltage regulators to get voltage down to 5-6 volts or 2) buy a Runtz reducer or 3) just go to the nearest Radio Shack and get a zener diode and hook that in between power and gauge power terminals. 276-565 is the Radio shack number. Banded end goes to ignition power, other end to gauge power terminal. (This is what is in Runtz, $1.59 alot better than $9.) You should see 7-8 volts at the gauges.
if I am not mistaken your gauges unless somebody has already dicked with them, are voltage dumb except for the light bulbs, Oil is mechanical, coolant temp is bulb and tube, Amp gauge don't care except you will want to swap the wires on the terminals to deal with the switched polarity, and the gas gauge sends a signal based on resistance through a coil so it don't really care about how many volt just the difference from one end to the other. and it seems it would be easier to swap the bults to 12v than put voltage drops on them.
Thanks Plym 46 - I think you're right. Looking at it closer, the old wire I saw is for the bulb I think, not the gauges. I think all of the guages are mechanical. Now for my next question on the speedometer - Is there a way to hook the speedometer cable up to a newer (TH350 out of a 91 Chevy truck) tranny? The tranny looks like it has a plug in spot for a 4 pin electronic wire, but I didn't see where to hook up a mechanical cable at. Did I just miss it, or is there a way to do it?
take the retaining bolt off of the sender, pull the whole thing out......carry it down to your transmission shop, and swap it for one with a mechanical head. duck soup
Anyone have a link or website where I could purchase an electric to mechanical tranny convertor for my speedometer? I found one for $180 at the terf.com website and would like to know if that's the standard price for one, or if I could find them for less. I enjoy going to salvage yards and finding stuff, but I'm guessing finding one of these would be difficult.
Forget the $180 converter you mentioned. If you have access to a local junkyard, go pull a mechanical gear sleeve for your transmission, cost probably $10-$15, new at the dealer they are around $70. Also, the fact that you are seeing a four pin electrical connection and that your transmission is from a 1991 Chevy truck tells me that you may have a 700R4 overdrive transmission and not a TH350, as the 700R4 replaced the TH350's in the mid-80's. The speedo sending unit will be on the drivers side of the rear tailshaft and will have a two prong electrical connection for the electric speedo or a threaded connection for a mechanical cable. I'm guessing the four pin connector you are seeing is on the drivers side, pointing straight up midway of the transmission body? The four pin connector should be for the torque converter lockup wiring. Double check to confirm your transmission type and then we can get you converted to a mechanical speedo for cheap! ($180=bad, cheap=good) Don
The fuel gauge is unique and usually requires service to be accurate. Most of the time the sending unit develops a problem where the winding separates from the frame, essentially it is a poor design. We build new units instead of restoring the original tank unit. A constant voltage drop is better than a resistor since the gauge is a points actuated type.
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