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Speedometer Trouble

Discussion in 'A Body: Duster, Valiant, Dart, etc' started by ComputerBob, Jul 11, 2017.

  1. ComputerBob

    ComputerBob New Member

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    I have a '74 Dart Custom with an A904 trans. My speedometer is shot and the speedo repair guy says it's about a $200 fix. Well, just checking on-line I can get a set of nice looking Marshall gauges for about $350 (speedo + a tach & all the others I'd like to replace my dummy lites & not very informative gauges). However, ALL the new speedometers I found on-line are electronic requiring a "Hall-Effect Sender" unit. Here's the rub, EVERY picture of EVERY sender I can find shows a threaded connection while the connection from my cable to speedometer is a push-on with a side clip.

    My question is for anyone with any experience with all this:
    Can I get a new speedometer cable for my car that uses the threaded connection?
    OR
    Can I get a sender with the same connection as my old speedo?
    OR
    Do you have any other suggestions?

    All I want is a functioning speedometer & odometer that will actually work with my car.
     
  2. RalphP

    Level 2 Supporter

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    Umm ... check the OTHER end of the cable.

    It should be the threaded end; that's where the sender connects, at the transmission. (Or, if yours has cruise, possibly on the cruise control output, if it's like my 1988 Dakota).

    Shucks, my 1988 has a VSS sender (what the new gauges want) for the TBI ECU, and a cable to the cruise servo, and one from the cruise servo to the speedometer. (For some reason I've never been able to cure a bouncing needle on the Dakota; wonder why.)

    RwP
     
    Bob Lincoln likes this.
  3. ImperialCrown

    Level III Supporter

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    Is it the speedometer and not the cable?
    Older speedo repair is a lot like clock repair, you have to be careful not to damage the mechanism by handling delicate pieces.
    If you poke a stick into the end where the speedo cable goes and spin it, does the pointer move?
    Many older speedos have old grease that hardens into wax and will cause problems. Many fixes are just plain cleaning and lubing the assembly.
    Broken plastic odometer gears can also seize the mechanism.
     
  4. dana44

    Ad-Free Member

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    Yeah, couple things. You have verified the problem is with the speedometer itself, I take it. Not the cable, not the gear on the transmission (as in it has worn out or is actually in the wrong position so it isn't engaging). A speedo cable of this age is a speedo cable, meaning, if it is long enough, it is a spiral cable with a square end and a tiny flange so it can be stopped from just sliding through. If it is long enough and the ends are correct, it will work, meaning, if it is threaded on both ends, and happens to be from a Chevy or Ford or anyone else, and is as long as needed to go from trans to speedometer, it will work. It is the cable length and ends that is important, the plastic snap clip holder on the end is Mopar specific, but the cable otherwise is not.

    If you can spin the back end of the speedometer and the needle moves (jumps), then it is OK.
    You can pull the speedo cable out of the housing and verify there aren't any wires broken and that it is OK, same with the housing.
    Take a tiny screwdriver and stick it in the end of the speedometer gear in the transmission (where the cable connects), and try to gently turn the speedo gear. It should not move if it engages. If it does rotate, remove the one bolt (7/16 or 3/8ths wrench), have a drip pan, fluid will come out (a little, not a lot), and check the gear. If it is good, look at the housing and you will see numbers and markings for different ratios for it, be careful not to damage the O-ring so it doesn't leak, but reinstall and rotate the housing until it engages that gear to the output shaft gear in the transmission, verify with screwdriver it is engaged, reinstall bolt and clamp.

    These things should help ensure you need to actually replace, if you don't want to, and that you can get things hooked up correctly.
     
  5. ComputerBob

    ComputerBob New Member

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    Wow! You guys are great!

    First off, I did check the gear in the transmission where the Speedo cable connects & made sure the cover was situated appropriate to the # of teeth on the gear, all good.
    I put another known working speedo (from a 70 F250, not mine to keep or even buy at any price) on the cable and it works just fine (kinda off on the real speed, though, to be expected).
    I found a speedo shop about 40 miles away, took the speedo to him & he said it really is badly worn & needs a complete re-work. Cost of about $200.
    Also, with a bit more investigation & FINALLY finding the right guy at NAPA to ask, found out the Hall-Effect sender attaches at the transmission, NOT the speedo end of the cable!
    Learning as I go, this is my FIRST foray into re-gauging a car. Strange, considering how many I've had over the years...

    Here's the thing with this entire project.

    I bought this car about a month ago intended as a daily driver. Before I even got it all the way home I had a fire behind the dash & EVERYTHING died. Some MORON had taken about 3 strands of the wire for the main power thru the firewall & simply twisted them around the connector thru the firewall, then taped over everything. Took me 3 weeks to replace all the melted & hardened wire both in the engine compartment & behind the dash. PLUS, when it happened, it literally blew the Alt, Water Temp & Fuel gauges OFF the back of the dash. At least the car runs & drives now, but no gauges.

    SO, what I intend to do is get a nice looking set of new gauges with the stuff I really want (Tach, accurate Water Temp, Oil Pressure, Oil Temp, Volt Meter & Fuel gauge). Bend my own sheet metal dash to put them all into and get the wiring behind the dash simplified & wired CORRECTLY so no more electrical mishaps.

    Having trouble finding a fuel gauge that actually works with a Mopar sender (EVERYONE has ones for GM & Ford, though). Was thinking about replacing the fuel level sender at my tank with a GM or Ford unit to resolve this. Any suggestions about that or possibly recommendations where to find fair looking Mopar gauge sets on a budget? Time I have in abundance, $ I don't.
     
  6. Scrounge

    Scrounge Well-Known Member

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    Any Mopar-specific junkyards in your area? If not, you might want to check all of them to see if they have your model. Some junkyards have their inventory online. The '75 and '76 Darts should also work. I think the Valiants from '74 through '76 were the same, or similar. You might want to buy the entire instrument cluster, if one is available.
     
  7. 68RT

    68RT Well-Known Member

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    Mopar requires a voltage reducer not required by most. Look up Electrickery II in ALLPAR vintage repairs. Explains vintage gauges very well.
     

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