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Transmission interchange - mechanical speedometer w/ speed sensor

Discussion in 'GM Powertrain' started by dualdj1, Mar 14, 2011.

  1. dualdj1

    dualdj1 New Member 100 Posts

    The trans in my old van has seen better days. I'm gonna have to pull it to fix a leaky main seal or cam plug on the new engine, So I wanted to see if anyone knew of a good year/model transmission I could use.

    My main requirement is that I have a mechanical speedometer. I wouldn't mind going to an OD trans that's computer controlled, but it would have to have an electric speed sensor with a mechanical speedo cable. I'm thinking it would need to be somewhere in the 88-92 year range. Anyone know if any 2wd trucks/vans in that range had a mechanical speedo?
  2. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    Wait, so it needs both a speed sensor AND a mechanical speedo output? I don't think those exist. If you just need the mechanical speedo, I think you can swap the tailshaft with one from a mechanical speedo 700R4 and be fine. If you need both, I think you'd still need the mechanical speedo tailshaft and one of those speed sensors that ties inline with the speedo cable like they use for the cruise control setups. From 88ish on they only had speed sensors; not even Suburbans still used mechanical speedo cables.
  3. dualdj1

    dualdj1 New Member 100 Posts

    OK Thanks. I only questioned it as I wasn't sure if GM had put the sensor on vehicles with mech speedo. My 89 mustang had a cable driven speedo with an electronic speed sensor as well, where the cable went into the trans. So Ford did both, wasn't sure if GM did.

    I don't necessarily need the speed sensor, but I *think* it's required if you do trans control with the computer.
  4. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    With the 700R4/4L60E, the speed sensor and mechanical speedos pulled off the same spot, a couple inches into the tailshaft. So, you'd actually need the tailshaft and the gear off the shaft that drives the speedo cable.
  5. dualdj1

    dualdj1 New Member 100 Posts

    OK thanks for the info.

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