Adding Cruise Control to a Car That Never Had One???

Discussion in 'High Tech Retrofits' started by slayer021175666, Jan 23, 2018.

  1. slayer021175666

    slayer021175666 Veteran Member

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    Feb 29, 2016
    Idaho
    I been wanting a cruise control for a while now.
    I have seen the Rostra kits but, it looks like $300 or more!

    #1 Is there a cheaper option?
    #2 My car is an '81 but, I took out the computer and wire harness that ran through to the engine bay. I installed an old 327 so, no need for the computer. I don't see how it would but, will my Vehicle Speed Sensor (VSS) still work and should it be used?
    #3 Anybody want to sell a cruise kit that you aren't going to use?

    I'm sure I'll have more questions about this topic but, I can't think of them now.
    I'd appreciate any advice or insight.
    Thanks Guys!
     
  2. slayer021175666

    slayer021175666 Veteran Member

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    Any opinions on the vacuum systems? They look cheaper.
     
  3. Jim Streib

    Jim Streib https://www.flickr.com/photos/121766713@N04/albums

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    It's been many, many years since I put on the ones that relied on engine vacuum, and maybe the technology changed some but the vacuum systems I did had a vacuum dump switch that attached to the brake pedal and had a small chain that attached to the firewall. When the brakes were applied, this vacuum dump opened up and allowed the bellow diaphragm that pulled on the throttle linkage to get air into it and allow the throttle work off of the regular gas pedal or let the engine return to idle. If the car was a manual shift then this chain went through a small pulley on the firewall and then the chain ended looped back onto the clutch pedal to where if the clutch and/or brake pedal was depressed, the cruise was disengaged. Basically these were a pain to install and keep adjusted right.

    Another issue with the vacuum ones from years ago was if the engine had a low amount of engine vacuum. If it was not enough, the system did not work properly but one could add a vacuum reservoir but this too added to the complexity of the overall system.

    With the advent of the new systems using the vehicle VSS wire or a VSS generator, it's a lot better than when I had to glue magnets to the driveshaft and then position an electronic coil to pick up the pulses of the magnets spinning past it to generate a speed signal.

    If it were me, I would belly up to the bar and get the latest and greatest that is all electronic AND from a reliable supplier like Rostra.

    Most kits today also allow for optional stalks or console controls to operate them.

    The newer kits are also easier to calibrate unlike the old ones that you had to twist knobs on the control box to set things up and you had to do those things while driving the car.

    Jim
     
  4. slayer021175666

    slayer021175666 Veteran Member

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    Thanks for that, Jim. They do look easier install and "headache free" operation is a must.
     
  5. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    ^ That "kit" isn't complete.
    It will be $300 by the time you add the other parts.

    My cruise control hasn't worked since I bought the car in 1990.
    (It worked ONE time. But it got stuck in "Resume" mode.)

    I finally bought a new transducer last month. We'll see if it works this Spring.

    You're probably best to go with an electronic kit as the factory stuff will probably cost just as much if you can even find all of the parts.
     
  6. slayer021175666

    slayer021175666 Veteran Member

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    I was hoping you'd chime in, Terry.
    Ya, that "kit" is not complete. Have to buy a control switch and a VSS sending unit. That's where ya rack up the $300. Actually Terry, do you know if my VSS will work without the computer in the car? That would shave $60-70 bucks off my cost. I feel like they're being a little shady in their advertising, calling it a "kit" when in reality, there is more things you have to buy to make it all work.
     
  7. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    The Vehicle Speed Sensor (VSS) is part of the speedometer in an 81. (You knew that already.)

    It should still send an electronic "pulse" signal as the speedometer cable spins the input side of the speedo.
    But I have no idea if its signal is in the proper amplitude or frequency range to function correctly with the input to an aftermarket cruise unit.
    My guess.... It might work.
    If it simply controls the throttle to match the chosen speed (pulse frequency from the VSS) with no concern for actual wheel speed. It could work.

    But if there is a limitation to the speed it will hold (less than 20 MPH or over 100 MPH, for example) your normal road speed could be out of its engineered frequency (pulse) range.
    Especially if the speed sensor for this aftermarket unit was designed for driveshaft use. (?)

    A GM Speedometer cable turns 1000 (or 1001?) revolutions per mile.
    My driveshaft spins 2500+ revolutions in a mile. (If my math was right.)

    That's a pretty large difference for the speed sensor if there is some upper or lower limitation MPH engineered into it.
    See what I'm getting at here?
     
  8. greencamaro1981

    greencamaro1981 Veteran Member

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  9. dale68z

    dale68z Veteran Member

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    I have rostra in both my 68 and my 71. Thinking about getting one for my el camino. Bought them both from a member of this board.
     

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