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  1. #1
    Join Date
    Sep 2007
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    Peak District
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    139

    speedometer sensor

    Hi,
    I'm trying to get a speedometer sensor from speedycables working with my DAX. I've mount it adjacent to the propshaft UJ in front of the Differential but for some reason the speedo isn't registering any MPH. Does anyone know how close / far the sensor needs to be from the propshaft before it picks up a signal?


    Thanks in advance,
    Mark

  2. #2
    Join Date
    Apr 2005
    Location
    Worcestershire
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    44
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    2,155
    It needs to see pulses from magnetic bolts (or magnets bonded on), what is your sensor looking for?

    Needs to be within about 4mm I think
    Last edited by cperry; 07-07-19 at 06:39 PM.

  3. #3
    Join Date
    Sep 2007
    Location
    Peak District
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    139
    Thanks. I've missed something pretty fundamental! I haven't got any magnets on it. I'll bond some on and see if it works.

    Cheers,
    Mark

  4. #4
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    Apr 2005
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    Worcestershire
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    I made a bracket on my AK to look at the prop shaft bolts. Again, you need to make sure they’re magnetic.

    You then calculate the pulses per mile, taking into account wheel diameter and diff ratio.

    Or just us a satnav/phone app to match your speedo to

  5. #5
    Join Date
    May 2011
    Location
    Flimwell
    Posts
    772
    I’m pretty sure you don’t need magnets if it’s an inductive sensor. The bolt heads must be ferrous (a magnet will stick to them) and stainless steel is no good.
    With a gap of 1 or 2 mm you should be getting a good pulse which will light up the led on the sensor.
    If you aren’t getting the led to flash then you need to check the wiring.

  6. #6
    Join Date
    Apr 2012
    Location
    swansea,south wales
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    55
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    186
    if you have a sensor with 3 wires it is a hall effect switch which requires magnets to trigger it ,if its a two wire sensor its probably a magnetic reluctance switch which will trigger from steel bolt heads. a 3 wire sensor connects + and - and output to speedo ,however a 2 wire sensor has one wire connected to ground and the other to the speedo hope this helps,best of luck mike
    mike

    pilgrim sumo mk3 3.5l rv8 sold

    ak gen 1 ford 302ci otr

  7. #7
    Join Date
    Jul 2007
    Location
    peterborough
    Posts
    227
    Quote Originally Posted by petrolhead27 View Post
    if you have a sensor with 3 wires it is a hall effect switch which requires magnets to trigger it ,if its a two wire sensor its probably a magnetic reluctance switch which will trigger from steel bolt heads. a 3 wire sensor connects + and - and output to speedo ,however a 2 wire sensor has one wire connected to ground and the other to the speedo hope this helps,best of luck mike
    The 3 wire sensors do NOT require magnets, they pick up from the nuts/ bolt heads, you need to be no more than 2mm from the heads. If it's a speedy cables sensor it will have a led light where the wires go into the sensor, this should light up when you pass a bolt head.
    Brown wire is +12 volt
    Black wire is signal to speedo
    Blue wire is earth.

    If the led doesn't light up you probably have no live feed.

    Jon

    AK Sportscars

  8. #8
    Join Date
    Dec 2013
    Location
    Newark, Notts
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    Make sure you use ferrous bolts. You do not need magnets. I have found that the sensor needs to be as close to the nuts as possible or else it does not work. If you are placing the sensor against bolt heads then make sure you check each one as you can easily damage the sensor if you get the slightest touch on the nut head.
    Joint Area Rep - East Midlands Region
    AKCharlie - ''AKA SOOTY'' - AK GEN2 - LS3 - 6.2litre - 434bhp - A dream come true
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  9. #9
    Join Date
    Feb 2011
    Location
    Blackpool
    Age
    43
    Posts
    307
    Hi Mark
    What speedo and gearbox are you using?

    Anthony

  10. #10
    Join Date
    May 2008
    Location
    North Yorkshire
    Posts
    56
    Hi, is this method IVA/SVA acceptable? I know they wont accept GPS ones
    stephen

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