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Need My Rb20det R31 speedo!! help...

Mcboost
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SKY031 Grand Master

SKY031

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Information thanks to Bozz

If you've changed your diff or done something like putting the RB25DET gearbox in place, your speedo will be out due to wrong ratio's or different speed senders.

Take the dashboard apart, unplug the speedo part from the backing board. You will see two PCB's attached to the speedo assy, you need to concentrate on the one with the UAF2115 IC on it. Unscrew the two screws that hold the odometer motor and the board will come away. Now look at the BLUE resistor at the corner of the board, next to the IC. This is the one you need to change, in my car it was a 57.4 ohm 1% resistor. Unsolder and remove this resistor. Go down to your electronics shop and pick up a 50 ohm ten turn trimpot and a 33 ohm resistor. Solder these two in series and then put them back into the circuit via a flylead so you can externally adjust the value. Put your dash backtogether and make sure the trimpot is somewhere it can be adjusted.

Blend in with traffic in various zones and adjust it to what you think the rest of the cars are travelling at. Next enslist the help of your local friendly constabulary and ask him to get his laser speed gun and aim it at your car (in an 80 zone) and ask him to flash his highbeams at you when you hit 70km/h. Maintain the speed and adjust your speedo to be spot on.

Mcboost Enthusiast

Mcboost

Posted
  • Author
Posted
Information thanks to Bozz

If you've changed your diff or done something like putting the RB25DET gearbox in place, your speedo will be out due to wrong ratio's or different speed senders.

Take the dashboard apart, unplug the speedo part from the backing board. You will see two PCB's attached to the speedo assy, you need to concentrate on the one with the UAF2115 IC on it. Unscrew the two screws that hold the odometer motor and the board will come away. Now look at the BLUE resistor at the corner of the board, next to the IC. This is the one you need to change, in my car it was a 57.4 ohm 1% resistor. Unsolder and remove this resistor. Go down to your electronics shop and pick up a 50 ohm ten turn trimpot and a 33 ohm resistor. Solder these two in series and then put them back into the circuit via a flylead so you can externally adjust the value. Put your dash backtogether and make sure the trimpot is somewhere it can be adjusted.

Blend in with traffic in various zones and adjust it to what you think the rest of the cars are travelling at. Next enslist the help of your local friendly constabulary and ask him to get his laser speed gun and aim it at your car (in an 80 zone) and ask him to flash his highbeams at you when you hit 70km/h. Maintain the speed and adjust your speedo to be spot on.

great info, ill give it a go this week let you know if it works or not, stil no tacho though

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