1996 Quattroporte Speedo reading

[skyestuart]

Hi my brothers 1996 QP Speedo is wildly over reading, at 80kpm it's reading 100kpm. Any solutions or an idea of the cause, thanks

 

[Oneball]

If its a constant 20kph out maybe the needle isn’t on in the right orientation (had that once where someone had been at the instrument cluster).

some speedos have a signal adjustment for calibration on the PCB.

 

[MarkMas]

Or it is fitted with 225/85 R16s instead of 225/50 R16s which seems a bit unlikely.

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[James3200GTA]

Or wrong gear wheel at the rpm sensor. Don't know where that is on a QP, but usually at the gearbox for non abs cars.

 

[Oneball]

I think they’re a Hall effect sensor on the rear differential

 

[alpa]

Probably from an auto transmission if the car is manual. Auto diffs are much shorter, 3.45 I think.

 

[alpa]

I think they’re a Hall effect sensor on the rear differential

Yes with the ZF diff it's on the diff. With Ranger and earlier diffs the sensor is on the ZF gearbox or in the diff extension (auto trans and getrag).