F150 tranny with overdrive

[harleytoprock]

Speedo won't need calibration with the F150 overdrive because the speedometer is driven off the drive shaft. A change in rear end ratio would require a calibration change.

[wensum]

Originally Posted by harleytoprock

Speedo won't need calibration with the F150 overdrive because the speedometer is driven off the drive shaft. A change in rear end ratio would require a calibration change.

It's interesting that because the gearbox has an electronic take-off for the speedo, I was told that an expensive solution was required.
However a Ford Falcon speedo cable fitted perfectly.
Also, with the 42% overdrive the speedo reads 75mph when the car is doing 62mph (100kph in NZ)

[CarlG]

Originally Posted by wensum

It's interesting that because the gearbox has an electronic take-off for the speedo, I was told that an expensive solution was required...

You must have a different transmission than I have (which is a Tremec RTS), mine does not have an electronic take off for the speedometer.

... Also, with the 42% overdrive the speedo reads 75mph when the car is doing 62mph (100kph in NZ)

My transmission is 27% overdrive (4th gear). And since the speedometer take off is the original Model A gear, aft of the transmission, it has no bearing on what gear it is in as to how it reads.