Speedo help please !?!?!?

[itsaMustangtoo]

OK I have 16 inch rims with 225/55/r16 tires off a 99 mustang and need to know what color speedo gear to get. The guy at my Ford dealer said he could not tell me which one to use. SO, I thought if any one out there has done a tranny swap or had one out they could tell me. He also said that c-4 and the aod trannys use the same gear ( interchangable ) Any thing has got to be closer than it is now. About 20-30 miles an hour fast!!!

 

[77sleeper]

New teeth = (current teeth * speedo reading) / real speed

teeth = (20 * 60)/50 = 24 teeth

or

Driven Gear Teeth = (Drive Gear Teeth x Axle Ratio x Tire Rev. Per Mile) / 1000

 

[JonDawg]

....... He also said that c-4 and the aod trannys use the same gear ( interchangable )

I know that my old gear from the RAD 4 fit the AOD with no problem whatsoever.