Have a 4 speed top loader with a 3.54 in the back and 235/75/15's and 21 tooth driven gear, calculator says at 60 MPH indicated am actually going 68 MPH with this setup. I read somewhere on here that a tooth was worth about 2.5 MPH; so would 3 more teeth be about right?
fewer teeth maybe? 8 / 60 = 13% error .13 x 21 = 3 teeth you need to reduce so yeah, try a 18 tooth beware there are different angles of teeth on Ford speedo gears, left and
Right, I know about the gears being right & left; I divided 2.5 into 60 and got 24, so I thought add 3 teeth?
For my A, I went to NAPA, gave them the trans, tire size and diff ratio. They came up with a tooth count for the driven gear. I checked the speedo against the mile markers for 50 miles,it's within 1%.
68-60=8 8÷68=.11765×100=11.76% slow Ford gears are roughly 5% per tooth so 2 Teeth less will speed it up 10% . Squirrel was very close. As usual. Posted using the Full Custom H.A.M.B. App!
"I read somewhere on here that a tooth was worth about 2.5 MPH". If that is true, some of my Southern cousins could only get up to 7.5 mph.<!-- / message -->
Had to read that one twice to get it 36Tudordeluxe (that took three trys to get right) one simple way to figure how far your speedometer is off is to take a hand held gps and drive down the road with the gps set on the speed setting. If you don't have one a friend or relative most likely has one you can use. That way you can read your exact speed on the GPS and compare it to the speed reading on the speedometer and figure the percentage of difference and then find the gears that will correct that difference. No bs, no guessing on how many mph a tooth is worth in change.
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