Speedo Help
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Joined: Jul 2006
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Speedo Help
I need help with calibrating my speedometer. I had the manuel transmission replaced in my 94 Ranger and the speedometer is of by 5 MPH (65 reads 60 on speedometer). The drive gear is pink(?#teeth) and the driven gear is pink(19 teeth). What is my gear ratio? Axle code is 84 and rear diff tag reads S362B, 3 45 75, 4C28. Any help is appreciated, Tim.
Post Fiend
Joined: Jul 2005
Posts: 8,462
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From: Durant, OK (SOSU)
By your axle code and the tag on the rear end, you have a 3.45 non-limited slip rear diff.
You change tire sizes? If the drive gear and reading gear are correct, really the only thing that could be affecting it would be the tire size.
RP
Zach
You change tire sizes? If the drive gear and reading gear are correct, really the only thing that could be affecting it would be the tire size.
RP
Zach
Posting Guru
Joined: Jul 2003
Posts: 1,978
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From: Alvin, Texas.
Did the speedo gear get pulled along with the old tranny? I am betting that's the case. See if you ca nget it back and then swap in place of what you have now.
I think TRS has a calculator...you'd need a 21-tooth gear, if I am correct, since the speedometer is spinning slower now.
When I swapped in my bigger tires and wheels, I believe I was 4.5% off and went from the 20-tooth gear (red) to a white 21-tooth speedo cable gear. Since you are double my difference, go up double the teeth.
A stealership will have this part for about $9, same day if they have to order, I believe.
I think TRS has a calculator...you'd need a 21-tooth gear, if I am correct, since the speedometer is spinning slower now.
When I swapped in my bigger tires and wheels, I believe I was 4.5% off and went from the 20-tooth gear (red) to a white 21-tooth speedo cable gear. Since you are double my difference, go up double the teeth.
A stealership will have this part for about $9, same day if they have to order, I believe.
Posting Guru
Joined: Dec 2003
Posts: 1,651
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From: Maine
I put a rebuilt manual trans in my '97 this spring, and it had the wrong gear INSIDE the trans. So, when they swapped the external drive gear over (the one that came with my truck from the factory) it didn't read right.
The rebuilder told me to pull the gear and call back with the colors of the gears inside and outside, and they would find another external gear that would correct my speedometer readings. I was never able to get through to the guy after I got the information he needed. I just learned to deal with the speedometer being off.
**Note that the inaccuracy of your speedometer is not a constant 5 mph. Mine is off by about 20% (reads high).
The rebuilder told me to pull the gear and call back with the colors of the gears inside and outside, and they would find another external gear that would correct my speedometer readings. I was never able to get through to the guy after I got the information he needed. I just learned to deal with the speedometer being off.
**Note that the inaccuracy of your speedometer is not a constant 5 mph. Mine is off by about 20% (reads high).
