speedometer gear question
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Freshman User
Joined: Oct 2013
Posts: 28
Likes: 0
From: Simi Valley, Ca.
speedometer gear question
I bought a 66 f-100 a couple of months ago. It has a 352 engine and has been up-dated with a C6 trans. The speedometer didn't work when I bought the truck (broken cable) I replaced the cable and the speedometer works fine but reads very slow. 35 mph is more like 65 mph. The truck has a 2:75 rear gear, and a tan, or possibly white speedometer gear. Any suggestions on a gear that would get me closer to the actual mph?
Senior User
Joined: May 2013
Posts: 154
Likes: 0
From: Riverside, Ca
Definitely need to check tooth count. That's a pretty big discrepancy though. Generally each tooth should account for 3-5 MPH difference. I believe that with what you're experiencing you need to change with a gear that has quite a few more teeth.
Lead Driver
Joined: Aug 2003
Posts: 6,305
Likes: 18
From: Boulder Creek, Ca
Suggest contact couple supplier's and provide them the info noted in your original post; would think their tech or counter person can provide recommendation. 
I always contact supplier to confirm item is in stock; as probably aware, major pain in the backside having project on hold awaiting an item on 'back order'.
I always contact supplier to confirm item is in stock; as probably aware, major pain in the backside having project on hold awaiting an item on 'back order'.
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Fleet Mechanic
Joined: Oct 2007
Posts: 1,972
Likes: 103
I think you need a 16 tooth gear. Make sure it is for an auto, I seem to remember there is something different about manual and auto gears but the CRS is kicking in...
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Joined: Jun 1999
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From: Creedmoor, North Carolina
Right hand twist for the auto.
John
Elder User
Joined: Apr 2008
Posts: 619
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From: Montpelier, VA
I wish one of the moderators would make this program a sticky. This question comes up very often.
Speedometer Calibration Program - Method 1
Speedometer Calibration Program - Method 1
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