speedo gear
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Senior User
Joined: Jan 2003
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From: Marshalltown, IA
speedo gear
Hi guys, I just got a new speedo gear to correct my speedometer, but I'm not sure if I have the right one. I have 33's on my truck, the door sticker says 235's are stock, so my speedometer has been reading slow. I took my speedo gear in, which was yellow, 18 teeth, and my ford guy gave me a black one, which has 20 teeth. He said each tooth equals 5mph, I told him I was about 10 mph off, so he said it should be ok. I think he may have been confused, and needed to give me a 16 tooth gear, cause it still seems slow. Wouldn't less teeth give me a faster reading on my speedometer? Any help is appreciated, thanks.
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Senior User
Joined: Jan 2003
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From: Marshalltown, IA
speedo gear
I'm going to take this gear back and ask for one with less teeth to compensate for the bigger tires. Can anyone tell me if I'm correct in thinking I need more teeth on the gear to speed the speedo up?
Mountain Pass
Joined: Oct 2001
Posts: 177
Likes: 20
From: Belpre, OH
speedo gear
You are correct in your thinking--fewer teeth will make your speedo read faster--and it's not as simple as "each tooth is 5 mph"; if you think about it, the speedo error is linear--the error increases as your speed increase--more a percentage of error
I am in the middle of a similar fix on my 91 Bronco--just waiting on the special ordered gear
I am in the middle of a similar fix on my 91 Bronco--just waiting on the special ordered gear
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Senior User
Joined: Jan 2003
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From: Marshalltown, IA
speedo gear
Thanks jimzdat, I'll have to take this gear back today. I could tell the parts guy didn't really know what he was talking about, but hey, neither do I lol. For going from 235's to 33 in. tires would you recomend going 2 teeth less or just 1? I'm not real sure how to figure it, mine was 18 so I'm thinking a 16 tooth gear would be close. Thanks again.
Senior User
Joined: May 2002
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From: tx
speedo gear
Hi guys,
You are right about it not being linear. So the faster you go the more your speedo is off. You just kinda have to do trial and error. But the way to test your gear is to find a highway with mile markers. NO don't time and figure rate. Just watch your mileage or tipmeter. If your speedo is right it will record one mile of road equals one mile on the odomiter. IT works. Took me three gears to find the right one kept reading 1.1 or .9 for one mile on the first two gears.
Good luck,
Chuck
You are right about it not being linear. So the faster you go the more your speedo is off. You just kinda have to do trial and error. But the way to test your gear is to find a highway with mile markers. NO don't time and figure rate. Just watch your mileage or tipmeter. If your speedo is right it will record one mile of road equals one mile on the odomiter. IT works. Took me three gears to find the right one kept reading 1.1 or .9 for one mile on the first two gears.
Good luck,
Chuck
New User
Joined: Sep 2003
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speedo gear
You guys seem to know a little more than me about this.
Any recomendations on a speedo grear in a 77' F150 Ranger with a c4 trans and a 3.30 rear end? I don't know the current color or number of teeth. I can get that if it would help.
Any recomendations on a speedo grear in a 77' F150 Ranger with a c4 trans and a 3.30 rear end? I don't know the current color or number of teeth. I can get that if it would help.
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