transmission identification
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
Okay, the truck came out with a 325 gear. When I bought it, I lowered it down some and changed the wheels and tires. When I first got the truck the speedometer was already off about 7 mph. and the rear gear had been changed to a 370 gear by the previous owner. With the new rear wheels ( 29" tall ) that I have on it now , I changed out the rear gear axle ratio to a 255 gear which works great and ended up being right what I wanted .I'm just trying to get my speedometer to at least 5 mph of being correct. right now it's about 14 mph off on the low side. I used my app on my phone to check it and when I was running 70 mph my speedometer was only reading 56 mph. Now at 70 mph I'm turning only 2300 rpm which was what I was wanting. All I'm trying to find out Is how this type of speedometer gear (see picture) changes out ? I know about the nylon gear type and have changed them,but I have never changed this type. Thanks !
The problem is, since your truck was never available with anything less than 3.00 gears, there's no speedometer DRIVEN & DRIVE gear applications.
Originally, your truck had a nylon DRIVEN gear, type #2 in pic.
The two types of DRIVEN gears are shown in the pic. Types 1 - 2 - 2A are nylon .. Type 3 is iron.
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Junior User
Joined: Sep 2015
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I know that it originally came with the nylon gear, but it has been changed . That's the reason I posted the picture on here. As you can see in the picture it just has a threaded cap nut that screws onto the housing, were the nylon gear has a rubber O ring and a small metal bracket to hold it in. Thanks !
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Junior User
Joined: Sep 2015
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Okay Number Dummy, I got home from work early so I got up under the truck and removed the large nut were the speedometer screws into.I removed the metal gear that you described. On the chart you posted,my gear matches gear ( Type 5.) This is whats stamped on my gear ( 01T-71 & A-18 ) And the gear has 18 teeth on it. Right now my speedometer is 15 mph off on the low side .Do you know what the lowest and highest number of teeth were that these gears came in ? If I can find one that might help a little, it would be better than being off by 15 mph. You said 1 less teeth will increase the speedometer reading .Did they make this gear with like 15 or 16 teeth ? Thanks for your help !
Cargo Master
Joined: Feb 2006
Posts: 3,010
Likes: 250
From: North Pole, Alaska
Google is your friend. What is your drive gear? It could be 6T like this chart shows so try that with the formula here:
Speedometer Gear Calculator and Charts - TCI® Auto
Speedometer Gear Calculator and Charts - TCI® Auto
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 787
From: Simi Valley, CA
Okay Number Dummy, I got home from work early so I got up under the truck and removed the large nut were the speedometer screws into.I removed the metal gear that you described. On the chart you posted,my gear matches gear ( Type 5.) This is whats stamped on my gear (01T-71- A 18) And the gear has 18 teeth on it. Right now my speedometer is 15 mph off on the low side .Do you know what the lowest and highest number of teeth were that these gears came in ? If I can find one that might help a little, it would be better than being off by 15 mph. You said 1 less teeth will increase the speedometer reading .Did they make this gear with like 15 or 16 teeth ? Thanks for your help !
01T-17271-B = 19T / Obsolete ~ 5 available NOS
01T-17271-C = 20T / Obsolete ~ 2 available NOS
01T-17271-D = 21T / Obsolete ~ 3 available NOS
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Junior User
Joined: Sep 2015
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Yeah, I figured that all of these type gears are obsolete or impossible to find. I guess I will just get me one of those aftermarket adjusters that go between the transmission and the cable. Thanks !
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
See edited post #20.
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Junior User
Joined: Sep 2015
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The gear that I have is a 18 tooth, and my speedometer reads 15 mph below what I'm running. Would the 19,20,and 21 teeth gear make it worse or make it some closer ? Also is the 18 teeth gear the lowest number that ford made ? Thanks !
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Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
The 01T DRIVEN gears were introduced in 1940, there's no 16T or 17T version.
The speedo DRIVE gear is located on the output shaft, if this is a C6 from a 1972 or earlier.
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Junior User
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Okay so to speed it up, which is what I need to do, I need a gear with less teeth. But It has a 18 tooth gear in it now, and If ford only offered an 18 tooth up to a 21 tooth , then my only choice will to be put this 18 tooth gear back into the transmission and buy me one of those aftermarket gear ( reduction / increase ) boxes. Number Dummy was you able to see the picture that I posted ? You can see where the speedometer cable goes into the transmission .Thanks !
Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
Okay so to speed it up, which is what I need to do, I need a gear with less teeth. But It has a 18 tooth gear in it now, and If ford only offered an 18 tooth up to a 21 tooth , then my only choice will to be put this 18 tooth gear back into the transmission and buy me one of those aftermarket gear ( reduction / increase ) boxes. Number Dummy was you able to see the picture that I posted ? You can see where the speedometer cable goes into the transmission .Thanks !
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Junior User
Joined: Sep 2015
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I called them today, and he wants me to use my phone GPS app to see how far it's off at 40 mph,50 mph and 60 mph, and call him back with this information so He can set me one up correct. Thanks !
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