Speedometer gear 72 F-250 questions.....
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Laughing Gas
Joined: Sep 2011
Posts: 916
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From: Colorado
Speedometer gear 72 F-250 questions.....
Speedometer is off by 10 or more(too slow). I want to install the correct gear but have questions. So pulled the gear and it says it is a 20T 2 D
I did a bit of research and based on my tires and gearing in the rear end, I think that I need an 18 tooth. What do you think? Are the 18s the same used in the 3 speeds etc. and will the 18 slip on and fit my application?
My differential is 3.73 Dana 70
The 8.75-16 tire translates to approximately 235/85R16 in modern metric sizing. This conversion is roughly 31.7 inches in total diameter and 9.2 inches in width, perfectly matching your 16-inch wheel
I did a bit of research and based on my tires and gearing in the rear end, I think that I need an 18 tooth. What do you think? Are the 18s the same used in the 3 speeds etc. and will the 18 slip on and fit my application?
My differential is 3.73 Dana 70
The 8.75-16 tire translates to approximately 235/85R16 in modern metric sizing. This conversion is roughly 31.7 inches in total diameter and 9.2 inches in width, perfectly matching your 16-inch wheel
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Laughing Gas
Joined: Sep 2011
Posts: 916
Likes: 18
From: Colorado
So if I order one, does it matter the specific application or will the 18 slip on to the end of my current cable going to the 4 speed?
Cross-Country
Joined: Apr 2007
Posts: 67
Likes: 16
I just ordered an 18 tooth gear for my '72 F250 390 ATM 2WD off of Amazon. I had planned on getting it from Dennis Carpenter but they were out.
My gear is pretty chewed up and another forum member gave me the hint about reaching in to the hole where the gear came out and feeling the condition of the teeth in the tranny. Best I can tell, they seemed OK; and though the cable may need to be (should be) replaced it still works, so I will test the original cable with the new gear and see if the speedometer comes to life before ordering a new cable and a new retaining clip for the gear.
The Amazon purchase was about the only one I found that included the O-Ring for the seal at the transmission (and mine is really old). Anyway, it should arrive in the next week or so and I will verify the fit on what I believe to be an OEM cable.
For reference, below is what I ordered, I will update when I get it.
My gear is pretty chewed up and another forum member gave me the hint about reaching in to the hole where the gear came out and feeling the condition of the teeth in the tranny. Best I can tell, they seemed OK; and though the cable may need to be (should be) replaced it still works, so I will test the original cable with the new gear and see if the speedometer comes to life before ordering a new cable and a new retaining clip for the gear.
The Amazon purchase was about the only one I found that included the O-Ring for the seal at the transmission (and mine is really old). Anyway, it should arrive in the next week or so and I will verify the fit on what I believe to be an OEM cable.
For reference, below is what I ordered, I will update when I get it.
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