NP205 Speedometer Gears
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Logistics Pro
Joined: Feb 2011
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From: Townsend, MT
NP205 Speedometer Gears
1974 F250 4X4. Originally had 4.10 gears in the rear and 7.50x16 tires. I just swapped to 3.31 gears (Dana 61 out of a late '70's F250 2wd) and need a new speedometer gear/gears. Still running 7.50x16 tires.
Can anybody point me in the right direction as to which driven (and drive) speedometer gear that I need?
Thanks
Can anybody point me in the right direction as to which driven (and drive) speedometer gear that I need?
Thanks
Logistics Pro
Joined: May 2010
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From: Regina, Saskatchewan
1974 F250 4X4. Originally had 4.10 gears in the rear and 7.50x16 tires. I just swapped to 3.31 gears (Dana 61 out of a late '70's F250 2wd) and need a new speedometer gear/gears. Still running 7.50x16 tires.
Can anybody point me in the right direction as to which driven (and drive) speedometer gear that I need?
Thanks
Can anybody point me in the right direction as to which driven (and drive) speedometer gear that I need?
Thanks
Post #25 in this thread (below).
https://www.ford-trucks.com/forums/1...edometers.html
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
1974 F250 4X4. Originally had 4.10 gears in the rear and 7.50x16 tires. I just swapped to 3.31 gears (Dana 61 out of a late '70's F250 2wd) and need a new speedometer gear/gears. Still running 7.50x16 tires.
Can anybody point me in the right direction as to which driven (and drive) speedometer gear that I need?
Can anybody point me in the right direction as to which driven (and drive) speedometer gear that I need?
With 3.31 ratio & 7.50-16 tires, the nylon DRIVEN gear has 17T that with its shaft pointing down, run this-away: ////
Laughing Gas
Joined: Jan 2012
Posts: 888
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From: Santa Clarita
Since you're 4x4, presuming you have a divorced NP-205, you likely have 7 drive gear teeth according to this page http://offroaddesign.com/NP205Tech.htm. You can confirm by pulling the speedo gear out of the transfer case and counting the teeth.
Use the Ford Speedometer Calculator to determine # of teeth needed for your driven gear.
If you use 31.8" for tire diameter along with your 3.31 gears & 7 drive teeth, then you come up with a result of 15.19 driven gear needed teeth.
You'll have to verify whether or not 31.8" is accurate for your particular 7.50x16 tires.
Use the Ford Speedometer Calculator to determine # of teeth needed for your driven gear.
If you use 31.8" for tire diameter along with your 3.31 gears & 7 drive teeth, then you come up with a result of 15.19 driven gear needed teeth.
You'll have to verify whether or not 31.8" is accurate for your particular 7.50x16 tires.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
Since you're 4x4, presuming you have a divorced NP-205, you likely have 7 drive gear teeth according to this page Offroad Design - Tech.
You can confirm by pulling the speedo gear out of the transfer case and counting the teeth.
You can confirm by pulling the speedo gear out of the transfer case and counting the teeth.
In post #3, I listed the correct Ford truck parts catalog DRIVEN gear for the OP's application, but did not list the DRIVE gear, because I need to know if the OP's truck has a M/T or C6.
With a C6, the DRIVE gear cannot be replaced, as it's made as part of the output shaft.
Laughing Gas
Joined: Jan 2012
Posts: 888
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From: Santa Clarita
My understanding is that the transmission M/T vs A/T doesn't matter if you have a 4x4 because the speedometer cable goes into the transfer case. I came across another post on the topic by OP that NumberDummy responded to where OP was seeking info on the drive gear in the t-case x-post link.
With that in mind. 7 tooth drive gear is what you need in your t-case according to Offroad Design - Tech. (very bottom of page). OP - Are you replacing the t-case drive gear because it is stripped? Best way to verify what you have now is by pulling the speedo cable & counting teeth in t-case to verify.
With that in mind. 7 tooth drive gear is what you need in your t-case according to Offroad Design - Tech. (very bottom of page). OP - Are you replacing the t-case drive gear because it is stripped? Best way to verify what you have now is by pulling the speedo cable & counting teeth in t-case to verify.
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Logistics Pro
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From: Townsend, MT
DRIVE gear located on the output shaft, DRIVEN gear located at the end of the cable.
In post #3, I listed the correct Ford truck parts catalog DRIVEN gear for the OP's application, but did not list the DRIVE gear, because I need to know if the OP's truck has a M/T or C6.
With a C6, the DRIVE gear cannot be replaced, as it's made as part of the output shaft.
In post #3, I listed the correct Ford truck parts catalog DRIVEN gear for the OP's application, but did not list the DRIVE gear, because I need to know if the OP's truck has a M/T or C6.
With a C6, the DRIVE gear cannot be replaced, as it's made as part of the output shaft.
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