Speedometer gear

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Jul 22, 2011 | 10:33 PM

mhancock2

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Joined: Dec 2010

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Speedometer gear

I some how have managed to lose the speedometer gear that connects into the transmission. I have looked on www.lmctrucks.com website and all they have listed is a 3 speed and a 4 speed. I have a 1991 f350 7.3 2wd truck. My transmission is a 5 speed. As far as i know gears are still factor. I am trying to figure out what gear do I need. How to figure it out.

Jul 22, 2011 | 11:10 PM

84-6.9L

Posting Guru

Joined: Feb 2011

Posts: 2,216

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From: Princeton MN

You need the tooth count of the drive gear on the tailshaft of the trans, and your gear ratio, IIRC 4x4 and standard trans use the same style gear. Mine is a 4x4 w/3.54 gears

7 teeth on the drive gear, so I have 16 on the driven gear.

The rule of thumb is 1000revs of the cable per mile.

Here try this
http://www.moldyrabbit.com/liquid/speedo_gear.html

Jul 26, 2011 | 03:40 PM

mhancock2

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Joined: Dec 2010

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Ok, looking on my transmission it says speedogear 7. How do I find my gears in the rear end. I have a 5-speed manual transmission and as far as I know it probably has stock gears.

Jul 26, 2011 | 04:35 PM

Phy

Fleet Mechanic

Joined: Jan 2011

Posts: 1,709

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From: 8600 ft in Colo

The sticker on the driver's door jamb will tell you what gears it had stock...
A sure way is to jack up the back end, and count the revs of the driveshaft for 1 rev of the wheels.
(also, the speedo gears are color coded, if you remember what color it was...)

Jul 27, 2011 | 12:30 AM

87crewdually

Lead Driver

Joined: Dec 2006

Posts: 6,496

Likes: 94

From: So. Jersey

Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

Click above link.
Scroll down about half way and you'll see
Ford Standard and Transfer Case Driven Gears

You'll also see

Speedometer Calculator, Click Here

If all else fails call them. Enjoy.