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Mar 13, 2011 | 12:47 AM

shanesf100

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Freshman User

Joined: Feb 2011

Posts: 34

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From: ashland,new york

Help

When I bought my 1959 f100 it did not have a speedometer cable in it. I bought a cable thru lmc but did not relize I needed speedometer drive gear. How do I tell how many teeth my speedometer gear had? Here's the specs
1959
223
3spd on the tree
2wd

Mar 13, 2011 | 05:24 AM

dawolverine

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Joined: Jul 2007

Posts: 310

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From: Weston-super-Mare (UK)

The number of teeth needed on the gear can also be affected by the size of the rear wheels/tyres. I think there might be some sort of formula to work it out somewhere based on the wheel size and transmission output speed?

Someone who knows what they are talking about better than me will be along soon to help I'm sure!

Mar 13, 2011 | 07:20 AM

BBKtech2

Senior User

Joined: Sep 2010

Posts: 181

Likes: 2

You could find a stock one and be close depending on yor tire size like dawolverine said. If you can find a local speedometer shop they can set you up. Their out there, just hard to find. Maybe Google speedo calibration shops in your area. If you could give them the needed info over the phone they could figure it out and send you one. We've used United Speedometer in Riverside Ca for years.
www.speedometershop.com

Mar 13, 2011 | 11:06 AM

52 Merc

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Joined: Oct 2009

Posts: 16,135

Likes: 4,735

From: Burbank, WA

Quote:

Originally Posted by shanesf100

Are you sure you need a 'drive' gear, and not a 'driven' gear? The drive gear is part of the transmission mainshaft. The driven gear is on the end of the speedo cable.

The number of teeth you need on the driven gear will depend on many factors; number of teeth on the drive gear, tire size, rear end gear ratio, etc. It might be a good idea to find out what it had originally and then adjust from there if you've made any changes from stock. Your local Ford dealer parts department guy should be able to help you, if there's someone there who knows how to read the old catalog, not just look up numbers on the computer. Or perhaps 'Numberdummy' Bill will be along to help. I don't have catalogs that go that "new".

Mar 13, 2011 | 12:38 PM

shanesf100

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Joined: Feb 2011

Posts: 34

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From: ashland,new york

Yeah I worded it wrong. Thanks . I don't know the rear gearing because it was changed by it's 2 owner, it supposedly has higher speed gearing but I'm the 4th so I have no way of finding out. . The owner wanted to put a 318 dodge in it so that's why he did not change the cable him self. As for tires it has 225/75/15s all around

Mar 13, 2011 | 05:18 PM

sdetweil

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Joined: Nov 2000

Posts: 11,591

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From: Pflugerville, tx

you can get the rear gearing by turning the wheel (10 times) and counting the driveshaft revolutions.

Sam

Mar 13, 2011 | 06:22 PM

ALBUQ F-1

Fleet Owner

Joined: Jul 2004

Posts: 27,283

Likes: 1,046

From: NM

Ford still sells the gears as far as I know, and they aren't that expensive. Just go in and pick up a B5A-17322-A (20 tooth), and clock your indicated speed/odometer readings against at least 10 miles of highway mileposts. That is the one that is correct for the lowest (numbered) factory rear axle (3.73) on a '56, with 6.70 x 15 tires and your trans. It should be close, depending what your axle ratio is. Less teeth on the driven gear = taller gearing, so you may end up with a B5A-17322-C (19 teeth) or a B7C-17322-D (18 teeth).