The Ford Barn

alaskan_tnt · 12-19-2010, 08:35 AM

How do you calibrate a 1962 Speedometer? What equipment or tools are needed? No one around here works on anything that doesn't have a computer attached. Changing the cable and gear didn't fix the 10-15mph discrepancy. Thanks for the help in advance.

George/Maine · 12-19-2010, 10:14 AM

The rear end gears affect,trans gears, and tires.
If the needle is off at zero you maybe able to bend it.
Oil it and oil cable.may try another speedometer.

ford1 · 12-19-2010, 03:57 PM

i think there is another gear on the rear shaft that drives the speedo gear, check with your local trans shop

Dave72dt · 12-20-2010, 09:39 AM

You'llneed to change the gear drive set up inthe transmision. One piece on in the end of the speedo cable. The other is on the tailshaft of the transmission. Pullint the tailhousing off the trans will usually get you there.

JeffB2 · 12-20-2010, 11:22 AM

In most cities look in the Yellow pages under "Speedometer Repair" you should be able to locate a shop that way.If you can't find one contact Dick's Speed-O-Tach in Phoenix been in business since 1941 at 1(602)279-6463 website is www.dicksspeedotach.uswestdex.com

LOWRIDER · 12-22-2010, 10:00 AM

Sponsored Links (Register now to hide all advertisements)

Another place you can contact is Bobs Speedometer. They have a web site bobsspeedometer.com & 800-592-9673 phone #. They have been in business since 29' and are local legends.

40 Deluxe · 12-22-2010, 08:03 PM

Has the rear end been changed? If it has an auto trans, a standard trans rear end may have been put in or vice-versa. Or, trans may have been changed from standard to automatic, or vice-versa. Cars with an overdrive trans used yet another rear end ratio, too. The factory had the correct speedo gear for each combination, trick now is finding them.

coilover · 12-23-2010, 11:49 PM

Bow Tie Overdrives has a chart where you plug in your tire size and rear end ratio and it gives the drive gear and driven gear tooth count for correct speedo reading. It's for GM so the gear part numbers and colors (on GM plastic gears) won't mean anything but the tooth count will be right for any brand car. Ford probably has gears with the same tooth count. A good speedometer shop will also have an adaptor that fits on the tranny just like the speedo cable and then the cable fits on the other end of this. They can either over or under drive the output of the speedometer gears in the trans.

Frank The Plumber · 12-24-2010, 09:17 AM

speedometer service 414 463 6660

George/Maine · 12-24-2010, 09:40 AM

Some thing to think about.
Before someone takes your money see if the miles are correct.Drive 3 miles and check odomometer.

JerseyJim · 01-15-2011, 07:49 AM

I'm a little late seeing this post. But thought that I would put my two sense in any how. You didn't indicate whether it is high or low? You also didn't indicate if the difference in speed is consistent or varies according to speed. If it is a speedo gear issue, the percentage of variation should be consistent at all speeds. That means that as your speed increases, the variation should increase. Assuming this to be the case, the next question is did the replacement speedo gear that you put in have the same number of teeth? A fairly wide variety of gears are available. Depending on whether you are faster or slower, you can typically buy gears with more or less teeth as required.

On older cars, it isn't tough to figure out which one to use. These older transmissions (with the exception of over drive transmissions) typically have a final gear ratio of one to one. Drive your car at a set speed. Let's say 60 miles per hour. Get someone to pace you with a vehicle with a known accurate speedometer. At 60 in your car, ask them what they are reading in theirs.

If they are reading 70 miles per hour, simply divide your speed into theirs. 60 into 70 will give you 1.16. Now let's assume that you have 16 teeth on your existing gear. You need to reduce the number of teeth to increase your speed reading. So divide the number of teeth on the existing gear... let's say for example that it is 15 by 1.16 and you will get 12.93. Use a 13 tooth gear and your speedometer should be almost dead on.

If they are reading 50 to your 60, here's the way it works: Divide your 60 into their 50 and you get .833. Divide 15 by .833 and you get 16.8. You would round up to 17. Again you will be very close.

Hope this helps.

JerseyJim · 01-15-2011, 07:56 AM

An additional comment... Older speedometers using gear were notoriously inaccurate because of the fact that that are only so many speedo gear teeth variations. Car reviews used to always list the speedometer variation as a technical spec. Plus or minus 5 MPH was pretty much the norm.

12-19-2010, 08:35 AM	#1
alaskan_tnt Junior Member Join Date: Dec 2010 Location: Alaska Posts: 2	Need How-to info How do you calibrate a 1962 Speedometer? What equipment or tools are needed? No one around here works on anything that doesn't have a computer attached. Changing the cable and gear didn't fix the 10-15mph discrepancy. Thanks for the help in advance.

12-19-2010, 10:14 AM	#2
George/Maine Senior Member Join Date: May 2010 Location: Mid coast Maine Posts: 1,878	Re: Need How-to info The rear end gears affect,trans gears, and tires. If the needle is off at zero you maybe able to bend it. Oil it and oil cable.may try another speedometer.

12-19-2010, 03:57 PM	#3
ford1 Senior Member Join Date: May 2010 Location: oroville ca. Posts: 1,554	Re: Need How-to info i think there is another gear on the rear shaft that drives the speedo gear, check with your local trans shop

12-20-2010, 09:39 AM	#4
Dave72dt Senior Member Join Date: May 2010 Location: SW WI Posts: 359	Re: Need How-to info You'llneed to change the gear drive set up inthe transmision. One piece on in the end of the speedo cable. The other is on the tailshaft of the transmission. Pullint the tailhousing off the trans will usually get you there.

12-20-2010, 11:22 AM	#5
JeffB2 Senior Member Join Date: May 2010 Location: Phoenix,AZ Posts: 1,417	Re: Need How-to info In most cities look in the Yellow pages under "Speedometer Repair" you should be able to locate a shop that way.If you can't find one contact Dick's Speed-O-Tach in Phoenix been in business since 1941 at 1(602)279-6463 website is www.dicksspeedotach.uswestdex.com

12-22-2010, 10:00 AM	#6
LOWRIDER Senior Member Join Date: May 2010 Location: Kingman Az. 86409 Posts: 419	Re: Need How-to info Sponsored Links (Register now to hide all advertisements) Another place you can contact is Bobs Speedometer. They have a web site bobsspeedometer.com & 800-592-9673 phone #. They have been in business since 29' and are local legends.

12-22-2010, 08:03 PM	#7
40 Deluxe Senior Member Join Date: May 2010 Location: now Kuna, Idaho Posts: 3,779	Re: Need How-to info Has the rear end been changed? If it has an auto trans, a standard trans rear end may have been put in or vice-versa. Or, trans may have been changed from standard to automatic, or vice-versa. Cars with an overdrive trans used yet another rear end ratio, too. The factory had the correct speedo gear for each combination, trick now is finding them.

12-23-2010, 11:49 PM	#8
coilover Member Join Date: May 2010 Posts: 33	Re: Need How-to info Bow Tie Overdrives has a chart where you plug in your tire size and rear end ratio and it gives the drive gear and driven gear tooth count for correct speedo reading. It's for GM so the gear part numbers and colors (on GM plastic gears) won't mean anything but the tooth count will be right for any brand car. Ford probably has gears with the same tooth count. A good speedometer shop will also have an adaptor that fits on the tranny just like the speedo cable and then the cable fits on the other end of this. They can either over or under drive the output of the speedometer gears in the trans.

12-24-2010, 09:17 AM	#9
Frank The Plumber Senior Member Join Date: May 2010 Posts: 693	Re: Need How-to info speedometer service 414 463 6660

12-24-2010, 09:40 AM	#10
George/Maine Senior Member Join Date: May 2010 Location: Mid coast Maine Posts: 1,878	Re: Need How-to info Some thing to think about. Before someone takes your money see if the miles are correct.Drive 3 miles and check odomometer.

01-15-2011, 07:49 AM	#11
JerseyJim Member Join Date: Jan 2011 Location: Central Jersey Posts: 71	Re: Need How-to info I'm a little late seeing this post. But thought that I would put my two sense in any how. You didn't indicate whether it is high or low? You also didn't indicate if the difference in speed is consistent or varies according to speed. If it is a speedo gear issue, the percentage of variation should be consistent at all speeds. That means that as your speed increases, the variation should increase. Assuming this to be the case, the next question is did the replacement speedo gear that you put in have the same number of teeth? A fairly wide variety of gears are available. Depending on whether you are faster or slower, you can typically buy gears with more or less teeth as required. On older cars, it isn't tough to figure out which one to use. These older transmissions (with the exception of over drive transmissions) typically have a final gear ratio of one to one. Drive your car at a set speed. Let's say 60 miles per hour. Get someone to pace you with a vehicle with a known accurate speedometer. At 60 in your car, ask them what they are reading in theirs. If they are reading 70 miles per hour, simply divide your speed into theirs. 60 into 70 will give you 1.16. Now let's assume that you have 16 teeth on your existing gear. You need to reduce the number of teeth to increase your speed reading. So divide the number of teeth on the existing gear... let's say for example that it is 15 by 1.16 and you will get 12.93. Use a 13 tooth gear and your speedometer should be almost dead on. If they are reading 50 to your 60, here's the way it works: Divide your 60 into their 50 and you get .833. Divide 15 by .833 and you get 16.8. You would round up to 17. Again you will be very close. Hope this helps.

01-15-2011, 07:56 AM	#12
JerseyJim Member Join Date: Jan 2011 Location: Central Jersey Posts: 71	Re: Need How-to info An additional comment... Older speedometers using gear were notoriously inaccurate because of the fact that that are only so many speedo gear teeth variations. Car reviews used to always list the speedometer variation as a technical spec. Plus or minus 5 MPH was pretty much the norm.