Speedometer recalibrate
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1931 flamingo
Well-known member
Ck the "yellow pages", you should be able to find a speedo shop.
Paul in CT
Paul in CT
Joe Immler
Well-known member
I have had very good results from Bob's Speedometer 10123 Bergin Rd. Howell Mi.
1-800-592-9673 He can also clean and lube it. Try him.
1-800-592-9673 He can also clean and lube it. Try him.
51504bat
Well-known member
Rusty on the HAMB gets great reviews:
https://www.speedoservice.com/
On the HAMB he is: e1956v
He is in Colorado
https://www.speedoservice.com/
On the HAMB he is: e1956v
He is in Colorado
Flathead Fever
Well-known member
I don't know thing about those "modern" '49 Fords. Once the torque tube and straight axle was gone it got too high-tech for me. My guess is you can replace the plastic gear on the end of the speedo cable with one with a different number of teeth. Just like you would with the speedo adapters on the earlier torque tube rear ends. Drive the car with a GPS unit inside and compare the GPS speed to your speedometer's. Calculate the percentage difference and see if there is a gear available with that percentage of difference teeth needed to correct the speedometer. That would be the cheapest way to go.
I checked and Mac's has some gears, 19, 20, 21 '22 tooth gears. Pull your speedo cable out at the trans and count the teeth. Be prepared to catch some fluid. I don't know if the speedo gear is located above or below the fluid level in those transmissions. Some vehicles are below and the oil comes pouring out when you pull it out.
https://www.macsautoparts.com/ford_mercury_late/catalogsearch/result/?q=speedo&x=0&y=0
I checked and Mac's has some gears, 19, 20, 21 '22 tooth gears. Pull your speedo cable out at the trans and count the teeth. Be prepared to catch some fluid. I don't know if the speedo gear is located above or below the fluid level in those transmissions. Some vehicles are below and the oil comes pouring out when you pull it out.
https://www.macsautoparts.com/ford_mercury_late/catalogsearch/result/?q=speedo&x=0&y=0
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51504bat
Well-known member
From our friend, Mr. Google:
There are actually two ways to calibrate a mechanical speedometer. The ratio of the drive and driven gears in the transmission (or transfer case) can be changed, or you can install a reduction or overdrive calibration box between the cable and the driven gear. The simplest method is possible when only the speedometer driven gear needs to be changed. In some cases, the driven gear is not available small enough or large enough to complete the calibration, and the drive gear on the transmission output shaft must be changed. This is not easy due to the fact that the tailshaft of the transmission (or transfer case) must be removed to access the drive gear. An alternative is to install a custom made “calibration box” between the cable and the driven gear. This is a simple bolt-in procedure and the parts can be found at your local speedometer shop or by mail order.
There are actually two ways to calibrate a mechanical speedometer. The ratio of the drive and driven gears in the transmission (or transfer case) can be changed, or you can install a reduction or overdrive calibration box between the cable and the driven gear. The simplest method is possible when only the speedometer driven gear needs to be changed. In some cases, the driven gear is not available small enough or large enough to complete the calibration, and the drive gear on the transmission output shaft must be changed. This is not easy due to the fact that the tailshaft of the transmission (or transfer case) must be removed to access the drive gear. An alternative is to install a custom made “calibration box” between the cable and the driven gear. This is a simple bolt-in procedure and the parts can be found at your local speedometer shop or by mail order.
Flathead Fever
Well-known member
I read the post above. I forgot all about those adapters. If you look on eBay under Stewart Warner Speedometer Adapter you will see all kinds of them for sale. You unscrew your speedo cable nut, stick the the adapter on in its place and then stick your cable back on the adapter. It would take about minute to install.
Check this place out they have all kinds of speedo adapters. They claim they can make up any adapter. Its probably not going to be cheap. I remember buying those Stewart Warner speedo adapters 35 year's ago. I can't remember what phone company vehicles we had that came with these adapters from the factory? After a few years they would start leaking puddles of ATF and we would need to replace them. I'm thinking it was the Chevy 4x4 Suburbans with automatics back in the late 70s or early 80s, it's been awhile? They probably needed the adapters because of the 4.10 gears. Those adapters were really expensive from the dealer even back then. It had to be the Suburbans because I just found these photos of a NOS GM adapter for sale. As you can see it has the ratio stamped on it. The speedo shop could make just about any ratio you needed by changing the little gears inside.
Speedo adapters
http://www.txinel.com/speedo.asp
I don't know how you change the actual speedometer calibration? A spinning magnet is what usually moves the needle. Maybe you change the strength of the magnet? That's all going to be a lost art now that gauges are all electronic. There was a Stewart Warner Calibration machine on eBay awhile back. It was really neat and I wanted it bad, but it was too expensive for just a piece of garage art that maybe I would use once in a lifetime. That is the only one I've ever seen. It was a quality piece of equipment. I can't even find a photo of one on Google to show you. Now I'm upset, I should have bought it!!!!!
Check this place out they have all kinds of speedo adapters. They claim they can make up any adapter. Its probably not going to be cheap. I remember buying those Stewart Warner speedo adapters 35 year's ago. I can't remember what phone company vehicles we had that came with these adapters from the factory? After a few years they would start leaking puddles of ATF and we would need to replace them. I'm thinking it was the Chevy 4x4 Suburbans with automatics back in the late 70s or early 80s, it's been awhile? They probably needed the adapters because of the 4.10 gears. Those adapters were really expensive from the dealer even back then. It had to be the Suburbans because I just found these photos of a NOS GM adapter for sale. As you can see it has the ratio stamped on it. The speedo shop could make just about any ratio you needed by changing the little gears inside.
Speedo adapters
http://www.txinel.com/speedo.asp
I don't know how you change the actual speedometer calibration? A spinning magnet is what usually moves the needle. Maybe you change the strength of the magnet? That's all going to be a lost art now that gauges are all electronic. There was a Stewart Warner Calibration machine on eBay awhile back. It was really neat and I wanted it bad, but it was too expensive for just a piece of garage art that maybe I would use once in a lifetime. That is the only one I've ever seen. It was a quality piece of equipment. I can't even find a photo of one on Google to show you. Now I'm upset, I should have bought it!!!!!
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Vintage Copper 47
Senior Member
West Valley Instruments in Reseda CA.. right down the street from me.. great service!
https://www.westvalleyinstruments.com/
https://www.westvalleyinstruments.com/
Kurt in NJ
Well-known member
If the odometer is correct it's the speedometer that needs calibration, if the odometer is off the gearing needs change