I have a working Corbin speedo on my 1925 roadster. I even had the swivel assembly nickel plated as they were when new.
Allan from down under.
However, at a steady 35 mph on the dial, I was doing a GPS verified 38 mph. Currently it is fitted with a 68 tooth road gear and 18 tooth fibre gear. I can change the fibre gear. How much closer to an accurate indication would a 17 tooth fibre gear would I get?Speedo setting up
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Topic author - Posts: 5256
- Joined: Sun Jan 06, 2019 7:21 pm
- First Name: Allan
- Last Name: Bennett
- * REQUIRED* Type and Year of Model Ts owned: 1912 van, 1917 shooting brake, 1929 roadster buckboard, 1924 tourer, 1925 barn find buckboard, 1925 D &F wide body roadster, 1927LHD Tudor sedan.
- Location: Gawler, Australia
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- Posts: 65
- Joined: Thu Jan 17, 2019 6:55 pm
- First Name: James
- Last Name: Rodell
- Location: Kewaskum
- MTFCA Number: 14035
- MTFCI Number: 13594
Re: Speedo setting up
I don't have speedometer experience, but it makes sense that the small gear would turn 1/18th faster with one less tooth, which would give you about 2 mph higher reading at 35 mph, which would be closer to your GPS reading of 38 mph.
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- Posts: 1414
- Joined: Sun Jan 06, 2019 11:57 am
- First Name: Adam
- Last Name: Doleshal
- * REQUIRED* Type and Year of Model Ts owned: ‘13 Touring, ‘24 Touring, ‘25 TT dump truck, ‘26 Tudor, ‘20 Theiman harvester T powerplant, ‘20 T Staude tractor
- Location: Wisconsin
- MTFCA Number: 23809
- MTFCI Number: 1
- Board Member Since: 2000
Re: Speedo setting up
What size tire do you have? A slightly oversize tire might be the issue. Using the next smaller gear like Jim recommends makes sense.
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- Posts: 592
- Joined: Sun Jan 06, 2019 11:46 am
- First Name: Corey
- Last Name: Walker
- * REQUIRED* Type and Year of Model Ts owned: 1914 runabout, 1921 homemade truck, 1921 Speedster
- Location: Brownsboro, TX
- MTFCA Number: 51502
- Board Member Since: 2007
Re: Speedo setting up
The speedometer on my 14 reads fast as well. It has the correct gearing for a Stewart Model 100. If you put a different gear to make the chain spin slower then it seems like it would mess up the odometer reading, or at least in my case I think the problem is with the speedometer head. The mileage checks out good, which is determined by the gearing whereas the speed indicator is determined by the magnet rotating in the speed drum. I thought about turning the dial with numbers backwards one revolution against the stop to put more pressure on the spring that makes it return to zero. I’m not sure if that would work or not. I put the speedometer on mainly for the odometer.
Corey Walker, Brownsboro, Texas