02-21-2019, 08:39 AM | #1 |
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Speedo gear
My Speedo is off by 5 mph on the plus side. I’ve been checking into the drive gear. I didn’t rebuild the rear end. I see in the parts catalog that there’s 2 different gears that can be used in a stock rear. 18 and a 19 tooth gear. On the drive housing it has a 19 stamped on it does that mean I have to 19 tooth gear or is the housing interchangeable except ether gears?
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02-21-2019, 11:34 AM | #2 |
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Re: Speedo gear
At what speed is it off by 5?
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02-21-2019, 11:58 AM | #3 |
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Re: Speedo gear
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02-21-2019, 12:41 PM | #4 |
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Re: Speedo gear
The 19 stamped on your speedometer gear case means it had a 19 tooth gear when the car was made. As the gear can be changed it is easy to remove the gear and case assembly and count the gear teeth in it now. If a different gear is needed they can be changed.
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02-21-2019, 12:49 PM | #5 |
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Re: Speedo gear
Check your odometer first. If it is correct then you have a problem with the speedometer that needs to be fixed.
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02-21-2019, 01:13 PM | #6 |
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Re: Speedo gear
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02-21-2019, 01:15 PM | #7 |
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Re: Speedo gear
gps?
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02-21-2019, 01:27 PM | #8 |
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Re: Speedo gear
What John Buckley said. I rely more on my GPS than the speedometer. I don't think any of the instruments on the Model A are very accurate anyway and I don't rely on them. I don't drive much over 50 and I'm too busy with the controls to notice.
There was a guy here on the Barn that used a stick to check the gas. He calibrated the stick by adding a gallon of gas to the tank until he got to 10 gallons! David Serrano |
02-21-2019, 01:28 PM | #9 |
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Re: Speedo gear
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02-21-2019, 01:52 PM | #10 |
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Re: Speedo gear
I’ve checked it with my gps. When I’m going 40 mph on the Speedo the gps shows 35 mph so how do I fix it to be more accurate? Or should I just leave it alone
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02-21-2019, 02:49 PM | #11 |
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Re: Speedo gear
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02-21-2019, 03:50 PM | #12 |
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Re: Speedo gear
The attached may be of help.
Tom Endy |
02-21-2019, 04:23 PM | #13 | |
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Re: Speedo gear
Quote:
Leave it alone, you’ll never get a speeding ticket. Besides, it won’t cost you anything. David Serrano |
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02-21-2019, 05:29 PM | #14 |
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Re: Speedo gear
Here, if you go more than 3 kph (2 mph) over the limit, you stand to get a ticket so we are more fussy about speedo accuracy. There was a thread here a while ago about this subject and it became clear that there is an adjustment that can be made inside the instrument to make them more accurate.
The speedo in my '30 CCPU reads 10 mph fast at 50 mph - so far off that that internal adjustment won't do it. I won't get fined for being under the limit so i have decided to leave it alone and "drive by ear". I agree with what has been said above about check the accuracy of the odometer first, then worry about the speedo only after that is right.
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02-21-2019, 06:32 PM | #15 | |
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Re: Speedo gear
Quote:
Thanks
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02-21-2019, 06:42 PM | #16 |
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Re: Speedo gear
The first thing you should do is check and see if the odometer is reading correctly. Drive somewhere where there are mileage markers along the side of the road. Check your odometer against the mileage markers. You should do it for at least 5 miles. If the reading is off, then the gear needs to be changed. If the odometer reading agrees with the mileage markers, then the problem is in the speed calibration of the speedometer. When you get to that point, let us know.
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02-21-2019, 11:34 PM | #17 | |
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Re: Speedo gear
Quote:
Charlie Stephens |
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02-22-2019, 12:32 AM | #18 |
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Re: Speedo gear
Okay I understand thanks
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02-22-2019, 05:53 AM | #19 |
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Re: Speedo gear
>>When I’m going 40 mph on the Speedo the gps shows 35 mph so how do I fix it to be more accurate?
Use 4 inch bigger tyres. http://www.onlineconversion.com/bigger_tires.htm |
02-22-2019, 02:43 PM | #20 |
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Re: Speedo gear
I bought an adapter from Clark Brothers Instruments. You screw it to the transmission and then screw the cable into it. I sent them the speedometer reading and my GPS speed reading and they calculated the right ratio for the adapter. Reads dead on with my gps now.
http://clarkbrothers.net/ratio_adapters.html 56680 Mound Rd, Shelby Township, MI 48316 USA Tel: 586-781-7000, Fax:586-781-7005, Email: [email protected]
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