| fsacht | -- 10-05-2015 @ 4:29 PM |
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49 Ford speedometer reads 10 MPH low at all speeds. Any of you know how the speedometer itself is adjusted? The speedometer. We know all about speedo gear changing and tire size variations and check the odemeter to measured mile, and lude the speedo thru the little hole on top where the cable goes in, etc. The speedometer. How are they adjusted within themselves? Any help with that other than send it to a speedo repair shop? How does the repair shop do it?
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| cliftford | -- 10-06-2015 @ 7:01 AM |
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What method did you use to determine the speed indication? If indeed it is off, your only option is to send it to a repair shop. I have never seen a speedometer that has an external adjustment. This message was edited by cliftford on 10-6-15 @ 7:04 AM
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| joe b | -- 10-06-2015 @ 12:40 PM |
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I wondered the same as clift. To my knowledge there is no adjustment that you can do. In my '41 speedo there is a magnet that the shops do something with. My suggestion is to send it out for repair. I used: Bob's Speedometer 1 800 592 9673 www.bobsspeedometer.com You might call and ask for tech reps. They might help you understand how it works. I doubt they will talk you through the repair. (:
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| fsacht | -- 10-06-2015 @ 2:29 PM |
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Method I used to determine irregularity;: Drive at steady speeds. Driver of car with digital speedo display behind me recorded digital speed. This on long straight smooth country road. Had removed properly functioning speedometer and installed the one in question to perform study. The "bad " speedo had been repaired at a hefty price by a speedo guy in Davenport Iowa who used to advertize in V8 times who on report of my dissatisfaction suggested I was imagining things. Thought since I have a good one now in service I'd try to tinker with this one. Thanks to all. I'll just put it back in the box. Maybe sell it in the spare instrument cluster I have with caveat to buyer.
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| 40 Coupe | -- 10-07-2015 @ 4:21 AM |
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There is a spiral spring inside the speedo just behind the face. The spring has to be able to return the speedo to zero but it can be slightly tight and cause inaccuracy. Suggest you take a good reading speedo on a drill motor (reverse rotation) and check MPH at full speed should be about 70MPH then attach the speedo requiring cal. and go to full speed if still 10MPH off move the spiral spring adjuster slightly to correct, check zero to make sure the needle always returns. Recheck several times.
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| fsacht | -- 10-07-2015 @ 5:52 AM |
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40 Coupe. I've got the picture and I'll try that. Though the needle always returns to zero and the minus ten speed reading is consistant at any speed, my baseline must be off zero.
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| fsacht | -- 10-07-2015 @ 3:39 PM |
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OK! 40 coupe had the ticket. Yes, there is a coil spring behind the face attached to the shaft that connects the speedo needle to the speedo mechanism. A quater inch hex nut secures the needle to the shaft. Loosened the nut, rotated the needle, secured the nut and bent the downstanding flange that acts as a return stop, an integral part of the mechanism housing, to align the needle at zero when at rest. A couple tweeks and it's fine. Grateful too that you said run the drill motor in reverse. Would not have otherwise considered that. Many thanks to 40 coupe and all who offer suggestions and advice.
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