Re: Changing speedo gear???
[Re: moparx]
#2249658
02/08/17 01:17 PM
02/08/17 01:17 PM
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Joined: May 2003
Posts: 15,487 Florida
scratchnfotraction
I Live Here
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I Live Here
Joined: May 2003
Posts: 15,487
Florida
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the tech archive at the top of the page has a speedometer gear chart you may find useful also. I agree. I used it to figure out the collection of speedo gears I needed for my junk. yours will depend on tire size but mine are 235/75/15 2.76 = 25 tooth 3.21 = 29 tooth 3.23 = 29 tooth 3.55 = 32 tooth 3.91 = 35 tooth 325/50/15 2.76 = 26 3.23 = 30 3.91 = 36
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Re: Changing speedo gear???
[Re: RapidRobert]
#2249686
02/08/17 02:02 PM
02/08/17 02:02 PM
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Joined: Jun 2003
Posts: 2,406 Weatherford, Texas
RapidusMaximus
OP
top fuel
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OP
top fuel
Joined: Jun 2003
Posts: 2,406
Weatherford, Texas
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Excellent! Not only did I change gears you guys thumped me into remembering that I went from 14" to 15" tires also...sweet! Preferred gear sources?
1968 Plymouth GTX 1974 Dodge P/U Long Bed Stepside 318 2019 Ram 2500 6.4, auto, 4WD
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Re: Changing speedo gear???
[Re: A727Tflite]
#2250458
02/09/17 05:11 PM
02/09/17 05:11 PM
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Joined: Jan 2003
Posts: 25,618 Rio Linda, CA
John_Kunkel
Too Many Posts
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Rio Linda, CA
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Sxrxrnr- the diameter of the tire is not what is needed here - what you need is the "loaded tire radius". I disagree. The rollout (which computes to true diameter) will differ from the squatted radius.
The INTERNET, the MISinformation superhighway
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Re: Changing speedo gear???
[Re: A727Tflite]
#2251106
02/10/17 04:37 PM
02/10/17 04:37 PM
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Joined: Jan 2003
Posts: 25,618 Rio Linda, CA
John_Kunkel
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Rio Linda, CA
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You can disagree all you want - what do you have to back it up? My actual measurements...try it yourself.
The INTERNET, the MISinformation superhighway
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Re: Changing speedo gear???
[Re: BDW]
#2251235
02/10/17 08:37 PM
02/10/17 08:37 PM
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Joined: Jan 2003
Posts: 25,618 Rio Linda, CA
John_Kunkel
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Too Many Posts
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Posts: 25,618
Rio Linda, CA
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Example, the manufacturer of my 235/70R15's says they are 28" in diameter but the rollout is 84" which equates to a diameter of 26.73".
The INTERNET, the MISinformation superhighway
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Re: Changing speedo gear???
[Re: Sxrxrnr]
#2251743
02/11/17 06:25 PM
02/11/17 06:25 PM
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Joined: Jan 2003
Posts: 25,618 Rio Linda, CA
John_Kunkel
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Too Many Posts
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Rio Linda, CA
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At the risk of repeating myself, I think it's ill-advised to change a speedo pinion based on a GPS speed readout; the odometer is the best indicator of correct/incorrect pinion, not the speedometer. If the odometer is correct, then any speedo error is in the head, not the pinion.
The INTERNET, the MISinformation superhighway
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Re: Changing speedo gear???
[Re: John_Kunkel]
#2251799
02/11/17 08:02 PM
02/11/17 08:02 PM
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Joined: Jan 2003
Posts: 338 Montreal Quebec
STROKIE
enthusiast
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enthusiast
Joined: Jan 2003
Posts: 338
Montreal Quebec
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At the risk of repeating myself, I think it's ill-advised to change a speedo pinion based on a GPS speed readout; the odometer is the best indicator of correct/incorrect pinion, not the speedometer. If the odometer is correct, then any speedo error is in the head, not the pinion.
Thank you John, for the clarification. That's why I like Moparts.com
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Re: Changing speedo gear???
[Re: STROKIE]
#2252816
02/13/17 05:33 AM
02/13/17 05:33 AM
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Joined: Jul 2013
Posts: 1,272 Northern Calyfornua
Sxrxrnr
pro stock
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pro stock
Joined: Jul 2013
Posts: 1,272
Northern Calyfornua
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At the risk of repeating myself, I think it's ill-advised to change a speedo pinion based on a GPS speed readout; the odometer is the best indicator of correct/incorrect pinion, not the speedometer. If the odometer is correct, then any speedo error is in the head, not the pinion.
Thank you John, for the clarification. That's why I like Moparts.com The above illustrated app if you forego the 'free' version and step up to the paid version(2 bucks was what I paid) you get among other niceties, includes odometer support and a history/log file. . The cost of a small order of fries at Macdonald's. What could be simpler and more effective?
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Re: Changing speedo gear???
[Re: BDW]
#2253588
02/14/17 04:09 PM
02/14/17 04:09 PM
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Joined: Jan 2003
Posts: 25,618 Rio Linda, CA
John_Kunkel
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Too Many Posts
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Posts: 25,618
Rio Linda, CA
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The same size tire from the same manufacturer can be different in diameter due to coming from different molds and the diameter of the same tire will vary with the width of the wheel it's mounted on.
The INTERNET, the MISinformation superhighway
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