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: scratchnfotraction]
#2249667
02/08/17 01:37 PM
02/08/17 01:37 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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out in the parking lot put a rear valve stem at 6 o'clock then roll the car forward in a straight line till the stem returns to the same position (grab several bricks & your tape) & measure "rollout" then divide Pi into that number for your diameter then as said go to the chart & CNXT (SP) priorly posted a comprehensive chart that is in the tenths on diameter numbers & your gear ratio. Jack the vehicle way up on the DR side to minimize fluid loss.
live every 24 hour block of time like it's your last day on earth
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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: 2,411 Weatherford, Texas
RapidusMaximus
OP
top fuel
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OP
top fuel
Joined: Jun 2003
Posts: 2,411
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: L.R Helbling]
#2250018
02/08/17 11:39 PM
02/08/17 11:39 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I would think that "rollout" would be the most accurate measurement cuz it would be exactly what the # of turns is that will be imparted to the drivetrain & something I remember from drag racers way back is that the tire might even grow some at speed. If you grabbed 2 bricks, your tape and a calculator & have ~8 ft of space in front of your car I think you could knock it out in 5 to 10 minutes. If you do it you might compare it to the tire listed dia & we can see for sure.
live every 24 hour block of time like it's your last day on earth
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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: 25,785 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,785
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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