correct speedo gear for rear end?

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    Author Topic: correct speedo gear for rear end?  (Read 3207 times)

    Offline Katfish

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    correct speedo gear for rear end?
    « on: May 28, 2004 - 10:03:59 PM »
    I put a new nylon speedo gear in my transmission and noticed it had more teeth than one I took out (41 vs 36).

    I bought this part many years ago from year one.  At the time they had nice info indicating which speedo gear for each rear end.  

    The new catelogs no longer show these parts.  Anyone have any info that matches the speedo gear to rear end ratio.

    I probably bought this part when I was planning on putting a 3:54 Dana in the car, never did.  It still has the 8 3/4 and I have no idea what ratio.

    I'm trying to figure out just how much my speedometer will be off.

    Thx
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    Offline oldvamoparfan

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    • MOPAR; The only way to go!!!!!!!
    Re:correct speedo gear for rear end?
    « Reply #1 on: May 28, 2004 - 10:37:22 PM »
    You dont say what tire size is on car, but genrally speaking, a 41 gear is going to be right for a 3.91 or 4.10 gear, unless you have really tall tires.  One of the guys put a speedo gear/axle ratio/tire height chart on the thread a little while back.  Might have been Chryco???  I think finding that will help you.   Ovmf
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    '72 Challenger 360,  '05 Dakota,   04 Town & Country,   '82 Yamaha 650 Maxim

    Offline Moparmatt

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    Re: correct speedo gear for rear end?
    « Reply #2 on: June 02, 2004 - 05:05:49 PM »
    I thought the general assumption was that there should be an equal amount of teeth on the gear as to the first digits of the rear ratio: 35 tooth gear for 3.55, 41 tooth gear for 4.10...But I could be wrong.
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    Offline heminut

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    Re: correct speedo gear for rear end?
    « Reply #3 on: June 02, 2004 - 06:44:13 PM »
    Quote from: Moparmatt on June 02, 2004 - 05:05:49 PM
    I thought the general assumption was that there should be an equal amount of teeth on the gear as to the first digits of the rear ratio: 35 tooth gear for 3.55, 41 tooth gear for 4.10...But I could be wrong.

    That would probably get you real close with a 26" tire. I use a 39 tooth gear with my 4.10 rear and it is right on with 28" tires.
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    1970 5.7 Hemi Cuda

    Offline RusTy/SE

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    Re: correct speedo gear for rear end?
    « Reply #4 on: June 05, 2004 - 02:53:36 PM »
    katfish, this link might help...http://www.mymopar.com/speedometer.htm

    tfn
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    Russ
    2001 Durango     1B4HS
    1970 Challenger  JS29U
    Restoration thread: http://www.cuda-challenger.com/cc/index.php?topic=27173.0
    Member since December 13, 2002

    Offline Katfish

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    • 70 Challenger
    Re: correct speedo gear for rear end?
    « Reply #5 on: June 07, 2004 - 10:00:49 PM »
    thanks TFN, that's what I needed!    :)
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    Offline RusTy/SE

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    Re: correct speedo gear for rear end?
    « Reply #6 on: June 07, 2004 - 10:33:28 PM »
    You're welcome :)

    tfn
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    Russ
    2001 Durango     1B4HS
    1970 Challenger  JS29U
    Restoration thread: http://www.cuda-challenger.com/cc/index.php?topic=27173.0
    Member since December 13, 2002

    Offline GreenFish

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    Re: correct speedo gear for rear end?
    « Reply #7 on: July 16, 2004 - 12:32:26 PM »
    do a search on ebay for mopar speedo  and there is a guy selling the gears. he states on the description what gear and tire size its for.
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    70 cuda, 440, KB pistons, 10.5:1 compression, edlebrock heads,RacerBrown cam, 5-Speed Tremec, Megasquirt EFI

    Offline GreenFish

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    Re: correct speedo gear for rear end?
    « Reply #8 on: September 08, 2004 - 07:25:58 AM »
    I bought a gear from that guy.. good service, and he sells MOPAR stuff.  I havent installed the gear i bought from him as im going to a Kiesler 5-speed this winter.
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    70 cuda, 440, KB pistons, 10.5:1 compression, edlebrock heads,RacerBrown cam, 5-Speed Tremec, Megasquirt EFI
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