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    Author Topic: Swapped Out 3.91  (Read 914 times)

    Offline Madmax440

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    Swapped Out 3.91
    « on: May 19, 2007 - 09:08:59 PM »
    Swapped out the 3.91 gear for a 3.55 and now the speedometer is off by an estimated 5 MPH. The tires that I am running in the back are 275 60R15. Can someone tell me what I have to do to straighten this out ???   
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    Offline Moparal

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    Re: Swapped Out 3.91
    « Reply #1 on: May 19, 2007 - 09:15:31 PM »
    First off, you need to send me the 391's. Yearone and other suppliers sell the right gear for the speedo. Average price is 15-20 bucks for it :2thumbs:
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    Offline Madmax440

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    Re: Swapped Out 3.91
    « Reply #2 on: May 19, 2007 - 09:22:32 PM »
    Sorry, already gave it away. I just found this question posed in another coversation about the speedo pinion gear. Directed me to a nice little chart where I entered the tire size, gear size and lo and behold, it said that I woukd be needing to send Moparal the 391 and buy a 33.25 speedo pinion gear.
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    Offline BIGSHCLUNK

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    Re: Swapped Out 3.91
    « Reply #3 on: May 19, 2007 - 09:28:31 PM »
    Just curious, how many rpm's did you drop at 65 mph?????
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    Offline GoodysGotaCuda

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    Re: Swapped Out 3.91
    « Reply #4 on: May 20, 2007 - 06:32:19 AM »
    Quote from: BIGSHCLUNK on May 19, 2007 - 09:28:31 PM
    Just curious, how many rpm's did you drop at 65 mph?????

    3.91 @ 65 - 3049rpm
    3.55 @ 65 - 2769rpm
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    Offline Madmax440

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    Re: Swapped Out 3.91
    « Reply #5 on: May 20, 2007 - 07:10:09 PM »
    Actually the rpms were a little higher - Like 3300 at 65 and now its around 2700
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