2013 RAM 1500 321 > 392 Flash?

Discussion in 'Engine & Performance' started by nforkram, Jan 8, 2017.

Sponsored By: Moe's Performance
  1. nforkram

    nforkram Member

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    Just bought a used 2013 RAM 1500 Laramie, with 3.21 gears no LSD. Looking into possibly upgrading to 3.92s and adding the LSD. If I did that, would I need to have the computer flashed?
     
  2. Kotta390

    Kotta390 Senior Member

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    Not at all.
     
  3. Bobbo

    Bobbo Senior Member

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    Really? Jeeps go into limp home mode if you don't recalibrate for the new gear ratio. Since the vehicle speed sensors don't match up with the wheel speed sensors.
    I imagine the speedometer would be way off without a flash as well.
    I'm curious as I just ordered my 3.92s and look to install them soon.

    Sent from my LG-H820 using Tapatalk
     
  4. Kotta390

    Kotta390 Senior Member

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    I can't speak for Jeeps. On the Rams, changing the gear ratios require literally nothing more than the actual install. Been done thousands of time and there has never been in issue that I know of. I changed from 3.21 open to 3.92 LSD and have roughly 20k miles with zero issues.
     
  5. Bobbo

    Bobbo Senior Member

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    Good to know! Makes life a lot easier if warranty work for some other issue is needed. Don't have to worry about the dealer PCM updates.
     
  6. nforkram

    nforkram Member

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    Thanks for the replies.

    That front end is going to be a PITA. Moe's got me hooked me on (rear 3.92 R&P, install kit, got the Mag-Tech Diff Cover, OEM LSD and Bilstein shocks, w/ adj fronts for leveling) everything but the front diff, going to have to get that from MOPAR.

    I bet if I ask my dealer service rep guy, he'll say yeah you need to reflash!

    Kotta390 - Where did you find a front diff from? New or salvage? or something other, like maybe your truck is 2wd!
     
  7. 69GWC

    69GWC Senior Member

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    So is the ring gear welded to the carrier ? is that the problem with the front.
    Seems like the aftermarket would make a ring gear and new carrier if that's the case.
     
  8. WilliamS

    WilliamS Senior Member

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    I would think your speedo will be off with the new gears, as well the shift points in the trans are based on load and rpm, seeing that you will be higher than expected rpm Im surprised it doesnt throw a fit?
     
  9. Kotta390

    Kotta390 Senior Member

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    No because for the longest time the Dodge trucks have used "Speedometer" speed based on wheel speed, not ring gear/differential speed sensors. Change your tire size and the speedometer will be off. Change your differential gear set and it doesn't care. The shifting will also be the same. I have owned a 2nd, 3rd and 4th gen and changed the gears in all of them and the speedometer never once was off by anymore then it was from the factory.
     
  10. dkmesa

    dkmesa Senior Member

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    Man, you should really start checking the gear ratio you want on the build sheet haha. Just messing with you.
     

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