4-lo problems

Discussion in 'General Discussions' started by TxFx04, Mar 12, 2012.

  1. ksingltn

    ksingltn Full Access Member

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    the 4 lo is such a dramatic gear reduction you need to be going slowly with no load on the drivetrain. It would be comparable to shifting a stick shift car from 4th to 2nd while at road speeds without using the clutch. Shift on the Fly to 4 hi will allow you to shift into 4wd while maintaining the momentum you need, giving you an identical gear ratio but simply engaging the front wheels.
     
  2. iFX4

    iFX4 Chief

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    Every electronic 4wd drive truck i have ever driven i had to put the truck in nuetral and slow to 5mph before it would kick in...4high never matters...especially on my dads raptor....you can be doing 80 in 4 hi in that thing
     
  3. TxFx04

    TxFx04 FFS Frequent Traveler

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    oh but does 4-lo work miracles, i tried pulling my friend out in 2wd and my rear end began to sink and i put it in 4-lo(eventually) and she hopped out of the rut while attached to his truck with ease
     
  4. VanoFord

    VanoFord Banned

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    ok, so that makes sense then. you'd shift on the fly into 4hi from 2wd and have no problems, but then say you became stuck/stopped, you could then switch to 4lo to get that gear reduction for added bite and get you out of the hole. thanks for the lesson :birgits_tiredcoffee
     
  5. TxFx04

    TxFx04 FFS Frequent Traveler

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    alright vano now get that sas done lol
     
  6. backwoodscountryman

    backwoodscountryman Broken Truck Edition

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    I agree:jester:

    KSinlton-Thanks for explaning it the way you did.Made much more sence there than when a budy of mine tried to explain it to me:waytogo:
     
  7. ksingltn

    ksingltn Full Access Member

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    No problem guys. Found this pic and pointed out the key parts for a basic understanding.

    [​IMG]

    This is a typical setup. (Happens to be a ZF5-42 with a Borg Warner 1356, same setup I have in my truck, snagged the pic off google) The front output is powered by a large, heavy high speed chain. (Some older ones as well as some imports use gears, but most these days are chain driven) This chain runs inside the chain housing. See picture below
    [​IMG]

    When in 2wd, this chain is not under power. It is disconnected from the rear output and the gear reduction box.

    When the transfer case is shifted into 4 HI, it simply locks this chain to the output of the gear reduction box, thereby powering the front wheels.

    When the transfer case is shifted into 4 LO, it keeps the chain locked in powering the front wheels, but it also engages the gear reduction box, causing a gear reduction of about 2.5:1, depending on year and t-case model. (Mine is 2.69:1, a ranger/explorer is typically 2.48:1, an 04ish F-150 is 2.64:1) This gear reduction is what causes the "crawl" effect while in 4 LO. This is also why you can't go more than 40ish MPH in low range, because the engine/transmission reach their rpm limits.

    Simplified, driving an 04-08 F-150, if you were driving 15mph in low range you would be turning the same rpms in the same transmission gear as you would driving at 40mph in 2wd or 4 HI.
     
  8. TxFx04

    TxFx04 FFS Frequent Traveler

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    very useful info, thanks! :waytogo:
     
  9. THEPRODJECT01

    THEPRODJECT01 MARKK

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    mine goes in 4 low in nuetral every time, just mash the brake pedal and wait for the click sound to signal that its engaged, works every time for me, you just have to have it in neutral , and you have to have the brake pedal engaged
     
  10. iFX4

    iFX4 Chief

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    thanks bro
     

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