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Dawned on me last night... What are the chances....

Discussion in 'The Garage' started by PhoenixZorn, Apr 20, 2005.

  1. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    What are the chances that the original 3.08 gears in my front diff could completely rip apart my rear 3.42 diff? It dawned on me last night that while I have 3.42s in the back, I'm willing to bet I still have a 3.08 up front. This would explain why I tore out my rear end the first day I owned the truck, and it would explain why my auto lockouts are completely ripped apart.

    So, what are the chances that my slower turning front diff on dry pavement would be strong enough to alter the speed of the transfer case enough that it would spin off the driveshaft nut in the diff, causing it to jump a tooth in the rear end, and subsequently rip a 4 inch gouge in the Wheel part of the wheel and pinion??

    Or am I on crack and the front diff speed has no bearing on the rear diff, but would explain why my front end is torn apart...

    My reason for this gear ratio belief is that the guy fixed up this truck to sell it... made it all nice and pretty for the first sucker (me) who came along to sweep it up and get it off his property. I'm pretty sure with the 3.08 original rear end, it would have been super slow, and I would have been turned off by it. But with a simple $180.00 rear gearing swap, it would appeal to the first guy who drive it as long as it wasn't in 4wd... which I took his word on working... Me=Dumbass... but oh well... I'm sunk deep into this money pit now... As soon as I have a chance, I'll pull the covers off and count the splines... I expect I'll be super pissed....

    Oh yeah... in the LMC Blazer catalog, there is a locker available for the Dana 44 stock axle, but not for the stock 10 or 12 bolt... is the Dana 44 locker interchangeable with my Corp 10 bolt?
     
  2. 1979jimmy350

    1979jimmy350 1/2 ton status

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    if you have different ratios in the front in back it will break things. If you do have different ratios just do not put it in 4x4 at all or even take out the fron drive shaft complety
     
  3. tucsonkfive

    tucsonkfive 1/2 ton status

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    When I bought my blazer it had 3.08s in the front and 3.73s in the rear (unknown to me), Shredded the transfer case. :blush:
     
  4. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    if you used 4wd and your tires are the same diameter front and rear, very good. If not, it shouldn't be a problem.

    no they are not interchangable (AFAIK). Either way, don't buy a locker from LMC, they are almost certainly overpriced. A vendor here or on pirate would be a much better option.

    j
     
  5. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Having mismatched front and rear gear ratios will put extra stress into the drivetrain, especially when driven on dry pavement in 4wd, because they are "fighting" each other, and led to broken parts.

    However, the failure you describe sounds like either bad pinion bearings or simply a loose pinion nut. Mismatched gear ratios, assuming your truck is mismatched, didn't help matters but it would have happened eventually anyway.

    I'm not sure about your theory regarding the previous owner slapping in different gears just to sell it. The difference between 3.08 and 3.42 is relatively small and hard to notice........and 3.42 gears are still way to high anyway. Considering that he could have picked up a complete 3.73 1/2 ton rear axle for $100-$150 I really don't see why he would have paid almost $200 and spent the time swapping gears..........................

    In any case you should probably verify what front gears you have before coming up with these crazy theories.
     
  6. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    Hehe... thanks for the advice... I'll be checking it this weekend
     
  7. diesel4me

    diesel4me 1 ton status Premium Member

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    I had a "mismatch" too!

    I bought a 71 K5 CST for 300 bucks years ago,and it had the rear end swapped for a 3.73,and the front was still the original 3.08 gears!--found out the reason why i got it so cheap first time I locked the hubs in!... :blush:

    I drove it for a year in 2wd,when winter came I planned to swap in a 3.73 front axle I had from a 71 Burb K10 in it--but a guy wanted to buy it for twice what I paid,so I sold it and the axle with it--he never bothered to install it,he just put smaller front tires and 31's in the rear to help "match" the wheelspeed,he claimed it worked fine,no more binding,or snapping noises from the hubs or driveline...he moved to houston,and his dad called me and asked if I wanted the front axle back,so I went and got it...its still sitting out in the backyard,15 years later! :blush:

    Its going to the crusher soon,along with a 3.08 front axle from a 73 k10,and a matching 12 bolt posi 6 lug with a very rusty housing and backing plates...Nobody seems to want/need them,so its time to cash them in I guess.. :crazy:
     
  8. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    I'll take the posi 12 bolt off your hands for the cost of gas... =)


    Wait... it's 3.08 isn't it... nevermind.
     
  9. spearchucker

    spearchucker 1/2 ton status

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    :surepal::yikes::whistle:
    And the reasoning behind doing this is .... ???
     
  10. R72K5

    R72K5 Banned

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    man if its leaf spring axle then damn i could use it for sure


    gotta be way up there in northeast, hum,.

    :/

    good luck
     
  11. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    At the time, I had no idea they could be different... hell, I thought I had 3.73s according to the PO... I was pulling 2 tons of rock on a flatbed trailer because I thought I had everything set up right... had it inspected... had a towing package... I was in mud and gravel, dropped it into 4hi, and pulled the rocks and trailer out onto the road. I figured I'd be ok driving in 4wd for the trip home, and tore apart my rear diff... I was only going in 4wd because of the weight of the load, and thought it would be safer if all four wheels were keeping me in a straight line.
     
  12. Eric M.

    Eric M. 1/2 ton status

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    That's probably what busted your rear end!!

    Mismatched gears front and rear will damage the tranfer case or U-joints before either dif.

    Good Luck,

    Eric M.
     
  13. kennyw

    kennyw N9PHW Premium Member

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    No matter what killed the rear end, don't ever use 4 wheel drive on dry pavement! It is really hard on everything even with matching gears.
     

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