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Is the rear end about to fall out of YOUR IFS rig?

Discussion in '1992-Present Chevy & GMC models' started by HarryH3, Aug 15, 2004.

  1. HarryH3

    HarryH3 1 ton status Author

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    Location:
    Georgetown, TX
    While wandering through a junkyard a few weeks ago I stumbled upon a 6-lug, 9.5 inch, 14-bolt semi-floating rear axle. Hmm, it's got a 3.73 gear set, just like the weak-a$$ 10-bolt under our '94 1/2-ton Suburban, so it should be an easy upgrade! /forums/images/graemlins/thumb.gif (And it was an easy bolt in. The pinion yokes even interchange so that you can still use the stock U-joints).

    Anyway, the nuts on the U-bolts were pretty rusted, so I just cut the U-bolts off. I was pretty amazed to find that the ends of ALL of the U-bolts were nearly rusted in two! /forums/images/graemlins/yikes.gif You can't see it because of the way that GM installed the rear end under these trucks, but the inverted U-bolt design is seriously flawed. The stamped plate that goes on the bottom of the axle does not have any drain holes. So any water, mud, salt, etc. that gets splashed into the open top of the plate is trapped there forever. This stuff builds up until it is flush with the top of the plate. But it is also packed in around the last 1-1.5 inches of the ends of the U-bolts. This slowly eats away at the unplated bolts. The truck I got the axle from was a 1990 and the U-bolts were MORE than half gone. On our '94 Sub (which has spent its entire life in dry, salt-free Colorado) the U-bolts were slightly less than half gone. So you folks that live in wetter climates, and especially those of you that live where the roads are heavily salted, should check with your local GM dealer ASAP about ordering up some new U-bolts, before you hit a bump and get a big surprise! /forums/images/graemlins/yikes.gif /forums/images/graemlins/blush.gif

    The good news is that GM seems to already know that this is an issue, since they only charge $1.70 each for new bolts. I also ordered up a new set of rust-free attachment plates. If they don't come with drain holes in them, you can bet that I'm drill some before I install the new plates. /forums/images/graemlins/whistling.gif
     
  2. 55Willy

    55Willy 3/4 ton status

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    Keizer, Or
    thanks for the heads up, I'm gonna check the work truck.
     
  3. daleearnhardt01

    daleearnhardt01 1/2 ton status

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    Location:
    Richmond, VA
    I remembered this thread from years ago and wanted to update it with some pictures. Just finished the 14SF swap in my 98 and came across this same problem. This truck has lived its whole life in VA and relatively speaking is still new. When I got it almost 3 years ago it only had 44k miles and now it has 70k.

    We could not use the impact to get the ubolts off so a portaband was used. I wanted to see how they looked and sure enough what I found was quite scary.

    So if you are driving a 88-98 truck, maybe even the newer ones, please check the condition of your u-bolts.

    [​IMG]
     
  4. jac6695

    jac6695 1/2 ton status

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    Christiansburg, VA
    Must be a 1500 truck problem. Mine were in great shape when I did the lift, and I parted a 98 work truck worked hard in mining fields (in CO though) and they were fine also.
     

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