Truck is eating drive shafts

Discussion in '80-Series Tech' started by mechanist, Feb 24, 2017.

  1. mechanist

    mechanist

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    The stock rear drive shaft was toast when I bought it. Swapped ina driveshaft from my other truck and it ate that one up in a week. Now the stock driveshaft is back in after being rebuilt, but I'm nervous its days are numbered.

    The truck came with a lift, ARB bull bar w/winch, and a rear swing out bumper. At this point the front wheel-fairing distance is measuring 3/4 inch lift and the rear is measuring 2 inches. Could my springs be bad?

    Please advise.
     
    Last edited: Feb 24, 2017
  2. riffman12

    riffman12

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    what exactly is failing in the driveshafts?
     
  3. mechanist

    mechanist

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    Universal joints.

    It was pointed out to me that the donor truck has issues - that driveshaft may have been due. So maybe both driveshafts were already due for service and failed at roughly the same time.
     
  4. Oscar Witte

    Oscar Witte

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    Are any of the rear links bent or been replaced with adjustable?
     
  5. greentruck

    greentruck

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    How much lift? Whose?
     
  6. mechanist

    mechanist

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    I'm not sure. What do you mean by "links"?

    Looks like an OME lift. The shocks are labeled OME, and there are some yellow bushings in places. I'm not sure how much lift.
     
  7. mechanist

    mechanist

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    I looked up "80 series rear links". There may be some bent links. How does that work? What do they do?
     
  8. bloc

    bloc SILVER Star

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    They keep the rear axle in place, including its rotation in relation to the truck. That rotation part is important because it determines how parallel (or not) the flanges of the pinion on the axle and rear output of the transfer case are.

    These flanges need to be parallel and the driveshaft to be "in-phase" for the oscillations of the driveshaft (caused by the angle at each u-joint at stock ride height, increased with a lift) to cancel out.

    Significantly bent links effectively shorten them, which can throw out all of the geometry and impact the driveline flange parallel. The oscillation then puts lots of stress on the u-joints.. as well as the bearings in the diff and transfer case.
     
  9. Oscar Witte

    Oscar Witte

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    If you took some pictures of the links on either side of the axle and their mounts on both sides of the truck we might see something. There's also a link above the axle that might have something funky with it.
     
  10. LINUS

    LINUS Waiting for the Great Pumpkin

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    Sounds like you swapped in a DS with bad u-joints.

    I bet with a quality pair of new u-joints in the shaft now you're over this.

    Also, I had a poor planning moment on my part & had to use a Napa UJ once - it wasn't long for this world despite being before Napa took a dump 6-8yrs back.

    Going back in with a new Toyota (Koyo jumps to mind, not positive) & it's been a non-issue for 35K+ miles where Napa got me <10K before it was noticeable. Not sure what happened.
     
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  11. mechanist

    mechanist

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    I asked the shop to send it to Carolina Driveline and have them install Spicer ujoints. The truck is on jackstands to see if gearing was swapped. Photos of links will be along shortly.
     
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  12. LINUS

    LINUS Waiting for the Great Pumpkin

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    Spicers are what's in my trail spare box, I didn't buy them myself (came with the old LX450), but they aren't getting pitched by me either.

    This is a problem in your rearview mirror, that's my bet.
     
  13. greentruck

    greentruck

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    How much lift? Whose?
    A good driveline shop will fix whatever's wrong with the driveshaft. I'll throw in my 2 cents that you have ujoints going south in both by coincidence, just that the changeover called attention to one you thought was good, when it wasn't so much. R&R the ujoints and you may be good, but always the possibility it could be a bad yoke, too.

    Recheck what was said about phasing the yokes upon reinstallation. It can go different ways and hard to say which is right if A) you didn't mark them when removed and B) that even if they had marks before whether the were properly installed or not. Install and test, then be prepared to take one end lose at a time, rotate and try again until satisfaction takes hold.

    If a newly rebuilt and balanced shaft doesn't do the trick, then check more into the links, especially if the underside looks like it's seen a lot of trail. It the getting hung on rocks and slid off that mangles the links and there's usually some sign they've seen rough duty on them if they are less than straight enough.

    One sign of issues with the link/axle relationship being bad would be a leaky pinion seal. If you see that, then you may have link issue -- or could be just a bad seal -- but would need attention either way.
     
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