Tailshaft extension crooked?

Discussion in 'Transfer Cases' started by Regal_Six, Apr 9, 2019.

  1. Regal_Six

    Regal_Six Newbie

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    Long story short, about a month ago the rear end blew up in my '96 Suburban and took almost the entire powertrain behind the transfercase with it. Bad enough that the slip yoke snapped. Anyways, I'm 90% through swapping in a new axle unit and complete driveshaft from a junkyard. I pulled my old tailshaft extension off to check for damage to it or the output shaft, everything looked good so I put a new seal on and installed it. When I went to slide the new driveshaft in, it went about 1 and a half inches and then stopped. Could not get it in an further. So I took the old broken yoke and put it up there and was able to get it to slowly go with a little tapping with the hammer... didn't go for too long, just wanted to see if it would go. I messed around with it for awhile and finally decided to loosen up the bolts on the tailshaft and just cracking those loose was enough to get the yoke to slide in all the way with little effort. But when I tightened the bolts back down (between 30 and 35 ft lbs, my torque wrench sucks) the driveshaft was too tight to slide the back u-joint into the rear axle pinion flange. SO, I loosened the tailshaft and got it in place and tightened everything back up. Any idea whats going on here? I can't imagine the output shaft was bent at all, bearing looked okay... Maybe just the new seal being slightly oblong?
     
  2. Regal_Six

    Regal_Six Newbie

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    Well y'all are no help! Quick update in case anyone has a similar issue in the future:

    Started pulling the rear of the transfer case off so I could address a little drip leak from the gasket between the transfer case and the rear bearing housing (tailshaft extension comes out just fine, the bearing housing you'll have to loosen up the xfer case mounting bolts and put a jack under it so the housing will clear the crossmember with the torsion keys in it). Went to unbolt the rear bearing housing and after I took the first bolt off the flange that had the bolt hole in it fell off and hit me in the head. Apparently when the driveshaft snapped it put enough force on the transfer case to put a fracture in the bearing housing.

    The little flange was broken all the way off, but the crack was so neat I couldn't see it with everything assembled. I went over that case a half a dozen times with a bright ass LED light and never saw that crack until I took the bolt off.

    Anyways, I'm guessing the housing cracked, which made the output shaft sit a little crooked, just enough to give me a struggle reinstalling my slip yoke and throw my rear spead sensor off. I read somewhere that on this year GMT400 the ABS system used the two front wheel sensors and the speedometer sensor on the transfer case to do all it's magic. So even though my speedometer was working in the cab, it's probably a little off - just enough that when the ABS read the front wheel speed and then read the transfer case speed there was enough of a difference to turn the check ABS light on.

    Got a core from a local yard with a good case on it sitting in my truck now, going try try get the good parts on today or maybe tomorrow. I'll update again if this made the problems go away.

    Hope this helps somebody down the line, sure has been giving me a headache. :banghead:
     
  3. Regal_Six

    Regal_Six Newbie

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    Late update: New housing shaft didn't fix the ABS light, but it at least fixed the leak. Took it to a local shop to have the code scanned: came back with no left wheel speed sensor signal, no right wheel speed sensor, no speedometer sensor, and a rear dump valve fault. Guy figured the module was bad. Trip to the junkyard and $30 later I dropped an ABS module off a 99 suburban on and the light went away.

    So in the space of a couple seconds I managed to:

    Shatter the rear carrier, gouge both axle splines, dent the diff case cover, destroy both axle seals, gouge the pinion and ring gears, snap a spider gear, break the rear U-joint in half, shear the slip yoke, break the transfer case housing, and blow the ABS module. When I break stuff, I break it hard!

    Hope this helps someone in the future.
     
    andy396 likes this.

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