Vibration at 65mph after transmission rebuild (99 Suburban)...

Discussion in 'GM Powertrain' started by cbdbcbdb, Nov 17, 2009.

  1. cbdbcbdb

    cbdbcbdb New Member

    '99 Suburban 4wd 5.7L with 200K miles...

    Due to a failed thrust bearing in my transmission (according to the dealer), I had my transmission rebuilt. All seemed great until I took it on the highway where it began vibrating in the seat at around 60mph, then peaked at around 65mph and diminished as I got faster. I took it back and the tech drove with me and concluded it was a U-joint. I told him that the two other times that my rear U-joints failed the vibration was at 50 mph, not 65. In any event, they replaced the rear U-joints and alas the vibration did not go away, so I took it back once again. They had it for several days and concluded it was the rear differential that needed to be rebuilt for $1100. Well, I just spent $2000 on the transmission and U-joints, and I don't have a good feeling about their diagnosis.

    Wouldn't I heard whining or gnashing if the rear end was bad? I hear no noises. The car runs quietly.

    Does the front driveshaft spin with in 2WD mode (not auto-4)? Could it be that shaft? It vibrates in all drive modes (2wd, auto-4x4) and even when in neutral at 65mph.

    Since I didn't have a vibration before the transmission rebuild, what could they have touched that could cause this problem?

    I need help...

    Thanks!
     
  2. mrfixdit

    mrfixdit Rockstar 100 Posts

    vibration

    It may not be related to the transmission rebuild. I had the same thing after my rebuild ( what a coincidence) it would vibrate from 65 to 70 and smooth out. Turned out to be the front stabiliser bar end had snapped.
     
  3. ejohnson03

    ejohnson03 Epic Member 5+ Years 1000 Posts

    I had recently swapped out a 350TH in my '76 Impala for a 700R4.

    A similar vibration was noticeable after the install.

    Turned out to be the rear U-jounts on the driveshaft.
     
  4. joggi

    joggi New Member

    Almost like my problem.

    I have a similar problem with my 02 K3500 Silverado. Had the center bearing and bushing replaced on the segmented drive shaft after which I noticed a vibration that felt like driving on a small set of snow chains or studded tires between 45 and 55 MPH. The vibration is most noticable through the steering column. No vibration below or above that speed. Tried everything. Nothing helps. The vibration is not affected by tire balance, selection of gears, 4WD, coasting through it in neutral, whatever. Took it to a reputable shop where they installed a shim to get the vertical shaft alignment straighter. This moved the vibration down to 35 to 45 MPH. U joints are good. Now what? Haven't checked the fronn stabilizer bars. Would appreciate some suggestions from anyone.
     
  5. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Your differential is not going to vibrate unless the pinion nut is loose. It would also be very noisy if that were the case. I would run away from this dealership as fast as you can!
    My guess is during the R&R the drive shaft was taken apart without marking the 2 half's and now the drive line is out of phase. This is very common especially when the technician doesn't know any better.
     
  6. cbdbcbdb

    cbdbcbdb New Member

    Vibration Update

    After taking it to another shop which said the dealer installed the wrong U-joint on the rear of the driveshaft, I took it back to the dealer to confront them about it. I put the "faulty" U-joint on the counter and immediately asked for the mechanic that did the work. I had not spoken with that mechanic previously because I had picked-up after hours. This time, I got the full explanation.

    Apparently my rear driveshaft yoke has been splayed open and the U-joint can slide from side to side in the joint and cannot be perfectly centered. The mechanic said that while he had the driveshaft off, he noticed noises and excess play indicating that the pinion bearing in the rear differential was failing. He recommended the rear yoke replacement plus the rear differential rebuild, particularly since this suburban has 200K miles on it.

    His explanation made good sense and the dealer immediately offered to pay me for my excursion to the other shop ($150). I would like to know how the yoke magically got bent while in their care. I can't argue, however that the rear-end has over 200K on it and probably should be rebuilt.

    We'll see later today. I know to pick up during hours and speak directly with the mechanic from now on. It sucks, but after this I will have a rebuilt transmission, new rear-end and a new transfer case in the past 50K miles which should all give me another 150K-200K miles.
     
  7. joggi

    joggi New Member

    With the segmented drive shaft phasing is impportant, but the center joint has a doublt tooth to make it keyed. It can only be mated in one way. I believe that the transmission end is not keyed so there is a possibility that the shaft at the transmission may have moved a few teeth in either direction which would change the rear U joint phasing with the transmission but that doesn't seem like it could cause a vibration. Is it possible that one of the weights installed when the shaft was balanced may have come loose and fallen off during the repair? I may have the center bearing/bushing replaced again because it is definitely related to the drive shaft.
     
  8. cbdbcbdb

    cbdbcbdb New Member


    Good point about the center bearing. In my case, the center bearing is the transfer case. They had to pull the transfer case and rear driveshaft to remove the transmission for rebuilding. Maybe they knocked off a balance weight.

    It wasn't finished today, so I guess I'll find out tomorrow. I suspect they test drove the car today and the vibration is still there.
     
  9. cbdbcbdb

    cbdbcbdb New Member

    I picked up the suburban and was assured that the vibration was fixed as I walked out the door. Took it on the highway and it still vibrates. It's much tighter though, vibrating at 65.5 mph. It feels like it's coming from under my seat.

    I'm very disappointed. Could it be the front driveshaft U-joints?

    I'm going to check the front U-joints myself...
     
  10. JimmyHater

    JimmyHater New Member

    Same Issue

    I have a 96 GMC Jimmy 4x4 with the same 65 mph vibration that you have. Were you able to determine your problem? I have tried just about everything...tires, road force balance, new stabilizer bar links, cv half-shafts, rear u-joint, hub assemblies. I'm in the process of removing the half-shafts from the front to see if the vibration is caused by the front differential. The driveshaft doesn't appear to be missing any weights, but that doesn't mean it isn't balanced. I'm starting to think that my chances to write a letter to GM asking for a free vehicle will be more promissing than getting this vibration to go away.
     

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