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Real Time Help: Driveshaft alignment?

Discussion in '80-Series Tech' started by parabola, Aug 11, 2005.

  1. parabola

    parabola

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    I pulled my front driveshaft off last week to solve a vibration until I got my caster correction bushings put on. They are on now but I just realized that I only marked the diff side of the driveshaft and not the tcase side. :doh:

    Edit: From looking at the FSM it sas to mark the tcase side but I didn't see what to do if you get it mixed up. :dunno:

    Any help?
     
    Last edited: Aug 11, 2005
  2. Romer

    Romer fatherofdaughterofromer Moderator

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    I am bumping this because I would like a more knowledgeable person to chime in.

    Based on the mark that I can see in the daylight on the pinion plate, I can tell I did not put it back on exactly how it was.
     
  3. turbocruiser

    turbocruiser SILVER Star

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    Not any assistance from me, all I know is I scribed each and every connection prior to loosening them. I would assume that any section with any added weight on it at all (those round metal things spot welded to the shaft) would have to have the same orientation after removing as it did before removing. On this note I would also assume (emphasize assume) that if that section closest to the transfercase did not have a weight on it, it might not matter. Then again they likely balanced the driveshaft as an entire unit so who knows, like I wrote not any help at all huh? Do you feel any vibration??? If not I would not worry about it, if so well you only have like thirty possible orientations to try to get it right again! :doh:
     
  4. RavenTai

    RavenTai

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    Are you looking to align the two parts of the drive shaft? Or align the driveshaft to the T-case flange? I don’t know that the later matters, on the former the ears of the driveshaft must be a certain way, 90 degree's apart for the front shaft, in phase for the rear shaft. Also the 3 zirc fittings should face in the same general direction. See the diagram in the FSM.
     
  5. parabola

    parabola

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    Well, I went ahead and put it on best I can figure. Based on the existing marks on the flanges I could at least ensure that I had a 50% chance of getting it right on the tcase end. As far as vibration goes, it's again, hard to tell; the reason I took the shaft off was because I was experiencing vibrations from the lift and the caster issues. Now it vibrates at the same speed as before I took it off but significantly less (caster correction helped). I have no 'different' vibrations so I guess either I got the DS right or it didn't matter for my truck. Since I am still experiencing some vibration from the lift, I'm going to take it to a DS shop to get taken care of and I assume they'll balance it where it won't matter how I put it on.

    Raven, I was looking to align the shaft to the flange. It appears to matter because the FSM says to mark it on the tcase side when you remove it but I assume that if you are driving with it out you also need to mark the diff side. I marked only the front diff side.
     
  6. tarbe

    tarbe

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    Just make sure the guys at the shop don't try to fix your issue by putting the front shaft in-phase. That happens often. Front shaft out of phase, rear shaft in-phase.
     
  7. beno

    beno 23424-23216 Moderator GOLD Star

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    My assumption is that the marking of the drive shaft does indeed have to do with the orientation of the spinning with the relationship between the rear and the front being the same (how things line up). Before I took my drive shafts off in my driveshaft adventure experience, I did notice that when parked, all of the grease fitting (front and rear) were all the same--so basically even though the front is out of phase by 90 degrees and the rear is not, the zircs would be facing all the same direction (generally 'out') relative to the DS that they are on (they should all line up). For example, with the front DS out of phase by 90 degrees, I wasn't able to hit the one up front (on the yoke slip) because it's orientation was facing it up into the belly of the engine area. The rear one, was facing out and was accessible because it is in phase and was facing an available spot for me to hit with a grease gun. I then had to move back or forward to get the front one to appear in line so I could hit it with the grease gun (while the rear one went to a position that I could not reach--thus the 90 degree shift).

    That said, I rebuilt my DS's which meant that even if I did put match marks, they were going to be gone after I replaced the flange going into the diff., along with the mark on the yoke slip as well as on the dust cover and u-joints.

    And for balancing, they take the DS off the truck for balancing--ie: each shaft is balanced by itself, for itself...they don't balance the shafts on the truck (as far as I know with the experience I had at my DS shop).

    I would say that the matchmarks are generally used in the FSM because rarely do people actually replace drive shafts. they are inspected, cleaned, and regreased. So, the matchmarks are (again, maybe) there to allow for the DS to be replaced right back on if things are ok with the DS after removal (so you don't mess with the original orientation).

    I would try as hard as possible to 'remember,' or 'visualize' the orientation of the DS's before you took them off and try to get them back that way again.

    That said, if you did do a lift and you are experiencing DS problems, maybe a rebuild might be a good option (or at least new u-joints then a balance).

    DISCLAIMER: I am not a DS expert, but just relaying what I experienced and what seems to be intuitive to me at this point. Folks like Christo or Robbie, or CDan might have some better judgment on these issues.

    If it's any consolation, I'm just running my front DS currently and won't have my rear DS for another week. I do not have match marks on the new rear DS when I get it. Just going to throw it on and hope for the best.
     
  8. powderpig

    powderpig SILVER Star

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    Back in the old old days (some may remember) a drive shaft that comes either straight(balanced) may not then be vibration free once installed. You would then rotate the drive shaft on 90 degrees(one or more times) on the t-case or diff to find the best postion the drive shaft would be happy with. While this may sound hokey, it work very well. Now days I would not worry that much with the DS if you know they are balanced. If you just removed it and then put it back in it would then be a matter of keep the zerts all lined up to help with greaseing them. later robbie
     
  9. beno

    beno 23424-23216 Moderator GOLD Star

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    Robbie...

    Thanks for the clearer explanation.

    This makes sense.

    :cheers:
    -onur
    Akron, OH