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Driveline angles??? Please help...

Discussion in 'The Garage' started by cbrown, Feb 26, 2005.

  1. cbrown

    cbrown Registered Member

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    I recently rebuilt the rear-end in my 85 blazer. It developed a driveline shutter at certain speeds and situations (more info in other post). From reading old post I think I have narrowed it down to the driveshaft. I bought the truck with the 6" lift on it so I am not sure what degree shim is under the rear spring but it has one with the wider end towards the rear of the truck. The transfer case has also been lowered with the 1" stock spacers. My driveline angles are as follows.

    Pinon yoke is 15
    Driveshaft is 20
    Transfer case output shaft is 10

    Those seem to be off to me but I am not sure. I think I need to take out the degree shim to flaten the pinion out but I ma not sure. Any ideas. Also I think the noise could be caused my worn teeth on the slip yoke. It is a 208. Thanks
     
  2. k5floyd

    k5floyd 1/2 ton status

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    the tcase output and the pinion need to be the same angle. youll need some shims to get the pinnion angle where it needs to be
     
  3. cbrown

    cbrown Registered Member

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    Thanks for the quick response. I have a degree shim that is already installed. I am not sure what degree it is but there is one in there. Should I just take it out? Wouldn't that lower the angle of the pinion?
     
  4. ssls6

    ssls6 Registered Member

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    Since you recently rebuilt the rearend, has it ever worked right?
     
  5. cbrown

    cbrown Registered Member

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    I didn't notice it before but I think that was do to the old rear end having so much slop in it. I think it absorbed most of it. I really don't think it is the gears. Because it does it going down the road and when slowing down. Every other time it is fine. Highway speeds etc.... I read an old post and someone had had the same problem. They got a vibration once they installed new gears and most of teh advice leaned towards a driveline problem.
     
  6. FWP

    FWP CRS

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    The only way I was able to completely eliminate driveline vibration with my 6" lift was a high angle CV from Jess. If you remove the shim from the axle, you will get closer to the angles being identical, but you then increase the amount of angle. Your U joints won't last very long. You need to address the worn out parts of the slip as well.
     
  7. cbrown

    cbrown Registered Member

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    I there a bearing or something in the back of the TC? There seems to be a clunk in there when I am under the truck whike it is in N and rotate the driveshaft. The operating angle on the to ujoint is 10 and if I change the pinion angle to 9 the bottom ujoint will have 11 degrees of operating angle, I read somewhere that a uoint could sfaely operate up to 14 degrees. I may be wrong. I really just want to eliminate the vinration. It will take a lot of ujoints to add up to the cost of a cv shaft. But I guess it would eliminate the problem and I wouldn't have to mess with it again.
     
  8. FWP

    FWP CRS

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  9. AkMudr

    AkMudr 1/2 ton status

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    If yer gettin a good clunk from the bak of the tcase as you spin the yoke, keep in mind that after a while the chain stretches. My '85 does the same thing.
     
  10. ssls6

    ssls6 Registered Member

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    How did you get your transfer case to 15 degrees? Does your frontshaft work at all?
     
  11. cbrown

    cbrown Registered Member

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    FWP thanks for the link looks like exactly what I was looking for.

    SSLS6 The tranfer case is not at 15 it is at 10. It seems to slopoe down as it comes out of the TC. Almost like something is wore.

    Update I took out the rear spacers and got my pinion angle to 8 degrees. WHich put some extra stress on the ujoint but gets it to where it needs to be. The only problem is it made the noise worse. I think That may be due to pulling the slip yoke futher out of the TC. But I am unsure. Would too short a shaft give the same kind of sounds? Thanks for all the help and advice.
     
  12. diesel4me

    diesel4me 1 ton status Premium Member

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    might need new u-joints

    Be aware once a U-joint is run at extreme angles,the journals where the needle bearings ride often get "scollaped" and lumpy,once that happens they will be noisy no matter what angle they run at(and changing the angle after they have been run and have this wear pattern will aggravate the noise condition)--so to see if your angle adjustment really helped or not,you might have to put a new U-joint in to get an accurate test result..:crazy:
     
  13. cbrown

    cbrown Registered Member

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    The bottom ujoint is brand new like 20 miles on it. After talking with a local gear guy I really think it is because of an improper pinion instal. I think I haven't totally crushed the crush sleeve. But there is a lot going on so who knows.
     

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