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Driveshaft angles/operating u-joint angles??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by kpanza, Dec 26, 2001.

  1. kpanza

    kpanza 1/2 ton status

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    Hey guys,

    Did a search but couldn't find where I saw the info about d-shaft angles and how much is too much for a u-joint to handle? I have a vibration at higher speeds when I let off the gas that is really annoying me. I have a 6" lift, rear shackle flip (4") with 2.5" springs also, 14bff...anyways, got some time this weekend and measured the angles again. Here's what I got (I forgot my damn notes at home, but this is what I remember, if they are off, I will let you know):
    Driveshaft angle = 21 degrees
    T-case output = 6 degrees down
    pinion angle = 8 degrees up
    So, it looks as if the u-joints are within 2 degrees of each other, but is the operating angle (15 and 13 degrees respectively) too great? I could have sworn they were supposed to be much less than that, but thought I'd ask to make sure. Am thinking about flipping the rear shim around and seeing what happens to all the angles, and see if the vibe goes away. It is vibe free all the way up to speed, but upon getting off the gas it always vibrates on me, sounds horrible! Added info - I have the t-case spaced down an inch and the shims in back are 6 degrees...

    Thanks for any help...
     
  2. kpanza

    kpanza 1/2 ton status

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    Anyone have any idea of what the operating angles need to be? By the way, I also have a Detroit in that 14bff (I have heard that with low gears and a Detroit these vibes seem to be more prevalent...)
     
  3. Chaz88K5

    Chaz88K5 1/2 ton status

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    i am having the same prob with my shaft..i just put the 14 bolt in with the 465 so my agles are not quite as steep as yours would be with a auto...but i have them within about 2 deg. and it still makes noise when i let off doin anything above 60mph..so i also would like the answer to this one..my rear is a 14b FF 4:56 and detroit so we are set up almost the same except for the tranny

    <font color=green>Chaz</font color=green>

    [​IMG]<a target="_blank" href=http://community.webshots.com/user/chaz88k5>http://community.webshots.com/user/chaz88k5</a>[​IMG]
     
  4. blazen91

    blazen91 1/2 ton status

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    I have the same set up with the same problem. Is it possible it is the Detroit?

    <font color=red>....But I thought that sound was normal....!</font color=red>
     
  5. michaelm

    michaelm 1/2 ton status

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    i dont get what your measurements are in relation to?
    the pinion should be a few deg below so that when the axle wraps up under power it is in phase
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I got a welded 14 with the SM 465...the driveshaft is a fixed yoke version and my pinion is within 2 degrees of pointing directly at the T-case. I have no vibes at all and I've had my truck well over 90 MPH several times. Quite honestly my driveline looks like it is set up for a CV shaft.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
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  7. michaelm

    michaelm 1/2 ton status

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    relative to ground what is face of TC angle? of machined dif cover surface?
     
  8. Chaz88K5

    Chaz88K5 1/2 ton status

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    <blockquote><font class="small">In reply to:</font><hr>

    I got a welded 14 with the SM 465...the driveshaft is a fixed yoke version and my pinion is within 2 degrees of pointing directly at the T-case. I have no vibes at all and I've had my truck well over 90 MPH several times. Quite honestly my driveline looks like it is set up for a CV shaft.

    Rene

    <hr></blockquote>

    Thats what my pinion looked like befor i had the perches cut and rewelded for the 2nd time...thats when the noise was really bad....maybe there is no real answer to this question...just trial and error untill it works for you...ya think?

    <font color=green>Chaz</font color=green>

    [​IMG]<a target="_blank" href=http://community.webshots.com/user/chaz88k5>http://community.webshots.com/user/chaz88k5</a>[​IMG]
     
  9. 79Jimmy

    79Jimmy 1/2 ton status

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    Mine sounds exactly like yours Rene as far as the pinion almost pointing right at the TC, except for mine is a 14SF w/detroit. No vibes whatsoever. I never bothered measuring any of my angles, I figured if it aint broke......[​IMG] No shims on mine but I do have the ORD 4" shackle flip and 2" Tuff Country rear springs. I've lowered the TC the standard amount too.
    Works for me.

    James

    jimmy79@shaw.ca
     
  10. Chaz88K5

    Chaz88K5 1/2 ton status

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    the t-case i had it lowered but i had problems with the front shaft binding up...so i had to put it back up to the frame.....it solved some of the rear shaft vibrations but not all....witht he t-case back up stock and the pinon down its about the same as i had it with just the t-case lowered and the pinon pointing right at the t-case....have i confused ya yet...haha

    <font color=green>Chaz</font color=green>

    [​IMG]<a target="_blank" href=http://community.webshots.com/user/chaz88k5>http://community.webshots.com/user/chaz88k5</a>[​IMG]
     
  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    My T-case is dropped about 1/2"...I made some custom spacers for it.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
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  12. Chaz88K5

    Chaz88K5 1/2 ton status

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    i think i am goin to try dropin the t-case again tonight and see what happens....couldent hurt to try

    <font color=green>Chaz</font color=green>

    [​IMG]<a target="_blank" href=http://community.webshots.com/user/chaz88k5>http://community.webshots.com/user/chaz88k5</a>[​IMG]
     
  13. kpanza

    kpanza 1/2 ton status

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    But does anyone know the acceptable operating angle for a 1350 u-joint? I have dropped two shafts in the past and do not wish to repeat that...I lube the joints about twice a month to try to keep them from going dry...I also carry a spare shaft, but both times the shaft fell off it cracked the tailshaft housing at the same time...I wish I was as lucky as Rene with his setup (cv style but with no cv!), my attempt at that produced hideous vibes...as has every other way I have tried so far, except the way it is now - I just was hoping to get rid of that vibe when you are "coasting" between on the gas and off the gas...I am starting to think that it is just a side effect of the Detroit's sloppiness...I also remember someone saying that slip yoke 208/241s are more prone to this "mystery vibe" situation...
     
  14. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Are you losing your shaft due to U-joints essploding? Or is it that the shaft is too short? I really think the slip yoke is part of the big vibe problem we all hear so much about...

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
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  15. Esteban86K5

    Esteban86K5 1/2 ton status

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    Keith I get that same vibe your talking about. I have the flip in the rear with stock springs and no shim and it vibes like crazy. And only at the higher speeds while "coasting". I'm beginning to think it's just the Detroit too. I haven't done anything to it but have read everyones posts and it seems that it varies from truck to truck.

    <font color=blue>It's easier to teach a child than to fix an adult.</font color=blue>

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  16. HarryH3

    HarryH3 1 ton status Author

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    Spicer's "recommended" maximum operating angle is 4 degrees, but we're all past that as soon as the lift kit goes in. [​IMG] Wayne just spent a lot of time getting the vibes out of his. Maybe he has some ideas for you.

    <font color=black>HarryH3 - '75 K5</font color=black>
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  17. Chaz88K5

    Chaz88K5 1/2 ton status

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    well mine dose not have the slip yoke anymore and its still makin the noise..

    <font color=green>Chaz</font color=green>

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  18. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Wayne tilted his pinion up so it was sorta like mine...and it worked for him *shrug*.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
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  19. Chaz88K5

    Chaz88K5 1/2 ton status

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    shrug is right...i think its just one of thos things

    <font color=green>Chaz</font color=green>

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  20. kpanza

    kpanza 1/2 ton status

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    As long as the u-joints remain in one piece I guess I can put up with it, but I hate not being able to find the problem and get rid of it! [​IMG]

    4 degrees??? Damn, who runs theirs at only 4 degrees?? [​IMG]
     

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