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Ripped-out the rear driveshaft !

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Overdrive, Nov 27, 2000.

  1. Overdrive

    Overdrive Registered Member

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    Well it happend again, this time on the trail. I have a 77 K5 with a 4" lift, springs all the way around (no blocks), dropped transfer case (inverted the spacers), and still vibration killed the transfer case side u-joint. I did NOT have the factory drive shaft lenghtened. I cracked the drive shaft side ujoint mount so I need a new driveshaft. I spoke with Mesa driveshaft and it looks like about 320.00 for a new, longer one. I am debating on wether to just attempt a longer shaft or try adding a CV joint. It only adds 20.00 to the driveshaft price but I need a different yoke on the transfer case, 65.00. Mesa assured me that I will be able to service the CV joint myself (to replace the u-joints).

    I have seen several discussions on the vibration issue and people have reported that with a 4" lift, droped transfer case, and a longer drive shaft their vibration problems disappered. Has anyone tried this setup and STILL have vibration problems? I am leaning toward the CV joint solution to nip this thing in the bud!

    Here is my precise setup:
    77 K5
    NP203 converted to parttime
    4" Rough Country springs, front and rear (rides excelent! much better than rear blocks)
    Dropped transfer case using the stock spacers
    Had the factory driveshaft but moving to longer shaft and possibly CV joint

    Something to note, I bought an angle finder and the driveshaft angle is at 15 degrees (ouch). I have read that this is basically the MAXIMUM angle a u-joint can function at, so the u-joint life should be about 6 months, max.

    I had the same problem on a previous 77 K5, and a longer driveshaft still did not fix the vibration problem.

    Any further info would be apreciated.

    Thanks,
    Overdrive
     
  2. Overdrive

    Overdrive Registered Member

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    Yes, You can make it home !

    As a side note....
    I was 205 miles from home on Thanksgiving night and I limped the truck home! Kicked-in the 4-wheel-drive and putted back to Phoenix at 45 MPH. I can still say, "this truck has never left me stranded!."
     
  3. Pookster

    Pookster 1/2 ton status

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    Re: Yes, You can make it home !

    Not that I have done this myself, but I have read a lot of articles about the function of U-Joints. Basically, you are right, you will have to use a CV solution if your driveline is at 15 degrees. Im surprised it even turned.
     
  4. Jason73K5

    Jason73K5 1/2 ton status

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    Go for the CV joint, it will pay for itself many times over in the future. It should at least partially cure your vibrations. I used to blow out u-joints about every 500 miles untill I got a CV joint. Since then I've gone coast to coast 3 times on that CV joint with zero problems.
     
  5. FLWIV440

    FLWIV440 Registered Member

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    I have a 4"sus. lift on my 85 K5 and had a vibration from the driveshaft, lengthened it and guess what...no more vibration. hope this helps.
     
  6. KILLERK5

    KILLERK5 1/2 ton status

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    $320? That sounds a little steep. I paid $330 for my front and rear shafts to be lengthened. I would look around first
     
  7. Overdrive

    Overdrive Registered Member

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    Driveshaft is at the shop!

    Well, I bit the bullet and took the old driveshaft in to Mesa Driveshafts. They said if the slip yoke was still good it would save me about 40 bucks. I am going to get the CV joint setup.... I will report on the results next week. The joint is similar to the front, double cardon, CV but without the flat round plate hookup. The yoke on the transfer case needs to be changed and set in place with a "GASP!" Ford nut. I hope I can live with myself, having a Ford part on my Chevy, but if it cures the vibration problem, all will be well...

    I think the guys (or gals) with the 80's models (no 203) have less of a problem due to the overall length of the transfer case. The length from the end of the T-case yoke to the end of the pinion yoke is 35 1/2" on my rig with a 15 degree angle on the driveshaft. We'll see what if anything changes after the new shaft is put on.

    IMPORTANT!
    For anyone thinking of replacing their stock u-joints with the super de duper extra strong u-joints, DON'T!!! I did it and ripped apart the u-joint housing destroying the driveshaft! It is a lot easier to replace (and carry in your glovebox) a u-joint on the trail than driving home on your front driveshaft.....

    Thanks to everyone for their input!

    Overdrive
     
  8. FWP

    FWP CRS

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    Re: Driveshaft is at the shop!

    Definitely post what you find out after the mods- excellent info.

    <font color=blue>Maverick</font color=blue> <font color=red>CH 4 or 35</font color=red>
     
  9. Impex

    Impex 1/2 ton status

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    Re: Driveshaft is at the shop!

    Overdrive,

    Hey just to let you know I took my truck to Mesa Driveshaft last week and they do very good work. They are a little bit more $$ but the work is very well done.

    [​IMG]
     
  10. 1HIHUM

    1HIHUM 1/2 ton status

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    Re: Driveshaft is at the shop!

    Are you changing the pitch of the rear pinion, to zero the angle of the rear u joint. From what I have read, standard u joints need to be within a few degrees of eachother at each end of the drive shaft, in order to cancel the vibs from each other. The cv will not cancel the vibration from the rear joint if it is still angled. I read this in petersons offroad, awile back.

    [​IMG]
     
  11. BIGRIG

    BIGRIG 1/2 ton status

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    One question and you have probably thought or know this but always cover the basics....do you have a shim for your rear axle? Should be 3-4degrees for 4" lift. If not it might save your next shaft. good luck


    MY DRINKING TEAM HAS A FOUR WHEELING PROBLEM!
     
  12. Overdrive

    Overdrive Registered Member

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    Yep!

    1H1HUM and BIGRIG,

    The rear springs have a shim attached to them (Rough Country 4") which does angle up the pinion. I too have followed the ujoint saga in the pages of 4W&OR. I believe they are talking about the "ideal" setup for ujoints when they say the two angles should match, canceling eachother's vibrations. But at such a steep angle, 15 degrees, the ujoints would bind. Maybe not on smooth level road but definately off the beaten path. They refer to shimming the pionion to lessen the degree of the angle while also providing move maneuvering room for the ujoint. This does cause some vibration but it should be able to be controled to a minimum. I think I still have that particular article in my bathroom somewhere :)

    From what I have read ujoint life at that angle (15 deg) is only about 6 months since the optimal angle for them is 3 to 5 degrees, but then, what 4X4 has 5 degrees on the rear shaft?

    Thanks for the info!

    Overdrive
     
  13. 1HIHUM

    1HIHUM 1/2 ton status

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    Re: Yep!

    I'm not sure what my angles are, but I know they suck. I have an 8" lift, but I haven't made any real attempt to reduce the angle yet. The springs came with shims built in, but they aren't nearly enough! I plan on making some improvements soon though. Remarkably, I have no vibes from the shaft, And I'm going on a year now, and the joints are doin great! They are 1350's though, that may have something to do with their life. As for the article, double check what it says about cv shafts. When you have a cv at one end, the cv will not cancel the vibes from the other end, regardless of the angle. I know I have that article around here somewhere. If I find it I'll let you know.

    [​IMG]
     
  14. Shawn

    Shawn 1/2 ton status Premium Member Author

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    Re: Yep!

    My 1350 rear CV shaft eliminated all vibrations I had. I'm running a 7" lift. Also, the operating angle on my new 1350 CV shaft is 32 degrees where my old 1350 standard shaft was much less.

    Shawn
    87 K5
    few mods[​IMG]
     

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