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Do I have driveshaft issue or what? Problem Solved

Discussion in 'The Garage' started by sdavid, Apr 25, 2003.

  1. sdavid

    sdavid 1/2 ton status

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    <font color="red">Update: Lowered Transfer case and no more Clunk. Moved the spacers to between crossmember and frame and no more problems. </font>


    Got a lift installed today. 2.5" springs up front and 3" blocks in the back. Yeah, I know about the downfalls of blocks and what not and I am trying to figure out if I am suffering from one of them.

    When I am at a dead stop and punch it and the weight shifts to the back and I either let off the gas or it shifts to second I hear/feel a lound clang and jolt. None of this was a problem yesterday when it was stock. Only thing that has changed is the lift.

    Is it my springs wrapping up and then letting loose that makes the noise/jolt. I can't think of anything else but loose U-bolts or drive shaft(had new U-joints installed today also). I would think if it was drive shaft it would be a constant problem. It just feels like something is binding up and then letting loose or binds up when I let off the gas or it shifts into 2nd.

    What do you think? (other than I should have not got blocks)
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: Do I have axle wrap?

    Could be a little bind at the slip yoke...and axle wrap can make that worse. By all means check all the u-bolts and stuff too.

    Rene
     
  3. sdavid

    sdavid 1/2 ton status

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    Re: Do I have axle wrap?

    When I feel the clang it seems to be in the middle of the blazer, so the drive shaft is a good call. I also now get a slight wobble when I first accelerate (1 to 5mph). When the new U-Joints were installed could the tech have not got one centered in the ears of the shaft. They are the press in type. I also read in another post that the tabs could be over tightened, would that cause any of my problems?
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: Do I have axle wrap?

    The overtightening could be a problem, worth a look anyways. I don't think the strap style can be overtightened enough to crush the cups, but the u-bolt style sure can.

    Maybe check the tranny mount while you're under there too...

    Rene
     
  5. CHEVY 4WD

    CHEVY 4WD 1/2 ton status

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    Re: Do I have axle wrap/Driveshaft Issue?

    my guess whould be loose u bolts do you do ANYTHING else when you did the lift?
     
  6. sdavid

    sdavid 1/2 ton status

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    Re: Do I have axle wrap/Driveshaft Issue?

    Problem is that I didn't do it, so I am not sure what the deal is. Got the usual: new front springs, blocks for the back, all new U-Bolts, new shocks, and got the U-joints replaced in the rear shaft.

    I have crawled all over today and I can't see anything funny or wierd under there. I am going to test and see if the left back spring is hitting the exhaust pipe when it compresses and lets go tomorrow. I have a 3" single out the drivers side behind the tire, right below the spring, in front of the hanger that is a pretty tight fit.

    I have had LWB trucks in the past with alot more torque and power (granny low) that had blocks and I could not make them wrap up and make this kind of sound/jolt.

    I am hoping it is the exhaust, but have a feeling it is not going to be that easy.
     
  7. rick88blaze

    rick88blaze 1/2 ton status

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    Re: Do I have axle wrap/Driveshaft Issue?

    i did a 2 1/2" lift on my 88 k5 and afterwards my slip yoke was hitting my driveshaft. it also pulled my slip yoke out far enough that it wasn't seated completely on my output shaft. i ended up having a new driveshaft made up with a cv joint in it, and an inch longer. once i put it in, all of my vibs and clanging were gone.
     
  8. sdavid

    sdavid 1/2 ton status

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    Re: Do I have axle wrap/Driveshaft Issue?

    Narrowed it down some today. It is not the exhaust, U-bolts seem to be fine, and the blocks are not moving around. I had one transmission mount bolt that had worked its way out and was only finger tight. The other was pretty loose too. I tightened and test drove and it is still doing the same thing. Its the original transmission mount (rubber) on it so it may be shot. I can move the transfer case/transmission up and down with out much effort. Maybe between that and the new angle it is causing the problem. I marked the slip yoke and made it make the noise/jolt and looked at it, and it had only moved in about 1/4"-3/8" from rest to flooring it from a dead stop.

    It is going to be a shame that I dont even need extended brake lines, but I have to make a rear CV shaft. /forums/images/graemlins/crazy.gif
     
  9. rockmup

    rockmup Registered Member

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    Re: Do I have axle wrap/Driveshaft Issue?

    What makes you think its a drive shaft? If it was my money I'd get someone on the ground to watch my rear springs to see if they wrap. Might be better to watch the pinion though. Factory springs are soft so that would be my next guess. Good luck
     
  10. sdavid

    sdavid 1/2 ton status

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    Re: Do I have axle wrap/Driveshaft Issue?

    Well I am sure the springs are wrapping up somewhat. But my tires don't break loose and no wheel hop, no high HP or torque motor here. It is the stock 350 with 110K miles on it. The tires are probably around 32.5" tall and 3.42 gears and 3 inch degreed blocks.

    I marked the springs today also, and I can't find any markings where the rear spring is compressing enough for the bottom spring in the spring pack to touch the overload spring. And when I feel it/hear it, it is right under the middle console. Plus it does not take much to cause it to happen. So if I ever want to give it more than 1/4 throttle leaving from a stoplight again, I got to fix/do something.
     
  11. sdavid

    sdavid 1/2 ton status

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    Re: Do I have axle wrap/Driveshaft Issue?

    Update: Still not fixed. Need ideas or first hand knowledge.

    Replaced transmission mount with new Napa mount. Still makes sound and clunk. Will not do it in reverse, will not do it in 4wd. Only makes the noise in forward gears. It is really bad in first gear (700R4) when you floor it and let it travel 10-20 feet and let off. BIG CLUNK! It also did it this morning when I pulled into traffic and gave it gas, then shifted into 2nd(no clunk), but when I let off a little at around 45mph it made a slight clunk.

    So the more torque on the drive train, the worse the clunk is. It is coming from under the transmission hump or right behind it. Slip yoke does not look like it is pulled out too far.

    Do transfer case adapters get loose or will a cracked one do this? But no evidence of the problem in 4wd or reverse. /forums/images/graemlins/confused.gif
     
  12. txbluethunder

    txbluethunder 1/2 ton status

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    Re: Do I have axle wrap/Driveshaft Issue?

    pull your driveshaft out. clean it and the splines on the output shaft thoroughly. Take a little grease and coat the splines on the output shaft and the inside of the yoke and slap it back together. i had the same issue as you and this is what fixed it. its the slip yoke binding on a small about of slop between the output shaft and the inside of the yoke.
     
  13. sdavid

    sdavid 1/2 ton status

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    Re: Do I have axle wrap/Driveshaft Issue?

    Thanks! I will give it a go. Did not think about that. This gets to be like a wild goose chase trying to figure out what's causing the problem. I guess you got to spend your time and money on something. /forums/images/graemlins/smirk.gif
     

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