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need advice on pinpointing vibes!

Discussion in 'The Garage' started by Mr.Jimmy, Dec 19, 2006.

  1. Mr.Jimmy

    Mr.Jimmy Registered Member

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    My 83' Jimmy has bad vibrations when its in park and you rev up to about 2200 to 3k. The harmonic balancer was wobbling so I got a stock replacement. Still wobbles and vibe is still there. could it be my cranck is bent or possibly torque converter or flexplate bad? :confused: I also have bad vibes above 40 mph. Vibe has rythm to it. Any ideas guys?

    83 jimmy 350/700r4/208 14bolt/d44 shakle flip,front&rear cv drivelines,5'' susp., 3'' body, 35's
     
  2. vortec

    vortec 1/2 ton status

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    can we assume you've checked for misfires and other cheap/easy stuff? i always prefer a problem to be caused by a simple vac leak or bad distributor cap, or something, as opposed to messed up internals and stuff.
     
  3. sandawgk5

    sandawgk5 3/4 ton status

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    I had vibes at higher RPMs and it was my water pump. The bushing had gone out and let the pulley and shaft wobble. But like was said check all of the cheap and easy stuff first.

    Ira
     
  4. blazinzuk

    blazinzuk Buzzbox voodoo Premium Member GMOTM Winner

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    If your harmonic balancer is still wobbling than you have a problem there. I would concentrate my efforts there
     
  5. onetonbb74

    onetonbb74 1/2 ton status

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    try disconnecting the torque convertor and start the motor up. If there is still vibes than that eliminates the torque convertor. Also while the engine is running, check the flywheel for any out of round movement. If the vibes stop then id change the tc/ or flywheel accordingly. Also check the oil. If there is way too much oil in the motor, it will make vibes pretty bad. Another thing to check for is the pulley's. Id disconnect all the pulley's and start it up and see if there is any vibes. btw, did you beat the new harmonic balancer on with a hammer? That might have something to do with it.
     
  6. Mr.Jimmy

    Mr.Jimmy Registered Member

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    thanks for your input guys! Im gonna take it to a mechanic shop to see if they can tell me if my crank is bent or not. Im also looking into the cheap stuff. thanks again guys.
     
  7. Mr.Jimmy

    Mr.Jimmy Registered Member

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    I used a block of wood in between, but yes I did use a hammer. Did I screw up? Ill try disconnecting the pulleys and disconnect the tc and let you know the verdict.
     
  8. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    No one can tell you if your crank is bent unless it is out of the engine and on a set of V blocks and indicated in to check for trueness. It is HIGHLY unlikely that your crank is bent.
    Are you sure that the previous owner didn't install a 400 SBC which is externally balanced and someone has the incorrect harmonic balancer on it? Or just the opposite, a 350 engine with a 400 harmonic balancer.
     
  9. sandawgk5

    sandawgk5 3/4 ton status

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    You should never hit a balancer with a hammer. You can use the tool to remove and reinstall a balancer from Kragen for free.

    Ira
     
  10. Mr.Jimmy

    Mr.Jimmy Registered Member

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    I know the previous owner put the 350 in it, but could not tell me what it came out of. I do need to run the block #. I purchased a 8" balancer for a 350 and never actually hit the balancer itself with the hammer.
     
  11. sandawgk5

    sandawgk5 3/4 ton status

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    You do not have to hit the balancer itself. If you hit a piece of wood you had against the balancer you can and most likely will **** it up. That is why they have a balancer installation tool.

    Ira
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Are you using the pulley as a reference to figure out that the balancer is wobbling, or a dial indicator of some sort?

    Discoloration, dirt, water, oil, etc ALL through off your vision for wobble. As well as a bent or loose pulley.
     
  13. Mr.Jimmy

    Mr.Jimmy Registered Member

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    I purchased a harmonic balancer puller from my local part store which came with the hardware to remove it, but not put it back on! this installation kit you keep talking about what does it consist of? My kit came with a peace sign lookin plate with slots and a large center drive screw and smaller bolts that you use to fasten to the balancer. If this kit is the same, explain to me how you install with it.thanks ira. As far as the pully, you can just look down at the balancer when the motor is running and see that its definately not running true to the front face of the block. Im gonna remove that pully after work, start it and see what it looks like. your feedback is much appreciated.
     
  14. sandawgk5

    sandawgk5 3/4 ton status

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    It is actually pretty simple and resembles the installer for a PS pump pulley. It is a long bolt with a bearing surface. You seat the balancer on the snout of the crank with you hands, start the bolt and thread as far on as you can by hand then tighten with a wrench. It will suck the balancer down on to the crank you then remove the bolt and install the crank bolt and torque to spec. Really no need for a kit but I found out the hard way the crank bolt is not long enough to pull the balancer on. The factory bolt will only get aboot 1 or 2 threads of engagment and will pull the threads out of the crank. You can prolly make one buy getting a large washer and a longer bolt from the parts house.

    The parts stores have a puller kit (the one you have), an installer kit, and a "deluxe" puller / installer kit.

    Hope that helps.


    Ira
     
  15. Mr.Jimmy

    Mr.Jimmy Registered Member

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    yeah, the guy i bought the truck from must have found that out the hard way cuz i had to buy a longer bolt just keep th balancer on!( 1st 1/2" of threads are gone!) An issue thats a BIG concern for me. I would also like to ad the fact that my rpm vibe started after I bought the truck and has (over time) gotten worse.
     
  16. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Have you checked or replaced the motor mounts and tranny mount yet? That is a good source for vibes when they go bad. Also how is the tranny acting? A bad torque convertor could also cause this but you would start to have problems with the tranny as well. Check the fluid for color and smell.
     
  17. Mr.Jimmy

    Mr.Jimmy Registered Member

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    well the motor mounts seem ok, motors not sittin on the frame and dosent rock very much at all under throttle. The tranny ive had a few problems with. it was leaking at the out put shaft so i dropped the t case only to find that the bottom two bolt holes were stripped on the rear of the tranny(bolts looked replaced and too short). I heili coiled it and silicone gasket for new seal. about a month later, t-case started to throw itself out of all gears. replaced it with another USED 208 and here i am. flexplate has multiple hairline cracks arounds mounting holes. this might also be sugnificant, a while back i raced a f-250 and rpms almost pegged before tranny shifted to second! shortly after that i recall starting to notice worse rpm vibe. whats your take fellas.
     
  18. sandawgk5

    sandawgk5 3/4 ton status

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    Sounds like you need a flexplate to me.

    Ira
     
  19. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    So let me get this straight. You know you have a cracked flexplate but you left it there anyways? :rolleyes:

    Before i would be chasing my tail i'd be replacing the part that YOU KNOW is broken then go from there. :deal:
     
  20. Mr.Jimmy

    Mr.Jimmy Registered Member

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    ok guys, yes i left it there cuz i dont have the money for a new one yet and i also want to replace the tc at the same time while the tranny is down cuz i use my jimmy as main transportation. I know its a bad deal but sometimes you have to play a sh**ty hand. You guys are a great help, its nice to finally have someone on my side with this truck. My wife, family, and friends tell me to buy a newer truck, but i love the one i got. plus its paid for!
     

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