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Vibration Under Acceleration

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Lee, Jan 6, 2002.

  1. Lee

    Lee Registered Member

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    I know that this topic has been covered in depth on this board...I read thru most of the posts here regarding this issue before I decided to post this question...

    I just added a 6 inch procomp lift to my 78 K5 fulltime 4x4...It included 35 inch procomp mudders...Now that this has been done, when I am accleratiing from a dead stop the truck shudders till about 10 mph then it goes away, It really vibrates from 35-45 mph and then goes away at 50+ mph, when I gently come to a full stop it shudders from 10mph to the stop.

    These vibrations occur during acceleration. If I take my foot off the gas at 40 mph the vibration goes away. (The only time I get vibration without my foot on the gas is the slight shuddering when I am coming to a stop.)

    This k5 did not have any vibration before the lift was installed so after reading the posts here... my guess is ???? that my ujoint angles are to pronounced and the transfer case must be lowered to remove this problem . I am a beginner at this stuff so I welcome any response and advice as to what may be causing this problem and how to fix it.

    Again this K5 had no vibration before the lift was installed and 35s were added.

    Lee
     
  2. wayne

    wayne 3/4 ton status

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    Start with lowering the t case some and putting new U-joints in the rear drive shaft. Also you might want to put a new trans mount in.

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  3. Lee

    Lee Registered Member

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    Wayne:

    Why would lifting the truck require me to replce the rear ujoints if they were working fine before the truck was raised same question for the transmission mount

    Thanks
    lee
     
  4. hammer

    hammer 1/2 ton status

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    I have about the same problem but not from 10 to stop only under acceleration at the same speeds. I have 2" lift blocks in the rear 4 degrees of shim in the rear, and a custom d-shaft (longer and new u-joints).
    I was thinking it was the 2.73 gears with 32" tires I have so I will look for a 14 bolt come spring with 4.11 gears

    <font color=red>Let me at it I can break it</font color=red>
     
  5. wayne

    wayne 3/4 ton status

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    U-joints will be worn in the way they were and when you lifted it you changed the angles on them. It is always reccommended to change them when doing a lift. Also if the trans mount is worn it will be felt more when the truck is lifted. There have been a few guys on here that had no vibration before a lift then had some after the lift and it was caused by a worn trans mount. Hopefully you will not have the same problems as me when I was sorting out the vibration on my truck. I set the angles up the way they are supposed to be and still had bad vibes. What I wound up doing is pointing the pinion up like it should be set for a rear cv shaft but I don't have a rear cv shaft and that took care of my vibration.

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  6. Lee

    Lee Registered Member

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    Thanks
     
  7. bigredbeast

    bigredbeast Newbie

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    Just put a cv joint on the tcase side to take a little stress off the u-joints
     

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