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14 bolt and the shakes.....

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by OFFRDK5, Jun 13, 2002.

  1. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    I converted to 3/4 ton and did not install a lift. Has anyone else ever done this and has anyone had some driveline angle problems with this setup?
    Shakes bad when I get to higher speeds. Wondering if it could be the tires, but they all balanced out, but they have been sitting for a bit?
    Thanks
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

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    3/4 ton axles probably have lower gears, resulting in more shaft speed for a given road speed, thus vibration at a normal driving speed.

    In short, get your driveshaft balanced. It's turning faster now and needs to be re-balanced at the faster speed.
     
  3. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Did you remember to change the rear u-joint for the conversion joint? The u-joint on a 14bff is larger than your existing u-joint. If you haven't changed it then I am certain that this is your problem.
     
  4. Mudstud

    Mudstud 1/2 ton status

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    Yea, I'd say the tires have a flat spot. If you can drive it till they heat up it should go away.
     
  5. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    Yep, changed the U joint.

    Now the tires having flat spots...how long does it take for them to wear that flat spot out. Days? Weeks? Never?

    Thanks
     
  6. woody9

    woody9 1/2 ton status

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    my experience was.. (long)

    not sure what vehicle this was on (fill out your profile!!) or what all u did at the same time, but let me share my experience..

    91 350 1500 suburban, 10 bolt, 3:42, elec speedo, 6 bolt 15" rims, no lift but add-a-leafs.
    got a pair of 4:10 axles, 14Bolt, and HUGE brakes for $100/end.

    Went thru the drum end of things, and had the rotors turned, repack/seal front bearings, adapter U-joint, and longer U-Bolts. Got a set of newer factory take-off 8 lug 16" rims/tires (generals.. nothing to write home about there).
    Did 1 end @ a time to eliminate problems.... but... did the rear first, got a 2nd u joint and rebalanced/rotated tires on rear to try and hunt down a 'low freq' vib from about 40 MPH on up.
    Balanced drive shaft, checked U-Joints again, checked for loose rear hubs... nada!
    Isn't/Wasn't toooo bad a vib, so pressed on with front end a few weeks later. My calipers/new axle rotors mated up and no problems.
    Still had that pesky vib.

    Figured maybe a weight was tossed off 1 of the drums. Well, good enough excuse to convert to rear disc! (or at least I told the wife)...

    Now have 4 wheel disk, love the 3/4 ton running gear, have re-balanced, poked around, and can't for the life of me or 3 local shops find the source of that vib.
    Incidentally, the angles and length were fine on this swap and required no specail drive shaft work.

    I'm thinking it's something with the change of tires from BFG to Generals (a step backwards in my book), so plotting now to figure a way to get some new shoes on it as well as some custom rims.

    Not that this answers anything, but at least it's a shared experience!
    Now, if i could only get that dang brake light to go out! that started a week ago and this conversion has been done for about 3 months! hmmmmm, back to the manual!
     
  7. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    Re: my experience was.. (long)

    Sounds like I need to go over everything again...just to be sure.
    Sorry about my profile...I don't know what happened to it, it was just there.....hrm.....STEVE?!?
     
  8. woody9

    woody9 1/2 ton status

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    Re: my experience was.. (long)

    Just need to check, double check and check again!
    Could be any of a number of things! forgot to mention, i also changed the flange on the rear end (about $80 + the ride) It helped a TON, but didn't eliminate it 100%
    Drive shaft being in 'phase' (ends aligned) could cause it too!
    If you're in/near a big city, a good reputable drive line shop (I'm not.. figure 60-100 miles to a decent one).... they could trouble shoot it for your i'm sure.
    Doing it all yourself just takes some time, and allows your to run down all those loose ends!

    Keep me posted!
     
  9. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: my experience was.. (long)

    Generals are known to seperate belts.
     

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