Front yoke into 833 tail shaft, need your opinion

Engine, Trans & Driveline

  1. Outlawd

    Outlawd Well-Known Member

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    How far should the yoke be inserted into the tail shaft? 1968 coronet 440 motor, a833 4 speed, 8 3/4 rear 742 pumpkin. Drive shaft is 52" center to center on u joints plus yoke is 8" from center of u joint to end of yoke. The machined part of the yoke is 6" long and 2" is outside of the tail shaft housing (including dust boot) which leaves 4" inside the actual housing and as you know the yoke has no splines in the first inch so really that leaves 3 inches max on splines. My question...is the drive shaft measurements what they should be for a dodge b body 4 speed rb motor? I'm hoping this is the answer to a long battle with a vibration we been chasing for years. read all the past posts on vibrations, got it all covered, vibration is speed related excell or decell don't matter it's constant from 50mph on up. changed wheels and tires, tracked it down to drive shaft speed issue, covered all them bases, you know the routine....balance ds, pinion angle, clocking u joints, axle shafts, bla bla bla...just found out the guy i'm helping had his new drive shaft built using measurements from his old shaft so thinking he had a bent shaft had one built and balanced the same length which could have been too short from the very begining of this wild goose chase. The car was bought as a roller many years ago and is nowhere near any original drivetrain. Anybody out there have a vibration from too short of a drive shaft?
     
  2. Fran Blacker

    Fran Blacker FBBO Gold Member FBBO Gold Member

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    Don't forget the main trans sticks out of trans at least 1" if not a little more. I have 2" from machined part of yoke to the tail housing. How much play is there between yoke and bushing? DS7.JPG tb2.jpg ttool.jpg
     
    Last edited: May 4, 2021
  3. 5.7 hemi

    5.7 hemi FBBO Gold Member FBBO Gold Member

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    If you bottom out the yoke onto the tail shaft then pull it out 3/4 to 1 inch, you’re set. That’s plenty of room to slip on the tail shaft and not bottom out the yoke.
     
    Last edited: May 5, 2021
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    • Outlawd

      Outlawd Well-Known Member

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      Put new bushing in last year, no change. very very little movement but does have some play.
       
    • Outlawd

      Outlawd Well-Known Member

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      I can bottom out against the dust boot and have to come back around 1 1/2 to seat the u joint.
       
    • 5.7 hemi

      5.7 hemi FBBO Gold Member FBBO Gold Member

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      Not concerned with the dust boot. Gotta push the yoke till it stops. Then pull out 3/4-1 inch. If your ds is short by 1/4 inch to seat the u-joint caps, I’d be ok with that.
       
    • Outlawd

      Outlawd Well-Known Member

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      Yes, it bottoms out solid then I have to bring it back 1.5" to seat the u joint in the rear yoke. Is that too much travel that could cause bad vibration at fast shaft rpm? The car has 3.73 gears so at 50 mph or faster that ds is spinning fairly fast.
       
    • 5.7 hemi

      5.7 hemi FBBO Gold Member FBBO Gold Member

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      I don’t think so. I think you may have a problem with the ds, yoke, u-joints or tires.
       
    • Outlawd

      Outlawd Well-Known Member

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      DS, yoke, u joints all new and balanced. Swapped tires from other car still vibrates badly. Tried pinion angle shimmied to within a degree from front to rear. New tranny new motor all balanced. Vibration is ds speed related. Swapped gears and vibration comes in sooner but still same type of issue.
       
    • 5.7 hemi

      5.7 hemi FBBO Gold Member FBBO Gold Member

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      Trans mount?
       
    • Outlawd

      Outlawd Well-Known Member

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      Well, I don't think so. I used a pry bar and tried to move tranny tail side to side or up. I can see it move maybe less than 1/4 inch with good pressure on bar but what's normal? Could this be why it dont seem to vibrate real bad till i start hitting the throttle hard a few times. If i just start her up cold and drive like an old lady it dont seem to be too bad but after i beat on it a few times the vibration gets worse but always at the same speed, around 50 mph on up.
       
    • 5.7 hemi

      5.7 hemi FBBO Gold Member FBBO Gold Member

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      No! It shouldn’t move 1 bit. Get a poly mount for it.
       
    • Outlawd

      Outlawd Well-Known Member

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      ok, I ordered one should have it on early next week. worth a try!
       
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      • Dipstick

        Dipstick Well-Known Member

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        A rubber mount is gonna move some, that's why it's rubber.
         
      • 5.7 hemi

        5.7 hemi FBBO Gold Member FBBO Gold Member

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        It shouldn’t move a 1/4” like the OP stated. Also, poly will not move nearly as much and allows the power to be put to ground instead of being absorbed by a rubber mount.
         
      • Babyblue66

        Babyblue66 Well-Known Member

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        I've heard several times the yoke should be 3/4 to 1 inch pulled out from bottomed out.
         
      • Outlawd

        Outlawd Well-Known Member

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        I know, I've heard it too but nobody has an experience to share on having a vibration problem because there d.s. was too short only by 1/2 inch. I got new tranny mount on its way, I will bet good money thats not the problem but for 60 bucks I will do it....at this point there is absolutely nothing left to adjust or replace or fix. If tranny mount don't do it I will retube the ds 3/4 inch longer....if that don't work I will put 323 gears back in it and the vibration will be at a speed faster than the car typically is driven, now with the 373's the vibration is right at highway speed on up. I least I'm not the only one in this boat, there is literally thousands of threads on vibration issues, most don't end with an answer to their problem.
         
      • Babyblue66

        Babyblue66 Well-Known Member

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        My issue is low speed vibration, good at 30, bad at 40, then gets better with speed. If I'm going 70 its not bad at all. ‍♂️ This type is shit can drive a man bananas!
         
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        • Dipstick

          Dipstick Well-Known Member

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          Depends on how long the pry bar the OP used is and how much grunt was used. I wouldn't consider "less than 1/4" to be excessive. yoke_depth.jpg
           
        • 1 Wild R/T

          1 Wild R/T FBBO Gold Member FBBO Gold Member

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          The original driveshaft for a 1968 Coronet with a 383/4spd & 8.75 is part # 2852162 it is 52.07" long...
           
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