The change of the transmission yoke will depend on the vehicle design.  In my 
vehicle, the pull out length is 1-1/8 inch with the wheels off grade.  On 
grade, the slide in is 5/8 inch.  The drive line angle should not go below 1.5 
degree, best to have 2 degree of more. 

  ----- Original Message ----- 
  From: Brett Davis via EV<> 
  Cc: Electric Vehicle Discussion List<> 
  Sent: Tuesday, May 27, 2014 4:30 PM
  Subject: Re: [EVDL] Vibration

  Hi Roland,

  I suppose that the step involving jacking the rear wheels off grade is to
  compress the suspension in order to determine the amount of travel in the
  slip yoke. Unless the rear of the vehicle is restrained, it will raise with
  the axle (assuming a typical jack is used) and there will be negligible
  change in the position of the pinion yoke relative to the transmission yoke.

  Regarding the original question, likely a U-joint if the vibration just
  showed up.

  On May 27, 2014 3:13 PM, "Roland via EV" 
<<>> wrote:

  > The following info is per my master mechanic when assembling a different
  > engine or motor in a vehicle.
  > Before removing the original engine, place the vehicle on a level grade at
  > full weight.
  > Measure the distance from the transmission yoke to grade and the
  > differential yoke to grade.  Calculated the angle of the drive shaft.  You
  > could also use a angle level place on the drive line which will show you
  > the angle.  This is the angle of the drive line you must retain when
  > changing to a new engine or motor.
  > Also measure the transmission yoke slip or the amount of travel the yoke
  > slips out of the transmission while on grade.
  > Now jack the rear wheels off grade and repeat the above measurements
  > again.  The drive angle and yoke slip will change.  Record this change too.
  > The drive line angle and yoke slippage should be the same with a new
  > engine or electric motor installation.  You will note in some vehicles, the
  > transmission cross member has a slut while the transmission yoke clearance
  > can be adjusted for maintaining the same amount of slip that is use in
  > different prime movers.
  > Some of the guys had a problem with vibration and  scrapping, because they
  > had there drive line in a straight line or at not at the original design
  > angle.
  > The reason for the drive line angle, is so the needle bearings in the
  > U-joints will rotate.  If the drive line is too inline, then the needle
  > bearings will wear a flat spot, causing the drive line to buckle or try to
  > misalign.
  > In some transmission drive line assemblies, you will note there may be a
  > balance weight welded to the drive line near a yoke.  Make sure if the
  > yokes were replace or had the drive line shorten, the balance weight is
  > place in the same position as before either at the transmission end or at
  > the differential end.
  > Roland
  >   ----- Original Message -----
  >   From: Pestka, Dennis J via 
  >   To: Electric Vehicle Discussion 
  >   Sent: Tuesday, May 27, 2014 12:29 PM
  >   Subject: [EVDL] Vibration
  >   Didn't know if anyone had any clues to a problem I'm having.
  >   Since I have my new Lithium pack, I've getting my 65 Datsun out on the
  > highway and up to ~ 60 mph. Never did much of that before.
  >   When accelerating, I don't experience it, but when I let off the
  > accelerator, I'm getting a pretty good vibration.
  >   Step back on the accelerator, and it goes away.
  >   Don't seem to notice it at 45mph and lower, but when going 55 - 60 mph.
  >   I just put new tires on it, and have had the front end aligned.
  >   Any suggestions ?
  >   Thanks;
  >   Dennis
  >   Elsberry, MO
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