Interesting low speed vibration, 5KQ and 5KTQ

[john at westcoastgarage.net]

Mark J. Besso wrote:

> Is there anything you can do at that speed that makes it NOT happen? 
> (steering, braking, clutch-in, etc.)
>
> Is it under braking as well as acceleration?  Is the vibration felt 
> throughout the vehicle or just in the steering wheel?  Is there any 
> noise associated with the vibration?
>
> Any chance one of the wheels isn't properly tightened?  If so, I pray 
> you check BEFORE the next road test!
>
> ~Mark
>
>
>
> On Wed, 28 May 2008 14:47:27 -0700
>  "john at westcoastgarage.net" <john at westcoastgarage.net> wrote:
>
>  A new one to me, 86 5KTQ has a low speed vibration, feels like a
>  driveshaft U-joint when leaving from a stop.  Throttle position isn't a
>  factor, only speed.  After about 20 MPH, the vibration is gone. Doesn't
>  matter whether you start out in first or second gear. I thought maybe
>  we'd disturbed something when we did the clutch, but a phone call from
>  another customer yesterday is making me rethink that conclusion.  In his
>  87 5KQ, the vibration appeared 7 years after the clutch job, leading me
>  to believe it may not be related.  The driveshaft guy says it's not a
>  normal symptom of a driveshaft failure, but these aren't something with
>  which they deal with any real frequency.  Any hints/questions/BTDTs out
>  there that might help me solve this problem?  Lotsa miles on both 
> cars, BTW.
>  
>  TIA, John
>
Under acceleration, feel it through the floor, 2 different cars, wheels 
torqued properly, new tires on the 5KTQ, did it before the new tires and 
rear suspension repairs (I first noticed it after the clutch job, but 
the car was nearly undriveable because the TO arm had gone through the 
pressure plate. As I said before, the amount of throttle pressure has 
little effect.  At light throttle the vibration is lighter, at hard 
throttle it's harder, but it's ALWAYS there under load until you reach 
about 20-25 MPH.  It sure feels like it's happening at driveshaft speed 
.................  John