The fact that it gets much worse when the drivetrain unloads,
gives an indication that it is not just an unbalance in a wheel or
motor,
because those hadly suffer from the loading/unloading of the torque in
the drivetrain from acceleration/deceleration.
More likely it is related to the driveshaft or adjacent parts of the
drivetrain, possibly halfshafts.
One of the ways to test where the vibration might be coming from:
- jack up the complete rear end (both wheels off the ground)
- run the motor through its normal speeds in Neutral. If there is
vibration then the flywheel balancing or transmission input is suspect.
- run the motor at speed with the transmission in Drive, notice the
speed of the vibration.
- change jack to only lift a single rear wheel and run the motor at
speed again - is there a difference in vibration? then it might be the
half shaft else it is likely the driveshaft
- change jack to only lift the other rear wheel and run the motor at
speed again - is there a difference in vibration? then it might be the
half shaft else it is likely the driveshaft
- you can check for wheel unbalance (rear wheel that is) by removing the
wheel at the latest tests to check if that makes the vibration go away.

BTW, some vehicles have a mid-driveshaft bearing that goes bad and
causes vibration. Check the group discussions of your particular ICE
vehicle to see if that is a common problem and how to diagnose & repair.

Success.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: cwa...@proxim.com Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626


-----Original Message-----
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Michael Ross
via EV
Sent: Monday, June 09, 2014 1:27 PM
To: Pestka, Dennis J; Electric Vehicle Discussion List
Subject: Re: [EVDL] FW: Vibration

Dennis,

If it was any ICE car, where there is no DIY drive train stuff to
distract
one, I would ask them to check the tire balance once again.   It is
entirely possible a balance weight popped off.  Or they forgot to
balance
one of them.  I speak from experience here.  At one time I used to
refuse
balancing as snake oil, but I learned better along the way.

65 Datsun means rear wheel drive, correct?  A drive shaft is usually
making
clunky sounds going into reverse and back to forward if it is sick.  CVs
make clicking noises when turning if they are suspect.

Is there any indication at all that the the motor and drive train are
the
cause?  I presume they were fine at one time?  If it was once smooth
that
sort of precludes any issues with motor/tranny/drive shaft/differential
misalignments.  Postponing them as a primary trouble shooting point.


On Mon, Jun 9, 2014 at 3:55 PM, Pestka, Dennis J via EV
<ev@lists.evdl.org>
wrote:

> The shocks are new, but I'll take a look.
>
> I don't know if this means anything, but let me repeat one thing.
> Under acceleration with torque on the motor and drivetrain the
vibration
> is not too bad. Starts showing up ~ 55 mph.
> When you let off the accelerator at that speed, the vibration gets
very
> bad and gradually goes away as the vehicle slows down to ~ 40 mph.
>
> Thanks;
> Dennis
>
>
>
> -----Original Message-----
> From: Jay Summet [mailto:j...@summet.com]
> Sent: Monday, June 09, 2014 1:02 PM
> To: Pestka, Dennis J; Electric Vehicle Discussion List
> Subject: Re: [EVDL] Vibration
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> One thing to check is your non-drivetrain elements, although if you
get
> the vibration without moving in neutral it's probably in the
drivetrain.
>
> The reason I mention it is that our car had developed a vibration at
the
> 58-60 MPH speed range, and it turned out to be rear shocks that needed
> replacing.
>
> Jay
>
>
> On 06/09/2014 07:49 AM, Pestka, Dennis J via EV wrote:
> > Removed the drive shaft, had new u-joints installed, and had it
> > balanced. No change.
> >
> > I'm guessing it's either the angle on the motor/transmission in
> > relation to the rear end, or I may have to pull the
> > motor/flywheel/pressure plate/clutch assembly and have it balanced.
> > When I sit in neutral and rev to ~ 3000rpm, I'm getting some
> > vibration, although it doesn't seem to be as bad as when I drive.
Here
> > again I feel it at ~ 50 mph and up, but it is really noticeable when
I
> > let off the accelerator at those speeds.
> >
> > Thanks; Dennis Elsberry, MO http://www.evalbum.com/1366
> > http://evalbum.com/3715
> >
> >
> >
> >
> >
> > From: Daniel Busby [mailto:busby.dan...@gmail.com] Sent: Tuesday,
May
> > 27, 2014 1:52 PM To: Pestka, Dennis J; Electric Vehicle Discussion
> > List Subject: Re: [EVDL] Vibration
> >
> > I'd try balancing your driveshaft.  It's relatively inexpensive once
> > you get it out.  A local place in LA costs less than $70.
> >
> > My '64 Spitfire definitely has a wobbly shaft, but I haven't made
the
> > time to pull it out and get it balanced yet.  I stick to surface
> > streets in the meantime.
> >
> > On Tue, May 27, 2014 at 11:29 AM, Pestka, Dennis J via EV
> > <ev@lists.evdl.org<mailto:ev@lists.evdl.org>> wrote: 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 http://www.evalbum.com/1366
> > http://evalbum.com/3715
> >
> >
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-- 
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With your one wild and precious life?
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