[DeTomaso] Oscillating vibration

[Art Stephens]

     Mike,  I know its a long shot but on your next test drive,  you might
put the car in neutral and see if that has any affect.

Art


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Sent: Sunday, August 26, 2007 9:30 AM
Subject: [DeTomaso] Oscillating vibration


>I have about 200 miles on my new motor, and am in the debug phase of the
> project.  I've had an interesting issue pop up and wanted to post it to
> see
> if there is anything I am not considering as a potential solution.
>
> When I get up to about 75-80 in fifth gear (2500-3000 rpms), I get an
> unusual oscillating vibration.  I've certainly felt alignment or wheel
> balance vibrations before in other cars, but never of an oscillating
> nature
> that rose and fell at a constant speed/rpm.  I am pretty sure it is
> chassis
> related as hanging in the same rev band in lower gears does not induce it.
> I checked the tightness on all 16 half-shaft bolts, and they are snug.
> Next, I am going to have the wheels balanced tomorrow.  If that does not
> cure it, I am going to have the balance checked on my new half-shafts.
> Other than that, I know both rear rotors are slightly out of true,
> dragging
> a bit at one point when I spin the wheel while it's off the ground, so I'm
> wondering if the drag on the brakes at that particular speed sets up a
> harmonic between the two rear wheels to create the oscillating effect, but
> that would suggest the wheels were of a different diameter and rotating
> different speeds.  I had the alignment recently done and no changes to the
> suspension or bumps hit to knock it out, but I guess that could be
> something
> else to check.
>
> Any thoughts from you guys would be appreciated.
> Thanks
> Mike Thomas
> Panteras Northwest.
>
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