scraping and clonking noise from 86 Spider Veloce

[Chisheng Huang <cph@xxxxxxxxxxxx>]

My 86 Spider Veloce recently developed some weird noise that I can't
locate the source.  This noise consists of two parts: a scraping sound 
followed by a clonking sound.  The clonking part is much louder than
the scraping part.  The frequency of this scraping, clonking noise is
related to car speed, not engine speed.  I can not reproduce (or I
can't hear) the noise by driving my Spider backwards.  The noise seems 
to come from the rear right wheel.  I already took off the rear right
wheel, brake caliper, and rotor disc but found nothing loose.
Everything is tightly secured there.  While poking around with the
rear right wheel off the car, I rotated the wheel hub in car's forward
direction many turns with my hands.  Sometimes the rotation would
suddenly stop and I had to apply greater force to make the wheel hub
rotate again.  Once it passed that point of big resistance, I could
again rotate the wheel hub with less force.  I'm not sure if this is
normal or not.  I also got underneath the car but found nothing loose
there, either.  I don't know what to do next.  So, here I am, asking
for help.  I'll be very grateful if you can shed any light on the
source of the noise. 

Thank you.

Chisheng Huang
Los Angeles, CA, USA.
79 Alfetta GTV 2000 (Sleeping in Taiwan)
81 GTV6
86 Spider Veloce
87 Milano Silver

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