I don't know if it's the rear Axle going bad or the brake pad dragging or maybe even loose motor mount mount to Fiero Rog bracket.)

If I go forward, stop, put it in reverse and let Off the clutch I hear a clunking or two as it backs up. Then it's ok as I keep reversing , then I stop, put it in first gear , and I hear a quick clunk and then nothing going forward.

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Founder / President
Long Island's Little Fiero Owners Club
L.I.L.F.O.C.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Blue" <= '85 Fiero GT 3800sc series 2
~~~~~~~~~~~~~~~~~~~~~
"Boo" <= '81 Delorean DMC-12, VIN #5835, Stock PRV engine, Peugot 604 Intake manifold, Exhaust headers, Anti-3rd brake light

I think it's either a broken half shaft or something is loose.

How are your engine and transmission mounts? I would expect a torn mount to do just this.

I agree but I have all new mounts engine and trans.

Shut the car off in reverse, open the decklid, and manually push/pull the car back and forward. Watch for engine and transmission movement. It helps to have someone else with you for this, but it's a simple visual check that may or may not reveal a culprit. We did this with my 87 when I first got it to identify a clunking noise under initial acceleration. Unfortunately it didn't give us any answers but I can see the point in trying.

Further inspection and testing confirmed the issue was a loose dogbone mount. Once tightened REALLY tight, the sound is reduced to a minimum.

------------------
Founder / President
Long Island's Little Fiero Owners Club
L.I.L.F.O.C.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Blue" <= '85 Fiero GT 3800sc series 2
~~~~~~~~~~~~~~~~~~~~~
"Boo" <= '81 Delorean DMC-12, VIN #5835, Stock PRV engine, Peugot 604 Intake manifold, Exhaust headers, Anti-3rd brake light