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A lot of you have been following my posts concerning my driveshaft droning and causing a phasing in and out of a hatch rattle. Been dealing with this for ~15 years. Took it to two shops. One wouldn't even look at it- said that's just the way they are on a Z32. The second, said “I tried to put some weight on it, but it was just all over the place”. Not sure what that meant. I had come to believe that at least the heavy drone was just a characteristic of the 1-piece. Well, I found a cure for $3. I've read a couple of theories on this. You're fine tuning the balance and the bands change the harmonics traveling through the shaft. I'm going to list symptoms and the fix for fellow Z'ers to get search hits. Issues:
1. Around 60mph a heavy drone. So much so, passengers asking what the hell "that" is.
2. A rattle in the hatch phasing in and out. Fix: I borrowed most of these instructions from a YouTube video.
1. As discussed in this forum numerous times, first clock the driveshaft to every position and measure using a dial indicator. My total run out is .003 at best and .011 at worst.
2. If you have a lift, run the car up to speed and slowly move a piece of chalk towards the shaft to mark the high spot. It'll sort of start bumping the chalk.
3. Install a couple of 2-3" hose clamps(got'em at Lowes) roughly 6" from end such that the screws are opposite the chalk mark. Be sure to cut off some of the band such that it doesn't hang past the tightening screw much. I cut 2-3/4”.
4. Run the car back up to speed. Is it better or worse? If it's worse, try moving both clamps about an inch around the shaft until you find the best spot. You'll probably want to do this in both directions unless you find a spot you're happy with the first go around.
5. Once you've found an initial spot with both clamp screws located in the same position, repeat the process with just ONE clamp. It can take some time to dial it in. But it works. Did I mention $3? Notes on my application: Clock numbers looking from differential end towards front. Factory installed weights referenced at 12:00. I don't have a lift(working on jack stands) and not about to climb underneath with the car running 70mph. So I just installed them same side as the factory installed weights(12:00). I figured it would make things worse, but I didn't know what I was up against. As my gut told me, it made things a whole lot worse. Thumping and such. So I moved them opposite side of the weights(6:00). Wow! Actually getting somewhere. Ran the car up to 60 and I'm almost satisfied. Rattle is gone. Very little noise. So I move one screw to about 7:00. Worse. Move the same screw to 5:00. Man, the sweet spot! Ran it up to 60mph. No rattle. No noise. Ran it up to 75. No rattle, just a slight hint of noise. Probably get that noise with a 2-piece, right? Take it for a spin up to 80mph and the only thing I hear are the new tires and that sweet Genie exhaust. Pop beer and pat self on back.
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***FIXED***1-piece driveshaft drone/vibration - 
