I have noticed this for a while and can't figure out what it is, however it is getting worse & louder. Sometimes my car makes a loud metallic rattling noise when the motor revs down.
Say I start moving from an intersection and I have to stop again not too far away. It's fine accelerating in 1st gear, but after stepping on the clutch and letting the motor go back to idle it will make noise until it hits like < 1200RPM's. Sometimes it will go clack, clack, clack in quick succession, others it it just a single clank.

It is hard to hear unless you're actually in the cab, standing in front of the car with the motor running & playing with the throttle, it's almost inaudible.

Can someone help? It's getting worse and I'm concerned.

Thanks!

 

Are you stepping on the clutch real fast? Does the sound get less noticeable or go away by pressing the clutch slower?

I've had this same problem for 6 months now. If I accelerate and then immediately have to stop quickly, and hit the clutch peddle quickly, the clutch will bang around. It's almost like it is bounching off of the pressure plate when i disengage it

 

I'm trying to picture the noise you're describing, but is there any chance it could be your exhaust heat shield that's rattling? The shields for the main cat sit right below the cab.

 

I had a problem like that and it was the exhaust shield took it to a muffler shop they cut it off for free...

easiest way to check is look under they car see if anything is hanging down

 

I will try to get a video up with the sound in it, text is hard when it comes to noises. A couple friends also said maybe it's the exhaust. Nothing is hanging or visibly moving on the exhaust but I can't see all of it until I barrow a better jack in a few days.

As far as how fast I use the clutch it doesn't seem to matter. It is so random it's Hard to narrow down, engine temp affects it.

My car has 250k+ miles and I think the clutch was never replaced. That's pretty old even though ppl say RX7 clutches last forever.

 

It would be great if you could get a video up.

I just replaced a throwout bearing and from what it sounds like you might be having some of the same issues.

Just post a vid up when you can

 

I had the same problem - it was the split air pipe rattling against the exhaust. Get under the car (when the exhaust is cold!!!) and give some stuff a bit of a shake. The split air pipe, the exhaust its self and the heat shield. If you can re create the noise - great!