Transmission 5th gear
 

Hello everyone newbie here to the site and to Mazda both.
Just purchased a 1990 convertible in great shape, working on power window and wiper issues (seem to be common). Anyway my transmission makes noise in 5th gear when decelerating and only occasionally. There is a receipt from a previous transmission rebuild so not sure what is up. Thanks for any advice.

What's the noise?

Is it a clunk? Whine? Grind?

Need WAY more information to offer a suggestion.

The FC 5th gear is reasonably problem free. It was the previous generation transmission that tended to grind a bit going into 5th, and the later FD transmission suffered the same issue.

But there are common issues in the FC which could seem like a transmission issue. For example, the front diff mount can break, causing the diff to nose up and down during speed changes.

The noise is a loud whine and only when foot is fully lifted from accelerator. The noise does not happen all the time either. It is kind of like the whine from an old M22 GM "rock crusher" transmission before helical gears, but louder and higher pitched. The tranny has been "rebuilt" in the past as per a receipt in the car which I just read in detail now and it included a new clutch, tranny rebuild kit and 1-2 syncro. This was in 06 and the car sat for a few years after that.

Hmm, the fact it is intermittent is what is throwing me for a loop. Could be clutch related in the throwout bearing. Only one I've seen with a similar symptom was a loose flywheel nut!