I have an '04 with 64.5K miles, 6MT.

I changed my tranny and diff fluid at 60K. I'm currently using Redline's MT-90 and 75w90. Recently, i've suffered from grinds when shifting 8K RPM and up. It's a hit or miss between 7-7.5K RPM. No grinds during daily commuting. Here's the kicker, at about the same time i've began to have grinds, my car threw a pending code for a bad cat (P0420). However as of late, the code vanished and has not popped up. No power loss whatsoever, as far as I can tell anyhow.

Should I go back to OEM fluid? Do I have a bad synchro or pilot bearing?

 

i have a somewhat similar issue.

If I try to down shift from 3rd to 2nd it almost all ways grinds.

 

same exact thing, i was going to have my trans fluid drained and filled. PM me if you find a solution!!!!!!

 

bump

 

Could be your clutch is not able to handle the high rpms any more. That is where I would start.

 

Perhaps. Do you think these two are related? https://www.rx8club.com/series-i-tro...6/#post4612400

 

Replace your clutch.

 

Okay, i'll do that and report back here. I'd like to add that I don't grind if i double clutch. I'm just hoping I don't need a rebuilt tranny.

 

Don't replace the clutch yet! Check clutch play first and also inspect the clutch pedal bracket for signs of breaking.
Here under clutch adjustment:
http://foxed.ca/rx7manual/2003mazdar..._S01_0498.html

And here to check for breaking:
https://www.rx8club.com/series-i-do-...al-fix-170387/

Throwing a new clutch at the problem without properly diagnosing it is a waste of money.

 

Great info, Harlan. I believe the assembly is fine, it doesn't move left or right, go at an angle or make a squeak.

 

You may not be able to tell without looking at it, everything else is a symptom not the problem. Just take a flashlight and wedge yourself into the footwell until you can see it.

Also don't miss the first link on clutch pedal play, it might solve your problem.

 

Thank you for the clarification. I'll do so and let ya'll know how it goes!

*edit* I think the synchro in 3rd gear is worn. When I double clutch into 3rd at 8.5 grand it doesn't grind.
Displayed is RIWWP's symptoms and causes for my particular problem. I guess i'm going to live with it until I can get my tranny rebuilt or get my hands on a Series II transmission.