Hey guys. I noticed that under WOT shifting from 1st to 2nd above 5500rpm it would ALWAYS grind even with the clutch fully pressed firmly to the floor. I have just over 54K kms (34K miles) on my CX5 GX Manual. I took it into the dealer. After looking at it they told me they'll order some parts and give me a call. Fast forward ahead they dismantled the ENTIRE transmission and replaced the almost all the gears/syncros related to gears 1 to 4. They had the car for 2 days and when I got it back it shifts AWESOME now. Glad the 100K powertrain warranty applies! (Book time was 6hrs...took them 15.8hrs!) I guess that's the risk of buying a 1st year vehicle but I'm very glad Mazda stepped up to the plate. After talking to the dealer he said it's a known problem with TSB (05-16-02) and eventually it'll grind no matter what rpm you try to shift it at. Just thought I'd share my experience with you guys! Long live the manual CX5s!
Well you can maybe find some anti friction additive for the gearbox..I use to get the same problem in my Jeep Wrangler and it helped out alot when going from first to second.
I think I'll certainly look into a good synthetic gear oil after. Talking with the dealer the first batch of manual transmissions some were known to have manufacturing defects. That being said I don't know if friction additive would have helped or prevented it. I'm just happy that they fixed the problem and hopefully the problem is solved.
UPDATE: I've now put just under 20K kms (12,400miles) on the updated transmission and the grinding going into 2nd has resurfaced in certain driving conditions. It seems the syncros aren't matching the rpms. It's going in this Fri but because the condition happens randomly under hard acceleration above 4500rpm it's almost impossible to duplicate for the techs. Hopefully some dashcam videos will help duplicate the situation. I'll keep you posted.