When I shift into 2nd at a high rpm it makes a crunching noise sometimes and it does the same downshifting into 2nd.It doesn't happen in any other gear.What could this be???

2nd gear synchro.



It'll need a rebuild soon. You should change to synthetic fluid (Redline) to see if you can get any more life out of it.

thanks i'll change the fluid...how much will the rebuild cost?

If you let the RPMs fall back to near idle it'll go into 2nd just fine, but that doesn't mean that the synchros are okay.



As for rebuilds, you're looking at ~$500 or you could just buy a used one for less.

or learn how to rev match on your downshift and it shouldnt grind as bad.

Let's keep the bullshit out of this thread.

sorry...anyways its ur 2nd gear synchro thats shot.... you gotta start to match the revs like it was said

My N/A FC did that, and STILL does that.. 200,000 kms on the transmission



It had been doing it since 180,000. I switched to Redline MT90. It's still runs and drives fine.



(I have got another tranny since, though, just to give you a general idea that it can still have some life left).

Its a little late now, but mazda trannies are finicky, and intolerant of poor shifting habits. Not to mention the synchros are much slower than some newer transmissions. Dont try to jerk the shift lever too fast. If it grinds, you are trying too hard.



And just because its grinding, doesnt mean the synchro is completely shot, or it needs to be rebuilt immediately. You can drive for a very long time with worn synchros. The only real change is the engine is even less tolerant of imperfect shifting.



Bottom line: learn how to shift without grinding.

once the syncro is bad the only way to stop it from grinding

is to baby the car, you cant drive it hard and expect it not to grind