I know there's something wrong with my transmission but every time I take it to the dealer, they say they find nothing wrong. Now I've figured that 80% of the times I redline it in 2nd before going to 5th, it grinds. This is not normal right? If so, I'll take it to Mazda again and tell them to check it out :/

No, it should not do that. I do it sometimes too, and it shouldn't grind ever if you're going to a higher gear.... even from redline.

It WILL grind if you do a non-sequential gear shift with unmatched revs.

The synchros in the transmission in the 8 work sequentially, which means if you are not shifting sequentially, you need to double-clutch or at the very least rev match it very precisely.

I don't see how it should grind if I engage the clutch properly, take it to neutral, move it properly all the way to the right before putting it into 5th. Why would it grind when the clutch is engaged?

it does not have to be sequential. I do it all the time. Nevr had a grind. <30K miles on mine though.

It MAY be you just looking too far into it. Is it a big grind? Or just a minor one? Do you have to force it into gear? how long have you been driving stick?

Lastly, if all else fails... don't shift from 2nd to 5th....

granny shiftin. Not double clutchin like you should.

sorry had to do it. haha :rofl:

I don't see how it should grind if I engage the clutch properly, take it to neutral, move it properly all the way to the right before putting it into 5th. Why would it grind when the clutch is engaged?

http://en.wikipedia.org/wiki/Manual_transmission#Synchromesh
If the teeth, the so-called dog teeth, make contact with the gear, but the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together.
This is what happens when you do a non-sequential shift too quickly (or any shift really, I just find that it's much more present in non-sequential shifts) and you don't rev-match.

Always rev-match = save your tranny.

I agree with the rev matching comments. It is most likely your synchros grinding as the transmissions internal pieces are not synchronized with the engine, they are not expecting the shift you are making.

Take the shift slowly, dont force it into gear. Going from 2 to 5 you are not in a fast accelerating mode anymore, after you disengage second gear, take the shifter over to fifth gear, and as the RPM's are dropping apply gentle pressure to the gear selector. When the Engine RPM's are right in line with the transmission synchro's then the gearbox will literally fall into fifth gear with very little effort and no grind.

I also agree with the rev matching, it doesnt take any effort or thought on your part to give a slight tap of the throttle during a down shift. I do it everytime instinctively, as soon as I clutch in I give a quick tap to speed up the motor, makes downshifts smoother and easier.

it does not have to be sequential. I do it all the time. Nevr had a grind. <30K miles on mine though.

It MAY be you just looking too far into it. Is it a big grind? Or just a minor one? Do you have to force it into gear? how long have you been driving stick?

Lastly, if all else fails... don't shift from 2nd to 5th....

Well it won't go into gear at all really. I have to wait till the RPM drops a bit down again before I can shift. I'm aware that rev-matching is wise but that's not the thing here. I know my transmission is failing, I frequently experience grinding in other gears too, but I need something that happens frequently enough to make Mazda notice it. I haven't been driving anything other than stick btw.

I was grinding pretty bad in 2nd and replaced the fluid with Red Line MT-90 and I haven't grinded since.

Well it won't go into gear at all really. I have to wait till the RPM drops a bit down again before I can shift. I'm aware that rev-matching is wise but that's not the thing here. I know my transmission is failing, I frequently experience grinding in other gears too, but I need something that happens frequently enough to make Mazda notice it. I haven't been driving anything other than stick btw.
Actually, that is EXACTLY rev matching...

Is this usually happening under a cold operating temp? Does the problem go away or lessen as the engine/trans gets warmed up? Not to demean you here, but this sounds more like user error than a trans problem to me.

Try doing what I said as far as using gentle pressure on the gear selector while the RPM drops, and wait for the gearbox to be ready to go into the gear. Listen to the car and it will pretty much tell you what to do and when to do it, if it is grinding when you try to put it in gear, something isnt ready to go into that gear.

If you think about what you are doing when you perform a 2 to 5 shift, at redline in second gear the engine is revving at 9,250 RPM, the trans and output shaft are spinning at XX,XXX RPM, when you go straight to fifth gear, all of the internals of the trans are spinning at whatever RPM they spin at when in second gear at redline, when you go to third gear it changes the RPM they are spinning at a little, when you skip third and fourth and go to fifth, they change the RPM A LOT, and if the synchros and all the gearing arent up to that speed yet and you force it in, you are going to get grinding.

I am not saying that your trans is in perfect working order, I dont know everything well enough to tell you that. But this does sound somewhat normal. Maybe your synchros are worn, but they sound like they are working, just not the way you want/expect them to. Every car and transmission is going to be different, I have noticed that the RX8's trans seems to have some pretty tight tolerances as far as changing gears and getting grinding (if you dont do exactly what the car wants, you will get some grinding), but if you just let the car tell you when it is ready, it works great.

Actually, that is EXACTLY rev matching...

Is this usually happening under a cold operating temp? Does the problem go away or lessen as the engine/trans gets warmed up? Not to demean you here, but this sounds more like user error than a trans problem to me.

Try doing what I said as far as using gentle pressure on the gear selector while the RPM drops, and wait for the gearbox to be ready to go into the gear. Listen to the car and it will pretty much tell you what to do and when to do it, if it is grinding when you try to put it in gear, something isnt ready to go into that gear.

If you think about what you are doing when you perform a 2 to 5 shift, at redline in second gear the engine is revving at 9,250 RPM, the trans and output shaft are spinning at XX,XXX RPM, when you go straight to fifth gear, all of the internals of the trans are spinning at whatever RPM they spin at when in second gear at redline, when you go to third gear it changes the RPM they are spinning at a little, when you skip third and fourth and go to fifth, they change the RPM A LOT, and if the synchros and all the gearing arent up to that speed yet and you force it in, you are going to get grinding.

I am not saying that your trans is in perfect working order, I dont know everything well enough to tell you that. But this does sound somewhat normal. Maybe your synchros are worn, but they sound like they are working, just not the way you want/expect them to. Every car and transmission is going to be different, I have noticed that the RX8's trans seems to have some pretty tight tolerances as far as changing gears and getting grinding (if you dont do exactly what the car wants, you will get some grinding), but if you just let the car tell you when it is ready, it works great.

Ehm, why would I redline it if it wasn't properly warmed up? And yeah it's not a problem I can't live with but the real problem will be when the transmission fails for real and I'll have to pay for a new one myself. I'm barely out of warranty now but I complained about this a while ago too so I'd really like to get it fixed ^^

A victim of alfy's jdm secret shifting sequence?

Doing that kind of shift anyway as a habit can harm a transmission. Do it the right way, it is useless to redline 2nd gear and then put it in 5th. Since you're in norway i might point you out to a guy that's selling a cheap barely used transmission in italy though ;)

Well Italy is quite far away :p Anyway I'm not doing it often. Or never at all really because it won't go into 5th from 2nd :)

From what you said, it sounds like it's your tranny, not your shifting.

If you are an experienced driver with a stick, and it is more than just the one sequence, then it's probably your tranny.

Have you taken it to get looked at before?

Ya but they say they can't find anything wrong. But they're a useless bunch of asses so no wonder.