Elak

Besides the throw-out bearing noise discussed elsewhere, I'm noticing more gear noise than I've experienced in previous manual cars. It is especially noticable in low gears - e.g. driving the last bit of my driveway in first gear. Is this normal with Mazda's (someone suggested straight cut gears v.s. angular). I'm thinking of going back to the dealer to test drive one of the lot cars to see if they sound the same. The noise is more rattling than just whining. Not really loud, just louder than expected.

Anyone else have this?

/Elak

Paranoia never feels lonely

zoom44

could it be something to do with the triple synchros?

TerenceT

the 8 uses dog box???????

wakeech

hahaha... what?? hell no, then most of our forum members would probably be having significant problems with grinding...

nono, it's got TRIPLE cone synchros on first, second, and maybe (?) thrid, and dual cone synchros after that...

i cannot really offer any explination, as i'm extremely far removed from the RX-8 driving experience.

TerenceT

i know it's not a dog box, i wish tho... but Elak said straight cut.. :D

P00Man

uhhhhhhhhhhh whats a dog box?
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Wendie 99

Digisan

Yup, triple syncros on third

TerenceT

dog box is refered to transmission gears that are straight cut instead of angle cut (worm gears?)

angle cuts are quieter and easier to shift but dog gears are stronger, can shift clutchless at higher rpm and louder, i.e. motorcycle gears and race car tranny

wakeech

well, that's usually one difference, but a dog box usually refers to the transmission having no synchros (meaning you have to rev match every single shift yourself). the ***** on the side of the gear selector (which poke into the side of the gear you want to spin the output shaft) are called "dog teeth", and if the selector and your next gear of choice are spinning at different rpm, you hear (and feel) that characteristic *BUZZ* of gear grinding.

thus, synchro-meshing is now a part of the modern gearbox. these are little collapseable cones on the side of the gear selector (usually a copper alloy, i think: nice and soft) which act like mini-clutches in the gear box. when you depress the clutch, your gearbox is completely separated from any source of acceleration and is basically free wheeling. when you go to engage the gear, the synchros touch the gear first, and act as a point of friction between them, bringing them to the same speed: this is why you cannot shift clutchless in a box with synchros, and why it's also so damned easy.

for more visual references and a differently worded explination see http://auto.howstuffworks.com/transmission.htm

lefuton

i don't see why that meants you cannot shift clutchlessly...i've done it, and it seems to work just fine.

P00Man

why would you WANT to shift clutchless?
i mean, doesnt that like, destroy the transmission at worste, and make an awful sound at best?
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LEXUS LF-XH SPECIFICATIONS

DocHolliday

I clutchless shifted my 82 Sentra all the time. As far as I could figure it out it slipped into gear right at the point the shaft and the gear were spinning at the same RPM's. When you do this you spare the clutch some wear and extend its life. I could be horribly wrong though.

Also that would explain why my 01 Stratus R/T does not clutchless shift. Tried a few times without much success.

lefuton

oh, by no means would one force it into gear, if you match the revs perfectly, it just slips right in, no sound, no bucking, no nothing, it's not terribly easy to do, but not entirely difficult either... that being said, i normally do use the clutch i was just curious why wakeech said you couldn't clutchless shift

TerenceT

clutch is meant to be a serviceable item, transmission is relatively not. the general concensus is to kill the clutch before killing the tranny.
depending on the gear and syncro designs, some syncroed tranny can clutchless shift. but again, these ideas are not meant for everyday driving right?
i think it's good if the 8 cannot clutchless shift, don't want to see, i power shift and over rev my 8 kinda threads

Smoker

So how do you shift clutchless really ? (just wanted to know the theory behind it) Do you just shift into neutral rev match, and then shift to your next gear ? or do you just pop it to the next gear and couldn't careless ?

And another question ? What is the Throw-out bearing ?what is it purpose ?

wakeech

...what the?? dammit!! lost my post!! stupid server... i already answered this one: i'll do it again on my lunch break.

short answer: you CAN, it'll kill your synchro's if you eff up.

lefuton

eh, good enough, i thought you meant you'd ruin syncros regardless of whether you did it correctly.