Helo! i've been reading on this forums for ages but here its my first post.
I have a 1990 that i've installed a 6 speed form a 2004 miata.
it shift and goes great but when in 4th and 5th gear, if i push on the shifter to the right, it makes a grind noise. not in other gears, not to the left, only in this case.

i had a stock 2001 miata few years ago and it never made that...

whats can be goiing on in this one?

its not the bad slave or worn syncro im used too. maybe a bent shift fork?

its currently out of the car to fix the oil leak on the tail shaft joint and install a 2004 vvt engine.. so its time to open it if necessary..

Thank you for the help!

 

I am unaware of this specific problem but I do know that the aluminum shift forks on the 6-speed are often bent by rough handling.

If it does not make noise when you aren't pushing the shifter to the side then I would say don't push the shifter to the side and just run it.

It reminds me of the old childhood joke where the guy goes to the doctor and says, "Doctor, it hurts when I do this." And the doctor says, "Well, stop doing that."

 

ahahm thats pretty much where i am, but its one of those thing i would like to fix. i may open it and check the forks. i read that parts can be sourced from rx8 or toyobaru?

 

Rx8s and frs/brz center sections look very similar and seem to have some degree of interchangability but nobody's actually gone and done it...yet

90% sure you cant replace a shift fork without a near total disassembly of the gearbox.
Just the bell housing is easy but annoying due to the 5/R pivot. The tailshaft is a different story, there's alignment bolts and spring/ball caps that have to go back to where they belong.