Last night after a hard mis-shift a rattle/grinding noise can be heard and felt from the shift lever at high revs (above 6k) in all gears.

I was going to change the transmission fluid to try and get any metal out of there but I'm expecting it to provide a fix.

I think I broke off a peice of synchro and it's causing this vibration now. Any other thoughts?

 

i think you're 90% correct!

 

A fellow FD owner suggested that it could be either:

1) the ***** and detent springs which can be easily changed from the bottom of the car
or
2) the little nylon cap at the bottom of the shifter broke. I know mazdasport makes an aluminium one for $7.

 

As memmi said, it's probably that nylon piece.

If it's the same in all gears, it's probably just something (like the shift lever) vibrating at that RPM. Does the trans function normally otherwise? If the cap at the end of the shift lever broke, there should be more play in the shift lever now than there was before it started rattling.

 

I'll check for more play, i think there may be a bit more now, yes.

The transmission shifts normally otherwise, as it always has.

 

http://www.mazdatrix.com/shiftrat.htm

found this and it's interesting. I wonder what factor changed after the shift to now cause the rattle?