Greetings, a couple of older threads/posts/pics helped me get 4th gear spinning freely again in my 6 speed trans:
https://www.miataturbo.net/suspensio...7/#post1541632
https://www.miataturbo.net/suspensio...4/#post1459470

In my case it seems that 3rd gear separated enough to keep 4th from spinning freely. Pressed back together to close the gap and all is well. There is a suggestion to tack the two pieces together, though some questions remain for me:

Where to tack? See pictures, my thought -- see red asterisk
Do you tack a second time, 180* opposite, to "balance" the slight amount of added weight?
Do you do both 3rd and 4th because they're of the same two-piece press together nature?

This is going in my "rods only" VVT/6258 build. Thanks in advance.

 

Anyone done this before or was it just in concept?

 

Give it a shot and lets us know how it turns out.

 

Got dangit bobby

 

The asterisk in your picture is on a split shim, you don't want to weld that. The part that can separate in 4th gear is the synchro cone / dog teeth and the helical gear (red line in the picture below)


The newer miata 6 speed comes with welded gear from factory. The top gear in the picture if from an older 6 speed and you can see the the cone / dog teeth is simply pressed on the helical gear. The lower one come from a newer 6 speed and you can see that it has been welded all around

 

Excellent info, thanks. I didn't know the later trans had the gears welded already -- any idea if the cutoff of the gear revision is the same as when they modified the shifter?

For now, I do have a "late" 6 speed transmission in the car.

We haven't done the welding on the "early" transmission yet, but thanks for confirming my picture is wrong. The innards are new to me.

 

No idea. I didn't know either until I opened my 6 speed from a 2003 and found that they were welded.