A few days prior I started to notice the gear stick would want to pop out of 3rd and 5th when accelerating. It was very subtle and nowhere near actually popping out of gear, just the stick would move towards the neutral position when I accelerated. I had also noticed some what sounded like mainshaft bearing noise but it wasn't that bad. I bought bearings and ordered synchros and planned on doing them last weekend.

Thursday rolls around and the trans gets stuck in 5th. Pull over, shut car off and still won't come out of 5th. Start engine, rev engine and get it out of 5th and in neutral. Goes into 1st fine, upshifts to 2nd, then 3rd then won't downshift to 2nd. Long story short I limped it home by revving the **** out of the engine, only way to get it to shift. Pull trans and pull apart.

Obviously it got hot as hell. The synchro was fused to the taper ring. Had to press it off the ring. The hub got chewed up as well.







After I pressed it off.



I also have very light wear on 5th shift fork. It looks worse then what it is but I can catch my fingernail on one edge. Replacement necessary?




I'll be honest my experiences with manual transmissions is pretty much limited to bearing replacements. Is there anythings else with this I should be looking out for? Anything that may be toast that I'm not seeing? Anything I should be measuring? I can take more pics of anything just ask.


So far I have all the ball bearings, synchros on the way. Should I replace all the needle bearings? Just the one by 5th? They all seem ok.

What 5th gear hub/sleeve and taper ring do I need/should I get? M2F4? OEM? Aftermarket stuff? Diff bearings the same as M2F4?

Anything else that needs to be replaced when you replace the hub and sleeve?

 

Ok so I decided to just replace the shift fork while I have it out. I need to get the hub and slider and the 5th gear along with the taper ring.

Can anyone confirm these parts from a M2F4 will work? If not what should I be looking for?

The dog teeth on 5th aren't looking so hot. Is the M2F4 compatible? If so am I able to just swap the 5th gear on the mainshaft without touching the countershaft?

Also what diff bearings should I be looking for?

 

You need to contact synchrotech, those guys know everything there is to know about interchangeability.

Sounds like your fluid leaked out. Don't forget to change all your shaft seals and even the shifter seals while you're at it.

 

Acceleration and deceleration that leads to a release of the gear position is caused by shaft movement. You have a loose bearing and/or excessive clearance in the mainshaft and countershaft. When these shafts are allowed to move, the fork cannot move far enough to keep the detents engaged, resulting in a loss of gear position.

A lot of people ride that damage out and press the shifter as hard as possible to maintain gear position that the forks will usually show very heavy wear. I would measure each of your shift forks and replace them as required. Also inspect the shift change piece for wear and bending.

https://honda-tech.com/tech-misc-15/...ained-2051578/