Hey guys, I have a b16 j1 cable trans. I have just put in new synchros (1-5) and 3-4 sleeve in it, drove for a good 300 miles and my fifth gear starts to grind out of nowhere. The grinding mostly happen when the transmission hasnt warmed up yet. Once you drive it for an hr or whenever the transmission heats up good, my 5th doesnt grind at all. On top of that, my 3rd gear grinds at high rpms every now and then, still depending if the trans is cold or hot. It seems like the gap between my gears and synchros might be worn out. Has anyone of yah have this kind of problem?

Thanks!

 

Who rebuilt the trans? Were the synchro springs also replaced? If not, they would be the first things I checked.

Also, did you measure the gear to synchro clearance with feeler gauges? Should be greater than 0.02", and new Is close to 0 04"

 

What kind of oil did you use in it?

 

I rebuilt it myself. The rings had no damage what so ever. I haven't check the clearance between the gears. I first used 20w-50 but change it to 5w-30. Do you think it could have been possible that the 5th gear synchro ring broke?

 

No wear on 20+ year old synchro rings? Were they perfectly round?

With a broken/missing ring, the shifter will "fall" into gear very easily, usually grinding along the way. If there is any resistance at all, then the ring is probably still there, but badly worn, or the sleeve teeth are badly worn.

 

It must have been rebuilt before i got it, the rings are still round. To add on to this, its J1 internals inside S1 casing. The teeth on the gear and sleeve isn't in perfect shape but it isn't super dull or eaten off.

 

There is resistance when going in gear. It feels like it only grinding is with the gear's teeth not the synchro.

 

What synchros did you use? The J1 has a unique 5th, with unusually small synchro compared to other transmissions. I had found them to always be a weak spot, which is probably why honda quickly stopped using it. The rings are also crucial to have in perfect shape or it can easily pass across them and grind against the dogs prematurely, as mentioned already.