Rebuilt AX-15 but still having weird issue...

So my trans wouldn't hold first gear, it would violently jump out if you tried starting from a stand-still. Fast-forward to now... I just did a rebuild that replaced all Synchro rings and bearings, seems to work great... most of the time. It seems now if it's cold it's hard to shift into gear, needs some coaxing, AND it's jumped out of first twice again :tear: It's not quite as violent and if I put it back in then it holds fine. The problem seems like it's worst when it's cold.

OK, so my question is this, I cheaped out on the fluid and just got some GL-4 stuff from NAPA... I read that some Redline MTL might help with my issues, anyone else have experience of this? Am I looking in the wrong direction?

Get that GL-4 out of there as fast as you can!!!!! Like YESTERDAY!!!!

Switch to Redline MT-90. Been using it for 3 years now.

Best stuff made for our manual Trans with bass synchros. I spent over $1000 just on parts rebuilding mine, and reused just the case and one gear, and after about 4 weeks it would not go into gear. MT-90 solved the problem, and I had a GL-3 or 4 in mine, and it had already chewed up a ton of brass in just 4 weeks!

DON'T WAIT!!!!!

Yeah, it was a hunch I had... I'll do it today!

So, I did it... and I am pretty bummed to report that it seems like it didn't do much. Now it seems harder to shift when it gets warmer and there was a considerable amount of brass in the fluid I drained out... it's been in there for 2 weeks!! Could some cheap fluid really do that to my rings?!

Yep, the high sulfur in the GL-4, or 5 is death to the brass synchros. Mine took a few miles, and a day or so to go back to working perfectly. Is you clutch working OK?

If it does not settle down after after about 100 shifts, I would drain the fluid, and see if needs filtering (strain and reuse it?), maybe it is washing out more loose brass fines into the pan. Otherwise it may be too late already?

But IIRC it took several days of occasional hard shifts for it to completely settle down on mine. But it was huge improvement at first!!!! And only got better with time.

Good luck!!

That's good to hear, I also heard that possibly the new synchros need to break in? One guy recommended sanding down ever so slightly the inner grooves to help with this... I didn't do that though, anyways I hope it does get better, thanks for your input!

Ok, update.... It's getting worse!!!!

It's almost as bad as it was before I did the rebuild... it just wont hold first gear! 1st gear just doesn't feel right, never has. All other gears have a nice click into gear except 1st... Arrgh! I'm stressin because I have to get this drivable for my wife in the next few days. Anything else I should look into? I can't believe I trashed the synchros again in 3 drives.... please no.

Sounds more like a bad gear, bust tooth, or bad bearing now if the fluid swap did not fix it. Sounds like it is time to tear it open again. But I am not an expert on that transmission. Maybe some else will chime in? I think 5-90 knows a little about that one?