14 minutes ago, Jeff Berk said:

I'm assuming that the dust sleeve and seal need to be removed to pull off the tail end of the transmission.

The dust shield comes right off with the tail shaft housing.  The output shaft is hanging free inside, no need to mess around back there. 

If you don't have even a tiny gap at the mating area with the adapter plate (the solid metal plate between the front and back) then it's probably just glued together with sealant.  Give it some side to side love taps to break that seal.  The FSM procedure is pretty thorough.

Dust shield still attached.

Edited January 3, 20214 yr by Zed Head

Also, I believe it needs to be in neutral

Thanks all, got it off. I'll take a stab at the front half of the transmission case tomorrow.

OK, I pulled off the front transmission case. Keep in mind that that I have not done this before so I'm not 100% sure what I'm looking for. 

What seems to jump right out is that the baulking rings seem to have some teeth chipped off. My problem, however, was that I'm slipping out of 3rd and 4th gear.

 

Yes, your synchros (baulk rings) look terrible. Looks like one has been completely destroyed.

From what I've seen, just over the few years I've been browsing Z car internet stuff, I'll bet that one of the bearings in the adapter plate is falling apart. Grab the shafts and wiggle them around while you try to see down at the bearing area.

Check this recent thread out.  It shows the aftermath.  But the gears themselves seem very durable.  Several people have just replaced bearings and synchros despite the damage and been back to like-new condition.

https://www.classiczcars.com/forums/topic/64776-280zx-5-speed-wont-reverse/?do=findComment&comment=613709

 

If you look at MT-16-2 below, there is a little play in the main shaft at the point where it's shown as being separated from the rest of the shaft. I'm assuming that's normal. I can see the bearings in the adaptor plate and it appears to be in good condition with no play in the shaft as I try and wiggle the shaft.

Could the worn synchros be causing the slipping out of gear? I thought it would just be a problem getting into gear.

It looks like I might be able to do the rebuild myself as long as I don't need a press. If it gets too rough, I have a local mechanic that has worked on these transmissions I can fall back on.

Once you get chunks of metal floating around in there things can get jammed up.

zKars had a whole writeup on a transmission rebuild.  Others have also.  EuroDat comes to mind.  Tools can be fabricated.  There are basically two things that hold a gear in place once it's chosen, the balls in the adapter plate, and the inserts under the coupler sleeve.  It's late and I might have picked the wrong words but overall it's simple.  Making it all work right can be complex.  Definitely doable, but challenging.

I haven't looked but I seem to recall Dave WM, and maybe others, not finding the destroyed adapter plate bearings until they took things apart.  Some people rebuilt their transmission's for synchros and found the bad bearings by accident.  Most people are surprised at how well the transmissions work even with all of the damage.

If you didn't find any metal it might be that somebody already cleaned the drain plug.  Anyway, I think you need to tear it down all the way.  zKars, Dave WM, EuroDat, others I'm not remembering have all written some good stuff about it.  I'll post links as I find them.

 

 

 

Here's a shift fork problem, check those.

 

Edited January 6, 20214 yr by Zed Head

Blue's collection of tech tips   I used this link when rebuilding my 5 spped a few monts ago. Lot's of good advice that, along with the FSM, walked me through it.

Thank you Mayolives! There are many tips in there that will help. I'm on hold waiting for a bearing puller/splitter to arrive. I'm also mounting three dowel rods on my work bench to sting components on in order so that I can put everything back in the proper sequence and direction. It was suggested that I engrave an F on components on the side facing the front. I might do that as well.

I'm assuming roll pins should be replaced with new ones but snap rings are fine to reuse. Correct?

I reused mine with no problems. Be sure to use snap ring pliars when removing and reinstalling them. Best not to "dig" them out with a screw driver or other tools because you could bend and deform them. 

Edited January 9, 20214 yr by mayolives