1 minute ago, John Coffey said:

You're prepping for an event and having a debate on whether the transmission can be used?  Pull it and replace it with a known good unit.

True, if the event is the top priority.  

Pulling the transmission itself may knock him out of the event though.  Put a tow company number in your phone and just run the event and hope.  Assume it's toast anyway.  You'll provide entertainment when it starts grinding and self-destructing.  A way to make new friends.

Oh I know the 5 speed needs to be swapped out or rebuilt. The rally is about 1500kms in length and I want to make sure everything is going to be right. As far as finding a good used unit that may be harder then it was a few years ago. Maybe there are some forum members here in the Vancouver area of BC that may know of one.

Saw the 1970 and assumed 4 speed.  I'm losing it.  Good luck.  Put an ad in the Parts Wanted area.

http://www.classiczcars.com/forum/21-wanted/

If you don't know the condition or history of another gearbox, I would take this out and crack it open.

If its only a bearing, then I would buy new OEM synchros and a bearing / seal kit.

At least you know the history on this box and it wasn't jumping out of gear or screeming its head off at 60mph.

My 2 cents.

IMO, Tear it down, at least so we can see the guts. It may be that this trans is still usable but if I was going to put money into a trans, I'd prefer one that hadn't eaten and pooped out a bearing. Hard to understand how this tranny wasn't making noise. 

Here's a shot of the adapter plate stripped down with just the outer race.  If you have space and some ingenuity, the tear down and bearing replacement shouldn't be terrible.  The manual calls for special tools and large presses but people manage without them.

 

Well its out.... hardest part was the mark 1 center console! What a pain....

Mark and Euro know the tricks for rebuilding.  But if you want to get a head start, and maybe get lucky, remove the front cover.  It's the piece that has the snout for the throwout bearing collar.  You'll see the input shaft and countershaft bearings under it.  The cover can be tough to remove (Nissan glued them on), don't break it.

Edit - actually you won't get lucky because EuroDat already confirmed that it's an adapter plate bearing.   Were you I, I'd (you'd?) set it aside and find another.

Edited February 11, 20169 yr by Zed Head

Just thinking out loud but would the 4 spd adapter plate fit the 5 spd? Same bearings and positions?

4 hours ago, Mark Maras said:

IMO, Tear it down, at least so we can see the guts. 

 

2 hours ago, Zed Head said:

Edit - actually you won't get lucky because EuroDat already confirmed that it's an adapter plate bearing.   Were you I, I'd (you'd?) set it aside and find another.

Okay so which should I do? And which end do I start with seeing as the bearing seems to be in the adapter plate.

If you want to open it up. The section MT-5 in the FSM has a good procedure to do it. The front cover would be the easiest to start with if you want to get a look inside. You will need to remove the throw out bearing collar to get to the main input shaft bearing circlip. Like Zed said, it can be a pita.

"Okay so which should I do?" You get that often here. I don't think either way is wrong, just choose which one are you most comfortable with.

Your tranny is stuffed, spliting it apart won't make the damage worse and you will get to see inside one.

If I recall right the front case is easy to remove.  No need to mess with the shifting mechanism, just remove the circlip on the input shaft bearing (under the front cover), remove all of the bolts that hold the back to the front through the adapter plate and tap the front case off.  The back end will be loose and can create a gap but it can just be held on by hand.

Here's a link that describes a fairly common front case swap.  Your front case half to a newer gear set.  I did the swap and never separated the back end, only the front.  http://zhome.com/ZCMnL/tech/240SX5spd/transmission.htm

I know that EuroDat replied also but my internet is crapping out so I'm just going to hit Submit Reply.