main shaft nub FS5W71B 280 ZX

[Dave WM]

is there any way to know for sure if it right hand (normal) or left hand (CW loosens) on the main shaft?

I am back to trying a another crack at my noisy trans will get some pic later of what I think may be the issue. But I am closing in on having to remove that one.

I watched the village land guy video, he clearly is working on a later model ZX (can see the reverse lockout mech) and when time to remove the main shaft he goes CCW.

I cant see enough threads to figure it out. I suppose trial and error will get me there but would rather just know the correct answer. I don't know for sure but I think the trans is an 81, but that just from what I was told.

 

[Zed Head]

Are you sure that you can't see the end of just one thread?  All you need to know is which way it points.  A very bright light and a magnifying glass.

You might also look for witness marks on the flats.  If it's factory original, only one side of the flats will be marred, up by the point.

[Dave WM]

I think I can tell with a finger nail, turning one way it seems to pull in, will use the magnify glass in better light.

[EuroDat]

If its a close ratio transmission, it will have the same left hand threaded nut (E9803) as the 71C transmission in the 300ZX etc.

The wide ratio 5 speeds had the right hand thread

[Dave WM]

a little follow up on this. I removed the counter shaft nut, normal right hand (CW to tighten) so I could get a better view of the threads. when I spin the main shaft of course the countershaft spins the opposite direction. I can just see enough of the main shaft to see the threads moving the same direction, that is moving inwards at the same time as the counter shaft is moving inwards. This tells me the main shaft must be left hand to have the same inward spiral as the opposite turning counter shaft. Got me a 38mm box wrench so next post will be about getting the shift forks and rods out of the way so I can remove the rear main shaft nut.

[EuroDat]

Its good you could confirm which direction before you try to remove it. 

The left hand thread nut was used in the 280ZX Coupe NA with the close ratio 71B transmission.

A lot of people fall into the trap of thinking the 2+2 has the same transmission, but it doesn't. The 2+2 has the wide ratio like the 280Z and right hand thread nut.

Take your time and ask questions when in doubt. Goodluck with your rebuild.

 

[Dave WM]

thanks EuroDat. I hope to get some video soon of the fork removal. Hope it will be helpful for others, but also so I have a reference to go back to.

Can you give me any tips on re assembly? I see the use of a press and special adaptor tool to hold the plate for vertical pressing. I am hoping I can use the heat and cold method to get away from having to use pressing. I will heat up the plate and freeze the bearings hope they will just drop in. then use the same approach heating up the plate/bearings and freezing the counter and main shaft to install them.

The village land guy just uses the main nut to draw the main shaft in but using spacers instead of the rev/5th gear. tighten the nut to pull the shaft into the inner race.

[Dave WM]

a couple questions I assume new roll pins are a must, Nissan part? or generic.

There is a lot of talk about different thickness snap rings, I assume this has to do with manufacturing variances? or is some kind of wear issue on the shafts in the grooves for the snap rings?

Do I really need new woodruff keys? I did not realize these would wear enough to be an issue.

I will use new shaft nuts.

Lastly the kit I got came with a no name needle bearing for the input shaft, "china" on the bag it was shipped in. I am thinking I should get a Nissan one just to be sure. the other bearings had japan printed on the bearing and seemed to be from a big supplier. I am worried about the needle with no branding.

funny thing I noticed on the tear down, the magnet on the drain plug was missing a chunk, about 1/4 just broken off. I am sure it was not like that when I got it but I can't recall any thing I did that would cause it to break. Guess I will be getting another one of those as well. I don't know why the orig broke but don't want to take any chances of more breakage there.

[Zed Head]

Have you determined the source of the grinding noise yet?  If some major part is broken you might be planning to fix the unfixable.

[Dave WM]

The bearing on the back of the mainshaft closest to the speedo drive was somewhat rough. I have used my stethoscope on the two front bearings, they did not seem bad, but I have no point of reference since I am a newb to what they should sound like. At this point its a learning experience, hopefully when I get it apart and can really clean all the oil out of the bearings, I will be able to compare to the new ones. I can not see any obvious problems anywhere else but again my inexperience is a problem.

[EuroDat]

I agree with Zed. Try to find all the problems before investing to much. It might not be worth fixing.

If its ok. The woodruff keys should be ok, if they are not damaged. I would replace the roll pins and the springs behind the detent balls on the selectors. If the needle bearing quality is unknown I would replace it too.

I have an excel list with the sizes and part numbers of the bearings, seals/o-rings and synchros.

I have nether seen a kit with all the seals, so you will need to buy some extra items for a thorough rebuild.

[Dave WM]

I will hold of an any more parts buying until I get it torn down and hopefully find the problem part.