5 Speed Rebuild problems and questions

[Al 77 280z]

Hey Guys,

About a month or so ago I started having some issues with my transmission in my 77 280z. So I decided to remove it from the car and have a friend of mine rebuild it. We have ran into a few issues upon getting the case open and I could really use some input. First off the transmission is out of a parts car (my car was an automatic) the parts car was also a 1977 but it is unknown how many miles were on it. Anyways the transmission developed the following issues upon swapping it into my car. 

1. Downshifting into first was impossible except when at a complete stop.
2. would not stay in 2nd or 5th gear while not under load.
3. Vibrations in the clutch pedal upon initial engagement of the clutch.

I figured these issues were caused by the trans being 40 years old but when my buddy started the project he found...

1. The sleeve that is part of the front cover where the throwout bearing rides was completely sheared off. This is obviously the cause off the rattling but has anyone ever seen this happen or know why it might happen?

2. We found all this debris inside the case. This metal is not gear material it is sheet steel that appears to be riveted and hinges. We have no idea where it goes within the transmission

3. One of the 3 roll pins was broken in half but it was still in place until he removed it. 

Any input would be great guys, thank you.
 

Edited October 3, 2016 by Al 77 280z

[Zed Head]

Where's the broken front cover?  

The metal debris in your hand is the ball retainer from one of your bearings.  Check all of the bearings, one or two will not be the same as the others.  Check the nuts that hold the shafts also, one of them might be loose.  Which could have caused the bearing failure.

Doesn't look terrible.  People have shown similar and reported good fixes.

[Mark Maras]

 The sheet metal and rivets could be bearing cages. How do the gears look? Was the sheared off piece still in the release bearing? Inspect the gears, shafts and check the clearances. It was likely popping out and not going into gears because of bad synchros.

[Al 77 280z]

 This video is the only image I have of the front cover. I'll have a pic on Tuesday but yes the sleeve was inside of the throwout bearing and sheared off at the base of the front cover.

IMG_5227.MOV

 

Ahh the bearing ball retainer, that makes sense I just googled it and this seems to look like it.
 

Edited October 3, 2016 by Al 77 280z

[Zed Head]

How wobbly is the main/input shaft?  I don't know how loose it could get but if the input shaft bearing is the one that went bad it might have enough wiggle room to contact the throwout bearing support.  And the misaligned shafts can cause shifting and pop-out problems.

The front covers are all the same for the 71B transmissions, except that the early ones are made of steel.  Get that free 4 speed that was recently advertised here and you'll have a replacement front cover.

[Al 77 280z]

The input shaft was not very loose before the disassembly and there is no damage to the input shaft from broken sleeve grinding or riding on it. Luckily thanks to @Jeff G 78 I have a donor 4 speed to get a front cover and use as reference. The syncros do have some wear and one appears to be ground down and a step is evident in the teeth. The gears look decent for the most part but a few have some small chunks missing out of them likely caused by the loose metal floating around inside the case. 

How many gears and internal parts do the 4 and 5 speed share? If necessary could I use some of the matching gears from the 4 in the 5 speed?

Edited October 3, 2016 by Al 77 280z

[Jeff G 78]

1 hour ago, Zed Head said:

How wobbly is the main/input shaft?  I don't know how loose it could get but if the input shaft bearing is the one that went bad it might have enough wiggle room to contact the throwout bearing support.  And the misaligned shafts can cause shifting and pop-out problems.

The front covers are all the same for the 71B transmissions, except that the early ones are made of steel.  Get that free 4 speed that was recently advertised here and you'll have a replacement front cover.

The input shaft didn't have much, if any extra play Zed.  I was surprised to see the broken sleeve as I haven't seen a failure like that before.  If appeared to have broken right at the front cover, though I didn't study it close enough to see if it fatigued from flex.

I donated a 4 speed to Al for the front cover and whatever internals he can use.  Hopefully all goes well with the rebuild.

[Zed Head]

I think that I've read about broken sleeves, or snouts/noses.  Comments about aluminum over steel.  I have one that has a shallow notch worn it, probably from a throwout bearing that was seized.

Edit - found one example.  http://forums.nicoclub.com/transmission-front-cover-shaft-broken-t553719.html

Edit 2 - notice the comment at the end about the pilot bushing.  Don't know if it's true, but worth a look.  Might also explain the broken bearing.  Not uncommon, I would imagine, to forget to install a pilot bushing when swapping from an automatic.

Edited October 3, 2016 by Zed Head

[Jeff G 78]

I've never thought twice about that part.  I guess I will inspect it from now on anytime a trans is out.

[Diseazd]

7 hours ago, Zed Head said:

I think that I've read about broken sleeves, or snouts/noses.  Comments about aluminum over steel.  I have one that has a shallow notch worn it, probably from a throwout bearing that was seized.

Edit - found one example.  http://forums.nicoclub.com/transmission-front-cover-shaft-broken-t553719.html

Edit 2 - notice the comment at the end about the pilot bushing.  Don't know if it's true, but worth a look.  Might also explain the broken bearing.  Not uncommon, I would imagine, to forget to install a pilot bushing when swapping from an automatic.

Exactly....I had a throw out bearing seize and the rotating finger tips  of the pressure plate actually welded to the bearing. This locks up the collar to release arm.....thus torquing the shaft that broke. Transmissions are cheap.....replace the front cover with a good part.

Ditto on the pilot bushing....when swapping from auto to manual, it's crucial to install a pilot bushing!

[Al 77 280z]

Pictures of the front cover

[EuroDat]

I have heard a couple of reasons why they break, but can't prove any of them right or wrong.

Forgetting to fit a pilot bearing or spigot bearing as its sometimes called when going from auto to manual is a common reason. I would expect this to cause some vibraction because the clutch disc would be of center.

No lube on the clutch fork fingers. The dry contacts don't let the fingers slide over the tabs on the collar. That causes a sidewards force when the fork goes through its pivot radius. That force back and forth breaks the guide.

The bearing pieces are most probably from the main bearing in the adapter plate. It's the one that goes most the time.

Strip it down and inspect the parts first. Then decide if its rebuildable. I have a list of all the more common parts you will need and all the lastest Nissan part numbers or all the bearing and seal sizes if you want to go aftrr market.