FS5W71B Rebuild Thread - Tips tricks and discoveries!

[zKars]

There is always at least one really grumpy part of every job, like spindle pins, and for this job, its a very tight bearing sleeve that lives under the 5th gear cluster.

It is pretty easy to pull off, you use a bearing splitter in front of the 5th gear syncro hub , and a set of 18" rods to draw it all forward until the sleeve is over the threads, then its free.

Back on is more grumpy. 

It sits just ahead of the threads on the main shaft for that big nut, so if you can get it far enough on to start the nut, then just tighten the nut down to drive the sleeve to the end. Well, not quite, the threads run out just before you get to the end. You can use the thick washer that goes on at this spot (the one with the ball or little dowel that sits in a groove to prevent it spinning) to add a bit of thickness to finish driving it all the way with the nut back on.

I build a pipe with a hole in the end just the right diameter to hit the end of the sleeve. It slips over shaft that sits against the sleeve and lets me beat it in place with a mallet. You will need something like this if you can't get it on far enough to see threads that then allow you to use the nut to finish the job.

This is not the pipe tool thing I built, but it is the world's deepest 38mm 1/2" drive socket. Probably about 18" long. I built to let me do and undo the big nut easily. Bought a 1-1/2 socket, cut it so just the hex was left, then welded it a 1-1/4 black iron pipe (standard hardware store gas or water line)  and then welded the back half of a 1/2 drive socket to the other end.

 

[zKars]

Last bit of ingenuity is in regards to using a 4 speed bell housing, and the issues it raises. 

Back a few pages, I spent a lot of time creating a way to may a 56mm hole into a 62 mm hole. I did my first test on a somewhat expendable 4 speed bell housing.

It went better than expected, and I decided to put a 62mm front counter shaft bearing on this gear set to hopefully improve life span. So I of course feel compelled to use my new bell housing with the 62mm hole.

The worst thing about the 4 speed bell housing, is that the reverse switch hole is in the wrong place. It's about an inch too far back.

Location on a 4 speed

\

Location on the 5 speed, further rearward

 

The proposed solution is to make a new hole in the bell housing in the right spot, and plug the wrong spot. Not a terrible thing to do, it's a M14x1.5 threaded hole, I have a tap. When I looked closely at it, I noticed the hole does not pass through the case at 90 deg to casting. 

I threaded an M14 bolt in the hole to show you the angle. 

This doesn't look fun to drill or tap. I'm afraid if I go through at the wrong angle the tip of the switch won't hit the shift rod properly. So.....

So I looked at the two shift rods. 5sp on the right/top. 4 sp on the left/lower.

The depression where the tip sits when in neutral or 5th is of course farther forward on the 5sp rod (down in the pic is toward the front of the trans). Why not just extend the depressed area on the 5 sp rod farther back (up in the pic, sorry) so it ends at the same place as the 4sp rod and lets me leave the switch where it is? So that's what I did!

I first created an identical pocket in the 5sp rod in the same spot as the four speed rod. Then realized that would/might keep the light on in 5th too, so I flatted the area between the old and new pockets. Just imagine that the full diameter bit in the middle is gone, and its flat all the way across between the two flats you see here. Now the switch will turn "on" when the tip rides up the slope from the flat spot to the rod full diameter, as the rod moves to the right (forward) going into reverse. Will stay down when going to the left to get 5th

 

Edited February 4, 2020 by zKars

[Zed Head]

Pretty ingenious.  Easier than drilling, for sure.

[240260280]

Keep "chipping away" a it ?

[zKars]

Did the final assembly this morning, went pretty smooth. Have to work on my technique to get the tail housing on and the shift forks aligned at the same time. Good trick here is to take the reverse lock out assembly out and look in there with a flashlight. It’s in line with the shift forks and the tip of the shifter rod, so you don’t have to guess much.  

The other part of this is to make sure you have the through/retaining pin that is just ahead of the shifter in place, and the detent/spring thingy with the 19mm hex cap by the shifter in place as well. This keeps the shifter “kept” within the correct confines of its movement while you get the shift fork finger in “just” the right spot.

My fancy 62mm front counter bearing “schnicked” perfectly into the front cover. The C type front cover went over it without issue, needed 4mm of shim.

I can happily select all 6 gears. 

There are no extra parts laying around. 

AND I tried the reverse switch function with my slimmed down shift rod. It works! Only comes on in reverse. Bought it a new switch as well.

I stripped the cases and repainted with 2k epoxy primer (Eastwood stuff in a can) then VHT aluminum color caliper paint. 

[240260280]

 

Edited February 4, 2020 by 240260280

[zKars]

So I've been back in the transmission business again last couple of days. Mostly trying to assemble all the carcasses I have laying around here with new bearings and syncro's to get at least the clusters together.

The first I one I completed today is the one that had the very very failed counter shaft intermediate bearing. About the only thing I found that was also "Wrong" with it was the needle shell bearing under the 1st gear on the main shaft that was very very loose. I went to put it back on, and it was rattly loose. Couldn't see any damage, just worn I guess, so grabbed one of the old ones from another trans and it slipped on nice and tight. Didn't buy many new spares.

There was also a strange bit of damage I can't explain. You know that "Insert Retainer" on the main shaft on the back of the intermediate plate? The thing with the three fingers? Always makes me think it's home made the way it looks and fits. Three little tabs of metal welded onto a tube. Locks the 5th gear syncro gear to the shaft. Anyway.

Yeah, well one on fingers was bent. Toward the back. Couldn't make the shifting insert fit back in at that spot. Must have been an errant bearing cage piece got caught in there somewhere when the bearing just below it went KABLOOOWEEEE. It's quite buried, not sticking out or anything. Glad I caught it.

Then moved on tranny #2. This was the one with worn out 1/2 shift fork. 

Now old bright boy here stole its 4th gear set to build up that truck 5 sp I have with the custom ratio's I detailed earlier, that give me the .68 OD. Wonderful. Unfortunately, if I put the the truck 4th gear set in this tranny, I get stupid ratios, like a 0.9 OD. So now I'm kinda stuck.

So now the interesting part. Anyone have a busted 5 speed they kept around for parts, that they are willing to maybe give up their counter gear cluster and the matching main input shaft nose part with the 4th gear on it? Otherwise I have a really nice Close ratio 5 speed without 4 gear..... or any gear actually....

Along these lines, anyone ever see a listing that gives the tooth count of the counter cluster and main shaft gears for the common FS5*71 trans? There are a million places that list the final drive ratios, but not the internal tooth counts. I know the tooth count for the late ZX ones, (got lots of those open), but not the 79-80 and the earlier 77-78 280z. Need to know what their 4th gear tooth counts are to see what the final ratio's compute out to, should I procure some parts from those types...

 

 

[Captain Obvious]

12 hours ago, zKars said:

anyone ever see a listing that gives the tooth count of the counter cluster and main shaft gears for the common FS5*71 trans?

Need to know what their 4th gear tooth counts are to see what the final ratio's compute out to, should I procure some parts from those types...

I've got one listing sheet that I "found on the internet" somewhere, but I don't like the numbers. Doesn't look right to me so I'm reluctant to even post it.

Got a question though while I'm here... You said you want to know the "4th gear tooth counts". My understanding is that 4th gear doesn't HAVE a count. I've never been inside a Z tranny, but with the others I've been inside, it would be straight through with the input shaft locked to the output shaft. All the counter gears just coasting along for the ride. None of the intermediate gear counts matter at all.

Is the Z tranny not like that in 4th?

[zKars]

Common misconception I believe. All the trans I've looked at have a 4th gear pair, just like any other gear. The only thing that is 'special' about the 4th gear set is that its ratio acts as a modifier to all the other gear set raw tooth pair ratios, since the drive power goes through the 4th gear set first, for all gears, all the time. It's only a matter of which of the lock up hubs (on each gear set) is engaged to the main shaft that determines the power path. The counter shaft is engaged and spinning all the time, and since all if its gears are engaged to the gears on the main shaft, THEY are spinning all the time too (except 5th), though they may all be free from the main shaft (if in neutral) or any one of them is engaged (and only one!), which then drives the main shaft at that gears ratio.   

The confusion comes because for 4th, it's special because when its main shaft gear is locked to the mainshaft, power goes straight through the main shaft WITHOUT first going down to the counter shaft (at the 4th gear ratio) then back up to the main shaft (through that gear's ratio) through the selected gear set. That's why its ratio is automatically 1:1 no matter what the 4th gear tooth ratio is.

Hope that's clear as 25 year old GL-4 fluid.....

Edited February 25, 2020 by zKars

[Zed Head]

I've posted this before so it might bring up some deja vu.  But the numbers you seek might be in here.  It's a lot of pages though.  He's your Hybridz doppelganger, I think

https://forums.hybridz.org/topic/110792-high-rpm-shifting-dynamics/

[Captain Obvious]

10 hours ago, zKars said:

Common misconception I believe. All the trans I've looked at have a 4th gear pair, just like any other gear. The only thing that is 'special' about the 4th gear set is that its ratio acts as a modifier to all the other gear set raw tooth pair ratios, since the drive power goes through the 4th gear set first

I don't believe I'm misconceived or confused. I've not been inside a Z tranny, but your description of operation is exactly how other transmissions I have been inside have worked.

I guess my only confusion is why are you calling it a 4th gear pair? Does Nissan refer to that main front driving gear as the "4th gear"?

And my point is that there is no 4th gear pair because when you're in 4th no power is being put through any gears when you're in 4th gear. In fact, you could grind all the teeth off that front gear completely and 4th gear would still work. It doesn't need a pair.

it's just semantics really. You clearly know exactly what's going on inside. I'm just protesting the implication of the naming convention I guess. 

[Captain Obvious]

I just took a quick look at the parts breakdown and they call that front gear the "Main Drive Gear, and it's mate is "The Counter Drive Gear".

6 GEAR-MAIN DRIVE
GEAR-COUNTER DRIVE

The do, however, number the remaining gears:
19 ASSY-GEAR,1ST MAIN S
20 ASSY-GEAR,2ND MAIN S
22 ASSY-GEAR,3RD MAIN S

I probably should have checked first.