wide ratio FS5W71B slipping out of 3rd & 4th

[Zed Head]

Just to be sure, you said you can't move the shift lever.  Did you try rotating the input or output shaft?  If it's in two gears at the same time the shafts won't move either.  Everything gets locked up.

So I'd use the "one gear" method to put the front case on, then rotate the shafts to make sure everything's okay.  Then put the tail shaft housing on.

[Jeff Berk]

I inserted an endoscope into the hole I drilled and realized that the striker was just short of engaging. I switch to another striker and this time it engaged and I was able to go through the gears. I could see the ends of the fork rods in the bell housing moving in and out as I shifted through the gears and the input shaft turned freely. Unfortunately, I need to disassemble the case since I didn't apply RTV to the adaptor plate yet but If it work once, it should work again. I've attached a photo from the endoscope showing the non-engaged striker. I knew that endoscope would come in handy some day. Sorry for the poor resolution.

 

[Jeff Berk]

I've got up the nerve to install the transmission, that and my wife wants her half of the garage back so I had to move the transmission out of the way. I was just about to start the install when I tried to give the input shaft a spin and it wouldn't budge. I checked and I was in neutral so I started back tracking and pulled the front cover off and it moved freely again. I checked to make sure the spacer was in the counter shaft well and I reseated the main shaft seal so it was properly seated and tried again. As soon as I started to torque the bolts to about 13 ft/lb, the input shaft seized up again. I tried another front cover and had the same results. 

I noticed that both bearings seems to protrude above the transmission case, 0.21 and 0.17 inch for the main and counter shaft bearings, respectively. Should the countershaft bearing be recessed and a shim added to bring it flush? The input shaft bearing cannot move back any further that it is now because it needs to have a retaining ring installed. I removed the bellhousing and checked the bearing and it seems to be up against the countershaft drive gear. There is a C clip between the countershaft bearing and drive gear, but it is up against the drive gear so it should not be holding the countershaft bearing from where it should be.

Anyone have any ideas?

Jeff 

[Zed Head]

The countershaft bearing actually requires a shim to get proper preload once the cover is installed.

I remember that the countershaft bearing was tight against the gear on mine when I removed it.  I had to fabricate a sort of bearing splitter to get under the edge it was too close to get puller jaws in.  Yours looks like it has lots of space, like the countershaft bearing is not fully seated.

Mine was right up against the gear.  The inner race should be driven all the way down to a seat area, I believe.  Edit - you can see the inner race seat in the illustration above.

 

Edited April 9, 2021 by Zed Head

[Jeff Berk]

I cannot move it any further in on the counter shaft. That gap you pointed out is a step on the shaft. Maybe I need to force the entire counter shaft in a few tenths of an inch?

 

Edited April 9, 2021 by Jeff Berk

[Zed Head]

3 hours ago, Jeff Berk said:

As soon as I started to torque the bolts to about 13 ft/lb, the input shaft seized up again. I tried another front cover and had the same results. 

Can you see or feel a gap under the front cover before you try to torque the bolts?  Are you using a gasket?

 

For any future lurkers, I found the part about sealing the "withdrawal" lever (pivot) ball pin threads.  Didn't know it was in there.  Not your issue, just adding...

[Jeff Berk]

I'm not feeling a gap under the cover. I'm using a paper gasket without sealer.

After disassembly again, and bumping the counter shaft in with a dead blow hammer, I got the following measurements of the protrusion of the bearings beyond the casting surface:

Before hammering the difference between the protrusion of the main and countershaft bearings was 0.04 inches

After hammering the difference between the protrusion of the main and countershaft bearings was 0.13 inches

This extra 0.09 inches seemed to have helped although I'm feeling some resistance when I turn the input shaft by hand. I'm assuming I must use a countershaft shim. Is that correct?

Should I use a fresh gasket maybe of thicker material to compensate for compression?

Edited April 10, 2021 by Jeff Berk

[Zed Head]

I'm not an expert.  And not really sure where your problem is.  I remember measuring several front covers and transmissions, from 76 to 83, and finding that they all needed a 0.3mm shim, so there was not a lot of variation over the years.  But the table shows that if A is big then you can go without a shim.

I also remember realizing that the gasket must be involved in the measurement since it adds to the depth of the bearing pocket.

In your case, for what you're doing and working with, I'd leave the shim out and use a thicker gasket until you get free shaft movement.  Just to see if you can, and if that is the problem.  

[Zed Head]

Here's a thought though - put some modeling clay or thin gasket material or grease across the full width of the bearing pocket.  See if the shaft end itself is interfering with the front cover.  The ball bearings in the races have quite a bit of lateral movement and are designed to take a load.  It's sounding more like the end of the shaft is getting jammed in to the cover.

[EuroDat]

On 4/9/2021 at 10:08 PM, Jeff Berk said:

I've got up the nerve to install the transmission, that and my wife wants her half of the garage back so I had to move the transmission out of the way. I was just about to start the install when I tried to give the input shaft a spin and it wouldn't budge. I checked and I was in neutral so I started back tracking and pulled the front cover off and it moved freely again. I checked to make sure the spacer was in the counter shaft well and I reseated the main shaft seal so it was properly seated and tried again. As soon as I started to torque the bolts to about 13 ft/lb, the input shaft seized up again. I tried another front cover and had the same results. 

I noticed that both bearings seems to protrude above the transmission case, 0.21 and 0.17 inch for the main and counter shaft bearings, respectively. Should the countershaft bearing be recessed and a shim added to bring it flush? The input shaft bearing cannot move back any further that it is now because it needs to have a retaining ring installed. I removed the bellhousing and checked the bearing and it seems to be up against the countershaft drive gear. There is a C clip between the countershaft bearing and drive gear, but it is up against the drive gear so it should not be holding the countershaft bearing from where it should be.

Anyone have any ideas?

Jeff 

 

Looking at your photo. I see a Circlip between the input shaft bearing and gear. I shouldn't be there. It should be on the outside of the bearing. Gear - Bearing - Spacer ring - circlip. See exploded view pos#1.

The circlip between gear and bearing will push the bearing out too far and the bearing cover will then push on the outer circlip and the input shaft will bind up on the main shaft. The input shaft is held in position by the circlip on the outside of the input shaft bearing. It has absolutly no pre load and without the circlip, you can push it into the gearbox a mm or so. Check this before you fit the bearing cover. This is important otherwise the input shaft will bind on the main shaft and the metal filings will damage the needle bearing and the synchro on 4th.

The bearing on the counter shaft should be up against the cluster gear shoulder (the circlip holding the gear in place is a little further along the shoulder) and the bearing should protrude just passed the circlip groove on the input shaft bearing. See input and cluster shafts photo.

Follow the steps Zed Head posted the determine the shims needed. The bearings don't require preload. That will destroy the counter shaft bearing in the adapter plate, but too much end play will create slack and clunking as the counter shaft moves back and forth from engine load to no load.

Take your time to get it right. If you are new to these transmissions the FS5W71B manual is not your best friend. If in doubt keep firing questions at us.

[Jeff Berk]

EuroDat,

I think you spotted the problem. I took a few measurements and couldn't see how the countershaft would NOT fit so I was wondering about the input shaft. Nissan must of put the kerf in the input shaft where they did just to see what fool they could fool. 

Thanks all for your help.

Jeff 

[Jeff Berk]

I installed the transmission and give it a try. I'm getting a bit of whine; however when I let the clutch out, even in neutral. For some reason, no whine in 4th gear but it reappears in 5th. I checked the fluid level and it is up to the fill hole. Gears 1-4 are out of a 4-speed transmission.

I might of put the wrong throw-out bearing (I had 2 different ones sitting out) in since the noise is only present when the clutch is out. Any suggestions? The attached video has the whine. 

Edited April 24, 2021 by Jeff Berk