Transmission Noise in 3rd Gear - F4W71A

[AnvilZ]

10 minutes ago, EuroDat said:

Pos#19 is designed to remove any axial movement between the adapter plate and the adapter plate bearing. I don't know why they chose this method to remove end play. The point to all of it is the bearing should fit neat in the adapter plate housing without any forward / backward movement.

Understood, I suppose my last question then is how important is it for the center line of the gears on the main shaft and countershaft to be perfectly aligned. I assume the thickness of #19 plays directly into this, and that you would want the mesh to be as aligned as possible. Here is a picture of my setup before disassembly, the center lines are a bit exaggerated but it illustrates the point, they did seem to be very slightly misaligned which could be due to the original shim being replaced by the thicker aluminum one. Which may also explain why there was no #18 in my transmission. 

I should be able to easily determine a thickness for #19 if I align the gear mesh. Wonder if misalignment has anything to do with my original issues.

[AnvilZ]

@EuroDat @Zed Headhopefully I haven't exhausted your patience on this thread but I have an interesting update. After digging through quite a few old parts catalogues I actually found the OEM thicknesses for #19 from my previous post in a catalogue for the R3W71A of all things. Here are the part numbers from carpartsmanual: 

 

And the parts catalogue with thicknesses listed for those part numbers:

 

I believe I mentioned it already, but the current shim #19 in my transmission has a thickness of 2.65mm, where the OEM range given is 0.40-1.00mm. This brings me back to the gear mesh alignment question, here is another shot of my gear alignment with the 2.65mm shim installed and the new adapter plate bearings in place: 

Seems to me the effects of the thicker shim are most evident on the second gear mesh, pretty easy to tell since the countershaft gears are at a fixed distance as part of the shaft itself. I also noticed on third gear where I drew the blue arrow that the gear teeth are very close to the synchro assembly teeth. I see no chipped teeth or damage but feels like my thicker shim pushes those too close to each other, maybe some rubbing there caused the noise I heard?

My current thought process is to put a 1.00mm shim in for #19, reassemble and check measurement "A" from post #57. What confuses me a bit is the F4W71A seems to be the inverse of the F4W71B when it comes to shim #18. Notice above only one part number is given for #18 on the A type. Still searching for an OEM thickness for that part (32224-20100), but that must have been one of the changes from A to B type. Thoughts? 

 

Edited August 30, 2021 by AnvilZ

[Zed Head]

Type A definitely looks different than type B.  I really don't know much about either.  I did find your part number under the Sports pages though.  You probably did too.  You might see if there's another old Datsun forum out there somewhere.

Your idea of trying a 1.0 mm shim makes sense.  Can't hurt.  Might be the guy before you was in a hurry or just didn't have the tools to do it right.

https://www.carpartsmanual.com/datsun/sports-1965-1970/power-train/transmission-shaft-gear/5-speed-(warner)/20

Here's the link that you copied the numbers from.

http://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/transmission-gears/4-speed/to-aug-71

And for those who want to see the change...

http://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/transmission-gears/4-speed

[EuroDat]

Im out for a couple of hours, but when I get back Ill post what you need to do. It's allbecoming clear to me now. Looks like a PO has made a shim and didn't understand what shim Pos#18 was doing. Now the geomentry is allmessed up

[EuroDat]

The alignment on those gears in your photos is a little off. Thank you for posting the information about the different sizes for the #19 shim. That cleared up some things I couldn't understand.

With yhe 71B the bearing in the adapter plate is fixed and you remove end play by adjusting shjm thickness in #18 located in the front bearing assembly cover.

The 71A does not have the front bearing assembly cover. Instead it has the bellhousing with a fixed size shim. (And because it is a fixed size they won't mention the thickness anywhere). You adjust endplay by changing a shim in the adapter plate/main bearing retainer plate. You do this before fitting the rear extension housing.

If I was doing this, and because finding the #18 thickness will be very hard, I would assembly it with the home made 2.65mm shim and check end play. If the end play was correct then I would have a 1.65mm shim made for #18 and a new 1.00mm shim for #19 to replace the home made shim. Or a 2.00mm #18 and a 0.65mm #19, just keep #19 in the range of sizes Nissan supplied.

I'm not sure if the "A" reference will work on the 71A. That is why I would check end play with the old shim.

When done it will move the cluster shaft back and align the gears.

 

[AnvilZ]

16 minutes ago, EuroDat said:

If I was doing this, and because finding the #18 thickness will be very hard, I would assembly it with the home made 2.65mm shim and check end play. If the end play was correct then I would have a 1.65mm shim made for #18 and a new 1.00mm shim for #19 to replace the home made shim. Or a 2.00mm #18 and a 0.65mm #19, just keep #19 in the range of sizes Nissan supplied.

I'm not sure if the "A" reference will work on the 71A. That is why I would check end play with the old shim.

This was my exact thought process, although looking back through the 71 FSM last night that Zed Head pointed me to earlier in this thread Nissan does seem to suggest that #18 is not a fixed thickness and uses the same "A" measurement for end play. This is definitely for the F4W71A: 

 

Confusing. Now I am wondering if carpartsmanual.com has #18 and #19 backwards? Based on the FSM it seems #19 may be a fixed thickness, which I still doubt I will be able to find, and #18 is variable. It even gives the same range of thicknesses for #18. 

Given that I likely won't be able to determine an OEM size for #19, I am now thinking I will try to align the mesh as much as possible and use that to determine a thickness for #19. Maybe 1.65mm there and a 1.00mm for #18 as you suggested.

[EuroDat]

Do you have the manual where your screen shot came from? Would be nice to add it to the manuals database on this site.

Looking at the figure TM-68 the front shim #18 is the adjustable shim like the 71B and it should be somewhere between 0.40 and 1.00mm.

You now have no shim #18 in the front bearing and a 2.65mm shim in #19. I would still check the end play and if the end play is good make a shim for #18, preferably closer to 1.00mm and deduct it from #19.

[AnvilZ]

11 minutes ago, EuroDat said:

Do you have the manual where your screen shot came from? Would be nice to add it to the manuals database on this site.

I actually pulled it from this site, Zed Head pointed me here https://www.classiczcars.com/files/category/11-240z/. It is the 1970 FSM uploaded by CanTechZ. Page 57 is the one I referenced. 

13 minutes ago, EuroDat said:

You now have no shim #18 in the front bearing and a 2.65mm shim in #19. I would still check the end play and if the end play is good make a shim for #18, preferably closer to 1.00mm and deduct it from #19.

I will check the end play after reassembly. If it is good Ill go with 1.65mm for #19 and 1.00mm for #18. If not Ill likely add additional thickness to #19 up to maybe 2.00mm. Can't imagine the total end play would exceed 3.00mm. 

[AnvilZ]

Update to close the loop on this thread, end play was correct on the countershaft so I installed a 1.65mm shim in the adapter plate for #19 and a 1.00mm shim in place for #18. The noise is gone after the rebuild and the transmission is smooth and quiet. I can only assume it was the misalignment and maybe some interference between 3rd gear and the synchro assembly causing the problem. Correcting that plus replacing all the bearings and it feels like a new transmission. 

@EuroDat @Zed Head @Dave WM Big thanks for your input and assistance on this.