Has anyone ever pulled the front cover from an FS5W71B and find no shim between the front countershaft bearing and front cover? There isn't a shim on this one I recently purchased. I know it's been run in a car without the shim but don't know for how many miles - I wasn't able to see/hear it run while in a car either. Everything seems to checkout when turning the front shaft by hand in all 5 gears and reverse; no ablenormal slack or funny noises (checked before removing the front cover). There was no worrysome shavings on the drain plug magent. All the gears and internals appear to be in great condition. The front cover does not show any abnormal wear where the shim would normally go. As far as I can tell the front of the countershaft bearing and main shaft bearing are on the same plane (is that correct?). If anything, the counter shaft bearing may be about .04" forward, but there's a normal degree of slack in both bearings' outer rings that could cause it to look that way. So what should I do? Run it as-is or buy a shim? The FSM describes the shim as a shim, not a thrust washer. If it were a thrust washer it would definitely something I'd buy and use.

It's easy to miss because it usually gets stuck in the front cover. The shim is larger than the distance between the case and the bearing races, meaning that it will preload the race. My best guess is that it was designed to make up for expansion of the aluminum case as it gets hot. Aluminum expands more than steel. If there's a gap the bearing would be loose in its space.

Just a guess. Regardless, it's just there to make sure everything fits correctly.

For what it's worth all of the shims that I measured when I had several tranmsissions, from 76 to 83, were the same. I think that Nissan probably got their manufacturing processes tightened up and didin't need the others anymore. Can't remember the number, I think it was 0.3 mm. I also have a vague memory of finding that only that size was available anymore.

My usual morning overpost...

https://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/transmission-gears/5-speed/12

https://yoshiparts.com/es/parts/nissan-32218E9002

Thank you, Zed Head! I'm going to go ahead and pick one up. zcardepot has a .3mm shim available. I did see in the manual regarding taking measurements but wasn't sure exactly how to do that. Plastigauge? I also didn't know it's supposed to preload so thanks for mentioning that. I'll do a dry fit with a .3mm and see if the front cover bottoms against the case easily or not. If it's snug then I'll check for any unusual noise or resistance by turning the input shaft. Also, thanks for the link to yoshiparts. I'm stateside but they may have something I need in the future.

Just realized that I miswrote about the shims being larger than the measurement. I would take the measurement first, after everything is assembled except the front cover, then get the shim.

A depth gauge like on a caliper, is an easy way to take the measurement.

I don't really understand what their logic is for the shims. Apparently the cavity in the front cover is precisely machined and the shim is meant to make up any tolerance stacking in the rest of the assembly. Irrelevant but I needed to ponder the puzzle. I think that I actually measured the cavity in the front cover in the past and that's why I thought it was about preload. The cavity is smaller than the bearing and shim combined.

p.s. you can get an inexpensive digital caliper at your local auto parts store.

Edited February 6Feb 6 by Zed Head

So no preload? OK, I do have a depth gauge (actually shown in one of the photos above) and will try measuring it first. If it measures <.1mm then I'll probably just leave it without a shim. It does appear to have been working the way it is without any issues. Thanks again.

I think that there is preload. The total height of the race and shim sticking out of the case is more than the depth of the cavity in the front cover if I remember right. Doesn't really matter, when you're working with gear boxes you just need to follow instructions. Don't forget to check that the gear is bottomed out on the shaft.

One other thing I thought about though is the thickness of the gasket. It's part of the total. Might be that with the gasket and shim, the bearing is precisely centered.

https://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/transmission-case/5-speed/4

My posts showing parts are just examples, not recommendations.

https://www.nissanpartsdeal.com/parts/nissan-gasket-cover~32112-e9001.html

Edited February 6Feb 6 by Zed Head

Ya, I'll measure with the gasket. The one I have on hand is OEM.

EDIT: My mistake. I should measure without the gasket per FSM.

Good point about making sure the bearing is fully seated on the shaft. I'll check that. Could also be maybe someone replaced that bearing with one that was a tad (very tad and unlikely) wider than OEM.

Edited February 6Feb 6 by 268Z