Quote:Yes, that started in 1974 or 1975, it is a stronger box.

Quote:Agreed, I weighed my 60A 5-speed at 70 lbs for transmission alone.

Quote:All the gear ratios are listed here in a table: 5-speed Overview.

Quote:I don't know that I would agree that 56A gearbox with it's inexpensively made Torrington race to support the front of the cluster is stronger. I would suggest that the earlier design 56 gearbox was changed because the new design was lower in cost to manufacture, yet retained all the strength that was required behind a standard, or even a GX, A12 engine.

I suggest that the earlier ball bearing in the 56 gearbox would be stronger, but more costly to manufacture.

Ah, stated like a true Guru ... yes, usually things are done to lower costs. In this case Nissan stated:Quote:reference: Service Bulletin Vol. 188 "Introduction of New Model Datsun B210 Series" page 69, July 1973, Nissan Motor Co., Ltd. Tokyo Japan Telex: NISMO.

I guess that also answers your question about the gear cluster: it is different.

Quote:I don't know about this Guru thing, I feel more like a cynic.
OK, we now know that it is 'different', but is it 'interchangeable'? Does the old number supercede to the new number? I suspect that it might. [I hope so]

So from the bulletin that you quote, i read that
A. The gears are made wider, & therefore a little stronger, & that can only be a good thing
B. The main shaft bearing is strengthened. [But which one, pilot, or main support bearing in the sandwich plate, & how is it strengthened?]
C. The bearing at the front of the countershaft is strengthened.
D. there was a change in the extention housing to help get oil to the rear bush.

I'm guessing here, but this is what I think.
Point 'A' needs no explanation.
Point 'B & C'. I wonder if they simply case hardened the countershaft front snout as it now becomes part of the bearing itself, & must endure not only the side load from the constant mesh gears when in the intermediate ratios, but now it must also serve as a wearing element of the bearing itself.
As for the mainshaft, I suspect that the pilot bearing hardness was either increased, or made deeper, or both, as this is also a high load area when in intermediate ratios.
I have never heard of early 56 series gearboxes having a bearing problem at the front of the cluster or at the mainshaft support [ball] bearing in the sandwich plate, but the mainshaft pilot bearing is a common problem area in many gearbox designs.

I suspect that there might be a bit of 'spin' used here when describing these changes & if the 56A countershaft is interchangeable with the earlier 56 item, then I suggest that an even stronger box could be built by using a 1000 or 1200's 56 gearbox case & front bearing on a 56A gearbox. [The ultimate 56 series box?]
I notice that there is no mention of the obvious cost saving benefits to the change to the countershaft bearing.
Well, that's what I reckon anyway.

Have a look at the bearing on the countershaft in the photo I posted earlier. That just has to be stronger than the much smaller pressed tin race that they use in the later box.

Thanks Guru, know you have me thinking again.

I can only ponder the question, but here are some more info:

Mainshaft PNs for F4W56 transmissions:
32241-H1010 SHAFT-MAIN B110 F4W56L up to 03/73
32241-G1101 SHAFT-MAIN B110 F4W56A from 04/73
32241-G1101 SHAFT-MAIN B210 F4W56A
32241-G1101 SHAFT-MAIN B310 F4W56A

Quote:reference: same as previous, page 70.

Of course, we interchange the transmissions so it is still an open question about the gear cluster.

OK, so the newer ones use a small needle bearing on the countershaft, versus a larger ball bearing on the originals. I thought that needle bearings in general are stronger ... and less subject to wear than ball bearings?

My Datsun 1200 parts book, issued December 1974, shows only one number for the main shaft & it is the first one on your list. Does your book indicate that the new shaft is interchangeable with the earlier one?

The transmission assembly is probably interchangeable conditionally. That means that you would probably need to change some other parts, like perhaps the earlier rear oil seal [if applicable] & you might need to use the earlier clutch arm or delete some smog switch. We interchange these gearboxes all the time. It takes only one tiny difference & they declare that some parts are not interchangeable.

All rolling element bearings are good, but their load carrying ability depends on their size. The 56A gearbox continues to use ball bearings to support the input shaft, the rear of the main shaft & the rear of the cluster, so they are not an inferior design pre-se, but the closed end roller bearing for the cluster saved quite a bit of machining, several separately made parts, custom fitting of the bearing with shims & additional assembly functions.
While it saved all this, it was obviously also quite adequate in the strength department too. There is nothing at all wrong with the newer design, but I personally prefer the ball bearing from a design/ engineering standpoint. In reality, the ball bearing is probably three times stronger that it ever needs to be while the roller bearing is probably only twice as strong as it would ever need to be. Like killing ants with a three pound hammer, or a two pound one I suppose.

Are you able to confirm, or otherwise, the interchangeability of the two versions of the cluster?

anyone else think this priceless thread should be put in the tech section? or has it already been done?

OK, I put a link to this discussion in the 5-speed overview article.

Dman, my parts book shows no interchange. It doesn't list a 1 or 2 or anything like that in the ICA column. Nor is the original one superceded.