SD2x transmission issues: FS5W71x series of 5-spds

[pbknowles]

Hi all, a little OT but I am getting ready to re-do my S10 and will be using a 720 4x4 tranny (sd22 front case of course) as it fits much better, so if anyone has any interest in the dimensions of one of those let me know. Apart on the bench now....
PK

[ecomike]

I have put another 100 miles, including highway miles in 5th gear now, and I have really given it a thourough test, and so far it shifts better than it ever did since I acquired it 4 years ago. Not a single hick up, or lock up, or even iffy shifting so far. Looks like I may get lucky on this one.

Just ordered 2 quarts of Redline MT-90, planning to get the right oil in there next, for sure! Not sure exactly what got put in it when it was installed last year. Could have been GL-5, which has me worried now!

[goglio704]

Does anyone have an opinion on using Mobil SHC 600 series oil in the transmission? I have never used it in an automotive application, but when I pulled wrenches in industrial maintenance, we used it extensively in worm gear applications where sulfur would eat the brass or bronze gear.

[ecomike]

I completed the replacement of my 50% Lucas gear oil (GL-5), 50% unknown (probably also GL-5) gear oil, replacement with Redline's MT-90. From the looks of the old oil it wasn't a minute too soon either. The old oil looked like a dark chocholate metallic bronze paint when I drained it, and after only about 6 to 8,000 miles. The synchos were brand new.

I will probably drain it and change it again in about 6 months, 3000 miles or less to make sure I get the rest of the brass fines out of there.

Been apx. 600 miles since I replaced the shifter / control lever and bushings, and it has not hung up a single time since. Shifts just fine, and shifts a little easier with the MT-90 into first and between first and second. Second to third gear shift is smooth as glass now.

I am calling it fixed for now!

[pbknowles]

Hi all, just a note FWIW that the front transmission case that is machined for the smaller front CS bearing CAN be opened up to accept the larger one. I don't know what year any of my core tranny's are, but the gas 4x4 trans I just went through to use in my rig had the larger bearing. I had a machinist friend open up the older diesel front case and it all worked out fine. I just gave him both cases and he matched the size using a milling machine and boring bar. Note: you must also use the matching front cover (what I did) or open up the counterbore (somewhat tricky) in the "small bearing" front cover. So now I have a diesel trans with an aluminum front cover, but I don't see it as a problem.

[asavage]

Hi all, just a note FWIW that the front transmission case that is machined for the smaller front CS bearing CAN be opened up to accept the larger one.

This is the SD22 front case you're referring to? Very good to have that confirmed.

[pbknowles]

Yes, the SD22 front case can be opened up to accept the larger bearing (I am at work and don't remember the bearing # but I think it is listed up thread).

[pbknowles]

Hi all, I just tonight got around to doing final assembly on my hybrid SD22 front case-on-later 4x4 rear case and gearset trans. As noted previously, I had the SD front case machined to accept the later (larger) countershaft bearing. Upon final assembly I note that the new CS bearing is also thicker. This is not a problem as long as the matching front cover is used, since the mating counterbore is also deeper, however here is my problem:
I have a 1983 FSM (thanks again Al!). The procedure for calculating the CS bearing shim is unfortunately no longer applicable, since the new CS bearing sticks out of the case further than the old "small" bearing that the writers of the FSM were expecting. Also, the 1983 FSM tells one how to calculate the required shim, but is silent regarding what the CS end play should actually end up being. My measurements indicate the following:
CS bearing stick out = .176"
Front cover counterbore = .175"
Old gasket = .029"
Old shim removed = .015"
These measurements yield a CS end play of .013"
So.....
a) Does anyone have access to a later FSM written with the larger CS bearing in mind, or...
b) Have an idea what the CS endplay should be
Thanks!
PK

[asavage]

Quick-n-dirty:
Page MT-8
Page MT-18

I won't be able to do a better job until tomorrow night, but this should give you more data.

[pbknowles]

Thanks Al,
Based on those numbers and the following assumptions:
1) All front cover counterbores are exactly .175" deep
2) All front cover gaskets are exactly .029" when compressed
We can reverse engineer that:
Nissan wants the CS bearing end play to be .022 - .026
This works (approximately) for the other "stickouts" and shim thicknesses referenced in the table in MT18.
Maybe I am a worry wart, but this seems loose to me given that the case will grow roughly twice as much as the gearset (linear coefficient of expansion for aluminum is 13.33, carbon steel is 6.5).
The fatal flaw in this is of course the gasket. It may be that I do not have a genuine Nissan gasket, and that the gasket I have is thicker than as designed, yielding extra end play that is not accounted for in the FSM, since it assumes a known constant gasket thickness. I think the purchase of a genuine gasket is in order before proceeding.
PK

[asavage]

Nissan wants the CS bearing end play to be .022 - .026 . . . Maybe I am a worry wart, but this seems loose to me given that the case will grow roughly twice as much as the gearset . . .

Given the design: when the case grows, the endplay shrinks, correct? Those figures don't seem too far out of line, though yes a bit on the loose side for cold.

OTOH, how much does it matter? It won't affect sychonizer operation. It won't materially affect layshaft-to-mainshaft gear tooth engagement. I can't see for certain, but it looks as if actual shaft float is controlled by the brg on the other end of the CS, which looks to be firmly affixed to the intermediate plate. If that's the case, the actual number on the front end doesn't matter much.

Or I could be all wet.

[pbknowles]

Calculating what happens to the case casting when the temperature increases is beyond my limited skills, but I was approaching it this way:
Consider the front 1/2 of the transmission case as basically a hollow tube, anchored at the bellhousing end and the steel bearing plate end. This tube will grow more than the steel guts inside it, increasing end play with increasing temperature. The back half will do the same. Your point about the center steel plate being the datum from which everything else is relative is well taken however, and I believe you are correct since the center bearings are captured in this plate.

[asavage]

. . . This tube will grow more than the steel guts inside it, increasing end play with increasing temperature.

Hmmm. Looking at the exploded view (it's been years since I had one apart now), the front CS brg floats in the case; the shaft's play is the rear brg only, isn't it?

While the case growing may move the whole shaft assy (and the gears on it) to the rear, I don't know that the shaft is going to have any more effective end play, since the shaft end play isn't constrained by the front brg. At least, that's the way it looks from here.

[philip]

Some Feb '07 and .... I'm tired of the oil drip leaking out the pinion seal inside the gear house so ....



$33 and ... the dealer had on in stock!

Be CAREFUL that Nissan tells you ALL speedo pinions fit ONE (automatic) part and that it would have to be Ordered. I said that could not be. "What transmission GEARS and SYNCHROs do you sell?" So... looking harder, the Parts man found the manual transmission pictures. NOW he finds 5 different pinions for the manual transmissions AND has the one I need in stock! Imagine!

[TruckA]

Is there a tip for putting the case pieces back together? I have assembled the front and rear cases, and the striking rod is able to move back and forth, but I am not able to move the striking guide to the left or to the right any more, it seems to be stuck. Should the striking rod and guide be positioned in the first gear position when assembling the cases like during disassembly? I believe I assembled the cases with the transmission positioned in neutral, and the striking guide did move to the left and right, but now it is stuck off to the right in what may be a third or fifth gear position. I want to make sure I've got everything right before putting the tranny back in the truck and then beginning the engine installation work.

Thanks for any help,

David