captainOCD

I guess I'll plan on pulling the whole main shaft out then. It looks like I should be able to inspect at least one syncro without having any special tools to pull apart the mainshaft.

We'll see how ambitious I am after work tonight as far as disassembly goes.

skpyle

captainOCD, the differential comes apart quite easily. Greg gave me the same advice: Keep track of the shims for each side bearing. As for the pinion nut, go with what he says. Mine is the A28.07 Mercedes automatic. I just put it in PARK while removing and then torquing the pinion nut.

captainOCD

Well I found the problem. I only got as far as pulling the countershaft out and pulling the input shaft out tonight since I couldn't find any of my punches and had to make out out of a hunk of aluminum from an evaporator core (ugly but it worked) to get the countershaft out.

It's definitely the needle bearings in the input shaft. The ball bearing turns smoothly with no noise.







So here's what I believe, at least, is the good news. While they look like they've been to hell and back, they were still turning. I don't have any good micrometers or anything like that here, it looks like this might have been caught in time to prevent damage to the mainshaft. There is a bit of pitting under the thrust ring/spacer, but there is no lip or anything like that where the needle bearings ride.



Here's what my observation here is, and by all means someone correct me if I'm way off here, but I think these two needle bearings look like they may be the worst lubricated parts in this transmission. The bearings under the other gears appear to be able to be lubricated by oil being carried up by the gears and then running down onto the shaft and wicking it's way back into the bearing. In the case of these two bearings, only one side of the gear has oil running down it, and it has to make it's way all the way back into the input shaft to get to the innermost bearing.

What I think happened here is that because of this car sitting for an extended period of time (I'd have to call the junkyard and ask for sure, but I think it may have been close to a decade), all the oil eventually ran off the gears and into the bottom of the trans. Since inside the input shaft appears to be darn near sealed off, some sort of temperature differential or something let moisture condense and rust these two needle bearings. And even when I poured fresh gear oil over the tops of the gears to fill the trans, still not much got to those needles.

I only drove the car about 100 miles since putting the trans in the car. Most of that was on the highway the day I drove it to work and another day when I took it to a buddies house, which was in 5th gear, which if I'm not mistaken has that input shaft locked to the output shaft (1:1) so those bearings weren't turning then anyway. So perhaps I caught this in time before it did any real damage?

Again these are my observations and hypothesis here, if it's way off please correct me.


Here's some pictures of the one syncro I could get to while the mainshaft was all still together in the trans. I freely admit I don't know really what to look for here, but nothing jumps out as terrible. What do you think?










So I guess here's where I'm at now. It seems like the mainshaft didn't get wrecked by the needle bearings, so a couple new ones should make it happy (again, unless I'm way off there). I can continue taking the diff apart, take the mainshaft out, and I think get to just the countershaft and reverse idler bearings without any special tools. To get to the bearings on the mainshaft I'd have to find some special tools to get the gears apart. All the other gears turn smoothly with no noise. What would you do here?

Kiln_Red

It should be noted that I am merely following along for my own education at this point. Take any perceived advisement with a grain of salt. That said...

Holy moly!! I am thoroughly satisfied with your assessment. I, myself, wouldn't hesitate to give it a go according to your plan.

GregBBRD

That's crazy!

I need to think about this one.

belgiumbarry

"nice" find ! me too , can't give advise , i'm learning….

makes me wonder, my 2 boxes are also 10 years non active…...

Kevin in Atlanta

Was there any chance this transmission has been stored in the vertical position outside allowing water to pool the leak past the seal?

captainOCD

I don't think so. It was installed in the car when I bought it, then the junkyard pulled it for me. You can see the line where the oil was in the bottom of the trans too.

Kevin in Atlanta

I guess we're left with condensation that accumulated over the years.

GregBBRD

With zero corrosion on the steel shift rods, which are higher than the bearings and conpletely exposed?

That makes no sense.

GregBBRD

There's a thin metal plug in 5th gear to separate the external splined area from the internal bearing area. I've seen these plugs so loose, they fall out.

My guess is that the plug in this 5th gear is not water tight and this car sat in water deep enough to reach input shaft height, but not deep enough to have water run into the vent on top.

Water simply seeped frim the outside into the bearing area.

captainOCD

The car didn't look to have water damage, but who knows what happened in it's past. The torque tube had some surface rust and a little bit of nasty water in it (really not much). Maybe that was where it condensed then seeped through there into the input shaft?

This is a picture of the trans end of the torque tube when I was pulling out the original bearings. It had a bit of surface rust that I cleaned up just at the end.
Attachment 1345039

And the bearings and dampers that came out. I believe the bearing nearest the trans was the one that was seized up. The throw out bearing that came with the parts was also seized up
Attachment 1345040

captainOCD

Also thought I'd add that there was no evidence of water in the oil I drained out from the trans.

GregBBRD

Yeah, there's no reason for there to be rust on the bearing carriers.

This car was up to water to the torque tube, at least.

Mystery solved.

Hopefully, there's not very many "pits" in the pinion shaft and 5th gear and you can salvage them with a little bit of polishing.

captainOCD

I think it'll clean up ok, the pictures make it seem worse than it is.

I'm still not positive from looking at them what kind of shape the syncro is in there. Does it look like it's in good shape.

And with that, what's the best way to get bearings and seals ordered from you? I'm definitely going to need those two needle bearings, an input shaft seal, input bearing cap o ring, layshaft oring, top cover gasket, and diff cover gasket. If I continue taking the main gearset out I'll need some more seals for the diff and probably some roll pins too I think.