WIAD backgear countershaft bearing question

Question about the little upper bearings on the countershaft in the backgear gearbox. The bearings in mine, not original, were New Departure 3203. I replaced them with SKF 203. These bearings are identical, 17x40x12. However, when reassembling my gearbox, when I have proper spacing for the shaft the front bearing is too far forward in the front casting and the bearing cap will not tighten down on the paper gasket, and that is with the rear bearing sticking out the backplate the thickness of the paper gasket and rubbing the motor front plate, which I am not really comfortable with. All gaskets are new and from Monarch. The lathe is functional, but oil leaks out from underneath the bearing cap since it is not tight to the casting.

when I disassembled the gearbox originally there was no gasket under the bearing cap, only worthless silicone.

I disassembled the gearbox and have been pondering the pieces and checking clearances for the last 2 hours.

The only conclusion I can come to is the bearings are not the proper ones. The bearings in the flat belt idler have an inner race that is slightly recessed (0.025") to the outer race on one side and is the same OD as these in the backgear gearbox, so now I am thinking that the original bearings were some special New Departure type that had the inner race recessed slightly as well. The bearings in the pulley are doubly weird in that the inner race protrudes from the outer race on the other side, so that bearing type can't be used. If I had an extra 0.025" clearance both front and back I would have a much better installation.

Does anyone know positively what the original countershaft bearings were on a WIAD type gearbox?

I think there were multiple versions of the gearbox. My notes suggest that mine took 6203 bearings front and back.

I can't see where the bearings could cause this. If the ends of the shaft are hitting both front and back, then the bearings can't make up for that except by keeping the backgear housing away from the motor's mounting plate, right? Can we assume that there's no evidence of the shaft rubbing before? If I am reading the problem right, even with no bearings installed at all, the shaft would be rubbing on both ends.

I'm curious what you find, as I'll be taking my backgear off of the DC motor and adapting it to my AC motor in the next few months. It seems that spacing is important.

rke[pler said:

I think there were multiple versions of the gearbox. My notes suggest that mine took 6203 bearings front and back.

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Four, I think. Keyed input or splined, MG / WiaD crossover, sight glass diff and feet or no feet, Modular-era?

But only two minor differences in internals? "Maybe", anyway.

All the gearboxes here are MG-era. I have a WiaD-era MOTOR, but no splined-input-shaft gearbox for it.

i recently did this but can't think of a reason you would be having this problem.

here are a few pictures of my rebuild. may be differences between Modular and WIAD? but, may help understand issue???

Thanks Mark, It looks like your rear bearing is flush with the back of the back casting, and your front bearing is definitely more rearward in the front casting than mine.

The front casting, the bearing cap, and the shaft are the same between the WIAD and module. The back casting is obviously different because of the feet, and the bearings are different part numbers so it is hard to draw a conclusion.

Honda makes a 17x40x11 bearing which would give me 0.040 extra clearance, but right now I think I will just mill down the bearing cap so it can tighten to the front casting. I will call monarch Monday and see if they have bearing numbers.

bll230 said:

Thanks Mark, It looks like your rear bearing is flush with the back of the back casting, and your front bearing is definitely more rearward in the front casting than mine.

The front casting, the bearing cap, and the shaft are the same between the WIAD and module. The back casting is obviously different because of the feet, and the bearings are different part numbers so it is hard to draw a conclusion.

Honda makes a 17x40x11 bearing which would give me 0.040 extra clearance, but right now I think I will just mill down the bearing cap so it can tighten to the front casting. I will call monarch Monday and see if they have bearing numbers.

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Honda? WTF?

Your parts, your rules, but I'd try, and try HARD, to find a way not to mill ANYTHING until trying to fit the proper bearings.

Monarch ordinarily HAS such items in stock, not just their numbers.

Otherwise, even if you document a change to the gearbox right o na bespoke brass plate attached to it, you would be creating an "orphan" even for your own future maintenance, let alone some future, unsuspecting next-owner.

Not that it is a mortal sin, but.. why bother?

I may have found the answer. The 8503 bearings are the ones in the flat belt idler that have a recessed inner race on one side and the extended inner race on the other side, and I said they would not fit because of the extended inner race. They actually will work, because both the bearing cap and motor front plate are recessed for the inner race. I was talking out of my @$$ as my wife says.

Once I realized this I cleaned out the old bearings I removed from the pulley and installed them, and with the additional 0.050 clearance I can get a good fit of the bearings and counter gear shaft. My parts drawings don't show the same part number for both bearings, but as Bill said, there have been many changes over the years. I think I will go with this solution and order 2 more new 8503 bearings.

Update, just called Monarch. He said that the original bearings were the ND 77203, which is the double shielded version of the 3203, which is what was in mine. His only suggestion was that maybe the shaft was homemade and made too long. It doesn't look like it, but who knows. All I know is that the 77203 will not work. I am back to using the special 8503 bearings.