Transmission Bearing 2-16-29


Ed Price


I looked at the MRC/SKF web site, and found the MRC 305SZZG. The MRC bearing has
an OD of 62mm, an ID of 25mm and a thickness of 17mm. It has two grease shields
and an external retainer clip.

Then, I noticed that a simpler, and maybe cheaper bearing, the 305S, is the same
size, less the shields and clip. I got the impression that the Amphi doesn't use
the external retainer clip, and maybe the shields aren't needed. Maybe even
better lubrication without the shields.

So, I tried to look up the 2-16-29 bearing. (I'm still trying to learn about
finding my way through the docs.) I went to Section 2 of the Parts Manual. OK,
this is for the Transmissions & Differential. (So the first number, the "2",
refers to the Section).

Then, I make my way to Plate 16. Sure enough, this is an exploded parts view of
the land and water transmission gears, bearings and shafts. (So the second
number, the "16", refers to the Plate view within the Section.)

And, on Plate 16, Item #29 looks like a bearing mounted on the transmission
output shaft, #10, and held onto the shaft by a castellated nut, #30. (So, the
last number, the "29", refers to the Item number on the Plate.)

Next, I looked in the tabular listings, Pages 2/7, 2/8 and 2/9, for details
about the Items on Plate 16. Item #29 is listed on Page 2/8. Item #29 is
described as a "taper roller bearing" and is called Part Number 0208-0186160. Is
the documentation Part Number, the "0208-0186160", just the manufacturer's part
number? Both Gordon Souter and Gordon Imports' list parts by the "2-16-29" Parts
Manual system, and seem to ignore the manufacturer's part numbers. Maybe this is
just fine, since it's very unlikely we'll ever order anything from IWK.

But now, things get weird.

The problem is that the MRC 305SZZG bearing is a single-row ball roller bearing,
not a taper roller bearing. (Granted, I have never been in there that far to see
for myself.) But, if Item #29 carries axial load (created by the force reaction
at the differential pinion gear on the other end of shaft #10), then it should
be a taper roller bearing.

Gordon Imports' Parts List says that Item #29 is a "special" BALL bearing,
unique to Amphis, with BRASS races.

Now I'm thoroughly confused. A ball roller bearing with brass races? That is
rare. I would think that the hardened steel balls would cut right into a brass
race. I have never seen one like that, and I could understand how it's hard to
find new ones.

From what I can see of the output shaft design, bearings #11 and #29 must be
what carry the axial thrust of shaft #10. How could these bearings NOT be taper
roller types? Or did somebody make a dumb change while Hans was on vacation?

El Cajon
67 Rust Guppy

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