Why not beat the OD discussion further into the dust. I just rebuilt my
Fairey OD a couple of weeks ago. While it was apart I took a good look at
what the oil level would be at the notch with the dipstick screwed all the
way in, and what it would be if the level was taken without screwing it in.
I'm not sure what the manual says, but since I always screwed it all the way
in when checking the oil level, I was more than a little shocked at how
little oil would be present. With the dipstick screwed in, the oil level
barely reaches the bottom of the small gear on the layshaft. Without
screwing the dipstick in, the oil level would be just under the bottom of
the layshaft itself.
I also noticed that the needle bearing under the input gear gets its
lubrication through a couple of holes drilled radially through the gear.
Maybe this is standard practice for gearboxes. These holes are about 1/16th
of an inch in diameter. Maybe the oil is supposed to be sucked in through
the back end of the mainshaft and travel along it through one needle bearing
and a couple spacers, up a shoulder and into the needle bearing under the
input gear, and then get thrown out the little holes (centrifugal force?).
Just a theory, but it doesn't seem like the design allows for a whole lot of
oil to get into this bearing, whether it is coming in the holes or going
out. All other needle bearings on the mainshaft and layshaft are lubed in
the same way - if that's how it's supposed to work. By that, I mean that
there are little holes drilled radially over the place where each needle
bearing rides on the mainshaft and layshaft.
Maybe enough oil gets thrown around if the level of it barely reaches the
bottom of the layshaft gears. I know a lot more gets thrown around if the
oil level is just under the layshaft. How do I know this? I used a piece
of plexiglass for the inspection plate, and I could see it. Since my
operant fantasy is that the more oil that gets thrown up on the mainshaft,
the better, I fill my OD up till half the layshaft is covered - I don't care
where the little notch is. I don't have a problem with oil going out the
little breather hole, because I've got a couple of vent hoses, one going to
the T-Case and one to the outside (with a filter on the end). I'm using
clear plastic tubing for the lines so that I can see if any oil is being
pumped out of the OD. I added the vent hose to the outside, and moved the
location of the vent hole to the other side of the inspection cover (over
the selector shaft), after I noticed that using just one hose to the T-Case
let oil get pumped from the OD to the T-Case. Maybe some oil gets forced
through the seal on the Output Gear into the T-Case directly, but I'm
checking the oil level a lot more often nowadays, and the vent hoses should
help keep that from happening (another theory).
Tom Gross
'67 NADA 109 6cyl
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