I finally got around to getting a Timken roller
bearing catalog. IMHO tapered roller bearings are
the way to go. They are light weight for the thrust
load handling capabilities and compact.

The Marcotte uses them but I have decided the offset
in the Marcotte is too much for most 13B installations.
Most 13B installations fit fine in cowlings with stock 
thrust lines and there is no need for PSRU offset.
In fact it is a slight disadvantage in some cowlings 
as it leaves less room for one large single radiator 
under the engine.

In some cowlings it would be better if the engine offset
was up rather than down.

Besides, the Marcotte is over $3000.00 the last time
I checked.

I also want to use a six pinion planet carrier
as I think it gives the most amount of torque
handling capabilites for the weight.

My 13B  engine will be detonation limited and not
boost limited. I estimate the max short term HP around
350 to 400 HP. I don't want to have trouble with
the four planet gear box.

My target for the weight of the gear box is less
than 35 pounds.

The main housing in this design is machined from
a six inch diameter one inch wall aluminum tube.
the output shaft could be machined from a three
inch diameter 3/4 wall 4130 tube. The flange
could be silver soldered on after heat treat.
I am not sure about that. In any event if that
does not look like it is going to work I will
hog it out of a 5.5 inch 4130 or 4340 billet.

The input shaft has a double deep row ball
bearing to prevent fore and aft movement of
the sun gear that is destroying a lot of Mazda
engine thrust bearings.

If your Ross is developing end play it is not in
the Ross gear box. Your needle thrust bearing
in your Mazda engine is slowly being destroyed
by the sun gear end thrust in the Ross gear box.

Take your front cover off and check those needle
thrust bearings.

I think Ross is now installing thrust bearing in
the PSRU  to handle that end thrust.

In any event my new design solves that problem.
 
Paul Lamar
 
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