I think you are on to something there Al. Rubber works better as there is
more damping. Tracy takes this one step further by using a bit of friction
damping in the metal and plastic washers clamping the rubber bushings.

BTW looking closely at the 2.17 sun gear with the small lube hole in it
appears the hole is designed to lie outside the gear engagement area.
In other words there would be very little cantilever beam bending
on the tooth in the area of the small hole. The differences is about
.1 to .2 inches of engagement. In other words if the sun gear is
inserted into the planet carrier too far the small hole then becomes
a factor. I find it hard to believe the Ford engineers were unaware
of the inadvisability of drilling a small hole at the base of a loaded
gear tooth.

Chris Ross may have missed this subtle point and machined the box
incorrectly. Usually the gear unscrews itself moving the small
hole away from engagement. If a thrust bearing was installed
in Tom's gear box the gear could have been positioned incorrectly
or if no thrust bearing the gear could slid back and fourth
within the planet carrier. Also there is some sort of thrust bearing
installed ahead of the sun gear limiting its travel into
the planet carrier. If this thrust bearing is incorrectly dimensioned
the same scenario could happen.

As I said before this failure mode has been unheard of up until now.
Bottom line is I am still not convinced the four pinion is unsuitable
for a 3 rotor. We will probably never know as I am sure all you
three rotor guys will switch to the six pinion.

Paul Lamar

Paul,

If I remember correctly ( from one of your photos) the Ross has the ring
gear turned around in the 2.85 to allow for holding the ring gear by way of
some rolled pins (only two I think) lodged between the ring gear and the
housing.

Turning the ring gear around puts the oil hole directly in contact with the
sun gear- the oil hole is very close to the end of the tooth as well. In My
ring gear the hole cuts through, half of two teeth.

It was not the ring gear that failed George. It was the sun gear.
The load on the ring gear is less than the load on the sun gear. PL

This appears to be a disaster waiting to happen, IMHO - now that this has
been drawn to my attention.

I notice with the front plate and thrust bearing in place the planetary
teeth do not come in contact with that 'oil hole' section.

This may indeed be the problem - however not discounting the frequency
vibration concerns. A valid point in my opinion.
George (down under)

 
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