Paul
 Tel me how the driver shaft is attached to the sun gear on
 Tracy is pressure fit ,welded or others??
 i still waiting the shipment of gears

 Jean Prudhomme

 Pressure fit and then two welded in 1/4 or 5/16 pins welded
 in 90 degrees apart. He used to use one and Dave Leonard
 broke it with his turbo.

 Paul Lamar



 Do you think Paul
 Dave took some photos of broken sun gear shaft and do you have more
 clearly
 photos showing the shaft attached to the gear


 Jean Prudhomme

 Here is what I have Jean.

 Paul Lamar


 --
 Paul I receive all the gears components but i guess i do have the wrong
sun
 gear for this application it fit on the planet but if i look yous is all
the
 same outside diameter and i guess it,s a weak point at the big groove
 I do have the Slauson catalogue, could tell me which part number it can be

 Jean Prudhomme

 I don't have the catalog here. I'll be home in a couple
 of days. That looks like the right part. If it does not fit
 You may have the wrong planet carrier.

 Grind or cut off the teeth on the end you don't use.
 The weak point is not the groove. It is always the root
 of the tooth.

 Paul Lamar

 There used to be no pin at all, just rosette welds. That is what I
 broke(not the shaft, and not a pin). It was not the turbo that did it, but
 a backfire due to a bum chip in the computer. There is a picture on my
 website under 'trials and tribulations'.

 --
 David Leonard

 Turbo Rotary RV-6 N4VY
 http://N4VY.RotaryRoster.net <http://n4vy.rotaryroster.net/
 http://RotaryRoster.net <http://rotaryroster.net/


 Jean, here is all I have on the sun gear.. Use the large part
 and the front planet carrier.

 There a third in the A4OD. It is the overdrive planet
 carrier. That is not the one to use.

 Paul Lamar


                       Hi David
 I went back on your web site reading about the sun gear problem due to the
back fire and i saw the photo of the new sungear which is the same size
outside diameter and i am wondering from which planet this one come from



 Jean Prudhomme

Paul,

Why doesn't Tracy use a keyway, and press fit the gear on?
Better yet would be to have the sun gear, and  drive shaft be
cut, from the same forged strong alloy and then heat treated.
Maybe the  cost would be three or four hundred dollars?  Cheap
insurance for a critical component.  COST  never is a good
reason to cut corners.  Pining is used as a technique when you
expect the pins to shear if the output shaft is suddenly
arrested.   The pins  are of a dissimilar metal and hardness.

For an example, think of the flywheel attached to a large metal
shearing machine.  It  has a pin connection  in the gear that is
driven by the huge flywheel so when some dummy tries to cut a
5mm thick piece of stainless steel on a machine rated  for 5mm
mild  steel, the pin shears and isolates all that energy in the
flywheel. BTW I was the dummy and yes I had to replace the shear
pins.

The shear  loads on the sun drive shaft pins coming  from the
propeller or flywheel if you prefer, are magnified by both the
gear ratio, torsional slop in the system and at some rpm,
torsional resonance.

The design may be adequate on most installations.   Dave's
turbocharged engine was the only one I heard of that sheared the
pins.


Doug in Japan


It was a question of what tools he had to work with at the time.
No mill. The other problem is the stock gear and stock shaft are
hard so it takes a carbide bit just to drill a hole. I can see how he
thought just a rosette weld would work as the NA 13B side port
only puts out 160 foot pounds at best. Same goes for the RX8
side port.

BTW I am still not convinced it was just a rosette weld.
If Dave presses it apart I think he will find a sheared pin.
I think I had a conversation with Tracy on the subject and
as I recalled he told me there was a taper pin in there.
The weld was just to hold the pin in.

Since the gear ratio is at least 2:1 the torque
load is half the prop torque. Peak torque is mitigated some
what by the rubber coupling. I'll buy the back fire scenario.
We just blew up our trick muffler on Brian's Miata
for the third time after a back fire.

One pin.

Paul Lamar



In the '70's, modifying tank transmission in
Spain, the Spanish engineers thought we could bore lube holes in gears with
carbide drill bits. After five bits and less than one hole drilled they let
me buy the Elox machine (electronic discharge) that I asked for. Great for
removing broken drill bits and thread taps.
Hurant Karibian