Bryan wrote:

   The truck most days will  hold 50 miles per hour on a 5% grade
  The last big failure was on a 8 to 9 % grade at about  35 miles
per hour.  Now with that said we are overlooking ( IMHO ) 2 important

points

1.  The diesel engine in front of the gear set has a very nasty
torque pulse and it gets worse under load. Picture someone
with a 5 lb hammer beating on your gear set all day.

2.  The failures usually occurr at gear change- the shock load
finishes the job the load and the hammer started.

I do not know how to account for those factors in your calculations.
But my gut feeling is that you should be fairly safe with the 6
planet set up as you are under constant (compared with a truck)
load and a steady torque load with the prop.  The only shock loading
would be in the event of some other mishap like a prop strike. You
might ask the transmission guys if the gear set in the latest Ford
products behind the 7.3  power stroke are the same as the
E4OD.  The newer transmissions are very bullet proof at
much higher horse power than the E4OD ever thought of being.
   Hope this contributes something.  Bryan in Princeton B.C.

It sure does Bryan and thanks for the hard data.

Paul Lamar

Yes, really great data.   Bryan, could you give us some details about the
E4OD in your truck.
Since it is the 7.3 diesel, I assume this is the super duty version? True?
What gear was in use before the gear change?
What gear failed (2nd?) and which planet set is in use for that gear (front
or rear).

It should be noted that this diesel engine produces about 1000 ft/lb torque.
The 13B is around 160 and a 20B about 240 (normally aspirated).

Tracy Crook

Also some pictures would be great Bryan so we can compare the damage to what
happened to Tom's gear box.

Paul Lamar
 
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