Subject: planetarys
From: rotaryeng
Date: 8/29/2014, 10:31 AM
To: AA-1-Me


Hi Paul, I have been looking through Ford auto trans spec's in regards to the Ford/Jatco  parts JPG on your site, but cannot find those specs. It shows 3.17 ratio. What Ford model is that from?

Thanks Steve Carlisle

Ford has changed the tranny number over the years.
Call http://www.makcotransmissionparts.com/ <http://www.makcotransmissionparts.com/>  sales and ask for the 6 pinion rear
planet set from an A4OD. He will know what you are after.

Paul Lamar


Okay, I am even more confused. If I new for sure what tranny has that ratio, I can buy a used trans locally. You tell me the pinion set comes from a A4OD. You can buy many 4,5,or 6 pinion sets for many models as upgrades. What confuses me now is you send a parts diagram for a E4OD. I have a trans re-builder locally and say the 2 a quite different. I have looked at the specs for the A4OD, and the offer standard ratio and Wide ratio, but no planetary with the 3.17. Sorry for the confusion, it seems not as simple as I had hoped.

Anyways, thanks for effort,  Steve Carlisle

You are talking to the wrong person Steve.
Transmission re-builders know very little about planetary theory.
All they know about is how to take them apart and put them back
together. The E40D is a descendant of the C5 that came out in the

early 50's. Most if not all the parts are interchangeable. The early
planetary had 3 pinions, then 4 pinions and the latest incarnation
6 pinions. The hot rodders had six pinions long before Ford did it.

In the mean time Ford changed the transmission designation
number several times. One of them was the E4D.  The E4OD has a third planetary
for over drive. That is the "O" is in the designation. We don't use that
planet set. That smaller planet set  is located at the front of the transmission.

If you talk to the parts guy he will know what
you are after.  The Jatco is a scaled down C6 and the parts look the same
but are smaller for the Japanese market.

The gear ratio depends on what part gets the input torque, what part puts out
the torque and what part is held stationary. Early Tracy's were 2.17:1. Later versions
were 2.85:1. For a rotary 3.17:1  gives the most power. It is also a beefier planet
set. Ross made all three. It is the last planet set in the box.


Paul Lamar

Paul, Again, thanks for the help,

Steve Carlisle

Do you plan on building gear box?

Are you in the US? Milo is just south of Seattle.

I think. He travels back and forth to Texas sometimes :)

Brian Trubee is at Paine Field. http://www.painefield.com/


Paul Lamar


Yes, I am looking at using good ideas from previous gear designs, and dumping some other ideas. Coal Harbour, northern Vancouver Island.

Steve Carlisle

If you are considering plain journal bearings I would reconsider. I would use needle bearings
like the Ross. It puts an additional load on the Mazda oil pump. Dave Leonard seized one of Tracy's boxes with a plain bearing at Reno.  Fortunately it happened on the ground.

Another member of this list (Larry)  who happened to be at Reno had one of Tracy's boxes back in Marin County Ca. A another friend of Daves's flew his airplane back 400 miles to pick it up. We had Dave back in the air within hours at Reno.

The reason this problem did not show up sooner was it was just marginally close to failure.
In fact there was a plumbing decision made that made the situation worse.
Dave used one oil line out of the engine that was supposed to fed the turbo charger.
Dave simple  teed off this line to feed the gear box as well. I re-plumbed it
at Reno with a separate line to feed the gear box. That seemed to work for Reno practice
and flying home but Dave never raced it at Reno because of the Mustang fatal crash.

Day to day one never runs the engine flat out for 20 minutes at a time
at the same altitude.

Air racing is the acid test. If there are any weaknesses in the design it
will show up while air racing.

Paul Lamar


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