I had a whole hour to think, while driving back from Ventura, about the
idea of cutting the planet cage onto one end of the prop shaft. Can't
think of any good reason why we should not do that. I think the od of
the 7075 shaft material we intended to use for the steel planet may be
slightly too small.The only added issue is the potential need for longer
planet shafts to give them greater depth in the alum cage/shaft. I guess
that means I can use the 6 planet gears from the unit I left with you
today and forget about doing the edm or finding special bolts.

The center shaft (pn#675 Makco) you had in your box could be used for
the link to the modified forward drum. This will make getting parts
simple because they all come from the same source. What we might do is
machine the teeth down to our preferred od of the small end of the sun
gear in order to slip a steel tube over it, and use a smaller tube to
slip into the id of the same sun gear. This way the sun gear is slipped
in between the two tubes thereby doubling the shear strength of the hold
pins; while also lowering weight. The two tubes would be welded to the
trimmed end of the modified center shaft.

Ed Carver

Better get a quote on the job first. The planet shafts are not easy
or cheap.

Paul Lamar



I might have a couple thing going for me on this. The planets apparently
have different shaft sizes for different trannys. I need to learn which
size might be most readily available. How should I go about getting the
pins out of the planet shafts so the shafts can be precisely measured?
Screw a tap into them and pull them?

Ed Carver


So far all the front planets I have all have the same .440 shafts
more or less. There is room for a 5/16 EDM.

The area of a 5/16th bolt is .0767 so max clamping load per bolt is
7,670 pounds. 46,020 pounds total for six. Using Murray's statement
about the clamping load doing all the coupling and figuring a coeff.
of friction of only .1. the outer 1/2 inch width  of the planet 4
inch diameter carrier is about six square inches. That would give a
torque of about 4,600 x 2 or 9200 inch pounds or 766 foot pounds. No
help from bolt shear.

Steel on steel coef. of friction is actually higher than .1. As I
recall for locomotives it is about .7 so we might be looking at as
much as 5360 foot pounds.

In addition Grade 8 bolts have a proof load of 120,000 psi and not
100,000 so there is another 20%. No help from bolt shear.


Paul Lamar


I've sort of assumed we would use grade 12 or better. I believe rod
bolts are at least that. If I have any worry about bolting, it is
preventing them from backing out, or pulling the alum threads out. I can
see using the nord lock fastening system to solve that problem, and
wiring with loctite, plus maybe thread inserts in the alum shaft. A lot
depends on how hot it will all get.

Ed Carver

Drilled heads and safety wire. If you can find shafts and afford an
integral aluminum planet carrier that would be a real cool solution.
We need to figure out how to retain the shafts without the roll pins so
it can be repaired.

Paul Lamar


Ed, I just figured out two good reasons to not do an integral planet
carrier. When Ford went to six pinions they also went to a steel
planet carrier. The problem with an aluminum planet carrier is the
planet gears get closer to the steel ring gear and further away from
the steel sun gear with higher temperatures.

The other downside is the 5/16th bolts now lock the back bearing to
the prop shaft. The back bearing will then take all the prop thrust
load.


Paul Lamar



Spreading the thrust load to both bearings is part of the puzzle. The
prop end back bearing needs to push the front bearing to share the load.
The load is transfered via the shaft directly, or via a tube between
them.

Is our preferred alum shaft material going to expand beyond tolerance?

Ed Carver

I don't really think sharing the trust load is possible with two
widely spaced bearings.

If one bearing is not up to it use two back to back near the planet
carrier. I think one bearing can do it. 99% of the time there is no
radial load on the bearings at all. It is all axial or thrust loads.

Paul Lamar


We should use an angular contact bearing on one end or the other. Then
the opposing end bearing can just float to handle radial loads
exclusively. The angular bearing can handle as much radial load as it
can thrust load, but is designed for thrust. The opposing bearing may
only need to be held in the housing, and perhaps siliconed onto shaft.

The planet assembly (ring/planet/sun gear) uses a thrust bearing in the
ford tranny. We could always use a similar thrust bearing for a pusher
arrangement meaning the large bearings need only be loaded radially.

I want to know if the integral alum planet arrangement cannot work.
Aside from the possible expansion issue, it is the best option for a
pusher. The planet tolerances appeared to be designed to be loose.

Ed Carver

It is up to you Ed. The prop shaft will have to be  turned down all
the way to a slip fit so the rear (tractor set up) bearing can be
installed. Then a snap ring grove made in the prop shaft to retain
the bearing. Not  a good idea as it introduces a stress concentration.

The sun gear always tries to unscrew itself so yes a thrust bearing
is needed there. A stack of three 75 cent needle bearings works fine.

Paul Lamar



What we could use are thrust bearings for the back of the integral
planet to thrust against. These would encircle the thrust bearings of
the sun gear. On the other hand, the sun gear could catch the thrust
from inside the planet. There are thrust bearings in there on the Ford
tranny. Instead of turning the shaft down for the large bearing on the
planet end, we could use a 4.25x5.25x0.5" bearing, then create a long
tube between the two large bearing on the shaft.

Why do you believe Ford changed the planet cage material from alum to
steel because of expansion? Who is the source? I don't want to toss the
idea until I am certain.

Ed Carver

A few comments.

Large diameter needle thrust bearings are very RPM limited.

The 4.25x5.25x0.5" bearing is very heavy.

No source. Just logic. Gear Engagement is critical on any
gear box but Ford got away with it for years on the lower rated C6 and
other early designs. Steel planet carriers got to be more expensive than
die cast aluminum in the quantity Ford makes.

The tube spacer idea will work fine.

I would get a quote on the integral planet carrier/prop shaft. It is
only money :)

Getting the roll pins out and replacing the current planet shafts with
special hardened and ground bolts may be cheaper and stronger than the
EDM trick. I'll know a bit more about this later today when I try Jeans
trick.

Here is a section dwg of the ring gear, prop shaft, thin section
bearings, and green sleeve that holds both the ring gear and rear
bearing in place.

This well illustrates how simple this gear box really is.
The planet carrier is not shown for clarity.

Paul Lamar

Here it is with the housing added.

Paul Lamar