D69U direct electric start

Looks very professional!

Did you make the adapter?

Nice looking project, thanks for posting. More pics please!
Craig

Thanks for the kind words.

We chose the 39MT starter for two reasons; it is shorter than the 42MT, and it is rated for a larger displacement diesel than the D318, so lots of power.

Yes we made the adapter, from 1/2" 5052 aluminum plate, welded to the (shortened) cast aluminum nose section of the 39Mt.
A splined shaft was welded to the shortened armature shaft, the planetary gear array in the starter was left untouched.
The fork and linkage were removed from the solenoid, leaving the plunger as was, to activate the starter when voltage is applied to the solenoid.

The stock Caterpillar pony clutch housing was sawn off at the 4 bolt flange, leaving the stock bearing carrier in place, to allow it to locate and support itself within the flywheel housing.

A splined hub that matches the new splined starter shaft was welded to the (shortened) pony clutch/pinion shaft.
There is a new caged ball bearing inserted into the old clutch housing at the flange, this both supports and locates the new modified shaft, while a heavy duty external snap ring
and the stock nut with lock tab washer at the pinion end keep it all in place.

I removed the spring loaded catch (the one that 'locks' the pinion gear into starting position) my concern was that it would not disengage quick enough
after the diesel starts, to avoid damage (over speeding) to the starter. The 2 coil springs that reside within the shaft seem to provide plenty of force to hold the pinion gear back when not in use.

The starter alone can be removed, leaving the pinion shaft etc. in place in the flywheel housing.

I have not run the diesel yet, still finishing up a few details such as servicing, the machine has not been used for a few years.

Results and what I have learned;
The new set up spins the diesel over enthusiastically, even with compression.
I will have to learn the trick of coordinating manual engagement of the pinion gear with spinning the starter (lets just say that grinding noises are the result of non coordination!)

I realize this approach has been done before, but I think we have put our own spin on the idea.

More pics to follow.

Quite an achievement . And it also explains why it is not more popular - although desirable for machines with no starter hole in the case. Some great fabrication skill and ambition there.

It is unique in that there is no latch mechanism used. Might be hard on the engagement lever which becomes compromised with no latch function.