I'm an engineering geek, and particularly sensitive to sounds and noises. A few years ago, I sent my then-trusty rotating-electrics wizard a large-frame Chrysler gear-reduction starter to build, and specified a 3-series/1-shunt field winding setup as was used in the 1962 through early 1973 versions of the original small-frame variant of this starter design (for which the original Chrysler patent is here). No such winding setup ever existed for the large-frame Chrysler starter, and I figured he'd see my attempt to mess with his head and we'd have a laugh over it. Instead he turned it into a practical joke on me: he went ahead and built it, fabricating the needed parts! He hand-wound the shunt and modified the original 4-series winding into a 3-series winding. The resultant starter looks just like every other '74-'89 large-frame Chrysler OSGR starter, but doesn't sound like either the small-frame or the large-frame starter. You can listen to it cranking and starting the 225 slant-6 engine in my '62 Dodge. And you can listen to it cranking a 383 in a '66 Dodge, cold and hot.

I also geek out on the differences found in same-make cars in different markets around the world to comply with different laws and contend with different operating conditions. Here's a scarcity in the Northern Hemisphere (real hard to find in the Southern one, now, too): a gear-reduction starter physically interchangeable with the Chrysler starter, made by Bosch of Australia to comply with that country's local-content laws of the '60s and '70s:


Beautifully rebuilt by the wizard, of course.

The Australian starter is smaller and lighter than the large-frame Chrysler item, but cranks the engine an estimated 25% faster. It, too, doesn't sound quite like any conventional Chrysler starter. You can hear it crank and start my Dodge. I swear, sometimes I wonder about myself...!

Modifying the Lester 3258's Field Coils

Now, back to that custom-built Chrysler large-frame starter. Here are the specifics on how the field coils were reworked. Look at this image below, and disregard the numbers on it for a moment:


Figure A

The fields on the right are a new replacement set for a 1.3hp series/shunt starter (the '62-'73 small-frame item; Chrysler 2095 150, 2875 560, 3656 650), and the ones on the left are OEM originals from a 1.8hp four-series large-frame field starter (Chrysler 3755 250, etc). The left fields were originally one piece; the ground connection was cut in order to lay them out for pictures.

Notice that the point at which the fields attach to the negative brushes is common to both sets of fields, regardless of how they're wired.

Okeh, now look at this next picture:


Figure B

Notice the the direction of winding on the field coils. It's easier to look at the bottom set for reference. Working out from the center, they're wrapped clockwise. Now, look at the fields above it, in particular the coil on the far left, and see how it's wrapped counterclockwise. Bear in mind that direction of wrapping as well as polarity (in other words, how the leads are attached to the inside and outside of the coil) determine which magnetic 'pole' that particular coil becomes when energized.

Another good thing to remember is that the direction of rotation of the starter is controlled by the clocking of the brushes relative to the field coils. Turn it ninety degrees out of phase and it will run backwards. Now, suppose we try to make our 3-series/1-shunt coil set by simply prying the original ground connection away from the case, removing the fourth field coil (assuming the positive connection as the starting point, the 'fourth' field would be the second one from the left—remember that the ground connection is not split in two originally— and grounding the lead coming out of the third coil (far left, in the picture) to the motor case. This method won't work. Not only is the field wrapped the wrong direction, but the polarity of it has now been reversed, applying power to the ground side and grounding it through the positive side. Starters wired with the three coils like that, plus a shunt coil, will free-run beautifully but will choke on the load tester. No torque whatsoever. Look back at Figure A again. Notice the position of the first coil in the series fields on the right. Looking at it from the top, it's at three o'clock. Notice the way that the four-field coils are wound. The coil that connects to the negative brush MUST be wound correctly to be the magnetic opposite of the field at three o'clock, since it's directly next to it in series. It's also wound in exactly the same manner as the field coil at six o'clock on the three-series coil set.

This is where the numbers in Figure A come into play. The original three series fields have two fields at 3:00 and 9:00 (the '2' positions), and one field at 6:00 (the '1' position). Now, how do we emulate this with our new custom-modified coilset? Well, because of how the 1.8hp field coils are set up, the new coilset is going to be 90° rotated relative to the factory three-field set. We will thus have two coils at the '1' positions (at 12:00 and 6:00), and one coil at the '2' position (at 3:00). The number of '1' and '2' fields in each set really isn't important, as long as there's three coils total and they're clocked correctly in relation to the brush plate.

Down To Brass Tacks: The Wizard Tells Us How He Did It

"I started with two sets of 1.8hp four-series field coils. Using the top set in Figure B as a reference, I cut off the two leftmost fields. I then cut out the field that's second from the right from the other set, and snipped off the lead where it attaches to the negative brush (notice that that coil is wound identically to the middle field coil of the series set, which is what it's supposed to replace). Leaving enough material on the fields, I installed them in the case, soldered the 'end' of the first set of fields to the single coil (at the point where the power lead was snipped off) and grounded the other side of the coil to the case. I stuck in a shunt coil and wired it, put the starter back together, and it cranked like nobody's business."

As far as the shunt fabrication is concerned, he used the factory shunt from a Chrysler 2095 150 (small) starter as a basis for calculating the necessary length of wire for the 3755 250 (large) starter, then used a pole shoe from a large starter as a winding jig.

More Chrysler starter sounds

Stock shunt-wound (2095 150) small-frame starter cranking and starting a 383 engine

Brand-new stock series-wound (3755 250) large-frame starter cranking and starting a 440 engine