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Discussion Starter · #1 ·
Decided for a new fall project I would play around with a spare starter generator and voltage regulator that I picked up a few years ago to see if they could be repaired in case I ever needed them for my 1053. Thanks to Bruce Dorsi and Kenny P there are some service bulletins and parts lists that cover these items in the manuals section of the site. Since the search function on the site appears to be in retirement status I thought I would post the links to them in case other members were wanting to read up on these handy electrical items that keep batteries charged and engines starting with the turn of a key rather than the pull of a rope.

Parts break down of the starter generator https://gardentractortalk.com/forums/files/file/2735-bolens-delco-remy-starter-parts/

Bulletin on the starter generator https://gardentractortalk.com/forums/files/file/4647-delco-remy-sg-service-bulletin-img-150/

Bulletin on the voltage regulator https://gardentractortalk.com/forums/files/file/3042-delco-remy-regulator-service-bulletin/

Interesting that the Delco Remy bulletin refers to the unit as a motor generator rather than a starter generator. While there are multiple posts about starter generators in various threads on the site I don't ever recall seeing a thread that showed pictures and the steps to take one apart so I thought I would take some pictures at various stages and do a thread on the one I have in hopes it might help someone in the future.
 

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A Little Off Plumb
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Discussion Starter · #2 ·
Here are pictures of the S/G and the regulator - after taking a bit of hand cleaner to the tag to remove some black paint overspray I was able to read the S/G model - it is 1101970 and there is a 6L28 for the serial number. Have been doing a bit of reading about Delco Remy generators and the 4 digits of the serial number appear to be a date code that they used on them. The first character represents the decade year, the second character the month and the last two the day - so this unit appears to have been made Dec 28, 1966 if I understand this correctly which makes sense as I assume the S/G's would have come form Wisconsin Motors as part of the engine package. As you can see by the pictures the outer part of the case has some rust and looks like someone has drilled a hole in the pulley nut and installed a cotter key which I don't think was there when it was made. The voltage regulator doesn't look to bad on the outside but the rubber straps that the mounting tabs attach to are rotten. The picture underneath shows the wire wound resistor that connects to the field terminal and ground when the voltage regulator points are open to reduce the field current but still provides a path to ground for the current built up in the field windings to travel and reduce arcing at the point contacts inside.
 

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A Little Off Plumb
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Discussion Starter · #3 ·
I removed the two screws that hold the regulator cover on and had a peak inside. As you can see the regulator consists of two parts - a cut-out that connects the armature terminal to the battery when the unit is producing power and a combination voltage / current regulator that controls the output of the unit so the battery remains charged. There was evidence of moisture having been present at some point and the wire running from the field terminal to the regulator frame is broken - perhaps from vibration or old age depending on whether the unit was still in service when the rubber mounting strap broke. The point contacts look to be in decent condition so it may be possible to repair the broken wire.

Then I turned my attention to the S/G and removed the wire that was still attached to the field terminal - fortunately the nuts on both the A (armature) and F (field) studs moved with a bit of lubrication and luck so things were off to a good start. Once the nuts were loose I used a centre punch to mark the body and the front and rear bearing plates so that I could easily align them when I put the unit back together. I loosened the two long bolts that hold the rear plate, front plate and centre housing together - the one bolt turned easily but the other one was quite happy where it was. Since I did not know the condition of the bolts inside the housing I wanted to make sure it did not twist off so using a 7/16" wrench I gently tried to turn it and watched the end of it where it threads into the front plate to make sure the bolt was turning and not twisting inside the housing - it finally moved with a bit of force. Then I gently tapped on the rear plate and removed it from the housing - as you can see there is a ball bearing pressed into the rear plate that the armature shaft turns on. The bearing turned freely so I assumed that the front bearing must be seized and that was why the pulley wouldn't turn. The brushes and commutator appeared to be in decent shape but as you can see some rust had formed on the inside.
 

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You have explored the smaller, but vitally important, of the starter and charging system.
The Delco S/G was also used on Cub Cadets and John Deere units as well. There may be other brands.
The S/G needs to be checked for rotation before putting into the system. They may look the same, but, turn differently.
The Delco VR is a beast of its own. If you do not understand thermos-dynamics of bi-metals working on the voltage regulator may be above some mechanical abilities.
 

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Discussion Starter · #5 ·
You have explored the smaller, but vitally important, of the starter and charging system.
The Delco S/G was also used on Cub Cadets and John Deere units as well. There may be other brands.
The S/G needs to be checked for rotation before putting into the system. They may look the same, but, turn differently.
The Delco VR is a beast of its own. If you do not understand thermos-dynamics of bi-metals working on the voltage regulator may be above some mechanical abilities.
Good points as they were made for various small engine manufacturers. The S/G on mine turns clockwise when you are viewing it from the front and the voltage regulators can be interesting as they contain moving parts and contacts that do wear with age.
 

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Since I don't know much about the history of this S/G I will be removing the fields so I can do a thorough clean up of the rust inside the housing as well as check the condition of the insulation on the fields. Inside the setup is fairly simple as it uses two brushes that contact the commutator at 180° to each other to allow current to flow - the one brush holder is riveted to the housing providing a ground path as the brush wire connects to it with a screw. The other brush holder is riveted to the housing as well but in such a way that it is insulated from the housing - one wire from each of the field coils as well as the other brush wire are attached to the screw on the insulated brush holder. This allows the one field (that is used when the S/G is used as a starter) to be connected in series with the armature - it consists of a heavy flat metal conductor wound in a coil that has an insulator material sandwiched between the layers of metal. The other end of this field is connected to the A (armature) terminal on the S/G. The second field consisting of multiple turns of insulated wire and has the other end of it connected to the F (field) terminal on the S/G - it is used to control the amount of voltage and current produced when the S/G acts as a generator as the field terminal is connected to the voltage regulator that decides whether the field is connected directly to ground to produce output voltage and current or connected in series with a resistor built into the regulator to limit the amount of current going through the field coil. In this configuration the field coil is said to be shunt wound meaning that it is connected in parallel with the armature. Fortunately the screws were not rusted badly and they came out without any problems - as you can see by the last picture the one brush was not bonded to the wire which would result in a poor connection creating heat and a loss of power when the unit was starting and probably also create some heat when the unit was generating electricity as well.

To continue taking things apart I gently tapped on the front bearing plate and got it to move enough that I could get the blade of a small flat screwdriver in to start the armature to move towards the front of the housing - it turns out the front bearing was not seized but that the main metal body of the armature had rusted to the two metal field poles that the fields slide onto. As you can see the moisture had created enough corrosion that the two pieces were bonded together with corrosion resulting in the armature not being able to rotate as there is not much clearance between the armature and the two pole pieces. Once the armature was removed I carefully scraped off some of the rust corrosion on the body with a screwdriver being careful to avoid the insulation on the wire windings and then I sprayed the armature with WD40 to try and soften up some more of the rust. Then I removed the retaining nuts for the two studs and the outer insulators and pushed the studs out of there holes in the housing.

Something to note is that the S/G (unlike an automotive alternator or stator plate) produces D.C. current and that all the current passes through the two brushes in starting and generating mode - that is why the brushes are so heavy duty and do wear out sometimes. An automotive alternator which produces A.C. current is constructed differently so that the rotor (which acts as a field in an alternator) is the part that is moving and connected to brushes that appear light duty in comparison (since only a few amps of current flow through them to electrify the stator windings) and the stator which produces large amounts of current is stationary and the output connects directly to the charging system with no losses incurred by a brush and commutator connection the way a generator does. Similarly a stator plate on a small engine remains stationary as the magnets inside the flywheel revolve next to it to produce an alternating current that is then fed to a rectifier/ regulator set up to convert the current to D.C. and control the voltage and current produced. This is one of the reasons why the connections and brushes inside the S/G are so important to a good working electrical system as any point of resistance creates heat that can result in component failure and poor performance from the S/G.
 

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Next I moved on to removing the two screws that hold the field poles inside the housing. As you can see by the pictures someone had already been there before me as the slots were badly deformed. I gently set the housing in the vise between the two jaws with a piece of carboard in between the jaws and each side of the housing - I only wanted the vise to keep the housing from turning as I tried to turn the screws so I did not clamp the housing tightly as that might deform the round shape of the housing. Using a large flat screwdriver that had a nut up by the handle I could put a wrench on I tried to loosen the two screws but the screwdriver just slipped in the damaged slots. I contemplated welding a nut to the top of the screw head but then I remembered a trick my dad showed me many years ago when generators were still common on vehicles so I tried that first and it worked. Using a large punch and a hammer I set the flat end of the punch at the very outer edge of the damaged screw slot and hit the punch with the hammer to start the head to turn counter-clockwise . After hitting the punch I moved it to the other end of the slot and did the same thing and after doing this a few times the screws had turned enough that I could turn them out with a flat screwdriver. Then I gently removed the field coils from the poles that they were slid over since I wanted to check out the insulation on the coils and clean any rust off of the poles and paint them. The insulation was stuck to the pole in a few spots so I gently worked a small flat screwdriver in between the pole and the insulation to get the combination of rust and adhesive bond to break being careful to keep the damage to the insulation minimal and to make sure I didn't damage any of the wire insulation. As you can see in the pictures the insulation on both coils is not in the best of condition and the windings of the one field are much heavier than the other.
 

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Then I set about the task of removing the cotter pin and nut from the front of the armature. Fortunately there was enough left of the head on the cotter pin that I could grab it and turn it - with the help of some WD40 I got the pin to move a bit before the head broke off. Then I used a small nail to drive the two halves out of the shaft and nut. With the pin removed I removed the nut and then used some gentle persuasion with a plastic hammer to get the pulley to finally move on the armature shaft. The pulley is keyed to the shaft to prevent it from turning but the key, key way and key seat are not in the best of condition and will probably have to be repaired or replaced. With the pulley out of the road I removed the front spacer and slid the armature out of the bearing and then with a bit more persuasion with the plastic hammer I got the rear spacer to move from its home where it had decided to rust in place. Once that was done I checked out the bearings and since they felt rough when I turned them I decided they should be replaced so I removed them from the end plates. The rear plate has a metal plug pressed into the rear which I removed with a flat punch gently driving it out with the punch on an angle to catch the outer area of the plug through the bearing hole so that the punch did not tear into the metal plug. With the plug out it was easy to press the bearing out of the plate - a slide hammer with a jaw that would fit inside the bearing hole could also be used to pull it out through the inside opening which would not require removing the metal plug. The front bearing plate has a metal cover on the inside retained with three slot headed screws that I removed which allowed easy access to press the front bearing out. I believe originally the groove in the metal cover had a piece of felt in it to help seal out dirt and keep grease in since the original part number appears to cross reference to an unsealed bearing the same dimensions as the rear. Since both bearings I removed are sealed I will probably replace both bearings with sealed units as someone probably did before me. The armature shaft area where the front bearing sits appears to have a bit of wear so I am thinking that at some point the front bearing seized on this unit - may build that area up with JB weld or weld so the shaft is centred when the pulley and spacers lock it up as the nut tightens. First I will have to do some tests on the armature and fields for opens and shorts and also check to make sure the armature shaft is not bent. Given the condition of the red wires on the one field coil looks to be relatively new I am assuming that it or both coils have been replaced at some point in time.
 

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Found another used voltage regulator and inspected the insides of it - they appear to be in a bit better shape and the field wire going to the regualtor frame is still intact. I checked the resistor on the bottom to make sure that there was continuity through it and there was on both units - one measured about 64 ohms and the other one about 68 ohms. If you go to check it on a good regulator you will need to insert a piece of paper in between the voltage regulator contacts to prevent them from giving you a false reading as the points are normally closed - they will result in givng you a reading of 0 ohms across the resistor if they are not insulated from each other. This reistor very seldom fails but it is important as it serves as a path to ground for any current built up in the field coil with the points constantly opening and closing - otherwise the points would be the only path to ground for the field coil as the points opened and closed. They would be subject to excessive arcing which would shorten their life and could result in the points sticking together at some point - this would result in the field coil being continuously connected to ground with full generator output and no voltage regulation which would not be good for the generator or the battery.

Got the housing and end plates cleaned up a bit with the wire brush - while I was cleaning up the rear plate I noticed there was a groove in it with an o ring - not sure whether this was how it was made as the parts list for the generator does not show an o-ring - it could be the rear plate was replaced at some point in time. I also cleaned up the commutator a bit and ran the end of an old hack saw blade by hand through the grooves in between the commutator segments to remove any debris from the brushes wearing. Checked the commutator for opens between any of the segments and also for any shorts from them to ground with an ohm meter and did not find any so it appears the armature should be ok if I can repair the damaged key seat and worn area at the front of the shaft.
 

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Discussion Starter · #10 ·
Got some pieces cleaned up a bit better and gave them a quick trip through the sand blaster - gave the tage area a light dusting - not sure if that was a good plan or not - will see how it looks at the end. It is hard to get the inside of the housing but I got rid of a lot of the rust and crud. The rest of the parts aren't perfect but with some primer and paint the rust should be slowed down quite a bit. Cleaned up the two screws that hold the poles but I am not sure if I am going to repair the heads or replace them. The springs were being a challenge to hold onto in the sand blaster so I slid a piece of mechanics wire through them so I could hold onto them without worrying about loosing them in the sand. The pulley has seen better days - looks like someone bent the sides a bit by using a puller - I may end up making a new one.
 

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Discussion Starter · #11 ·
Used two small pieces of masking tape to cover the contact area of the brackets where the brush screws go to insure good conductivity when they are installed. Then I gave the majority of the parts a couple of coats of self etcing primer to slow down any future rusting. I also ordered and picked up two new bearings - decided to use the same bearing with two seals at the front and back locations. At the same time I got a new set of brushes. Next I will have to see about replacing the insulation around the two coils and making two new paper insulators that are shown in the parts break down that go between the pole pieces and the coils. I assume they deteriorated and someone tossed them the last time the coils were out.
 

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Discussion Starter · #12 ·
Decided to try and repair the slots in the two screws that hold the pole pieces in place. With the help of the MIG welder , a flat file, a hacksaw, vise grips and two 3/8" UNF nuts here are the results. They are not perfect but at least now I should be able to tighten them with a large flat screwdriver blade.
 

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Just a crazy amount of detail you put into all your projects Stew. No different to all the rest of the build threads of yours ive followed, fantastic work!!!.
Ditto! Looking great!
 

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Thanks for the kind words.

Decided to tackle the armature to see if the worn areas where the key seat is and where the bearing sit could be repaired. My first concern was the threads on the armature and in the nut were not in good shape as the nut was very sloppy - my guess is that is why someone drilled the nut and installed the cotter key. My first challenge was to see if I could locate another nut as I knew it was a larger thread than 1/2" - did some research and it turns out that a 70's GM alternator nut is the same size and thread pitch and I happened to have a spare. Tried to find out the size and thread pitch to see how much a die would be to chase the threads on the armature - the threads per inch measure 20 with my thread gauge but the O.D. of the threads wasn't matching up to a normal size such as 5/8" or 11/16" so I did some more research. As it turns out the thread is an odd ball that GM used on the generators and continued using it on the alternators when it replaced the generator on cars in the early 60's - the thread size is .668"-20. Some GM car forums say it is a metric thread but the consensus on the older car forums seems to be the .668"-20. Once I learned this I stopped thinking about finding a die and instead used a wire brush, hacksaw blade and a small file to clean up the threads as best I could to see if the alternator nut would thread on and fit ok. Got the thread to where the new nut would thread on and was a good fit so I stopped working on the threads - will probably use Loctite on the threads when things go back together. Used a flat file to clean out the key seat so a new 1/8" woodruff key would fit in - as you can see in the last couple of pictures there is not much material on each side of the key to keep it from rolling sideways in the key seat. Not sure if there was a key used originally as the parts break down does not illustrate one and I don't ever remember seeing a key on any GM alternator I have taken apart but I figured it would be a good idea to repair the seat if possible in case I decide to use a key.

As I stated the thread is a strange size - .668-20 (this is also the size of the shaft where the spacer sits _ I assume the shaft was this size where the bearing sits as well but since mine is worn I cannot say for sure). It was used by Ford And GM on their generators - the GM original # 1915172 - and subs to # 1911324 which appears to still be available from GM. Here is a link to a website that shows the nuts and lists the thread - the one on mine appears to be the 5/16" thick version.

https://www.maniacelectricmotors.com/95001300.html
 

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Discussion Starter · #17 ·
I thought about welding in the worn key seat and cutting a new key seat but my milling attachment that I have for the lathe would not hold the armature so I opted for an easier repair method that I will share. I cut two small pieces of 16 gauge steel and shaped them with a file so they would fit nicely on each side of the key. Once that was done I clamped one piece to the key with a pair of vise grips and tacked it to the shaft. Then I removed the vise grips and finished welding it to the shaft. After that I turned the shaft so the key was laying flat and set another key beside it and placed the second piece of steel in position and clamped it with the vise grips. It then got tacked, the vise grips were removed and then I finished welding it in place. Got a little off with the weld and accidently welded the front edge of the key - OOPS! Filed the weld to weaken it at the edge of the key and with some gentle persuasion the top key rolled up and got removed. After a few more strokes with the file the key in the key seat also moved and I now had two flat sides that replaced the missing material - not quite as strong as a new seat but stronger than what was there.
 

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The excess metal and weld then got sanded away with a flap wheel until it looked close to the correct size. Then I used the die grinder with a sanding disc and the flat file to finish shaping the material to the correct shape. Things looked good so after I cleaned out the sanding debris out of the key seat I did a test fit of the key.
 

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Discussion Starter · #19 ·
With the key seat repaired I turned my attention to building up the worn area of the shaft where the bearing sits. Using the mig welder I did a couple of weld passes and then cooled the area with water so things didn't get too hot - clamped the ground clamp between where I welding and the armature core to act as a heat sink. After cooling and wiping the water away I would do a couple more passes and then cool things again and eventually I got the area built up. Used the sander to do a rough clean up of the welded area and then I mounted the armature in the lathe to finish the job. While I had the armature in the lathe I also gave the commutator a quick polish and then cleaned out the segment grooves and verified the armature still tested ok with an ohm meter. Tested the segments to the shaft and and got an infinite resistance reading which is a good sign indicating the segments are not shorted to the shaft. Also checked the segments at 180° to each other as well as side by side and got consistent readings of .3 ohms which indicates that all the segments are connected to each other. I could dig out my dad's old growler and test the armature with it and a hacksaw blade to see if the blade vibrates on any of the segments but I think I will take a chance on it as is. Did a test fit of the new bearing and it is a nice snug fit so the armature should run true inside the filed poles. Cleaned up the edge of the core segments with a file to remove a bit more rust and then I gave them a couple of light coats of primer in hopes they won't rust much in the future - gave the two screws for the poles a splash of primer as well. I also found a part number stamped in the armature core segment that appears to be the original part number for this application - I remember an older gentleman at a lawn and garden tractor dealership telling me about a starter generator that he had had rebuilt and when he put it into service it worked but never seemed to have much power. He took it back to the rebuilder and they tested it and couldn't find anything wrong with it so he reinstalled it but was not happy with the way it performed. He got talking to an older guy who did generator repairs as a hobby (he had worked at an auto electric shop for years) about a year later and the guy said to bring it to him and he would have a look at the unit. The old guy did a few checks and then looked up the part number on the armature and found out it didn't match to the model number on the generator. The old guy replaced the armature with the correct one and the dealership put the starter generator back on the tractor and it had all kinds of power. Given the age of most of the starter generators still in service it is a good thing to check if you are having problems with a starter generator - no telling what has happened to some of them since they were new.
 

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