Starter restoration for a Ford Flathead V8 is a straightforward proposition. In this case the starter came to us in a box, having been removed for the purpose of full restoration. When we pulled old starter motor out of the box of parts, we noticed the usual buildup of grease and dirt, as well as signs of age and lack of repair. A picture in this case is definitely worth a thousand words...
This is where we started. U-u-ggly! More grease than in a fast food burger.
The most important part of a motor is the drive gear, so we took our time to carefully inspect this one for signs of failure such as broken or scored teeth. The gear showed little, other than a little leading-edge wear, so we went on to examine the condition of the rest of the shaft and the centrifugal actuator (the bulbous end of the shaft). Everything was in good shape — after cleaning — so we tested its movement by spinning the gear up and down its travel, then pronounced it "workable."
We scraped off some of the more loose detritus to minimize gunk in our solvent tank, then started disassembly. Before loosening the two bolts that hold the starter together, we took the time to scribe the orientation of the two end caps to the case. Sometimes this doesn't matter, but other times it does, since the caps sit in the vehicle in a certain way. We didn't know either way, but it didn't hurt to do the exercise. The Ford's starter assembly mounts to a plate that forms part of the bellhousing shield. The long screws that hold everything together thread into the plate rather than the end of the starter motor itself. In this case, care must be taken to avoid the entire assembly falling apart before noting any specific order of parts. Besides, it's always a good idea to stay in the habit of laying out parts in order of disassembly to avoid confusion later.
Disassembly. You can clearly see the scribe mark (circled in red).
Once apart we removed everything possible from the motor housing, but were unable to take out the "shoes" that form the field windings around the armature. These require a special tool that we simply didn't have, but close inspection of the windings indicated no problems. That inspection, by the way, was done with a magnifying glass. We took our time and looked through the glass to spot any deterioration of the lacquer film on the windings. Satisfied that the windings were in excellent condition, we carefully cleaned the housing with mineral spirits and the inner electrical components with alcohol.
We first cleaned everything up with mineral spirits, followed by a bath in denatured alcohol to clean the electrical components.
After cleaning everything we inspected the rear bushing and ring gear engagement assembly, making sure there was no significant wear or binding. Once the bushing and shaft-end were cleaned we measured both the shaft diameter and bushing inner diameter with a caliper to determine need for replacement. The measurement showed a .003 inch clearance, within reasonable tolerance for a short duty cycle motor. If the clearance had been more than .006 we would have replaced the bushing. There is no point in making a starter motor — or anything, for that matter — look new if it doesn't work properly.
Next came the commutator. Our starter was a true veteran of many engine engagements, and the commutator showed the wear. There were deep grooves and heavy glazing due to the scraping of the brushes and accumulated dirt in the housing. A "serious" sanding of the surface was required, using 320 grit sandpaper followed by 600 grit to smooth things out.
We used the old "shoe-shine" method of sanding the commutator. Sand a little, then turn a little. On the right are the results.
To maintain correct curvature, we wrapped sandpaper around the commutator when dressing up the brushes.
Oddly enough, the brushes looked good, although their "wiping" surfaces needed a sanding to take away grooves and glazing. We wrapped some sandpaper around the commutator, making a perfect radius of curvature with which to sand the brushes. By the way, most shop manuals list the minimum size of brushes, beyond which they need replacement, and our's was 1/3rd inch.
A little sanding cleaned up the starter case nicely. The middle photo shows the inside after its bath in alcohol. On the right, we're lookin' good and ready for paint.
A little paint remover made quick cleanup of the end plate.
We consulted our shop manual for any electrical checks and made all the ones we could, using a high-quality voltmeter. We would have taken the armature to a shop to get it checked on a "growler" but since the starter turned over the engine fine before it was removed we decided to take our chances.
Ready for painting and reassembly.
To prepare for painting, we covered everything we didn't want to receive paint, and suspended it from our garage ceiling with coathangars.
With everything ready for painting, we prepared the housing by using chemical stripper on the end pieces and a sander on the housing and bellhousing plate. We chose not to use stripper on the housing for fear that some might splash onto the windings. This would instantly strip off the protective film and cause shorts and adding significant time and expense to the project. (Note: There's no set procedure here, just do what is the most practical and least invasive.)
Getting a coat of paint.
To install the brushes, we held the spring clips out of the way with a dental pick, dropped the brushes in and released the spring clip.
After cleaning and priming, we sprayed the motor housing with a gloss black finish. The original motor was flat black, but we chose gloss because it looks nicer and is easier to clean (wipe off, that is).
Our finished starter.
Once the paint cured for a few days we bolted everything back together. The only thing that was difficult was getting the four brushes over the commutator. We found a dental pick to be the perfect tool for doing so. After assembly we connected jumper cables from a battery. The starter jumped to life and sounded great, so we wrapped it in some plastic and stored it away for final reassembly.