Replacing brushes on 1940 LaSalle starter

[BrentA]

Has anyone replaced the brushes on their 1940 LaSalle (or similar) starter?

My starter started running real slow, and eventually stopped turning the engine all together. I decided to replace the brushes to see if that will help, and figuring it won't hurt, so I pulled the starter out. I removed the metal clip on band that covers the brushes and unscrewed the two copper connections between the brushes and the hot terminal. I've also removed the two long bolts that go through the back plate, but I can't seem to get the back plate of the starter off.

Before I start hitting this thing with a hammer to try opening it up the rest of the way, I wanted to see if anyone knows of some other step I'm missing. Is there some other trick to removing the back plate, or do I just need to hit the thing hard enough to pry off that back panel?

I did discover on inspection that one of the brush springs is broken, so I should definitely get it open to fix that. If anyone knows where I could find a replacement spring, that would help a lot too.

Thanks,
Brent

[Doug Houston]

After you've disconnected the two brush screws and removed the long assembly bolts, the rear commutator housing SHOULD come of of the starter frame. Now, finding a new brush spring should be simple If it's stuck on the main housing, get a drift pin, and tap it with a hammer. It should come off.  A starter-generator rebuild shop should have brush springs for you.

Once apart, check the shaft bushings for wear, and replace them. Clean up the commutator segments by turning in a lathe, using a light cut, jut enough to clean them up.

s long as you have the starter down all the way, may I suggest that you drill the commutator end plate, and install a 3/8' grounding stud. After installation on the car, conect the battery ground to this grounding stud. You'll never believe how that starter cranks the engine after that.

Be sure, of course, to use grease sparingly on the new bushings.

If you are going to send the starter out to a rebuilder for the job, all of the above is out the window.

[BrentA]

Thanks for the details. That gives me some confidence to try prying it apart a bit harder. This should be a good holiday weekend project.

I'm planning on doing the work myself, so the only part I won't be able to do is the lathe since I don't have one. Do you think there would be anything wrong with lightly polishing the commutator segments by hand, or would it really be best to find a shop?

[Doug Houston]

The best advantage  in turning the commutator is a lathe is that to true it along its length. Most likely, the brushes have worn the copper with a groove in it, so new brushes won' ride evenly on the commutator.

[Yesteryear]

As a rebuilder of starters/generators I can say that the vast majority of units that have been together for quite some time have some level of corrosion whether you have the original cast iron com plate or 1941-newer aluminum comp plate.  Bear in mind there is also the locator pin that will also hang up while the armature shaft is still in the bushing hole.  Usually a couple raps with a rubber mallet or gently prying up through the brush inspection holes and the brush arm pivot pin will pop the com plate free.  Reminder: do not undercut the commutator on starters-only on generators.  Undercutting commutators on a starter will allow bits of copper bar or brush to fill the gap, shorting two bars together.  If you do not want to drill the com plate you can also attach a ground strap directly to one of the starter mounting bolts to the bell housing.  Since you have the through bolts removed, I'd suggest wire wheeling them clean so you have a good grounding connection through the starter from com to nose housing upon re-installation.  Dave S.