busted starter

pooch

pooch

Well-known member
Snapped the main shaft off level where it comes out of starter motor.

Lucky, I was working on it and testing without ignition on.

If it had broke and got caught in there with a running engine ...ewww.

Bendix drive was just sitting on flywheel.

The fracture looks like it has been working for a long time.

I suppose this starter is scrap now?

Is a main armature shaft available?
 
You can buy a shaft, or take one from another starter. Do you have a picture of the break, or can you describe the starter?

The only time I saw a shaft break was on a 1928 starter that was cut back on the shaft for the new 1/2" service drive. The Service Bulletins warn that the cut must have a radius at the end of the cut. Someone cut the shaft with a sharp corner, and that's exactly where it snapped.
 
Tom, 1/2 inch shaft and it fatigue cracked right as it exits the motor.

Is the shaft complete with armature included?

I can see some hitting of the front spring bolt head.

I presume this has been hitting on the rear of the flywheel and stressing the shaft at the point of break.
 
Tried the crank handle, it has 2 ways to go in at 180 degrees.

It seems they are in the wrong place to turn motor over on TDC.

The piston comes up at compression at top of swing.

Is whatever in there on the end of the crankshaft moveable?

Like can it be shimmed or whatever to get in a different purchase spot for the hand crank so that piston goes over TDC about at the 9 o'clock position?
 
The crank handle should locate at 4 places 90 degrees apart. Look at it if you can or just keep trying, it has 4 places. Maybe your crank nut is damaged?
 
pooch said:
Snapped the main shaft off level where it comes out of starter motor.

Lucky, I was working on it and testing without ignition on.

If it had broke and got caught in there with a running engine ...ewww.

Bendix drive was just sitting on flywheel.

The fracture looks like it has been working for a long time.

I suppose this starter is scrap now?

Is a main armature shaft available?
Click to expand...
PV Antiques is making a new replacement starter armature. A report will be in the next issue of the Model A Times.
 
Why not replace the starter. There wil be plenty availble at Hershey next week. I don't pay over $10 for one.
clem
 
OK, from what you say it sounds like you have the 1928 starter that was cut for the SERVICE DRIVE, but wasn't cut leaving a proper radius. It also sounds like a common hex bolt was installed in the pinion end of the drive spring. This common hex bolt will hit the multiplate flywheel, and you can see what happened. You need a slotted headless bolt on the pinion end of the 1/2"drive, as shown in the SERVICE BULLETINS.

You do have a multiplate flyhweel on this engine.....right??? If so, then you need the correct starter, which has a 1/2" shaft and drive. These are much harder to find, but are still around.

There are 2 styles of multiplate flywheels and the second style has a recess for more starter drive clearance, as shown in the SERVICE BULLETINS.

A lot of NEEDED INFORMATION is found in the SERVICE BULLETINS. If you don't already own a copy of them, do yourself a favor and buy the full size edition from either of the national clubs. This is much nicer, easier to read, and more complete than the small yellow book of service bulletins.
 
pooch said:
Snapped the main shaft off level where it comes out of starter motor.

Lucky, I was working on it and testing without ignition on.

If it had broke and got caught in there with a running engine ...ewww.

Bendix drive was just sitting on flywheel.

The fracture looks like it has been working for a long time.

I suppose this starter is scrap now?

Is a main armature shaft available?
Click to expand...

I am bringing an Abel starter with the drive unit to Hershey. Space CV 4-9
Rainmaker Ron
 
Tom, how do I determine what flywheel I have?

I can feel inside past ring gear and it seems to go straight in and then a radius around rear.

Cannot feel any recess.

On your description and after the fact, I can see that the hex bolt did in fact hit the flywheel every starter rev and caused the break.

moz-screenshot.png
modelAbustedstarter.jpg
 
Yes, you do have the very early 1/2" starter. Notice your starter has 2 screws holding each field pole in place. Your starter also has 6 short screws holding the end plate in place, instead of the two long through bolts. This starter also has ball bearings on both ends.

That would be a nice starter to save. I'd take it to a machine shop and have them bore the broken end of the armature shaft. This early starter has a large shaft diameter where it goes through the bearing, so it could be bored and a new 1/2" shaft inserted. It could be a very tight press fit, or welded, then you could have a new keyway and screw pocket cut to duplicate the broken ones on the broken shaft.

You can make your own headless bolt by cutting the head off a grade 8 hex bolt, then cutting a screwdriver slot into it. This is held in place by a circular wire clip. (see the SERVICE BULLETINS and Chassis Parts Books) for pictures of the screw and clip.

If the machine shop cost is too much for this, you might try to find another good used armature or starter like this one. I have one for my own use, but don't have a spare to sell right now.

You should remove the top cover to see the clutch and you will know right away that you have a multiplate flywheel. From your description, you have the early multiplate flywheel without the relief cut for the later drive. Having the very earliest starter would also lead me to believe you have the earliest style flywheel.

Let us know what the machine shop says. With their fix and a correct bendix spring bolt, you should be good to go.

It's VERY IMPORTANT to never forget to retard the spark when starting, especially with the early starter with the smaller 1/2" shaft.
 
Ok, that sounds doable, if the shaft inside has enough meat to bore.

What grade steel should I aim for for the new shaft and how far in should I bore?

As I don't have access to any service bulletins atm, any chance of posting or pointing me to a description and pic of the correct screw and clip.

I will need a new pinion, as this one is chewed back about 3 mm and was only just reaching ring gear.
 
30f6e0ac.jpg


Here is a picture of the correct headless bolt for the "SERVICE DRIVE", which you have. From your picture, the pinion looks good to me.

To make the headless bolt, buy a grade 8 bolt long enough to have a smooth shaft under the head. Cut the head and part of the bolt so you still have a smooth full diameter part of the bolt to fit inside the bendix spring end coil. If the threaded part of the bolt is so long that it hits the 1/2" shaft, then that will also need to be cut back. You want full threads in the pinion, but the bolt shouldn't touch the shaft. Once the bolt is cut to proper size you can cut a slot in the top for a screwdriver. You will also have to drill a small hole for the locking ring to fit into. This will keep the bolt from backing out.

Also notice that the end coil around the headless bolt has been ground a bit for added clearance. I will come back with a picture of the two different multiplate flywheels.
 
Flywheel1928a-1.jpg

Flywheel1928b-1.jpg


These are the two pictures showing the early multiplate, with the larger bevel on the rear edge. But, that's just because the outer diameter hasn't been cut down like the later one. The service bulletins tell about when this change took place. Without looking it up, I seem to recall it was around August or September when the flywheel changed.

In November 1928 the new single plate clutch came out.
 
Thanks for pics Tom.

My flywheel is the top one.

Got some good shaft steel today, EN19, went to machinist, bored and reamed hole in armature shaft, then arrgghh, he hurried and made a mistake on the final cut of the turning of the extension.

Got a new piece of steel and will do it again tomorrow and I will make sure he goes slowwwwwww.

On another tack, years ago I fitted a new starter to a suzuki car.

It only went half speed.

After a wasted half day, I found it was only firing on 2 out of 4 brushes, one brush had a bad holder screw.

Would it be feasible to remove 2 brushes from the 6 volt A starter, so it only goes 1/2 power on 12 volts and does not go so fast and thump into the ring gear?
 
Ok, on last hurdle.

Have new shaft pressed in with super locktite and fitted a 1/8 roll pin in a hope to make sure it don't come out.

I notice that the front ball bearing is sliding within the housing, and there is about .015 inch free end float in armature.

Should I try to shim this out to almost zero end float?

I thought the end float might upset the pinion as it tries to engage and the shaft moves.
 
pooch said:
Ok, on last hurdle.

Have new shaft pressed in with super locktite and fitted a 1/8 roll pin in a hope to make sure it don't come out.

I notice that the front ball bearing is sliding within the housing, and there is about .015 inch free end float in armature.

Should I try to shim this out to almost zero end float?

I thought the end float might upset the pinion as it tries to engage and the shaft moves.
Click to expand...

.015" isn't too bad for a Bendix service drive. I wouldn't worry about it. If you have a thin washer handy you could slip it in to reduce the end play to .005" or so.

If you still were using the original Abell drive then the end play is much more critical.
 
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