Starter issue - armature runout

[RW1930A]

Good Morning

Was having a problem cranking the engine (6 volt system). Would act as if there was a bind, hi compression, or a weak battery. Plugs out still wants to stop turning. Think the battery is ok so took the starter out to check. Removed the armature put it in a lathe and checked runout on the shaft. Have about 130+ thou at the end of the shaft.

So I think it is binding up as it turns. Is there any spec for max runout on these armature shafts?

I'm running 6 volt with a modern drive. If I use 12 volts with plugs out it turns quickly but still there seems to be noticeable binding as it rotates

Thanks for your help
RW

 

[Flathead]

I don't know the spec but I would guess you have exceeded it, might be time for another armature.

 

[Kurt in NJ]

press it straight—- i used to put a old bendix end on and put my foot on the starter and whack it with a hammer to straighten them

 

[nkaminar]

Don't know what the spec is but I would shoot for 0.005 runout or less. Since you have it in the lathe, you could use some wood blocks and a long 2X4 to lever it into compliance. Over due the correction then turn it 180 degrees to correct it into the proper runout. This will help to compensate for the spring back.

There is a reason why your armature is bent. Look for the reason. Is this a very early starter with the small diameter armature shaft? Is the Bendix binding or jamming?