What causes a dead spot on the starter?

Sometimes the old Chrysler starter on my '77 318 does not turn over now (about 1 in 25 times)


The relay and battery are good. I was wondering whether I can fix it myself with a new brush set, or if the issue is more internal to the motor.

I would rather rebuild it myself if possible!


Cheers!

Greg

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http://www.youtube.com/hyperpack

Either a shortened bar on the armature or a field coil problem. Only acts up if that spot on the armature lands in "the" spot as it spins down as you release the key

A faulty commutator causes a dead spot on the starter. There is no field coil problem that does so, and neither does a brush problem.
See here.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thank you Dan. I have some studying to do, eh?

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http://www.youtube.com/hyperpack

What province issued your licence to say that?

Seriously, though: if your armature is indeed faulty, you'll have to get one that isn't. It'll have to be the right kind, depending on whether you have a small-frame or large-frame starter. If you're not sure, post the 7-digit number on the motor housing (round part of the starter).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

None. I am allowed to be idealistic sometimes.

Thank you. I do have plenty of starters here to sort through and about 30 more at Dad's House. I am sure I can scare up something.

I have gotten into rebuilding my own Mopar things when possible, as there is so much junk out there.
I have done alternators and power steering pumps to date. Easy Brush replacemnts on starters as well but want to dive deeper and this presents a good opportunity to do so.

Greg

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http://www.youtube.com/hyperpack

Used to be possible to get all the starter parts out of cattledogs; that's not so easy any more. I'm thinking of the friction washer (which, if absent or worn or too thin, causes the extended spindown people carp about and claim is inherent to these starters). You may need to get crafty and spend some quality time browsing the McMaster-Carr website. I might take a notion to make a new friction washer out of this stuff, for example, and wind up with a better one than the factory piece.

Keep in mind with the mix-and-match created by the need for a replacement armature: drive and driven gear mesh and match will determine whether or not your starter will sing like a Highland Park Hummingbird or scream like a Highland Park Banshee; this is why so many "remanufactured" ones sound like hell. The large-frame starters have the drive gear as a separate piece, removable from the armature shaft, so you could swap the armature but keep the same gear.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.