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Discussion Starter #1 (Edited)
I have a 7HP Briggs and Stratton model 170452 1403 01 78073112 engine on my 1978 BobCat. The starter is a 110volt American Bosch part # 391489. the brushes are both gone. I mean GONE as in one is down to the braided wire and the other is part way into the spring! It looks like they are not available anymore, if they ever were? the commutator looks not too bad though. I checked on this site, and could not find anything useful.
Briggs and Stratton 170452-1403-99 Parts List and Diagram : eReplacementParts.com
Does anyone have a better source or has anyone McGivored a fix for this?
 

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Is it a 120 volt starter ??
Is there a part number or brand on the starter.
There are a few different starters listed for your engine on Jackssmallengine

https://www.jackssmallengines.com/Jacks-Parts-Lookup/Model-Diagram/briggs-stratton/170292/88242

  • 311 390081
    More Info Brush-Starter (For American Bosch 110V Starters) No Longer Available
  • 311 390449
    More Info Brush Set (For 12V American Bosch) $29.60
  • 311 390990
    More Info Brush Srt (For Mitsubishi Starters) $27.70
  • 311 391705
    More Info Brush Set (For 3 1/16" Housing Length) $31.15
  • 311 391705
    More Info Brush Set (For 3 1/16" Housing Length) Old Style: Brush End Head is 13/16" Wide $31.15
  • 311 393612
    More Info Brush Set (110v 3-1/2" Housing Length) No Longer Available
 

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Do the contact assemblies look like either of the sets in 43's post? If so maybe try the one that looks closest. Wonder if the vendor could give you the measurements of the carbon brush part. Think you can reduce the size if necessary. Another option might be to check a power tool repair shop to see if they have a brush that might fit. If you can find a brush, you can probably cut the electrical contacts off the braids, and solder them to the braids on the replacements, maybe
 

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Discussion Starter #5 (Edited)
None of the above are the same. I don't think these are meant to be replaceable except for replacing the entire end cap. I will go to the local small engine places and see if they have any used or NOS parts. If that does not pan out, I will take a set of brushes out of an old angle grinder and file them down until they fit. The hard part will be dealing with all the rivets.
 

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You might want to look around your area and see if there's a shop that rebuilds motors and generators, and take it to them. If you have one... shops like that are getting kind of rare these days.

From the looks of things, you really need not only to replace the brushes but to clean up the commutator... if you don't do that the motor may not work well and/or will consume the new brushes very quickly. A rebuilding shop can put the armature in a lathe and get the commutator as good as new.

If you do want to just replace the brushes, you might try to find a good hardware store in your area. The ones that have those trays full of different fasteners sometimes have generic brushes and you might find some that fit. I don't know if you have Home Depot in Canada but I've seen brushes there in the past.
 

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Discussion Starter #11
This is what I was sent from Briggs customer service but I don't see what you need in there. It's also for a 1403-99 instead of your 1403-01

Results
Thanks for trying. My local power equipment dealers didn't have any luck either. I was picking up some stuff at another supplier that also services power tools today and asked if I could talk to their tech. He took me in the back and we rummaged through his used parts bin and we found a set of brushes that I think might work. I will post my results as I progress.
 

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Discussion Starter #12 (Edited)
Well it was a bit of an ordeal. I had to file down the oversized brushes until they fit into the brush holders. I used a micrometer to gage my progress as I filed them. I then made a set of 1/8" male spade terminals to fit the females on the factory 120v cord out of ring terminals and crimped them onto the new brushes.
I abandoned the original terminals that were riveted onto the end cap and instead plugged the wires together and covered them with shrink wrap. The new brushes are slightly longer than the originals, since they would not retract far enough to get the commutator in. So I filed the slot in the brush holder a little deeper to clear the braided wires and cut the good spring down to match the length of the burnt one.
After four tries, I got everything assembled and clocked correctly. I clamped it in the vise, crossed my fingers and plugged it in. It ran like a top! Whew!!
 

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Discussion Starter #13
I have a question regarding the plastic drive gear on this unit. obviously centrifugal force forces it out to engage the flywheel. What makes it return to disengaged position?
 

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There's no spring? I've never worked with a Briggs starter but the Tecumseh starters have a spring that returns the gear to its rest position.
 

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After looking at the photo I'd guess it's just the energy of the flywheel pushing it back against those threads that push it out when it's energized.

I'm with ELaw, haven't seen one without a spring before. Once of those things you don't pay attention to until someone brings it up.
 
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