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DIY Starter Motor Rebuild

Posted: Tue Mar 12, 2019 9:34 am
by sweet victory
This write up focuses mainly on rebuilding the starter. Removing the starter on this vehicle is actually very easy assuming you have some extensions and 15mm swivel sockets. There are several other DIYs showing how to remove the starter, so that will be excluded from this write up.


1. Here is our starting point. On cold starts, my starter gear would not disengage quickly enough and make a godawful noise. I gave the mechanism a quick visual inspection to make sure nothing appeared to be damaged.

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2. We will start by removing the motor housing. You will need to remove these two 7mm hex head screws and the 13mm nut holding on the ground wire.

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3. We will now need to remove what I'll refer to as the "plunger assembly". I will pretty much garuntee that you will need to bust out your drill bits to remove these screws. You can either drill the heads off, or use an extractor. I opted to use an extractor, which removed them with no drama. You'll want to order new 5mm flat head screws. Overall length is roughly 33mm.

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4. Once you get the plunger assembly housing off, this is what you'll end up with. By this point, it should be a little more clear on how the gear disengages. Don't loose the little rubber L piece!

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5. I started by cleaning the plunger assembly and re lubricating it. All of the grease on my plunger was solidified and was "sticking." I cleaned off moving surfaces with brake cleaner and used high temperature grease as replacement.

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6. I'm using Mobile SHC 220 high temperature grease, since it's what I had. What's important here is that you don't go crazy with the grease. Less is more, and a light film is all you should need.

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7. Moving onto the planet gear assembly. If the "cap" for it is still stuck in the motor housing, you can remove it using a 90 degree pic. If your cap came out with the assembly like mines did, you can lift it straight off.

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8. The ring gear has three rubber feet that friction fit and can be easily pried out. I gave this a good cleaning with brake clean and wiped out the teeth. I repeated this process with each of the planet gears, gun gear (which is inside the motor housing), and the planet gear carrier.

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9. I did not disassemble anything beyond this. What I did for this spline area was wipe it as clean as I could get, then reapplied a new moly grease.

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10. The last place you'll want to clean and add a little bit of grease is at this nose cone. I cleaned out the dried up white lithium grease and applied a very light coat of grease. Just enough so that the lip seal isn't going to get torn up on a dry shaft.

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11. By this point, everything should be ready for reassembly. For reference, this is what my planet gear assembly looks like after regreasing. You don't want to pack this with grease, as there is a brushed motor in the housing. There is no seal between the planet gears and motor. You may want to add a light coat of grease to the motor shaft as well.

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12. To reassembly, I recommend that you put the long screws through the body of the housing, and use it to keep your mechanism aligned as you put everything back together. Here, you can see the threads of the screws protruding through, and the note the notch on the starter housing. The notch needs to align with the rubber L. Make sure you install the plunger assembly before sliding the motor housing on all the way. You will not be able to get the plunger into the fork lever if you install the motor housing first.

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13. Here is everything back together with the new fasteners.

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Here are the fasteners I ended up using for the plunger assembly.

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Re: DIY Starter Motor Rebuild

Posted: Tue Mar 12, 2019 10:18 am
by gnat
Nice write up and excellent pics. Thanks!

Re: DIY Starter Motor Rebuild

Posted: Tue Mar 12, 2019 11:28 am
by 32wildbilly
Nicely done! May it provide numerous years of noise free starting.

Re: DIY Starter Motor Rebuild

Posted: Tue Mar 12, 2019 1:59 pm
by Einsteiger
Many thanks. Filed away for future reference 8-)

Re: DIY Starter Motor Rebuild

Posted: Tue Mar 12, 2019 9:25 pm
by ipman
Nice writeup. However, why not replace the plunger and brushes? Do they sell them separately?

Re: DIY Starter Motor Rebuild

Posted: Tue Mar 12, 2019 11:17 pm
by sweet victory
ipman wrote:
Tue Mar 12, 2019 9:25 pm
Nice writeup. However, why not replace the plunger and brushes? Do they sell them separately?
The plunger is not a consumable like brushes are. My main goal in here was to resolve the issue of the starter gear not disengaging on cold starts. Sounded pretty awful; something I wanted to take care of as soon as I could. If you can find placement brushes for this starter, please feel free to share and I'll at least include it in the OP for future reference. A quick search before the job started did not yield any results on the usual suspects (pelican parts, sun coast, auto atlanta, etc). Brushes can typically last 1000+ hours. I've never actually needed to replace brushes on a starter before, so did not feel the need to. I understand that makes this sort of a "half baked" rebuild. If I ever need to replace them, I'll document it and update the OP. :)

Re: DIY Starter Motor Rebuild

Posted: Wed Mar 13, 2019 7:10 am
by ipman
I appreciate the write up, and the pics are very clear. For your case, it sounds like this solved the problem for sure. I will see if I can find some numbers for the brushes and report back if they are found. I am guessing this is a Bosch starter? The other part is, if this is a bosch starter, it appears you can get one for sub-$200, far less than the near grand the dealer wants. At $200, it may just make sense to replace it with a new reman'd with warranty.

Re: DIY Starter Motor Rebuild

Posted: Mon Mar 18, 2019 8:56 am
by 5chn3ll
Good thinking.
sweet victory wrote:
Tue Mar 12, 2019 9:34 am
Just enough so that the lip seal isn't going to get torn up on a dry shaft.
Yup, that's what I came up with after reading the entire (excellent) DIY. Sorry, I'm an ass.

Re: DIY Starter Motor Rebuild

Posted: Mon Mar 18, 2019 4:36 pm
by sweet victory
I spent a lot of time figuring out how I wanted to write that sentence. I'm surprised it took this long for someone to jump on the opportunity. :lol:

Re: DIY Starter Motor Rebuild

Posted: Mon Mar 18, 2019 4:49 pm
by 5chn3ll
Isn't it rewarding when someone finds your easter egg?