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Broken Case Fix at Starter Gear Boss

40K views 35 replies 10 participants last post by  st96badboy 
#1 ·
Another Learning experience that I'd like to share; this one's a possible solution for those who have a broken starter gear boss on their engine case.

I was messing with the AFR and made the mistake of too much fuel at idle.....so rich that I had some backfire when starting.
It turns out that a backfire at idle puts stress on the starter "idler gear boss" which can break it, as a good number of fellow WC 1000/X owners have experienced.
The "right" thing to do is replace the case, but that's some serious cash and requires pretty much rebuilding the engine. So being the cheap (yet handy) guy that I am, I went the easy/inexpensive (and ugly) route......

... and this is what I did:
 
Discussion starter · #2 ·
First off, this is a pic of the broken boss. Seems this is typical

Auto part Wheel Vehicle
 
Discussion starter · #3 ·
I needed to pull the engine and take it to an expert TIG Welder. The plan was to build up and reinforce the Boss with new aluminum. AND to do this WITHOUT taking the engine apart (whoo hoo!). It took less than an hour for my Welder to get it done. All I had to do was take the engine to him dry of all fluids and with the stator cover removed.
This is the aluminum build up he did.

Auto part Engine Vehicle Automotive engine part Wheel
 
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Discussion starter · #4 ·
Now I needed to carefully recreate the hole for the gear shaft. i used a dremel first, and then a few drill bits, stepping up slightly larger and then larger again without making the hole to big. I also drilled deeper by a 1/2 inch into the boss then the original shaft went in.

Auto part Wheel Vehicle Crankset Tire
 
Discussion starter · #5 ·
The original shaft for this boss was 44mm (0829-032). Since I drilled deeper into the boss, I used the longer 58mm (0829-031) shaft as the #1 boss uses.

Auto part Wheel Engine Tire Gear


Then putting the Stator cover on to check fit I found I needed to grind off some of the shaft to shorten it. I did this a few times until the cover would sit flush.

Auto part Tire Automotive tire Wheel Gear
 
Discussion starter · #6 ·
Now I checked how the idler gear fit into the flywheel and filed flat the area where it rode against the boss. Notice the gear bevels are OUT.

Auto part Gear Tire Wheel Automotive tire


It fit nice.... so I fit the #1 gear as well

Auto part Bicycle part Gear Differential Groupset


and the spacer

Auto part Engine Gear Automotive engine part Differential
 
Discussion starter · #7 ·
Through the entire process I was fitting the cover on after every step to check fit. I took my time to help eliminate mistakes.
Even though the new shaft was pretty snug, I put a small amount of JB Weld into the boss on final assembly. This made the whole thing rock-solid.
Before I put the engine back in I'll replace the Stator cover seal; the spring came off the old one.

Auto part Engine Automotive engine part Vehicle Machine
 
Discussion starter · #8 ·
I'm pretty confident this will work well. AND it's stronger than original.
Special thanks to Doghouse for inspiration and the name of a good welder :)
 
Discussion starter · #13 ·
Is it possible that your starter is not ALL the way seated? With the play in the starter bolt holes (oblong) it's possible to bolt down the starter and not have it fully seated.
 
Discussion starter · #15 ·
I used a dremel to oblong them.... took like 5 minutes. But that's not the issue..... what doesn't make sense is it's an upgrade made for pre-2016 motors....and it won't fit those without the "oblong" mod. Go figure...
 
Discussion starter · #29 ·
I think it can be done with the engine in. And I like mbrandt1402's suggestion with the plate. be nice it you could elevate the cat 4 or 5 ft (platform) for easy access.
 
Discussion starter · #32 ·
No clue how it happened; that part of the starter is isolated from everything. Wonder how it even started when I drove it out of my toy hauler to check the engine.
 
Discussion starter · #33 ·
Replaced the starter with the new version (and gear). With the cover off i could see some wear on the magneto and stator (?) so I replaced both. Did not notice and crank play. Started right up. Ocotillo Wells tomorrow.
 
Discussion starter · #35 ·
I would think that it can be done with the engine installed, but really really hard. Pulling the engine is NOT a big deal
 
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