Spur gear wobble

[Voodoobrew]

This is for top shafts that use a center pin. So I been having issues fairly often with my big 96t 48p spur gears wobbling. The larger gears amplify the wobbling.

Step 1: to see if this will work for you, disconnect the drive shafts so tires dont spin, then get a paint pin or marker that shows on the spur and lightly press it to the spur while its rotating. This should mark your high spots. also noe weather or note the shaft itself wobbles. (if the shaft wobbles, its probably bent, I suggest getting a new one.)

Step 2: carefully remove the spur and rotate it 180° and tighten it back down.(Maybe mark the shaft to keep track of which side is which)

Step 3: with a different color paint pen, or wax marker spin up the spur again and mark it as in step 1.

For me the marks ended up on opposite sides of the spur gear. This means the issue was in the shaft or in my case the center pin. I know its the center pin because the shaft doesn't wobble, or at least something related to the center pin, like a crooked center pin hole.

Step 4: So what I did was grind/sand down (I used a rotary tool with a cutoff disk) the pin on the side that the paint marks show up on.

It took me a few tries, and if you go too far you can grind down the opposite side some as well. The saft in question had the smaller pin hole drilled out to fit the larger sized pins. and the larger pin fit in pretty tight. so it wouldn't rotate when sanding.

If the second layer of markings shows up over the first, then the issue is in the Spur gear or the clutch mechanism. This is a whole nother can of worms and the solution is highly dependant on your specific clutch mechanism and spur mounting system.

Hopefully this helps someone, sorry there's not pictures, I never think of them while I'm tinkering. if i ever take it apart again, maybe i will remember and add some.