MattsAwesomeStuff wrote:- Took apart an old almost-junk grinder after I realized they must have 90 degree gearboxes in them, (it does, 3:1) and considered using it instead of the propeller gearbox (2:1) if I never add another geardown stage. But I couldn't figure out how to take the damned thing apart any further than the back casing.
Post some pics, we might be able to help. Most come apart pretty easy, but also some of the cheap ones have so much lash (gear slop/wiggle) that if you really put a lot of power thru them you may well rip teeth off the gears with power from a bike motor. Also, they don't always use bearings in them, but sometimes just bushings, and those tend to be very worn in old grinders, and end up causing lash or other slop that wears gears quickly. I've got a harbor freight one that is trashed like that, becuase the bushings wore too much. Motor works great but gearbox is junked.
Keep in mind also that often the hsaft of the motor has one of the gears machined into it, meaning you must cut the shaft and create a coupler between it and the motor you are wanting to use.
- Couldn't figure out how to get the cranks off their posts. Tried prybars and such. Bought a $10 gear pullet, but couldn't get the teeth in. Returned it and bought a $6 bearing puller that uses rectangular jaws rather than round ones. It just flexed and bent. Apparently there's a "Bottom Bracket Tool" for this. Some of my cranks are on shafts with a female (nut) thread, some have a male (bolt) thread. I hate buying 1-purpose tools, so maybe I could get a local bike shop to lend me one overnight. Stuck there.
Many bike shops will take them off for you, but they usually charge for each set to be removed. Around here the going rate varies from $5 to $30, when I asked around before I just said screw it, and bought my own tool, because the tool can often be had for less than $10, which I think is about what I paid for mine.
The way it works is the cranks have threads on the inside of the hole surrounding where the nut or bolt goes in. You remove the bolt or nut using a regular socket wrench, then thread in the tool to those big threads. Tighten that down with the wrench (often part of the tool), then wrench the other half of the tool (usually clockwise, I think) to push against the threaded-in piece, which pushes the part you're now turning against the crankshaft (where the nut or bolt actually was at before), and forces the crank off of the shaft.
If you have any very large bolts with the same thread pitch and diameter as your cranks' hole, you could drill a hole in the bolts, and then tap them for a smaller but longer bolt to thread into them, and this will do the same job as the crank-removal tool.
- Tried to pull off the rear cassette like in Warren's linked tutorial, but they won't budge. I'm stumped, cone nuts are off, I can see clear through the other side.
First question: are you trying to get the sprockets off, so you can use them or the wheel hub (and it's built-in freewheel) separately, or are you wanting to use the whole freewheel mechanism on something other than the wheel hub?
I ask because that looks like a freehub type, using a cassette of sprockets that slide onto a splined section of the hub itself. The freewheeling mechanism is part of the hub, and is not easily going to be usable without the hub or at least some part of it.
Have you removed the locking sprocket(s) on the outside? Usually one or two of the smallest sprockets unscrews, or a separate lockring just outboard of all the sprockets. Depending on how they are made, it may require a "chain whip" to hold the other sprockets while you use the sprocket removal tool (splined with a nut built in for a large wrench) to loosen the small sprocket. Sometimes you just need the sprocket removal tool, turning against the locked freewheel mechanism (but it may require a very large amount of force / leverage to get it started--I've often had to use a hammer on the end of the wrench, while standing with my feet on the bottom edge of the rim to keep it from spinning).
I'll have to come bakc to try to help with the gearing--my brain isn't up to doing math right now.