# RockE the Electric Rocket Moped



## NabilAhmad (Feb 26, 2011)

A friend gave me an old rusted 1985 QT50 Yamaha "Yamahopper". 








The engine block is combined with the transmission - a rather simple design, I'd say. But it had one problem. The engine head and piston have been missing for years. Judging by the bald tires, someone had fun till they seized the engine.








The great thing is that it's gear driven. What's better is that after enough butt scratching and head thumping, it became obvious that the best way to connect the 5/8" keyed motor output shaft would be with a 15mm 12point 3/8" drive socket.
















It is supposed to be 10mm, not 3/8", but this gives plenty of slop - hopefully not too much though.









And so begins the new life of RockE the Electric Rocket Moped!
http://www.diyelectriccar.com/garage/cars/314


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## NabilAhmad (Feb 26, 2011)

The drive coupling Explained:

A 15mm 12pt socket almost slides over a 5/8" round shaft. So off the the drill press I went with my trusty 5/8" drill bit. Fingers crossed, I started; half expecting the loose chunks of the bit. Thankfully, Ace does not have too hard of sockets - I imagine if it were too hard, they'd shatter. It went surprisingly easy! I was all the way down into the socket in seconds. There really wasn't much material to remove, after all. However, there was a problem. My bit wasn't quite enough. I ended up sliding the socket around on the drill table like a ouija to widen it out some more. After a few tries, it worked like a charm!

Next, I started a pilot hole with a 30-bit in the side of the socket. I then placed the socket onto the motor and went back to the drill press. The motor kept trying to spin as I pressed down, as I expected it would. To combat this, I broke out the drill press vise again. It was the PERFECT height to hold the motor in place from tipping and the shaft from spinning. I was in business! After about 5 minutes of easy going I was through! Make sure to be constantly dribbling cutting fluid down the bit and pulling the shavings out. It didn't get more than slightly warm!

After thoroughly cleaning the socket and shaft - being extra careful since this is a permanent magnet motor, I reattached the socket. The 1/8" tension pin slid in with a satisfying amount of resistance, yet surely slightly eased by the 30-bit being just that much larger than an 1/8".










Now I have two female square sockets. I set my 12" long 3/8" square stock into both sockets and measured the remaining exposed stock length. 12 1/16" - 10 15/16" = 1 1/8"  This max depth will provide for just over 1/16" slop overall in the drive length.










Hopefully the tension pin will shear long before the gearing in the hub will. And I can easily make another 15mm socket coupling if that fails (which i doubt).

Tomorrow brings a fresh day of fabbing up the motor mount. I can't wait!


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## NabilAhmad (Feb 26, 2011)

Last week I finally got the motor coupling portion of the mount made and welded. I spent most of my time scratching my head on how to actually do it and about 15 minutes just doing it. 

What stumped me on the spot was that I had envisioned welding both the drive shaft mount plate and the motor mount plate directly to the base plate, with a fillet weld on each side. This of course assumed that the welding gun could fit between them. When all was said and done, the plates left just over an inch of space between them.

So I bevelled the edge of the drive shaft plate to provide a better weld on the outside, and then just welded the back side and called it a day. Aluminum being what it is shrank my perfectly square parts down to around 88-89 degrees. 



The motor mount plate ended up being welded to the base on one side only. Between the motor plate and the shaft plate I put in 1-1/2" blocks cut to the desired spacing and bevelled on both contact edges. This left enough room to get wrenches and nuts in between for bolting things up while still providing an over-ample amount of structure.

I'll see about getting better pictures soon.


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