Woodruff Key Comes Out

[allenl44]

Have an 80cc (so called) engine on a Huffy Cranbrook. Have logged about 250-300 miles just riding through the subdivision and terrorizing the neighbors.

Appx 1 month ago, all at once, the engine was running fine, but the bike was not going. Inspection revealed that the woodruff key had come out and was lodged inside the gear case in some excess grease. Hum.. wonder how it got out of the keyway??? Put it back in place, and about 5 miles later - came out again. Even tried cleaning the crankshaft & keyway, and using locktite. In about 3-5 miles - came out again. Latest episode, lasted about about 2 blocks.

Additional, maybe useless info: With woodruff key in slot/keyway and small gear in place, teeth on small gear stick out appx 1/8" past (toward gear case cover) the large gear/clutch's teeth. Also, you can see behind the small gear and about 1/8" the woodruff key and slot/keyway is not covered by the small gear, however, the recessed area in the front of the small gear (where the big-headed screw goes) is flush with the end of the crankshaft. So, it appears that the small gear is seating properly on the crankshaft.

OK, enough (or too much) words. It's obvious the key is coming out to the rear of the small gear. Anyone experienced a woodruff key problem like this?

[Norman]

Kind of sounds like the key way was cut in the wrong place or a little too far in on the shaft. I wonder if you could grind a little material off of the gear so it will go in to cover the key way better or a dab of J B weld on the shaft and key to help hold it in place one thing you might try is make a wood ruff key out of a little bigger one by grinding it see if you can make it fit the slot tighter.
Seems to me that the key should fit in the slot pretty tight I think I needed to tap it in place with a brass drift punch.
Could you post a photo if it? Then I'd have a better idea of what you have thats messing with
you.
You might be able to get it to stay in place with the loctite stud and bearing stuff. you might need to get the accelerate to make it work. or try super glue.

[freewheeling frank]

there was a whole other thread here about a month ago that addressed that problem try a search as i cant remember what the solution was but i know someone nailed it

[diceman2004]

ok 1st i know nothing about the chinagirl engines , 99.9 percent of the gears i have seen that have keyways , have a setscrew on the key and another 90 degrees to the key . sounds to me you key isn,t very long ( might as well be using a ball bearing for all the good that would do )
why don,t you just get a new piece of key stock as long as the key in the shaft . then theres no way it can pop out .

i,ve never looked inside the cover of a chinagirl engine . is there a washer and screw in the end of the shaft , that would prevent the key from coming out the end of the shaft .

if theres nothing to stop the key from coming out the end of the shaft, a long key may " not " be a good idea , because it would be possible if the key came out that way it could bore a hole thru your cover

[Kevlarr]

Problem is it's a woodruff key so the slot in the shaft is half moon shaped. Yea there was a thread but I can't remember who it was or what they did to fix it.

[Kevlarr]

Ah here it is http://motorbicycling.com/f3/my-firs...lem-10503.html

[freewheeling frank]

i see 2 pieces did that thing break into 2 pieces? if so probably just a new key should do it

[diceman2004]

ok now that i,m sure its ( woodruff keys ) , Allen , a picture is worth a thousand words .

i,m going to agree with Norm that the key is machined out of possition . the woodruff key should be totaly inside the key of the gear ideally .

as i have never seen one of these puppies apart its hard for me to think of a cure ...but

there must be a shoulder on the shaft for the gear to seat up against

can you make a washer to fit behind the gear , but over the stepped shoulder that will cover up the woodruff key , and prevent it from comming out

I ASSUME , what is happening ( figure A ) is the key has an oppertunity to come out .

is there room to make a washer fit over the open end of the key ( figure B )

[Kevlarr]

Forgot that Reel Adventure had started another thread. Here's how he finally fixed his.

Originally Posted by Reel Adventure

Thanks again guys. Well not one for waiting, I broke out the Dremel tool and some Guiness. I carefully shaved off some of the inner diameter of the small gear and it slid on about 1/8 " further. Made absoutley sure the key was positioned correctly before and after the gear was installed. Then I put on the spider crush washer thingy and screw and tightened it down tighter than fort knox. I took my big ace hammer and small screw driver and bent the teeth in on the spider washer thing so there was no play between the small gear and the screw.


Since not too much Guiness at this point I ran the mess out of it. So far so good!

Now I gotta figure out how to increase me idle!

[allenl44]

Thanks everyone. Had thought about making the i.d. of the smaller gear slightly larger where is would go about 1/8" farther back on the crankshaft. Seems it would make the two gears mesh better and place the smaller gear more nearly over the woodruff key (where it couldn't come out at the rear of the gear). But I didn't know what to do about the extra 1/8" or so of shaft that would now stick out into the recessed area in the front of the small gear. Saw where Reel Adventure bent the teeth on the "spider" washer thingy that goes on with the big-headed screw. Not sure that will take up the 1/8" or so that I will need. Anybody have advise about maybe just adding standard washers (slightly larger than the 1/2" +/- shaft) as spacers? Got some pics that Norm asked for, but this is my first forum and I don't know how to add/post them.