Author Topic: Scary! (Front sprocket came off - now fixed!) (Read 5507 times)

Tugboat · « **on:** July 06, 2011, 07:26:43 AM »

So I was riding my KZ to my girlfriend's house last night. Bike's running great, just humming along at 60 mph on Briley Pkwy. One exit up from hers it starts raining - no biggie. I'd worn my rain pants & leather jacket just in case. As I pull off on her exit though I downshifted and suddenly the clutch lever won't release and there's this grinding sound - loud! So I hit the kill switch and coast to a stop on the side of the road. WTF?!?

Hop off the bike and take a look - my chain is dragging on the ground, and next to it is my master link. Just laying there on the ground!!! I pop the bike up onto its center stand and pull the chain through. Call my girl up and get her to meet me at the bottom of the big hill she lives on and duck-walk it over there.

That hill is a MONSTER!!! Took me probably a half-hour to push it up. Didn't even think to call my girl to give me a hand pushing. Anyways finally got it over to her house and parked for the night.

Then took a look this morning, and my sprocket is literally laying on its side inside the sprocket cover. Haven't had time to inspect it more but at the very least, I probably need to figure out why my sprocket just fell the f@*k off and be grateful that it didn't come off while I was cruising down the interstate.

Duke McDukiedook · « **Reply #1 on:** July 06, 2011, 08:00:32 AM »

Sounds like ya got lucky, did you have a chainguard on?

coldwave007 · « **Reply #2 on:** July 06, 2011, 09:41:41 AM »

Woah, lucky! Glad you came out unscathed.

Tugboat · « **Reply #3 on:** July 06, 2011, 10:51:53 AM »

No chain guard, but I may put it back on now!!!

WarwickE36 · « **Reply #4 on:** July 06, 2011, 11:00:14 AM »

I just had mine off to replace the chain...

You're making me want to put some lock-tite on those 10mm bolts!!

Coyote13 · « **Reply #5 on:** July 06, 2011, 11:21:34 AM »

Took my guard off to clean it and left it off for the past couple of weeks. Note to self: put that biotch back on!

jahmic · « **Reply #6 on:** July 06, 2011, 11:46:11 AM »

Check the threading on the sprocket shaft...

I had that happen to me a few years back on a Yamaha I was riding at the time...PO didn't install the locking nut properly. Sad thing is, once the sprocket was able to come loose and gradually spin off, it ate away at the threading on the shaft pretty badly.

Make sure that when you put the sprocket on, you're able to get it snug again and the threads aren't shredded. Mine were pretty bad, but still semi-functional...I ended up drilling through the shaft and installing a cotter pin to hold things in place as a temporary fix.

Tugboat · « **Reply #7 on:** July 06, 2011, 12:11:37 PM »

So, worst-case-scenario, what am I looking at? Splitting the cases to replace that shaft? Ugh.

jahmic · « **Reply #8 on:** July 06, 2011, 01:07:54 PM »

Yes...I'd call that a worse case scenario. I actually ended up doing that on my Yammie, but it also needed a 2nd gear shift fork replaced, so I was going to be in there regardless.

If you end up seeing stripped threads that are still somewhat functional, you could probably get away with the cotter pin through the shaft. It took me a few drill bits to get through there, but it wasn't too bad. I left enough room to install a large washer between the cotter pin and the sprocket, then JB welded the cotter pin to the washer to make sure it wouldn't come loose. I checked it after every ride, and easily got in 5k miles before I had the parts (read: finances) in order to split the case and do the rebuild.

How safe that is, I can't say...but it was my primary transportation at the time and I never had an issue with a pin slipping out, even before deciding to JB weld it to the washer for added 'protection'.

Spanner 1 · « **Reply #9 on:** July 06, 2011, 08:40:50 PM »

Wow!, glad that happened on Briley Parkway, Gnashville TN. and not I-20S Birmingham, AL last April !
Hope there's no damage......... ( I'm coming over to drink all your beer very soon.....later ! ).

Tugboat · « **Reply #10 on:** July 07, 2011, 09:08:15 AM »

I know right?!!? Well, the chain is undamaged except I'll need a new master link retainer thing. I have one from my old chain so that's no problem. Will need a new splined washer for sure.. and maybe have to drill the shaft for a pin as suggested above.

When it happened I think the chain got jammed up against the clutch mechanism in the sprocket cover, because the clutch was "pulled" about halfway in and wouldn't release. Weird sounds coming from the tranny as a result. Once I pulled the chain out it freed up the lever and it seems to engage/disengage okay. But, when I tried to shift up or down from neutral (without the motor running) the shifter pedal is stuck. I haven't tried to force it, and I haven't started the motor yet. It usually will shift up or down no problem. Ugh..... just DREADING internal damage.

turboguzzi · « **Reply #11 on:** July 07, 2011, 09:32:05 AM »

Why people keep on using chains with clip master links instead of riveted master links in 2011 is a mistery to me.....

Duke McDukiedook · « **Reply #12 on:** July 07, 2011, 10:19:08 AM »

Quote from: turboguzzi on July 07, 2011, 09:32:05 AM

Why people keep on using chains with clip master links instead of riveted master links in 2011 is a mistery to me.....

+1, I guess it is easier to put on, however it is also unfortunately easier to come off.

Tugboat · « **Reply #13 on:** July 07, 2011, 10:56:07 AM »

Well the thing that really bothers me is how the hell did the sprocket come off?!? When it was replaced I torqued it down and used the splined washer to keep the nut from moving. Any thoughts?

City Boy · « **Reply #14 on:** July 07, 2011, 11:46:28 AM »

Hi gang.I have used clip links for 40 years and have never experienced a failure.The chains of today are so much better than years ago I doubt any machine would do one in!My DID gold chain requires the side plate to be pressed on before the clip is installed and I believe this is more than adequate.It pisses me off that a clip link is no longer available for this chain that I can find.

jahmic · « **Reply #15 on:** July 07, 2011, 09:54:15 PM »

Tug, my yammie had the same shifting symptoms. It's likely nothing too horrible, probably damaged the shifting mechanism, and possibly the clutch rod. That's exactly what happened to my bike, except I knew I broke the clutch rod as soon as I got on the brakes...I was spewing oil all over my back tire for a few seconds before hitting the kill switch.

Your bike can be fixed easily, don't sweat it...the fact that you didn't go down is a %#*@ miracle...speaking from experience.

Be thankful for that.

Tugboat · « **Reply #16 on:** July 09, 2011, 11:27:17 AM »

So here's what I found when I took the sprocket cover off. A small nick on the case above the shaft (there is no damage to the shaft itself) and a couple of small nicks on the inside of the cover:

The nut is a little banged up, but the splined washer isn't broken or anything as I expected it to be:

Does it look like I didn't bend the washer up enough to keep the nut from spinning off?

Also, as to the transmission: when all this went down, the clutch lever wouldn't return all the way - only about halfway. I assume this was keeping the transmission about halfway in gear? And that was the grinding sound I heard - like when you can't find the gear while shifting in a car? The chain must have been jammed up against the mechanism in the sprocket cover and keeping the clutch from re-engaging, because once I pulled the chain out the clutch lever works fine.

Do you think it's okay to start it up and see what's up as far as shifting goes? If it's damaged I don't want to mess it up more, you know? Sorry for all the questions at once!!!

jahmic · « **Reply #17 on:** July 09, 2011, 08:36:38 PM »

I'd say you lucked out on this one. IMHO, you should be just fine to start her up. Maybe pull the clutch cover and take a peak; if everything checks out and the clutch disengages properly, you won't damage anything by starting it in neutral with the clutch pulled...then just let it out slowly. Does it shift through the gears? If so, i definitely wouldn't worry much. Having to roll the bike to go between gears is normal, btw...so keep in mind you may need to install the chain to test the shifting.

Tip on the lockwasher to keep the nut secure: bend the tab down from each outer edge, rather than the center. It will allow you to get that entire length of the tab snug up against the nut. Do that, and it won't back off next time. Loctite also helps if you aren't already using it.

Tugboat · « **Reply #18 on:** July 12, 2011, 09:18:43 AM »

Thanks for the tips. So is there a preferred method to bending the washer? Last time, I remember that getting under its edge was difficult after I'd torqued the nut down, and that's why the bend was so dodgy!

jahmic · « **Reply #19 on:** July 13, 2011, 10:23:26 AM »

Sure, take the washer and the nut, line them up on the shaft, and mark where the edge of the nut lines up on the washer. Pull the washer off, and hold it in a bench vise.

CAREFULLY put a slight bend in the washer where your mark is...you don't want to over-do it. It helps if you put the washer pretty far down in the bench vise when you clamp it down so that it bends at your pliers, and not at the vise. I tend to place the washer so that the hole in the center is being gripped by the vise, that way it won't bend there. Again, bend the washer's tab down from each outer edge rather than the center so that you get a "uniform bend".

With a 20-30 degree bend in the washer before you put it on the bike, you should be able snug the nut down and still get a grip on the tab with the pliers. Even if you mess up and bend the tab at a point that's too low, torquing down the nut will straighten things out for you.

edit: The caveman alternative that I used to go with before using a bench vise was to snug the nut down over the washer like you did, and then use a flathead screwdriver + a rubber mallet to tap behind the washer and start to bend it down. It works...but I figure "chipping away" around the shaft and chain was a bad idea after a couple slips.

Tugboat · « **Reply #20 on:** August 22, 2011, 08:42:18 AM »

So I finally was able to put the sprocket back on. I ordered a new washer and a new nut (why not?) and this time did a much better job, I think. Blue locktite, torqued to about 85-90 ft/lbs (using a "bar"-type torque wrench.. this was as tight as I could make it. Manual says 87-107 is correct). Bent the washer as suggested above using a bench vice and starting from the edges & working inward. I used a sharp chissel, centerpunch and the edge of a socket. The results:

Side #1:

Side #2:

Thanks for all the help fellas!

kirkn · « **Reply #21 on:** August 22, 2011, 11:19:33 AM »

What locks the lock tab washer to the sprocket itself? From the pictures, it looks like you've just locked the washer to the nut, which does no good whatever. What keeps the washer-nut assembly from loosening?

Normally, one leg of a pant-leg washer locks to the nut, one leg locks to the sprocket (or whatever) which is splined. THAT way, the washer can't rotate relative to the sprocket and the nut can't rotate relative to the washer.

The way it looks in the pictures, the nut and washer together can rotate relative to the sprocket.

MCRider · « **Reply #22 on:** August 22, 2011, 11:32:24 AM »

Kirkn, in a prior picture a few posts back, you can see the tab that slips into the spline of the shaft itself, keeping the washer from turning.

kirkn · « **Reply #23 on:** August 22, 2011, 11:56:20 AM »

Ah - I see. The small tab aiming into the splines. Got it.

Tugboat · « **Reply #24 on:** August 22, 2011, 12:19:17 PM »

Correct - there's a tab on the washer that goes into a hole on the sprocket itself - you can see it in pic #2 above. Here's to hoping it stays put now!!!

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Author Topic: Scary! (Front sprocket came off - now fixed!) (Read 5507 times)