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WARNING front sprocket nuts tend to loosen
http://www.kawi2strokes.com/forum/viewtopic.php?f=14&t=4355		 Page 1 of 2
Author:  Ja-Moo [ Sat Sep 08, 2012 9:03 pm ]
Post subject:  WARNING front sprocket nuts tend to loosen
Counter shaft sprocket nuts tend to loosen and come off. Usually they just fall in the cover, but can cause a dangerous situation.

Four reasons (I know of) for the problem:

1. Some replacement sprocket does not have the hole for the lock tab, so the sprocket is installed and there is nothing to lock it on. This can be remedied by using a grinding stone to grind through the hardened layer on the sprocket, and then drilling a hole. Or make sure the new sprocket has the locking hole.

2. Using a old locking tab that is weak, and is easily bent, slipping out of the hole. You can cut a new tab easily if the tab looks beat up.

3. Improper prep or lack of torque on the nut. The nut and threads should be in good shape, and thoroughly cleaned of all oil or grease, then blue loctite applied. Torque should be from 70 to 80 ft/lbs. DO NOT use an impact to install the nut. And of course one of the locking washers side bent up to hold the nut.

4. The most important, sprockets have some play, so they can move a bit on the shaft. With all the heavy pulling and pushing on the sprocket, it can move back and forth, slowly loosening the nut. To remove the slop, make a shim from a feeler gauge blade to go between the sprocket and a flute so the sprocket is tight and can't move, then properly install the sprocket, torque the nut, and bend over a side of the locking tab. this will highly reduce the chance of the nut loosening.
Author:  67lotus49 [ Sat Sep 08, 2012 11:50 pm ]
Post subject:  Re: WARNING front sprocket nuts tend to loosen
I tried all the above and my sprocket nut still would loosen. Used a brand new locking washer, blue loctitie and torqued to
80lbs. Sprocket was new and looked correct but I finally ended up putting 2 welding tacs on the lock washer and nut. Will have
to grind them off when its time for a new sprocket but it has stayed on for about a 1000 miles. I think some of the replacement
sprockets out there must be different in some way from what was original.
Author:  Nigel72iv [ Sun Sep 09, 2012 12:09 am ]
Post subject:  Re: WARNING front sprocket nuts tend to loosen
67lotus49 wrote:
I tried all the above and my sprocket nut still would loosen. Used a brand new locking washer, blue loctitie and torqued to
80lbs. Sprocket was new and looked correct but I finally ended up putting 2 welding tacs on the lock washer and nut. Will have
to grind them off when its time for a new sprocket but it has stayed on for about a 1000 miles. I think some of the replacement
sprockets out there must be different in some way from what was original.

:D That was the solution I ended up with. Nearly 20 years later I have yet to have had another failure.
Just tacking the washer to the sprocket is sufficient though. You can use a spare shaft to align and weld.
Author:  MikeH1A [ Thu Sep 20, 2012 4:58 pm ]
Post subject:  Re: WARNING front sprocket nuts tend to loosen
This very thing happened to me on our last big trip with my classic bike group. One of the guys was behind me and noticed that my chain had become obviously loose and soon after my H1A failed to proceed (as Rolls Royce call it :D ). We were stumped as to what had happened until we took the cover off and there it was - the front sprocket had worked loose and shifted outwards. Luckily everything had stayed intact and the chain hadn't wrapped around anything. A quick tighten up and we were underway again. So ... your post reminds me it's time for a more permanent solution :!:
Author:  rusty34 [ Wed Aug 07, 2013 8:08 pm ]
Post subject:  Re: WARNING front sprocket nuts tend to loosen
I just looked at mine and it was loose. Thanks for posting the warning!
Author:  Walms [ Wed Aug 07, 2013 10:05 pm ]
Post subject:  Re: WARNING front sprocket nuts tend to loosen
Great thread! Does anyone happen to know the thread size? I'd like to do some searching for an all metal locknut. Spieth might make one.
Author:  Jim [ Wed Aug 07, 2013 10:20 pm ]
Post subject:  Re: WARNING front sprocket nuts tend to loosen
Ja-Moo wrote:
To remove the slop, make a shim from a feeler gauge blade to go between the sprocket and a flute so the sprocket is tight and can't move, then properly install the sprocket...

It would be less damaging to the feeler gauge set to use some shim stock. :) The sprockets I've bought have always been held firmly in place by the nut, but I'm sure if one were loose on the splines after the nut is tightened, there would be all kinds of problems.
Author:  Ja-Moo [ Wed Aug 07, 2013 11:08 pm ]
Post subject:  Re: WARNING front sprocket nuts tend to loosen
Most guys do torque down the nut, the sprocket is "tight", but they still come loose though. And don't you have bunches of feeler gauge sets too? :P
Author:  rotortech [ Thu Aug 08, 2013 7:32 am ]
Post subject:  Re: WARNING front sprocket nuts tend to loosen
When I bought my S3, this is how I found the sprocket and locknut:

Image
Author:  67lotus49 [ Wed May 21, 2014 12:10 am ]
Post subject:  Re: WARNING front sprocket nuts tend to loosen
Over the weekend I noticed oil under my H2, more than normal :lol: I moved it into the workshop and put
it on the lift. Looked like it was coming from under the sprocket cover so took it off the have a look. Nice and
dry around Rolf's clutch pusher :thumbup: Lot of trans oil around, crap. I always tack weld the locking washer
for the countershaft sprocket and the washer broke. Nut was half way loose and I pulled it the rest of the way off.
Pulled out the spacer to check the o-ring and it was toast. Well there is the source of the leak. :D

I pull the sprocket cover off on a regular basis to check the nut and washer. Lasted about 700 miles before the
failure this time. I remember this last batch of locking washers looked pretty thin, new one I used was much more
stout. Only a few weeks ago I did check the nut and washer before the Livermore ride and all was well.
Check those locking washers, some of the ones on ebay are not very heavy gauge.
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