crankshaft damage. need advise

Old 05-13-2012, 07:39 PM
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Default crankshaft damage. need advise

I think know the answer to this but i have to ask.

Recently, at the track I had a tuning issue come out of nowhere. Thought it was the tank, thought it was a leaky line but it turned to be a damaged clutch bell bearing. Apparently this thing had been bad for a while. When it finally destroyed itself I noticed it wore a nice little groove in the crankshaft. Now, a new front bearing has a lot of play sitting on the crank. So much play that when i installed a new set of bearings the bell was wobbly. I went out on the track and within one tank the front bearing was toast.

What I need to know is, is a new crank the only way to fix this? If so what is this engine based on because I can't find a "21 js crank" anywhere?

Is it Go based? I have a fresh os vspec crank. Would that fit?
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Old 05-13-2012, 09:24 PM
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No the Os crank wont fit, it has a different stroke. Yes the Js is Go based and I am pretty sure a Go crank will drop in. Try Nitro North he may have a Go crank.

Rex
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Old 05-13-2012, 10:56 PM
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Ok.

Its psses me off a bell bearing damaged a perfectly good running motor. Arghh!!

It's always something.
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Old 05-13-2012, 11:38 PM
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$54 for a crank is really cheap.

http://www.racerdist.com/JS_Racing_E...Parts_s/40.htm
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Old 05-15-2012, 11:39 AM
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I have had this happen to me before. What I did (I'm not always the pinnacle for the best advice) was I went ahead and bought a new motor and saved the one with the bad crank till the new motor gave out. Used the crank out of the new (which was then the old). Maybe not the best solution, but it worked for me.
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Old 05-15-2012, 12:03 PM
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You should replace clutch bell bearings often, you can get them for a $1 a piece and it takes about 10 minutes to change them. I try and replace mine once a week or before a race.
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Old 05-15-2012, 01:44 PM
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Ofna used to sell a pilot shaft nut.you cut the old pilot off and use the new nut with pilot made on it.Used them several times with good results.
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Old 05-15-2012, 01:54 PM
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Ofna 10091 I think is what you need.
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Old 05-15-2012, 02:06 PM
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I start a race with fresh clutch bearings, and replace them before the last final... Saves you alot of trouble and at the end..
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Old 05-15-2012, 05:12 PM
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Originally Posted by Aleq View Post
I start a race with fresh clutch bearings, and replace them before the last final... Saves you alot of trouble and at the end..
I start every raceday with a new set. I started out and all was good. Engine ran perfect like always. All of a sudden it kept randomly flaming out in slow/tight turns. Couldn't figure out why. I tried everything then a few tanks later the bearing basically blew up.


I put on a new set and engine performed perfectly again but unfortunately the bearing had wore a nice groove in the crank. Because of this, it ate up a new set of bearings in less than a tank.

Apparently that bearing was the source of my tuning problem and I didn't catch it. It was grabbing and stopping the motor. That allowed it enough time to chew up my crank.
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Old 05-15-2012, 05:23 PM
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Originally Posted by xxxntwv View Post
Ofna 10091 I think is what you need.
Awsome. It appeared it will work. The only thing is, will it work with my ascedency clutch? I might have toswitch back to a three shoe setup. Hmmm.
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Old 05-24-2012, 03:14 PM
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Originally Posted by xxxntwv View Post
Ofna 10091 I think is what you need.

Dude this thing worked like a charm. I did have to cut the all the way back to the threads. I had to go back with the traditional 3 shoe flywheel but all is good cause I still carry all the Shoes and springs in my box.

I'm bearing routine has changed I know that much.

Thanks a lot.
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Old 05-24-2012, 03:29 PM
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Cant say enough good things about Tko radial thrust clutch bearings, they are the best.

Rex
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Old 05-24-2012, 04:44 PM
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Originally Posted by 22Racer View Post
Cant say enough good things about Tko radial thrust clutch bearings, they are the best.

Rex
I will have to look into those. I'm not using the same bearings again.
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Old 05-24-2012, 07:22 PM
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Originally Posted by 22Racer View Post
Cant say enough good things about Tko radial thrust clutch bearings, they are the best.

Rex
Where can I find these bearings? Amain?
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