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What are the odds this will work?

1K views 17 replies 12 participants last post by  LilysDad 
#1 ·
I am working on a Briggs 3.5 hp motor on a tiller,no spark,Well the reason is the flywheel key way has a big ole chunk out of it so it looses time by a hair and wont fire,Basically one whole side of the keyway is broke out and gone,There is just enough left at each end of the crank shaft I got it to stay running for a minute or two,Question is what are the odds I can weld on the crank shaft ,build it up a little then grind it out to refit a key,I am not worried about my skills as this is right up my alley ,I just wonder if it can be done in the motor with out ruining the seals??I will get some pics of it soon
 
#4 ·
If you do try welding it, put a couple clamps between the seal and weld area to slow the transfer of heat. Then weld a bit at a time allowing it to cool some between welds times. Is it a half moon key or straight? Might try JB and put it together before the JB sets up - and hope you don't have to take it apart again.
 
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#8 ·
Get the key way as good as you can and then put the flywheel on with either red loctite or bearing mount. It will help considerably with keeping the flywheel on the shaft in the right spot, and some heat from a propane torch and a puller will have it back off with relative ease incase of future repairs.
 
#9 · (Edited by Moderator)
I vote for JB Weld. I had a wood chipper with a damaged output shaft. Ran for years with JB Weld. If it will take that abuse, a tiller should be a breeze. I made a key & a sleeve, installed the key, plastered on the JB & slide the sleeve over the shaft. I split the sleeve so it would slide on past the key & hose clamped it tight. Once it curred, I filed it to fit the chipper flywheel.

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#10 ·
I vote for JB Weld. I had a wood chipper with a damaged output shaft. Ran for years with JB Weld. If it will take that abuse, a tiller should be a breeze. I made a key & a sleeve, installed the key, plastered on the JB & slide the sleeve over the shaft. I split the sleeve so it would slide on past the key & hose clamped it tight. Once it curred, I filed it to fit the chipper flywheel.

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Motor end small1.jpg
That was a big chunk missing JB weld has saved my bacon before also
 
#11 ·
Get the key way as good as you can and then put the flywheel on with either red loctite or bearing mount. It will help considerably with keeping the flywheel on the shaft in the right spot, and some heat from a propane torch and a puller will have it back off with relative ease incase of future repairs.
I hadnt thought about loctite ,,,That will be next after i get the flywheel on straight.Right now it wobbles ,I need to shave some of my weld off,Its real close though!Its a customer machine and I told him it may not work out but i would try,He said not to spend more then $100 parts and labor on it,,,Well the labor end will be more but he is a good guy and will bring me more stuff so I will eat a little labor! :thumbs:
 
#12 ·
If you do try welding it, put a couple clamps between the seal and weld area to slow the transfer of heat. Then weld a bit at a time allowing it to cool some between welds times. Is it a half moon key or straight? Might try JB and put it together before the JB sets up - and hope you don't have to take it apart again.
It is a straight key
 
#13 ·
Myself, I would weld it up.

Take a wet rag, and wrap it around the shaft in front of the seal, weld it, and shape it. It will be just fine
 
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#15 ·
I hadnt thought about loctite ,,,That will be next after i get the flywheel on straight.Right now it wobbles ,I need to shave some of my weld off,Its real close though!Its a customer machine and I told him it may not work out but i would try,He said not to spend more then $100 parts and labor on it,,,Well the labor end will be more but he is a good guy and will bring me more stuff so I will eat a little labor! :thumbs:
Welding on one side of a shaft, or any thing else will cause distortion. the chances a machined shaft will still be straight after being welded are very close to 0. I have used red locktight on key way repairs before with good luck but never on a fly wheel. Don
 
#16 ·
This is after it was welded and is mostly cleaned up,Its back together and running fine,Hopefully it will stay that way a long time!I used a piecee of key stock as a kind of form to replace the key way,then it can be removed to install an aluminum key
 

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#18 ·
I vote for JB Weld. I had a wood chipper with a damaged output shaft. Ran for years with JB Weld. If it will take that abuse, a tiller should be a breeze. I made a key & a sleeve, installed the key, plastered on the JB & slide the sleeve over the shaft. I split the sleeve so it would slide on past the key & hose clamped it tight. Once it curred, I filed it to fit the chipper flywheel.

attachicon.gif
Motor end small1.jpg
Wow! That keyway was in bad shape before it broke. Look at the crack on the other side.
 
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