Installing new lawnmower blade

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  #1  
Old 09-16-14, 11:55 AM
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Installing new lawnmower blade

Hi,
I have a TroyBilt lawnmower that I recently banged against an outdoor cleanout. This broke the blade adapter so I ordered a new kit: http://http://www.repairclinic.com/P...306304/1620403. I cleaned and creased the crankshaft and adapter but can't get it to go on. Did I warp the crankshaft? Should I try to force it with a hammer? Any suggestions?
 
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  #2  
Old 09-16-14, 12:21 PM
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If you received the correct adapter it should just slide on without any problems, check it against the old one to see if they are the same. Have a good one. Geo
 
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Old 09-16-14, 04:34 PM
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Thanks Geo!

I've included images of (what's left of )the old adapter and the new one. They look pretty much the same and this is definitely the part that goes with this model number lawnmower, according to various websites. As you can see, the old adapter broke into pieces.

Does this mean I've damaged the shaft? It looks fine but maybe I'm just not seeing it. It seems like it almost goes on but the adapter hole seems a tiny bit too small. Maybe I just need to clean the shaft really well? There are some black spots on it.
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  #4  
Old 09-16-14, 05:04 PM
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Is the replacement part OEM? If it's a Chinese knock off then the fit may not be exact. Use some emery cloth and clean up the shaft so it's nice and bright. Use a bit of grease and using a rubber mallet see if you can get it started. If it does not go on fairly easy then its the wrong piece. If you were to run the engine for a quick moment can you see if the shaft is bent? Take out the spark plug and holding a piece of chalk or pencil at a millimeter space away from the shaft, turn the shaft and see if it hits the chalk or pencil. If it does then yes your shaft is ruined.
 
  #5  
Old 09-16-14, 07:27 PM
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Make sure the keyway is clear, it looks like the adapter broke at the key, part of it may still be in the crankshaft. Have a good one. Geo
 
  #6  
Old 09-16-14, 09:59 PM
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There are different size crankshafts and there are adapters that look alike that fit those different shafts. It may be that yours is for a smaller shaft. Do you have something to measure it and the shaft with?
 
  #7  
Old 09-17-14, 03:37 AM
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Use a caliper to measure the clean shaft. Don't close it but rather lock it with shaft size. The caliper then can measure the inside of the new adapter. If it is close, I would take a Dremil tool with a small stone and polish a bit of the adapter. A drill with a stone would work too. Take just enough of the inside off to make the adapter fit.
 
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Old 09-17-14, 07:03 AM
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Hi All,

Many thanks for all your replies. The part is OEM (at least according to the website). I've cleaned the shaft a little and it still doesn't get on all the way; I'll try cleaning it some more with emery cloth.


Three naive questions:
1. It seems really strange to me that hitting the cleanout would have changed the shape of the cylinder (shaft). Intuitively I could imagine it bending the shaft but I find it hard to see it changing the shape in a subtle way.

2. I haven't had a chance to test if the shaft is ruined with the chalk. If it's not, can I use the emery cloth to kind of shave it down to the point where I can put the adapter on?

3. If the crank is off, I assume that's not a DIY job. Is it worth trying to get a professional to fix it or should I just buy a new mower?

Thanks again for all the help!
 
  #9  
Old 09-17-14, 08:19 AM
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Hitting the clean out could've bent the shaft. If the adapter is the wrong size no amount of emery cloth cleaning will bring down the shaft to size. It might be easier to make the adapter hole slightly bigger as some else suggested. Is it worth fixing? IDK. How old is it and do you like it enough that you want it fixed? Lawnmowers are cheap now days. And the newer ones are easy start.
 
  #10  
Old 09-17-14, 09:01 AM
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When the adapter broke it could have flared the keyway some, try using a piece of emory cloth over the keyway in a shoeshining stroke to see if the metal brightens at the edge of the keyway. Have a good one. Geo
 
  #11  
Old 09-17-14, 06:00 PM
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if the crank is bent, you probably wont want to pay to get it straightened I worked for a outdoor power equipment dealer and it failed more than once it is not a given they can be straightened

You aren't going be able to get the shaft to fit the adapter. You are going to have to fit the adapter to the shaft. A rotary file or grinding stones are going to work best. The adapter is aluminum or pot metal so getting it to fit will be much easier to grind. Emery cloth is only good for polishing not removing material

I would get the adapter fit to the crank get the blade on start her up if you don't feel a whole lotta vibration...you got it
 
  #12  
Old 09-17-14, 06:17 PM
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Poppy, sorry to disagree;
Emery cloth is a type of coated abrasive that has emery glued to a cloth backing. It is used for hand metalworking. It may be sold in sheets, or in narrow rolls. The cloth backing causes emery cloth to be stronger in tension than sandpaper but still allows a sheet to be conveniently torn to size.
Emery is rated on the average grit size glued to the backing. Common sizes are, from coarse to fine: 40, 46, 54, 60, 70, 80, 90, 100, 120, 180, 220, 320, F, and FF. A 46 or 54 grade cloth is used on roughly filed work, while 220 to 320 grit cloth will give a good polish. Have a good one. Geo
 
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Old 09-17-14, 07:44 PM
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I don't recommend filing or grinding on the adapter. Find out what the problem is and address the problem, not the symptom.

Is the shaft bent? Take the spark plug out and have someone slowly pull the rope while you watch the crankshaft. If it is bent enough to be causing this problem, you will see it wobbling. If so, you can straighten it, replace it, or junk it.

If the shaft is okay, check the keyway for damage or burrs. If none found, get a caliper and check the sizes of the shaft versus the adapter.

Following these steps should net the answer.
 
  #14  
Old 09-18-14, 11:51 AM
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O.k. -- the shaft is definitely bent!!

Can I replace it myself? I didn't see it as a part on the website I was looking at. In terms of whether it's worth it, the mower is from 2012 and costs about $250.

Thanks again for all the help!
 
  #15  
Old 09-18-14, 12:18 PM
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I kind of suspected the shaft might have been bent. Hitting those vents or cleanouts can do a lot of damage. How did you determine the shaft was bent? With the chalk or pencil method?

Not worth fixing it. If you need a unit for the rest of the year buy a cheap used one. Then next spring start looking for a unit that you like.
 
  #16  
Old 09-18-14, 12:23 PM
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Just pulling on the rope made it pretty obvious! Thanks for the advise about a new one. The hardware store down the street a bit rents them; probably only need a couple more uses this year.

I'll be much more careful of that cleanout! I've run over it a lot without any issues; now I know though!
 
  #17  
Old 09-18-14, 03:55 PM
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You were lucky in the past. Perhaps the ground settled or freezing weather slightly heaved the pipe just enough to cause interference. My advice is to put an extension on the pipe so you have to go around it.
 
  #18  
Old 09-18-14, 06:10 PM
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There are mixed opinions about straightening crankshafts, but I have never seen one fail because of being straightened. I've even knocked some straight with a hammer and the old adapter on the shaft to keep it from getting buggered up from the hammer.
 
  #19  
Old 09-19-14, 04:13 AM
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The problem with straightening a shaft is getting a good balance on the blade thereafter. Most likely the mower will shudder and you'll get an uneven cut. But if it works go for it.
 
  #20  
Old 09-19-14, 10:16 AM
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You might get a shudder if you don't get it good and straight, but the cut will be even, even if the blade or shaft isn't. If the shaft is bent, putting one end of the blade lower than the other, it doesn't make one side cut lower... the blade goes all the way around and cuts to the lowest point.
 
  #21  
Old 09-19-14, 10:38 AM
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You'll get a scalping effect. Like lowing one wheel side lower than the other. You might not notice when standing still but as you move it will show an uneven cut.
 
  #22  
Old 09-19-14, 04:33 PM
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? How is that? I have seen plenty with bent shafts. If it is bent and one side cuts low, it swings around to the other side and is bent just as much that way as the other (and at over 3000 rpm, the low side cuts the entire circle). If it is scalping, then the deck has warped, allowing the entire engine to tilt.
 

Last edited by cheese; 09-19-14 at 05:50 PM.
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