B&S Motor with bent shaft

A friend ran his (maybe 3.5 hp) Briggs/Stratton push mower over an unmovable (sawed off) metal standard. CLUNK!
Didn't do much to the blade, but the shaft looks bent. Will turn OK for 180 degrees, -very- tight for the other 180.
Can such a shaft be straightened? If so, how?
Thx, Peetie
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Peetie Wheatstraw wrote:

You *did* remove the spark plug before testing, yes?
I'm just saying.
--Winston
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I had to think about that for a few moments. I can think of two reasons for removing the spark plug.
--
Christopher A. Young
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Stormin Mormon wrote:

Me, too!
--Winston
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Peetie Wheatstraw wrote:

While nothing is impossible, strightening a crankshaft bent enough to create that "tight" result will cost your friend a lot more than buying and installing a new engine or just purchasing a new mower.
Replacing the crankshaft with a new part (and new gaskets, keys and seals where required) is a possibility, but only if your friend knows what he's doing, has all the proper tools at hand,and doesn't place a dollar value on his time.
Jeff
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Jeffry Wisnia
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On Sun, 14 Jun 2009 21:47:35 -0400, jeff_wisnia

A big chunk of Sched 80 iron tipe the right size to fit over the shaft, with the blade removed, can quite easily straighten a B&S crankshaft. Taked a couple of tries, usually. A short chunk and a light sledge hammer can do the same job.
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wrote:

I've heard that it can be done but this is the first time I've read about it. Thanks.
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All manufacturers and most mechanics do not recommend it. However, it can be and is done. Some engine shops have a tool/fixture for doing it and others will not attempt it. I have straightened several, some while in the engine and some removed, and have never had any problems with them. There is a risk that the shaft might be already cracked or be cracked while straightening and that is why it is not a recommended fix. A shaft bent severely enough to bind would not be a good candidate for straightening.
Don Young
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"It takes a special tool/fixture and there are (obviously) risks involved"?
I had to ask: for all I knew, there might be a splined connector or some-such between crank and blade-shaft, which could be easily replaced. No such luck, evidently.
Thanks, Peeite
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be
others
engine
risk
to
involved"?
some-such
luck,
I'm pretty sure the blade is connected more or less directly to the crankshaft but I've not yet determined if the threaded fitting it attaches to is removable. It looks like it should be. In any case you can often find people giving away lawnmowers with those engines (or even better engines) on Craig's List so as long as you can get one that doesn't have another bent crankshaft you could probably make one good engine from the two.
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On Mon, 15 Jun 2009 09:53:04 -0700, "Ulysses"

The mowers I have owned had a hub on the motor shaft that is keyed and the bolt goes into the shaft holding the blade and the hub. I have hit plenty of stuff myself and simply replacing the blade usually makes the shaking go away, at least to a tolerable level. I hit something so hard with my current mower that I sheared off the bow tie key that engages the blade. That is why I know about the hub ;-)
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