Just wondering. I got a push mower with a bent crankshaft. The mower
starts on one pull and runs great except it vibrates so bad that it's
near impossible to hold it for more than a few minutes. I heard they
have some sort of jig to straighten them, but also heard about doing
it with a hammer and wood block. Is this really possible? If yes,
where does one get a jig, or what is the method with the hammer?
I dont need to get it 100% accurate, but right now it's beyond using
as it is. It's just an old beater so I am not willing to buy a new
crank unless I happen across a cheap used one. But if I can
straighten it for a few bucks, I'll give it a try. The worse I can do
is destroy it, and it's junk right now unless I get it straighter.
By the way, it's s 3.5hp Tecumseh
I don't know if this is the same thing but I had a push mower which I
accidentally used to try to hone down a concrete thing that used to
hold a basketball goal. The concrete thing won of course. This made
the mower wobble like a washing machine filled with pennies. The rod
that the blade attaches to was bent. Then someone stole the mower. I
was glad, I don't how to fix that in a manner that would *not* lead to
a repair bill that was higher than the value of the mower.
Did that when I was a teenager. Hit a softball when cutting high grass.
Just lay motor over, BE SURE to disconnect plug wire. Take off blade,
figure out direction shaft is bent, the beat with hammer, be sure not to hit
threads etc. Worse case buy a new mower.
Pick up a DVD of "The African Queen." Pay special attention to the part
where Humphrey Bogart straightens out the bent drive shaft of the boat using
nothing but a sledge hammer and a scrap-wood fire. Inspirational!!
If you really like this mower, and it ran OK right up until the 'event',
your best bet is to find a brand new short block. Google is your friend
here. Compare its cost to that of a new mower with a warranty.
At best, your basketcase will run for a while before destroying itself.
At worst, it will injure you when it happens.
Some mower shops have in-the-motor crankshaft straightening jigs even though
no manufacturer recommends doing so. I have successfully straightened them
using a long heavy pipe over the shaft and a heavy hammer. The last one was
a 5HP Tecumseh which has been run hard for about three years since and is
still going. The hardest part is holding the motor securely enough. You need
some sort of indicator to tell how much and in what direction the bend is
and how your straightening is coming along.
That is definitely not considered good practice as it is hard on the bearing
and the shaft may crack, but it definitely is possible.
OK, that's what I wanted to know. I will see what the local shops can
do, or try it myself if too costly. If I wreck it, it's already junk
the way it is anyhow. The shaft is definately bent. I can see it.
It's VERY bent. The blade even chopped the tip off one of the bolts
that hold the handle to the frame. It vibrates so much it creeps
across the lawn by itself if I let go. My hands can not take the
vibration for more than a few minutes. But I do like the mower. It's
always been reliable and it's lightweight and simple, unlike most of
the newer ones. So, if I do wreck it, I may check into a short block.
And there are always used mowers too taht I can strip the engine block
I'd say the shaft is 1/4" off center, as I turn it.
On Tue, 04 Jul 2006 08:12:44 -0500, snipped-for-privacy@UNLISTED.com wrote:
Straightened or not, worse can happen. You do NOT want to try to avoid
a spinning blade with a stub of crankshaft attached. You were correct
when you said it was junk.
--Andy Asberry recommends NewsGuy--
You'd want to anneal it first, hammer it to shape, and then
harden it again. If you know what your doing (which I
don't) it shouldn't be hard. If you don't know what
you're doing, then you'll have metal fatigue around the
bend, which means (as another poster pointed out) that
the shaft will shatter at some random time, at
which point the blade will turn into a propeller, and
chop you off at the ankles.
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