On Tue, 4 Jul 2006 21:57:26 -0500, "Don Young"
wrote:


wrote in message
.. .
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

Mark
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.

Don Young


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
from.

I'd say the shaft is 1/4" off center, as I turn it.