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

B&S Motor with bent shaft
 

Peetie Wheatstraw wrote:
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


You *did* remove the spark plug before testing, yes?

I'm just saying.

--Winston

B&S Motor with bent shaft
 

I had to think about that for a few moments. I can think of
two reasons for removing the spark plug.
--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Winston" wrote in message
...

You *did* remove the spark plug before testing, yes?

I'm just saying.

--Winston

B&S Motor with bent shaft
 

Peetie Wheatstraw wrote:

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

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

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

B&S Motor with bent shaft
 

"Peetie Wheatstraw" wrote in message
...

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
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

B&S Motor with bent shaft
 

On Sun, 14 Jun 2009 21:24:47 -0500, "Don Young" wrote:


"Peetie Wheatstraw" wrote in message
.. .

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
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.

"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

B&S Motor with bent shaft
 

On Sun, 14 Jun 2009 21:47:35 -0400, jeff_wisnia
wrote:

Peetie Wheatstraw wrote:

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

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
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.

B&S Motor with bent shaft
 

Stormin Mormon wrote:
I can think of two reasons for removing the spark plug.

Me, too!

--Winston

B&S Motor with bent shaft
 

"Stormin Mormon" wrote in message
...
I had to think about that for a few moments. I can think of
two reasons for removing the spark plug.

The left hand and the right hand?

--
Christopher A. Young
Learn more about Jesus
www.lds.org
.


"Winston" wrote in message
...

You *did* remove the spark plug before testing, yes?

I'm just saying.

--Winston

B&S Motor with bent shaft
 

wrote in message
...
On Sun, 14 Jun 2009 21:47:35 -0400, jeff_wisnia
wrote:

Peetie Wheatstraw wrote:

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

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
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.

I've heard that it can be done but this is the first time I've read about
it. Thanks.

B&S Motor with bent shaft
 

"Peetie Wheatstraw" wrote in message
...
On Sun, 14 Jun 2009 21:24:47 -0500, "Don Young"
wrote:


"Peetie Wheatstraw" wrote in message
.. .

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
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.

"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

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.