I remember reading somewhere in this ng where somebody straighted a
LawnBoy crank themself. Could someone respond, hopefully the guy who
accomplished this feat, and tell me how to? I could buy a new
crankshaft for this thing, but at $145.00 i want to give it a try with
my tools, I mean what have I got to lose?

THanks,
Fish

Total deflection at the tip of the shaft [lower tip] =1/16". Not too
much deflection near the lower seal.

What should I do? Reassemble with new seals and say my prayers? Or,
try to straighten the crankshaft?

THanks again,
Fish.



On Tue, 15 Nov 2005 00:17:19 GMT, fish
wrote:

I remember reading somewhere in this ng where somebody straighted a
LawnBoy crank themself. Could someone respond, hopefully the guy who
accomplished this feat, and tell me how to? I could buy a new
crankshaft for this thing, but at $145.00 i want to give it a try with
my tools, I mean what have I got to lose?

THanks,
Fish

On Tue, 15 Nov 2005 00:17:19 +0000, fish wrote:

I remember reading somewhere in this ng where somebody straighted a
LawnBoy crank themself. Could someone respond, hopefully the guy who
accomplished this feat, and tell me how to? I could buy a new
crankshaft for this thing, but at $145.00 i want to give it a try with
my tools, I mean what have I got to lose?

THanks,
Fish

Do you know a machinist in the area? The way I do them is with a small
hydraulic press, two v-blocks and a dial indicator.
This really isn't something you can eyeball.

On Mon, 14 Nov 2005 20:02:11 -0600, rastus
wrote:

On Tue, 15 Nov 2005 00:17:19 +0000, fish wrote:

I remember reading somewhere in this ng where somebody straighted a
LawnBoy crank themself. Could someone respond, hopefully the guy who
accomplished this feat, and tell me how to? I could buy a new
crankshaft for this thing, but at $145.00 i want to give it a try with
my tools, I mean what have I got to lose?

THanks,
Fish

Do you know a machinist in the area? The way I do them is with a small
hydraulic press, two v-blocks and a dial indicator.
This really isn't something you can eyeball.

I dont know a machinist, would a machinist do this as a service, or do
you have to 'know somebody'? i dont have any of these types of tools,
but do you think it is safe to use a mower with a repaired crankshaft?
I just read some information that says it might be dangerous because
of small cracks in the shaft after the straightening. I dunno.

Fish.

"fish" wrote in message
...
Total deflection at the tip of the shaft [lower tip] =1/16". Not too
much deflection near the lower seal.

What should I do? Reassemble with new seals and say my prayers? Or,
try to straighten the crankshaft?

THanks again,
Fish.



Bent crankshaft in a lawn mower engine?
As far as I am concerned it is junk! No manufacturer recommends
straightening crankshafts for good reason. Most mower crankshafts are cast
iron, once bent, they crack. Straighten them and they crack more!

Now all that said there will be 100 other posters that will tell you the
opposite. I did small engine repair for 5 years and ALL small engine
manufacturers said not to straighten cranks.

A while back someone here claimed that Briggs & Stratton sold crank
straighten tools. I asked for part numbers for the tools, and the poster was
never heard from again! there is some aftermarket companies selling
straightening tools, but no engine manufacturers!

It is a lawn mower with a sharp blade attached, spinning at 3200 RPM. What
is your leg worth? What is your leg worth after the crank breaks and sends
the blade through it?

As far as just running it, 1/16" of an inch of run out is allot when it is
turning at 3200 RPM. It will vibrate like a S.O.B.!!
Greg

On Mon, 14 Nov 2005 20:34:38 -0600, "Greg O"
wrote:

"fish" wrote in message
.. .
Total deflection at the tip of the shaft [lower tip] =1/16". Not too
much deflection near the lower seal.

What should I do? Reassemble with new seals and say my prayers? Or,
try to straighten the crankshaft?

THanks again,
Fish.



Bent crankshaft in a lawn mower engine?
As far as I am concerned it is junk! No manufacturer recommends
straightening crankshafts for good reason. Most mower crankshafts are cast
iron, once bent, they crack. Straighten them and they crack more!

Now all that said there will be 100 other posters that will tell you the
opposite. I did small engine repair for 5 years and ALL small engine
manufacturers said not to straighten cranks.

A while back someone here claimed that Briggs & Stratton sold crank
straighten tools. I asked for part numbers for the tools, and the poster was
never heard from again! there is some aftermarket companies selling
straightening tools, but no engine manufacturers!

It is a lawn mower with a sharp blade attached, spinning at 3200 RPM. What
is your leg worth? What is your leg worth after the crank breaks and sends
the blade through it?

As far as just running it, 1/16" of an inch of run out is allot when it is
turning at 3200 RPM. It will vibrate like a S.O.B.!!
Greg


I agree, I read that some where you shouldnt straighten them. Thanks.
I found a crank on ebay thats used, but still straight.

Fish

fish wrote:
On Mon, 14 Nov 2005 20:02:11 -0600, rastus
wrote:

On Tue, 15 Nov 2005 00:17:19 +0000, fish wrote:

I remember reading somewhere in this ng where somebody straighted a
LawnBoy crank themself. Could someone respond, hopefully the guy who
accomplished this feat, and tell me how to? I could buy a new
crankshaft for this thing, but at $145.00 i want to give it a try with
my tools, I mean what have I got to lose?

THanks,
Fish

Do you know a machinist in the area? The way I do them is with a small
hydraulic press, two v-blocks and a dial indicator.
This really isn't something you can eyeball.

I dont know a machinist, would a machinist do this as a service, or do
you have to 'know somebody'? i dont have any of these types of tools,
but do you think it is safe to use a mower with a repaired crankshaft?
I just read some information that says it might be dangerous because
of small cracks in the shaft after the straightening. I dunno.

Fish.

Junk it, don't bother. Cast iron is brittle. It can be broken with a
few whacks of a hammer. Even if you could bend it back straight, it
would most likey crack, if it isn't already. It will work for awile,
then catostrophically fail - perhaps embedding the blade in your leg in
the process.

I do nondestructive testing for a living, which means I'm paid to find
material defects such as cracks. I have seen what can happen when
somethng fails, and let me tell ya, it ain't pretty! Be safe and don't
do it. It's not worth the risk!

Joe Michel

"fish" wrote in message
...
On Mon, 14 Nov 2005 20:34:38 -0600, "Greg O"

wrote:

"fish" wrote in message
.. .
Total deflection at the tip of the shaft [lower tip]
=1/16". Not too
much deflection near the lower seal.

What should I do? Reassemble with new seals and say my
prayers? Or,
try to straighten the crankshaft?

THanks again,
Fish.



Bent crankshaft in a lawn mower engine?
As far as I am concerned it is junk! No manufacturer
recommends
straightening crankshafts for good reason. Most mower
crankshafts are cast
iron, once bent, they crack. Straighten them and they
crack more!

Now all that said there will be 100 other posters that
will tell you the
opposite. I did small engine repair for 5 years and ALL
small engine
manufacturers said not to straighten cranks.

A while back someone here claimed that Briggs & Stratton
sold crank
straighten tools. I asked for part numbers for the tools,
and the poster was
never heard from again! there is some aftermarket
companies selling
straightening tools, but no engine manufacturers!

It is a lawn mower with a sharp blade attached, spinning
at 3200 RPM. What
is your leg worth? What is your leg worth after the crank
breaks and sends
the blade through it?

As far as just running it, 1/16" of an inch of run out is
allot when it is
turning at 3200 RPM. It will vibrate like a S.O.B.!!
Greg


I agree, I read that some where you shouldnt straighten
them. Thanks.
I found a crank on ebay thats used, but still straight.

It probably makes more sense to just find a used mower with
other problems and swap parts.

Bob

UPDATE

I found a good used crankshaft, sent to me via email from a guy in PA
who found a terribly neglected lawn boy in the trash. he knew my
story, picked up the mower, and basically charged me shipping to get
it to me with all the remains of the mower engine still attached. I
just about had tears when he told me he would ship it to me just for
the cost of shipping.

Anyway, it was completely covered in moist greasy dirty oil and then i
opened it up i found more black soot than kris kringle ever saw, but
the metal parts of the piston and cylinder were solid, no scratches,
they nearly looked brand new after the cleaning i gave it. So now the
motor is assembled and on the deck, I still need to put on the little
things like tank and muffler, etc. I finally took the piston out of
my old mower and it looked like a cheese grater with all the pitting
and scorching on it, i could hardly beleive it even ran like that.

Thanks guys for all the advice, etc. Mission accomplished.
Fish.

"fish" wrote in message
...
UPDATE

I found a good used crankshaft, sent to me via email from a guy in PA
who found a terribly neglected lawn boy in the trash. he knew my
story, picked up the mower, and basically charged me shipping to get
it to me with all the remains of the mower engine still attached. I
just about had tears when he told me he would ship it to me just for
the cost of shipping.

Anyway, it was completely covered in moist greasy dirty oil and then i
opened it up i found more black soot than kris kringle ever saw, but
the metal parts of the piston and cylinder were solid, no scratches,
they nearly looked brand new after the cleaning i gave it. So now the
motor is assembled and on the deck, I still need to put on the little
things like tank and muffler, etc. I finally took the piston out of
my old mower and it looked like a cheese grater with all the pitting
and scorching on it, i could hardly beleive it even ran like that.

Thanks guys for all the advice, etc. Mission accomplished.
Fish.

Good for you!
I used to cobble mowers together from random "junk".
You lucked out finding a similar model so parts were the same. Lawn Boy was
good for that. Many different models, but very few different engines over
the years.
My first mower was built from two junkers, I believe it is the one my
neighbor is using now. It was 15 years ago when I cobbled that one together
and it still runs great.
Greg