I made a rear axle for my rigid-framed motorcycle out of 4140 steel, and
the thing bent in use. I was advised that heat-treatment was optional,
but not really necessary, so I didn't do that. Was this advice wrong?
The axle diameter is 9/16", and bike weight = 375 lbs. I do sometimes
hit the odd pothole, but nothing major.

Jordan

hitting the odd pothole would put a load of at least 10X the weight,
probably closer to 100 to 1000X the weight on the axle for a few miliseconds
"Jordan" wrote in message
...
I made a rear axle for my rigid-framed motorcycle out of 4140 steel, and
the thing bent in use. I was advised that heat-treatment was optional, but
not really necessary, so I didn't do that. Was this advice wrong?
The axle diameter is 9/16", and bike weight = 375 lbs. I do sometimes hit
the odd pothole, but nothing major.

Jordan

"Jordan" wrote in message
...
I made a rear axle for my rigid-framed motorcycle out of 4140 steel, and
the thing bent in use. I was advised that heat-treatment was optional, but
not really necessary, so I didn't do that. Was this advice wrong?
The axle diameter is 9/16", and bike weight = 375 lbs. I do sometimes hit
the odd pothole, but nothing major.

Jordan

You would have been wise to choose 4140 HT, which is pre-heat treated to
roughly 32 Rc. It is still very machinable, and much stronger than annealed
material.

Harold

On Sun, 02 Aug 2009 01:27:30 GMT, "Harold and Susan Vordos"
wrote:


"Jordan" wrote in message
...
I made a rear axle for my rigid-framed motorcycle out of 4140 steel, and
the thing bent in use. I was advised that heat-treatment was optional, but
not really necessary, so I didn't do that. Was this advice wrong?
The axle diameter is 9/16", and bike weight = 375 lbs. I do sometimes hit
the odd pothole, but nothing major.

Jordan

You would have been wise to choose 4140 HT, which is pre-heat treated to
roughly 32 Rc. It is still very machinable, and much stronger than annealed
material.

Yield for annealed material is about 60,000 psi, not much better than
low carbon cold rolled. Pre-hard (HT) is about 125,000 psi. Yield can
go as high as 250,000 with a 400F temper.

--
Ned Simmons

You would have been wise to choose 4140 HT, which is pre-heat treated to
roughly 32 Rc. It is still very machinable, and much stronger than annealed
material.

Harold


I didn't know about that option. Thanks, that's the course I'll take
next time.

Jordan

Bill Noble wrote:
hitting the odd pothole would put a load of at least 10X the weight,
probably closer to 100 to 1000X the weight on the axle for a few
miliseconds

But all my bikes hit the odd pothole, and the axles don't bend.

Jordan

On Sat, 01 Aug 2009 23:44:45 GMT, Jordan
wrote:

I made a rear axle for my rigid-framed motorcycle out of 4140 steel, and
the thing bent in use. I was advised that heat-treatment was optional,
but not really necessary, so I didn't do that. Was this advice wrong?
The axle diameter is 9/16", and bike weight = 375 lbs. I do sometimes
hit the odd pothole, but nothing major.

Jordan

A 375lb rigid frame bike, gee loaded, is going to require a heat
treated axel..particularly when its only 9/16.

Rigid frames dont have any spring to them..so they SLAM the components
hard.

http://www.ehow.com/how_4691309_heat-treat-steel.html

http://tidewaterblacksmiths.net/2.html

http://www.finishing.com/324/56.shtml

As is noted in the above link...4340 may be a better choice..as would be
a Grade 8 bolt

Gunner

'In the first place, we should insist that if the immigrant who comes here in good faith
becomes an American and assimilates himself to us, he shall be treated on an exact
equality with everyone else, for it is an outrage to discriminate against any such man
because of creed, or birthplace, or origin. But this is predicated upon the
person's becoming in every facet an American, and nothing but an American...
There can be no divided allegiance here. Any man who says he is an American,
but something else also, isn't an American at all. We have room for but one flag,
the American flag... We have room for but one language here, and that is the
English language.. and we have room for but one sole loyalty and that is a
loyalty to the American people.'
Theodore Ro osevelt 1907

9/16" annealed 4140 will bend almost as easily as cold rolled.

BTW: there is a major advantage to the annealed 4140 in impact strength
.......... but it only shows up in the -40F and below range. Sorta doubt
you will be out on a motorcycle at that temp.

Jordan wrote:
I made a rear axle for my rigid-framed motorcycle out of 4140 steel, and
the thing bent in use. I was advised that heat-treatment was optional,
but not really necessary, so I didn't do that. Was this advice wrong?
The axle diameter is 9/16", and bike weight = 375 lbs. I do sometimes
hit the odd pothole, but nothing major.

Jordan

On Sun, 02 Aug 2009 08:54:54 -0500, RoyJ wrote:
(top posting fixed)
Jordan wrote:
I made a rear axle for my rigid-framed motorcycle out of 4140 steel,
and the thing bent in use. I was advised that heat-treatment was
optional, but not really necessary, so I didn't do that. Was this
advice wrong? The axle diameter is 9/16", and bike weight = 375 lbs. I
do sometimes hit the odd pothole, but nothing major.

Jordan
9/16" annealed 4140 will bend almost as easily as cold rolled.

BTW: there is a major advantage to the annealed 4140 in impact strength
......... but it only shows up in the -40F and below range. Sorta doubt
you will be out on a motorcycle at that temp.

But if you were, think of how much of a bitch it'd be to have the axle
fracture!

--
http://www.wescottdesign.com

4340 may be a better choice..as would be
a Grade 8 bolt

Gunner


There's an idea. I'd buy one if I could find a UNF 9/16 x 7 1/2 hex head
bolt that's strong enough. But, it needs to be threaded only about 1 1/2
inches.

thanks,
Jordan

RoyJ wrote:

BTW: there is a major advantage to the annealed 4140 in impact strength
......... but it only shows up in the -40F and below range. Sorta doubt
you will be out on a motorcycle at that temp.


True enough, I'll be safe even without 4140.

Jordan

Yeh. Picture a snowmobiler on a 900 cc machine hauling across a frozen
lake in the middle of the night and hitting a pressure ridge: snaps the
suspension right off. All the high end sleds got the 4130 tube parts.

Tim Wescott wrote:
On Sun, 02 Aug 2009 08:54:54 -0500, RoyJ wrote:
(top posting fixed)
Jordan wrote:
I made a rear axle for my rigid-framed motorcycle out of 4140 steel,
and the thing bent in use. I was advised that heat-treatment was
optional, but not really necessary, so I didn't do that. Was this
advice wrong? The axle diameter is 9/16", and bike weight = 375 lbs. I
do sometimes hit the odd pothole, but nothing major.

Jordan
9/16" annealed 4140 will bend almost as easily as cold rolled.

BTW: there is a major advantage to the annealed 4140 in impact strength
......... but it only shows up in the -40F and below range. Sorta doubt
you will be out on a motorcycle at that temp.

But if you were, think of how much of a bitch it'd be to have the axle
fracture!

On Sun, 02 Aug 2009 03:06:02 +0000, Jordan wrote:
Bill Noble wrote:
hitting the odd pothole would put a load of at least 10X the weight,
probably closer to 100 to 1000X the weight on the axle for a few
miliseconds

But all my bikes hit the odd pothole, and the axles don't bend.


Maybe "heat treating is optional" wasn't all that great of advice?

Good Luck!
Rich

Rich Grise wrote:

Maybe "heat treating is optional" wasn't all that great of advice?

Good Luck!
Rich


Evidently not.
Thanks,
Jordan