my poor bike

[KevinTwoStk]

I e-mailed AJ at Service Honda a while ago about heat treating. He said that yes, they do heat treat their frames after welding. Also, you can have a metallurgy lab test the frame before you weld it to see what alloys the frame is made from. Knowing the alloys will help you select the proper welding rod and proper type of tubing for re-constructing the cradle. It (knowing the alloys) should also dictate how the heat treating should be done.

I know that many aluminum bicycle frames made overseas are built using alloy 7005. It wouldn't surprise me if Japanese motorcycle frames were also made with 7005.

No, I've never built an aluminum frame conversion, but I thought I'd pass along the info that I have. A broken-in-half frame is a frightful sight indeed!

 

[LundMx]

DSPMOTO~ do you know if you used .063 wall or .125 wall? i think that would make a huge difference  http://www.speedymetals.com/s-194-square-tube.aspx

[tkeen511]

Lund-in response to your heat treating question, I would refer to a book that the aws(American welding society) makes. It's pretty much the bible and tells you what heat, how long, and any procedures or precautions you need to do or take for every type of metal. My dad actually has 2, from 1997, next time I stop by his house I'll try to remember to look and I'll let you know. Sorry for bumping this post

[kkvslayer]

I don't know jack about metals but from my years online within the aluminum frame conversion community 6061 seems to be the way to go,I know that is what the mounts,head stay & swing arm spacers were made from for my old cr500 conversion and that's what most of the prefab downtubes & conversion parts are made from

[tkeen511]

Yes, I agree that 6061 is the best choice. Air craft grade baby

[DSPMOTO]

hey everybody sorry that i went mia…. i am not sure if the frame was heated treated or not. i do know the metal used was 6061. since that frame broke i have seen pics of 3 others all were 2006 frames as well as i talked to a buddy at team green and was told that they even had a few frames brake in the R&D. not sure what years they did this but i would like to think that is took place within the last4 years…… also was told they were built like mine and build like service honda does theres as well.

well since the frame braking i haven't wanted to build a mother one.. i did buy a mother steel frame kx250 and put 2012-2014 kx450 plastics on it, figured i was much safer keeping it in the steel frame.    /Users/dallasgarrettedmisten/Pictures/iPhoto Library.photolibrary/Masters/2013/10/31/20131031-195239/IMG_1807.JPG

[DSPMOTO]

[mxaniac]

I realize this is an old thread but, I broke my 2006 frame Friday.  I used 7005 alloy and heat treated it, but I think the real problem is I made my front motor mounts way too large and beefy and forced the rails after the split to be too rigid except for a small 1" section between the split and the motor mount.

[jBernard]

do you have any pictures of where it broke?

[mxaniac]

Not yet, have to dig the pressure washer out and find a hose that isn't frozen to wash the thing.  Everything between the cradle and the front motor mount is trashed in multiple places though.  Thinking I should die pen the frame if I repair it and have my front motor mount welded as low as possible to provide room for flex.

My frames a bit more redneck than some of them I've seen here.  I just moved the stock cradle up and welded new straight sections between the cradle and where the bottom rail ended its upward curve.  No machined pieces.

do you have any pictures of where it broke?

[jBernard]

this is surprising, ive seen some pretty smart people say the lower cradle(rails) hold very little weight, and most of the rigidity is between the headstay and the swingarm bolt.

if it broke below the Y, is it right on the weld? that may indicate a bad bond between Y and new frame rails.

[mxaniac]

[mxaniac]

Angled breaks would indicate tension in AL.  The straight across breaks are right past the weld beads indicates either lower strength material properties or stress concentration from the weld beads (or high shear forces).  Since the left side didn't even break near the weld I would guess material properties at the actual weld were fine.

I think it's all in the motor mounts.  Too stiff without enough flex in the remaining material.  Bending creates tension and compression, not any appreciable shear.

[jBernard]

thanks for the pics. thats a real interesting break, and looks like youre right in how it broke. looks like the engine got pulled backwards and just seperated itself and the rails from the static Y.
what does your headstay look like? it almost looks like the engine tried to move back 3/4" violently, cant really see how it did that with a solid headstay mount enough for it to straight shear off like the pictures show.
who did your heat treating? not to knock them or say they had anything to do with this, just i only have 1 source so far and they are $$$.

[sandblaster]

Because a few people had problems breaking their frame rails I wanted to be sure I understood where the transfer of energy was taking place at.
Here is a rough diagram of where the mounting points are in relation to the frame.



As you can see, when coming down hard on a jump the force is transferred in a radial motion pivoting on the 17mm swing arm pivot pin.
So, the rear head stay must be in line as much as possible with the direction of the force to prevent the engine from rotating forward and putting the frame rails under tension.