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Subframe Mount Cracked - Welding Tips?

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2004 CR250

I had the bike apart for some cleaning/maintenance today and discovered that the top mount (where the shock mounts) for the subframe was cracked. The part that is cracked is one of the "eyes" that the subframe bolt slides through - not the threaded side.

Does anyone have any tips for welding this? I will definitely have it done by an accomplished aluminum welder. I guess my main question is should I remove the electronics from the bike before I have it welded? I don't want to fry anything in the process.

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I partially welded my custom skidplate on my bike, and all I disconnected was the battery. All you really have to do is put the ground clamp as close as you can to where you are welding.

torch

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I partially welded my custom skidplate on my bike, and all I disconnected was the battery. All you really have to do is put the ground clamp as close as you can to where you are welding.

torch

Agreed.

I guess if you were still concerned, you could unplug the CDI and isolate the ground to frame connector. :p

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I just wanted to make sure there wasn't a major risk of frying anything.

Hmmm...I guess I should at least pull the tank, huh. :ride:

:p

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I just wanted to make sure there wasn't a major risk of frying anything.

Hmmm...I guess I should at least pull the tank, huh. :moon:

:p

Naahhh. There shouldn't be any ground connections under there...

:ride:

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I just wanted to make sure there wasn't a major risk of frying anything.

Hmmm...I guess I should at least pull the tank, huh. :ride:

:p

No. Use your nose. You can smell gas fumes, right?

If the tank is well sealed, and not venting fumes, you will be fine.

torch

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I have welded on 90k+ BMW's and Mercedes Benz's and never took the battery off. When I went to college they preached it, but when I got my first real job at a dealership's body shop they said don't worry about it. I wouldn't worry about the gas tank. If the welder is worried about he can either take it off or cover it up with a welding blanket.

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Agreed.

I guess if you were still concerned, you could unplug the CDI and isolate the ground to frame connector. :p

+1:thumbsup:

Is there a pic of this cracked frame???

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if your welding alum. better set the welder to DC

or about 40 amps AC and be quick about it

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if your welding alum. better set the welder to DC

or about 40 amps AC and be quick about it

Where did that info come from?

torch

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Naahhh. There shouldn't be any ground connections under there...

:p

Welding aluminum uses high frequency AC current and can damage sensitive electronics. I would say the risk is small but why take any chances? The Gas tank should be removed also.

Most don't take any precautions, but that is why you have hospitals and replacement parts I guess...

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Originally Posted by sonobob

Naahhh. There shouldn't be any ground connections under there...

:p

Welding aluminum uses high frequency AC current and can damage sensitive electronics. I would say the risk is small but why take any chances? The Gas tank should be removed also.

Most don't take any precautions, but that is why you have hospitals and replacement parts I guess...

I was being sarcastic...

Where did that info come from?

torch

WeldingPocket.jpg

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For alum, AC only for cleaning purposes. With a TIG welder, expect to run 120-150 amps on material of that thickness. 4043 or 5356 are the two most common fillers, either will work. 5356 will take to anodizing where 4043 will not but this will likely not be a problem as I doubt you are going to take the frame in to get re-anodized. I believe 4043 offers better strength where 5356 offers better %elongation. You might want to add some extra support material in considering you have already cracked the frame once. Welding it will soften the aluminum and make it more prone to failure in the future.

How worn are your shock and linkage bearings?

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... Welding it will soften the aluminum and make it more prone to failure in the future...

Wont welding heat it up, therefore making it hard and brittle, which will make it prone to failure?

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For alum, AC only for cleaning purposes. With a TIG welder, expect to run 120-150 amps on material of that thickness. 4043 or 5356 are the two most common fillers, either will work. 5356 will take to anodizing where 4043 will not but this will likely not be a problem as I doubt you are going to take the frame in to get re-anodized. I believe 4043 offers better strength where 5356 offers better %elongation. You might want to add some extra support material in considering you have already cracked the frame once. Welding it will soften the aluminum and make it more prone to failure in the future.

How worn are your shock and linkage bearings?

They work as smooth as a baby's butt. No slop and no binding... Can I ask why you ask?

Here is the area that is cracked...circled in red.

CRSubframe.jpg

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your welder person will love it if you take him a bare frame so he can turn it any way he needs to get that perfect weld, and then you will love the perfect weld while you ride. strip it bare

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your welder person will love it if you take him a bare frame so he can turn it any way he needs to get that perfect weld, and then you will love the perfect weld while you ride. strip it bare

Holy extra work Batman! :ride: The part that is cracked it circled in the pic above. It is cracked right across the top and is easlily accessible. I will be pulling the subframe, airbox, carb & tank...and disconnecting the cdi. That should be ample room to do the job.

Now, if any of you want to donate a CR500 engine to me, I will strip the frame bare before the welding begins. :p

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Holy extra work Batman! :ride: The part that is cracked it circled in the pic above. It is cracked right across the top and is easlily accessible. I will be pulling the subframe, airbox, carb & tank...and disconnecting the cdi. That should be ample room to do the job.

Now, if any of you want to donate a CR500 engine to me, I will strip the frame bare before the welding begins. :p

+1 well it depends on what type of welder your using i preffer a arc(stick) welding over a TIG and have always used DC for alum. but if you are using AC the more amps you push through there the hotter and faster its going to burn

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most tig welders that are good have a foot petal to work which controlles the heat which makes it harder to weld standing on your head to get in to every nook and cranny. I know its a little more work, but it will pay off in the weld, i've got a tig and that is the way i would insist on doing it.

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+1 well it depends on what type of welder your using i preffer a arc(stick) welding over a TIG and have always used DC for alum. but if you are using AC the more amps you push through there the hotter and faster its going to burn

Well aluminum with a stick welder is done with DC, but you are sorely mistaken if you think stick is a better process for welding aluminum. You get more heat input, poor arc control, slag inclusions, slag that must be removed after welding, etc...

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