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welding frames

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has anyone tried welding a dirt bike frame. my sons rm 85 has a hairline crack on the down rail just before it attatches to the foot peg area.i just rebuilt the motor and replaced a lot off stuff on it so i would like to try to fix it

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It can be welded, but you will need to scab on a piece on top of the frame. If you just fill the crack with weld it will most likely continue to run down the frame. Take a piece of flat stock and contour it to the frame, weld the crack up first and then weld the additional piece over it.

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Just ask around and try to find a welding/fabrication shop in your area that will weld it.

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depends on the material. if its just plain carbon steel, grind the crack out as best you can and reweld it with E7018(stick) or a good quality mig wire. If its cro-moly you'll just make it worse because of the hardenability of cromium(unless you heat treat it afterwards, which would be expensive).

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Rm 85's are notorious for this. They are made from DOM tubing. Its best to tig weld if you can get to it. I allways pulse welde these cracks when I can. This helps keep down the heat. If you cannot find someone to tig it then your next best bet is to mig it.

Its allways a good idea to weld 1/2" past where the crack ends. This helps the crack from reaperaing.

Once these frames start to crack it best to repair it and find a new home. It will not be long before it happens in another area. Most anywhere you see paint cracks especially at the joints its fixing to crack.

The RM85's usually get the steering stem first then by the pegs.

Norman

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I would drill a hole at each end of the crack and tig weld it...

Proper prep is 90% of success.....TMHO

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I would drill a hole at each end of the crack and tig weld it...

best advice so far, "stop drilling" a crack makes a big difference in keeping it from returning. Also IMO, tig is the the best process for fixing a crack like this because you have much more control over the penetration while welding.

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depends on the material. if its just plain carbon steel, grind the crack out as best you can and reweld it with E7018(stick) or a good quality mig wire. If its cro-moly you'll just make it worse because of the hardenability of cromium(unless you heat treat it afterwards, which would be expensive).

Right. :)

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definately, if you're going to take it to someone else, have it tig welded. thats the strongest. I thought you were gonna do it yourself......

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I would follow the suggestion above and put a gusset plate to strengthen the area that has cracked.

Also, I wouldn't be too concerned about the Chrome-Moly issue. Most modern dirt bike frames contain only about 2% Chrome-Moly. By adding some Chrome-Moly, the manufacturers get a little bit of rigidity, and a whole lot of advertising about it being a Chrome-Moly frame.............. :)

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I would drill a hole at each end of the crack and tig weld it...

Proper prep is 90% of success.....TMHO

"Be sure to "Stop-Crack" it B4 you do any welding....

My '81 YZs didn't stop breaking until we did this.

Also, adding gussett's, as suggested previously, is a REAL GOOD IDEA!

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