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Bent rear frame

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Posted by: trsrdr---------------------

In a race this past Sunday (HS), an obviously out of control rider slammed into the rear of my bike at a sideways angle. In the process, my frame behind the subframe on the left side was bent up about 1" in the back. What is the best way to straighten the left leg?


Posted by: Robcolo---------------------

Remove seat & all plastic. Get a torch [oxy acetylene] and heat the area where the bend is nice & cherry red - to- orange. slip a pipe over the end of the frame and slowly / carefully bend it back. Don't try to get it straight the first time or you'll likely have an s shape area --heat, tweek --heat, tweek. Mine was bent so badly that I had to cut the rear fender mount / crossover brace to get it straignt, then reweld it. Check your progress by mounting up rear fender & side panel


Posted by: DeSeRt_KaW---------------------

You dont have to go THAT complicated...
Just take off your Rear fender so you see your Subframe bars, and Get a rubber mallet, and wack away until it looks straighter...There...


Posted by: Zerotact---------------------

I used a deadblow sledge, otheres just slip a pipe over the end for leverage


Posted by: Dogz---------------------

Different bike same problem! I got a free RD350lc after a friend dumped
it backwards onto himself trying to wheelie. I stripped the frame, backed an old truck over a maple stump, chained the frame tight to the back bumper of
the truck, and used a long prybar on the stump through the middle of the
subframe and slowly pulled it back. I just eyeballed it against a piece of
string along- the center line of the frame. It seemes to be fine the whole process took about a full weekend because I dismantled the whole bike!


Posted by: NYkdxer---------------------

I had to straighten my rear frame in order to install my new fender. I just used a mallet and a long piece of pipe big enough to fit over the rear fender/silencer mount and bent it back little by little. You could heat it up, but repainting would be necessary and the metal would probably be weakend.


Posted by: Robcolo---------------------

Quote:
Originally posted by NYkdxer
You could heat it up, but repainting would be necessary and the metal would probably be weakend.


Just the opposite --the metal is weakened by NOT heating. You break a piece of metal by bending it back & forth [fatigue fracturing] Many harder alloys fracture after only 1 bend cycle -- eg. 4130 chromemoly. Yes, you will have to repaint it, but if it's bent enough the paint is likely to be cracked already


Posted by: trsrdr---------------------

Well,

Thanks for some of the tips. I used a big pry bar and verrrry slowly tweaked the left rear tube downwards using the right only slighty for leverage, mostly using body weight. It's not perfect, but it's passable. By the way, at both rear welds where the subframe connects, the paint was cracked, but just a bit. When there's snow on the ground, I'll redo it. Now on to the steering head bearings!



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