Hey folks, so when I went down on the 748, I bent the left side rearset mounting bracket ever so slightly - about 5-6 degrees back.  This has essentially kept me from being able to get the bike back on the road because I can't attach the shift rod and have it function normally because it eats into the swingarm when I shift.  
So the question is, do I necessarily need an acetylene torch to properly heat the tabs to bend back or do you think I can get enough heat on it with a propane bernzomatic torch to get it to bend?

On top of that, there's a bit of 'stuff' behind the area I need to heat, including the chain, so do I need to just suck it up and take the swingarm off, or do you think I can get away with leaving everything in place and just placing a heat resistant pad or something along those lines to keep from damaging stuff behind it?

Here's the problem: Ducatis frames are made of a steel similar to 4130 "ChroMoly"
Once you weld on it or heat it to the point it becomes flexible it greatly weakens the steel.
It is weaker and more brittle -and prone to cracking.

picture of a HAZ crack: Notice the WELD did not fail -but the heat affected zone next to it did!


The only way around that is to heat treat the whole entire thing again (yup -the frame)

It isn't as bad as it sounds ...and to be honest a lot of people get around doing it "the right way" just fine...
But it's something to be honest with yourself about and make an educated decision about.

The Pugglepod for example: the link arms (top and bottom) are made of 4130 tubing,
the threaded adapters for the heim ends, and the X-braces.
Most of the forces on the tube are torsion (twisting).  
This tends to not cause Heat Affected Zone ("HAZ") cracking as much.
Bending forces across the HAZ is more likely to cause HAZ cracks.
Thus I post-welding heat treated nothing (hell I was on a time crunch fabbing it so it wasn't possible anyway!  )

The bottom line is I would try to work the part cold if at all possible.
If you needed to make a heavy steel plate to bolt up to the tab and whack the plate with large hammer -I'd go that route
before heating it all glowing red to soften it up -because doing that is going to cause a BIG heat affected zone around the area.
(think of the HAZ as the area that would "blue" or change color after it was heated)
Tig welding makes a very small HAZ.
An Oxy torch makes a very large one.

If it could not be bent back I think the best option would be to cut it off with a sawzall or cutoff wheel and TIG it back on straight.

If it was just regular old mild steel I'd just heat and hammer -but it's not.  

it definitely won't budge cold, tried several attempts at that one.  So even the mounting bracket plate is made out of 4130? 

Yes sir.

V-Cut up the bracket in the direction you want it to "hinge" (don't cut all the way through -but put a deep V-notch in it)
Bend where you want it,
TIG it closed,
Finish grind the weld flat,
Paint.   

that sounds good, but the tabs on the bracket itself are actually bent and not the bracket itself, does that change anything?

I've bent several SBK rearset brackets back into position cold.
Go for it.

Quote from: Speeddog on May 17, 2010, 08:48:03 AM
I've bent several SBK rearset brackets back into position cold.
Go for it.

wait, really?? how'd you do it? because I'm not getting even a millimeter of budging... I guess I need more leverage...

I used a wrist pin and a long bolt, attached to the bracket.
You could use a deep socket too.

Then use whatever you need to get leverage, a piece of tubing or whatever.

Go slow, and alternate between the 2 ears, checking with the rearset to make sure you're keeping the ears parallel.

Thanks! I guess I'll head down to the hardware store and get a much larger piece of tubing than I have already (yes, I know there's a joke in there somewhere)... Thanks!

And Rich, THANK YOU for all the good info!  If this doesn't work out, I will need to go the cutting route and I wouldn't have made the right decisions what with the 4130 info and all.   

Will report back when I get a chance to breath a bit and sit and look at it

on Most 4130 spaceframes it isnt necessary to heat treat unless you are after strength post welding procedure.

If its under .095/.100 wall thickness, I dont normalize. Lincoln recommends using an ER80SD2 rod for 4130, and only normalizing on 4130 thicker than .120" wall....

Any idea how thick the frames are Rich?

can you post a pic Hiero?

still haven't had a chance to get to this, but yeah:

Looks like something is missing???

Quote from: Speeddog on May 17, 2010, 08:48:03 AM
I've bent several SBK rearset brackets back into position cold.
Go for it.

Ummm, yeah. A 2x4 helps. Been there. Done that.

Quote from: hiero on May 20, 2010, 03:33:30 AM

flame question

I'm dissapointed... was thinking you were going more in this direction-

So I tried a couple of things on the bracket in the short time I had to mess with it and only managed to scrape off a good chunk of paint. 
I'll need to try something different to get the leverage I need 
I think I will have to remove the swingarm completely to be able to get anything good on the bracket ears.  I'm hoping a gigantic plumber's wrench on each ear will do the trick