Topic: Whoa! Exhaust in the freezer gone horribly wrong!

[B.O.X.N.I.F.E.]

I did this with my last set of pipes. Filled them with water, left in the freezer over night, and in the morning they were dent free and bolted back up with no fitment problems at all.

Welllll, did it again with a new kerker I picked up and they came out like this! Bent every which-a-way.

There is one small crack I can weld up no problem. As for manipulating it back into shape, anyone think that can be done with a torch? Obviously the chrome would go bye bye. Beyond that is there any reason I can't heat them up and move back to a more familiar shape?

[bender01]

Wow. Never would of thought of that!  Could it work on a sealed tank?

[gregimotis]

You've got nothin' to lose by trying...  In my experience (too much of this kind, probably) 'do or die' is a good motivator;  Also, when you do pull it off, that's a good story.

[Hasenkopf]

I think i just figured out how to fix my header !!

[Cormac]

Way slick... With a tank it might not need to be sealed. Gonna have to try this.

[B.O.X.N.I.F.E.]

for God's sake be careful! Worked great on my MAC, obviously not so well on this guy.

Anyone with metal working experience think putting them in the oven might be enough? I've been bending and prying for about 30 minutes with a stack of wood blocks and have it closer. Problem is the middle two have twisted a little. I was thinking of putting them in the oven at 400 then trying to twist them back with a pry bar. What temp is enough to make steel more flexible?

[bucky katt]

i tried it on a gas tank and even with the cap off it swelled the tank too much and popped the seams on the bottom. take the chance if you want. it works sometimes but when it doesnt work, then you have the potential to be royally screwed.

[Hoosier Daddy]

Water expands about 9% to 10%, so do not fill a tank all the way full, leave a small airspace at the top, otherwise it will easily split the seams, better to remove large dents in small steps with several feeze and traw cycles thaan to fill it to the top.
 Don't ask me how I know, lets just say there is one less BSA chrome tank in the world.

[RatBikeRandy]

Dry ice duct taped on the concave side of dent sometimes pulls them out.  Put a barrier between ice and metal.  Pretty safe and worth a try.

[JS550]

Pretty cool idea. But my first thought was, " How big is your f-ing freezer?"

[KRONUS0100]

I have noticed with my Kerker....if i dont keep it bolted to a spare head when i take it off the bike...it will tweak itself out of shape just a little....and i dont have to freeze it first.

[Gordon]

Water expands about 9% to 10%, so do not fill a tank all the way full, leave a small airspace at the top, otherwise it will easily split the seams, better to remove large dents in small steps with several feeze and traw cycles thaan to fill it to the top.
 Don't ask me how I know, lets just say there is one less BSA chrome tank in the world.

Water doesn't just expand into the open air space when it freezes.  It expands in all directions.  You could put just a couple of inches of water in the bottom of the tank to freeze and it will still split the seams at the bottom. 

Ever notice how when you make ice in a plastic ice cube tray the sides of the individual sections swell outward even though there is infinite "air space" on top?

I would never recommend trying this method with any tank you don't plan on tossing out. 

[Old Scrambler]

Freezing a pipe should be done in small increments or with plumber's plugs (small air-bags) or putting a small amount of water in a small helium ballon and placing the ballon over the dent........I have successfully removed tank dents by placing an airbag on the inside for 30-40 lbs of pressure......and tapping on the outside with a plastic body hammer to relieve the metal. To get the plumber plug into the best position, a freind attached a length of air-hose with a filler valve.

[B.O.X.N.I.F.E.]

Can anyone answer my oven question? I don't have any dents in my gas tank.

[Gordon]

Can anyone answer my oven question? I don't have any dents in my gas tank.

I don't think a standard oven can get the pipes hot enough to make them easier to bend. 

[B.O.X.N.I.F.E.]

For anyone with a similar problem in the future...

I got it straightend back out. No heat, although I think that was risky. I used a combination of stacked wood blocks to isolate single pipes and push them back into shape. Take a stack of 3 wood blocks to elevate the pipes, then the pipe with no support under it could be pushed down towards the floor and back into shape.

To get the left to right twist out of them (there's supposed to be a little) I strapped a short wooden plank to a tree for a flat surface, then used another ratcheting strap to hold the pipes tight against the tree. Put a pry bar in the pipe and slowly bent back to shape. If you have a bolted down vice I think this could be done indoors.

[Hush]

You should have videoed that BOXNIFE, it would go well on Utube.

[wdhewson]

This water expansion trick seems pretty clever at first, but it is far more likely to go wrong more than right. 

The biggest part of the problem is the pattern or kinetics of crystallization or freezing.  Certain volumes in specific locations in the pipes freeze first. This forms plugs, then later and different locations freeze.  And this haphazard pattern of freezing is probably not predictable even with unlimited computer power and simulation.

I suppose this is why exhaust systems are expensive.