unsmashing a gas tank? - race bike

FriendlyFoe

FriendlyFoe

Well-known member
Falling down is proving to be hard on tanks, have 2 tanks with the side crumpled in, but neither are punctured. Is it possible to get the tank banged/pulled back out? Pretty sure my spare tank has already been banged out once on the opposite side of where I fell down this time.
 
There's really only two ways to 'bang it back out'. One is to cut the tank apart, and hammer it from the inside, then weld it back together. The other is to weld on pulling studs and use a dent puller.

Either way is going to cost a lot of money if you want it to look good. Far more than a decent condition used tank would cost.

What bike are you riding? Something common? Ebay or bike specific forum is probably your best bet. You can pick up something good, perhaps with a little ding or dent or scratch, for not much $$.
 
Can you seal it and put dry ice in it (if you can get hold of some), the dry ice will give off CO2 that will expand the gas tank out. Don't overfill it or you have a small bomb, you just need a small amount.
 
what if you were to seal all the outlets and use compressed air to "inflate" it? Not sure if it might result in it exploding though...
 
Don't care how it looks just don't want it crumpled in. My spare tank looks like it was somehow banged out from the inside. Its just a little SV parts are starting to get a bit more scarce from what they once were, altho I'm sure I could find one.

I heard RACE won't tech a tank that has a crease in it, and was thinking about doing a weekend with them. That's about how much I care. Ill grab pics today
 
Well it is true that a tank that has been down, and then banged back out, is far more likely to peel open in a 2nd crash.
 
I've heard tale of filling a tank with water and freezing it to pop dents. Probably works well for soft dents.
 
quit falling down, so you don't need to repair your tanks. just fill it in with bondo, paint it, and off to the races. you don't need a large volume tank for racing anyway.
 
sircastic said:
I've heard tale of filling a tank with water and freezing it to pop dents. Probably works well for soft dents.
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that might be worth a shot. Any other ideas? No bondo for this one, and this is the better tank, other one is smashed in way farther, but this was a crappy little low side, the other was a high side lol.

Hamilton202-20120706-00149.jpg
 
If the tank dent has bad creases in it, it wont just pop out, with ice...You will need to hammer it from the inside and bondo will be needed to fill it to make it smooth...If you dont need the fuel capacity lost by the dent, why not just do as best as you can from the outside and use bondo to fill it and paint over it?

Depends on how bad it is, this one still holds fuel...If I was going to fix it Id just try pulling it out as best as I could with welding on studs, then bondo it up...There is no way I could smooth out those creases and dimples without hammering it from the inside....And I have done that before, cut the bottom out of the tank, hammer it out then braze the bottom back on...
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I've used the compressed air method on a tank that was dropped with pretty decent results. It was only a single dent with no creases and it popped out enough that all that was needed was a little bondo to smooth it out.

On a tank with a larger dent i've used some bent pry bars that I have to pop it out from the inside. I have a set i got from Mac that are all bent in odd shapes. One is shaped sort of like a question mark, so I put in it through the filler and popped out the dent. You could try bending something sturdy enough to the shape you need and work it out like that.
 
Torren said:
I've used the compressed air method on a tank that was dropped with pretty decent results. It was only a single dent with no creases and it popped out enough that all that was needed was a little bondo to smooth it out.

On a tank with a larger dent i've used some bent pry bars that I have to pop it out from the inside. I have a set i got from Mac that are all bent in odd shapes. One is shaped sort of like a question mark, so I put in it through the filler and popped out the dent. You could try bending something sturdy enough to the shape you need and work it out like that.
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I was thinking there was probably body work tools for this purpose, not trying to even make it look respectable, just trying to take the smashy out
 
I have what appears to be an identical dent on a tank for my track SV as well. I recently bought a used one for around $200 online from a sport bike sight, great shape no dents and it is painted ,closely matches my current fairings.

I believe this is the only and most economical way of getting around this.

Having said this, I too would like to see how that dent can be successfully repaired without costing too much.
 
fuel tank dents are in three groups , soft dent with no sharp creases, these will often pop out with a suction cup or a hot melt glue stud pinned on. I use these hot melt studs, no paint damage. Dent with sharp creases but enough room to work through the filler neck with pry rods. Autobody supply places make these, they are tempered like a chisel so they dont deflect. Be very careful prying against the filler cap hole as leverage, you can make another dent. And the big holes where you cut out the tank bottom so you can get inside and work the metal back to shape, make a sandbag to hammer on and work slowly. The metal stretched from the dent and you need to shrink it a bit. Its half bashing and half art.
Be careful with the dry ice/compressed air thing and any spot welding around a tank. 95% of the time its no problem, its the 5% thats hard to explain to the doctors.
For those reading this thread that haven't had coffee yet, if your fuel pump is in the tank, consider that before banging and grinding.

ex autobody guy
 
Torren said:
I've used the compressed air method on a tank that was dropped with pretty decent results. It was only a single dent with no creases and it popped out enough that all that was needed was a little bondo to smooth it out.

On a tank with a larger dent i've used some bent pry bars that I have to pop it out from the inside. I have a set i got from Mac that are all bent in odd shapes. One is shaped sort of like a question mark, so I put in it through the filler and popped out the dent. You could try bending something sturdy enough to the shape you need and work it out like that.
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Those "paintless dent" repair guys use pry bars similar to how you are describing. Looks kind of like a set of golf clubs(they even keep em in a golf bag), all different lengths and shapes. I watched them repair a dent on one of our work vehicles, was pretty cool. Couldn't even tell the dent was there when they finished. I think it cost about $200 if I recall correctly.
 
Dino Z said:
I have what appears to be an identical dent on a tank for my track SV as well. I recently bought a used one for around $200 online from a sport bike sight, great shape no dents and it is painted ,closely matches my current fairings.

I believe this is the only and most economical way of getting around this.

Having said this, I too would like to see how that dent can be successfully repaired without costing too much.
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Yeah im looking but there are slim pickings on ebay and SVrider right now, i might see if i can get a body guy to bang it out enough that i'm not completely embarrassed showing up to the track.
 
crankcall said:
Be careful with the dry ice/compressed air thing and any spot welding around a tank. 95% of the time its no problem, its the 5% thats hard to explain to the doctors.
For those reading this thread that haven't had coffee yet, if your fuel pump is in the tank, consider that before banging and grinding.

ex autobody guy
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A buddy used a propane flame near an "Empty" gas tank. He replaced it after it bounced off the side of his house.
 
don't have much input on your tank repair (try to pry the dent out using pry-bar through the fill hole?).
I just like your subject line :p
 
nobbie48 said:
A buddy used a propane flame near an "Empty" gas tank. He replaced it after it bounced off the side of his house.
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I used to work with an old school mechanic that would braze gas tanks. I used to leave the building whenever he was going to 'flash the tank'. The only thing that scared me more were his electrical theories.
 
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