Q. How to fix dent in tank?

[Spliff]

I dropped the bike the other day at a stop...did no damage to the bike, but my dumb ass winds up denting the tank lifting it up. I have been told by a few people the easiest way to do it (without filler) is to fill the tank half way with water and freeze it till it pops the dent out. It seems resonable, but I want to make sure that I'm not going to mess anything else up by doing this...Has anyone tried this before?

[notec]

That is a good way to do it, but, you must watch it the whole time.........you can over expand the tank if not......

You can get a dent puller that attaches by a temporary adhesive(used by auto shops) at most auto supply shops.

You can also take a metal rod and bend it to push out the dent from inside the tank.........make sure to wrap the end in something soft so you dont scratch the inside of the tank.

The last way is to remove your petcock and use compressed air to slowly pop out the dent. For this you need to make a rubber plug with a hole in the middle to insert a small air line.

[Spliff]

cool thanks. i do have a big compressor, so i might just do it that way.

[Mojoe]

you must have a cheapass thin metal tank if you can glue something to it and pull it out....or bend a rod and pop it out from inside.
the only thing I see suggested so far that would put that much pressure that is needed is the freezing thing. but I would be worried that this would stress the seams around the bottom of the tank and cause leaks.

I've repaired maybe a dozen tanks through the years, and I have never gotten away with anything less than using fill to get it completely smooth. Even if you can pop most of it out, it is rare to dent a tank and be able to just pop it back out as good as new. It will always show.

[notec]

you must have a cheapass thin metal tank if you can glue something to it and pull it out....or bend a rod and pop it out from inside.

We arent talking about very thick metal here. An epoxy puller has enough strength to pull out big dents in a tank. And yes you can pop a dent out from the inside. Some tanks are double walled so this option might not work.


There is one other method I forgot.....it involves putting the tank in a freezer......once frost forms on the outside, remove it and quickly heat the dent with a hair dryer. The air will expand really quick, forcing the dent out. The gas cap must be open during the cooling process and closed before heating.

[Pitfan04]

I have a small dent on the top of mine, and I have been told to use Dry Ice. I know car dealers use it for hail dents.

[notec]

Dry ice works good, it just depends on how easily you can get it. I suppose a trip to the local high school would be a good place to check.

[The CyberPoet]

you must have a cheapass thin metal tank if you can glue something to it and pull it out....or bend a rod and pop it out from inside.

+1

Most modern motorcycle gas tanks are two to three times as thick as most modern metal car panels. 10 to 12 gauge steel doesn't pull easily.

I've seen a very musclebound brute take a tire iron to the inside of his SECA tank in a fit of rage, but all that did was change one large smooth dent into a major dent with a bunch of minor outward dents in it -- looked worse than when he started.

Bob over at EmpireGP.com drains the tanks, fills them with water, then welds on studs and uses a puller to get them close-to-flush again, followed by removing the studs and using filler over it. The other way is to cut the tank open and work on it from the inside (only a wise choice if the bike is a custom or is out of production and no tanks can be found, IMHO). You might also want to send him an email about what it would cost to repair/repaint the tank for you if you're not good with bodywork (and many of us aren't).

Other thoughts:
You can often find used tanks on eBay at reasonable prices in good condition. Look for ones from sellers in warm-over-the-winter states; bonus for desert locations. If you get a replacement tank, take the time to POR-15 it before you install it -- as long as it's off the bike, it's a great time to do this.

Cheers,
=-= The CyberPoet

[Mojoe]

you must have a cheapass thin metal tank if you can glue something to it and pull it out....or bend a rod and pop it out from inside.

We arent talking about very thick metal here. An epoxy puller has enough strength to pull out big dents in a tank. And yes you can pop a dent out from the inside. Some tanks are double walled so this option might not work.


There is one other method I forgot.....it involves putting the tank in a freezer......once frost forms on the outside, remove it and quickly heat the dent with a hair dryer. The air will expand really quick, forcing the dent out. The gas cap must be open during the cooling process and closed before heating.

have YOU actually tried any of these suggestions you are sharing?
I am just curious because I have been around a bodyshop pretty much all my life. Mind you it is not "hi-tech", but we have done all sorts of work that can be considered "first rate"......and NEVER have we used any form of ice or freezing. And as CP agrees......a tank is VERY thick compared to a car.

I guess the one thing about your suggestion that makes me question you is the info about being careful not to scratch the INSIDE of the tank. Tell me, what is the big worry about that?

Personally, I think you are just going to be fucking around with alot of methods that will give you poor results or waste your time. You MAY be able to get it popped out if you are lucky, but it all depends on the dent. If it is a "smooth" dent, as in no kinks at all, you might...and I repeat, might be able to do it, but I doubt it.
99.9% of the time, the only way...and most efficient way if you count the time involved, is to just grind the dent down to metal, fill it, prime it, touch up the spot with matching basecoat, then clear the whole tank. Someone who knows what they are doing and can "feather" of the spot will have it done in 2-3 hours tops. My dad could probably do it in an hour. He knows his shit. When I mentioned some of these suggestions, he laughed. But don't take it personally. He is ol' school.

I just hope you are not taking the long and complicated route just cuz of not liking the idea of having filler on your tank. If done right, it will never show and will last the life of the bike.

[The CyberPoet]

I just hope you are not taking the long and complicated route just cuz of not liking the idea of having filler on your tank. If done right, it will never show and will last the life of the bike.

Added note:
If you go the filler route, make 100% sure that you use fuel-resistant high grade top coat to clear it in. Cheap clears will have problems with even a minor fuel spill and can jeapardize the whole repair.

Cheers,
=-= The CyberPoet

[Mojoe]

I just hope you are not taking the long and complicated route just cuz of not liking the idea of having filler on your tank. If done right, it will never show and will last the life of the bike.

Added note:
If you go the filler route, make 100% sure that you use fuel-resistant high grade top coat to clear it in. Cheap clears will have problems with even a minor fuel spill and can jeapardize the whole repair.

Cheers,
=-= The CyberPoet

I guess you could go that way seeing as you are just doing the tank. I have never bothered with that myself. Not saying it is not a good idea, but I have always done ok with just basic clear. I am talking about the kind you have to mix....not rattle can stuff.
It was never an issue on any vehicle we ever painted. Cars seem to be what what gets the most gas spilled on them as you are pulling the nozzle out of the tank, and we never had any where it seemed to effect them.
Factory clear is just basic clear....not fuel grade.

[notec]

"have YOU actually tried any of these suggestions you are sharing? "
Of the ones I suggested, I have only used two myself. The adhesive dent puller, and the air pressure. As for the others, I was a custom cruiser fan before switching to sportbikes. So I have met alot of custom bike builders.
These are some of the many different methods they have used successfully.

Not to be rude, but there are many ways to do anything.......just because you have never heard of it being done, doesnt mean it wont work.

And yes....welding a stud and pulling the dent, followed by bondo is the quick and easy way to do it. I was just offering a variety of alternatives due to the fact we dont have any idea how deep the dent is, or if it has creased. Some can be pulled or popped without major dammage.

[Mojoe]

well I am not saying they won't work, but I do have my doubts. But like you said, anything is possible.

But I would like to see it done.

[Spliff]

well, i'm just going to use some filler and re-prime it. it is only black primer right now, so it will take me no time. thanx for the advice...

[notec]

well I am not saying they won't work, but I do have my doubts. But like you said, anything is possible.

But I would like to see it done.

Yeah, I understand where your coming from.....if you browse alot of the custom bike sites, alot of them have step by step pics posted. Unfortunatly my kat has a good tank.......so i dont think I will be able to show any step by steps for a while