dents in motorcycle tank

R

richrd

I've got an older Ducati tank to paint with 4 or 5 dents. I have a cheap stud welder and slide hammer puller.

Any tips or tricks you can give, and how good should expect to get them before any filler work?

thanks
tank1.jpg

tank3.jpg

tank2.jpg
 
I also have a Ducati Monster with a dent in the tank. When it comes time, I'm going to hire a paintless dent removal guy to work it out. I was quoted $75 for a tennis ball sized dent, but my tank will not need any paintwork and the thickness of the metal will not be compromised. It may or may not be worth it to you since you will require paint regardless, but those guys are talented when it comes to dent removal.
 
They don't look too bad, but depending on your experience, it could be a little difficult getting them out with a stud gun. I would only attach the studs with as little heat as possible, and pull on it till it comes off, then you know you need a little more heat. Keep doing that until you can pull it out without making a hole in the tank where the stud was. Or, attach the studs firmly so they won't pull off, then when finished, cut the stud and grind it flush. From what I have heard about the cheap stud guns, the second option might be your only option. I like the first one, because you may end up with a lot of studs to get it all out good.

You can get the tank as good as you want, depending on how much time you want to play with it.
 
ill tell you what, i have been pulling dents like that on tanks for years using a stud gun. after doing it that way for a couple years i stopped all together. the problem with a stud gun is many times the tank will leak afterwards. you can easily rip a stud off leaving a hole which then needs to be welded. of course you had better hope your weld is pure clean so that doesnt leak over time. #2 even if you dont pull a stud off, the shock and stress from pulling can leave a micro crack along the edge of where the stud is welded. you grind the stud off and you cant even see it. again you can end up with a leak and not even know it. in then end, and you'll think im nuts but your better off just filling it. i have seen many custom chopper tanks with filler thicker than what those dents will require. i have also stripped tanks that someone repaired previously which were still holding up fine and the repair was atleast 2" deep. i was able to bury a 2" grinder all the way up to the handle...lol. in any case, what i am getting at is these tanks never see any type of flex so if done properly that ducati tank could just be fixed with filler. to pull the dents it would certainly be better but you could easily be opening a can of worms that could haunt you.
 
Tin the tank and stick the end of a bar of solder on the dent and use that to pull while tapping around the perimeter, once it's mostly out melt the bar off a little high and paddle the rest out.
 
thanks for that. I never thought of the bar solder thing.
I have used the gun on thinner tanks and learned about grinding the heads off instead of breaking them. This tank is rather thick steel, so I will try to pull one to see what happens.
 
A good marine grade 2 part epoxy filler works well for a tank. Maybe a little more durable than plastic filler
 
Bob's idea is a great one, especially for the kind of dents on that Ducati tank. I also agree with everything Jim said. I know I've done some deep mud fills on bike tanks and have never had an issue. If a bike crashes hard enough to knock the mud loose it was gonna be totaled anyway.
 
Jim has a good point for sure. Some day the bike will be sold and the new owner will be wondering why the 3 gallon tank only holds 2.5 gallons. LOL

For really deep dents that would otherwise require a lot of fill, maybe you could use the stud gun, but leave the repair area low enough that you can solder over where the stud was. If there was a small pin hole in the weld, wouldn't the solder keep it from leaking?
 
solder would work fine, the old gas cans were built with solder, brass floats are soldered.
 
I have a question for you pro's, over the years, I have been told by a number of people that they fill the tank with water and put in freezer to pop the dents out.
Now I have never done a tank in my life, so I have no clue, is this true????
 
Never tried it but ice sure ruins a lot of stuff around here. Ice expands in all directions so I'd worry about the seams busting out also.

I've stud gunned a bunch of them but the tanks are always checked and I tig weld if I have a stud pull out. I'm messing with damaged antiques that are always dipped and relined after I repair the dents. Bob's approach with the lead bar is a good idea for those mild dents.

I have applied air to a car gas tank to work out some dents and the air wanted to blow the tank up like a balloon everywhere but the dent.
 
ive heard that as well barry but never tried it. if i get a tank in here that is really bad where i wouldnt feed right with filler on it then i just tell the customer its time to get a new one anyway. the ducati tank in the pics doesnt seem too bad from what i can tell but that would probably be as far as i would go before its just not worth the time into it. by the time i end up pulling dents, welding them, bodywork and everything else you could have just bought a new or good used tank. for something hard to find or irreplaceable then thats a different story.
 
I have a small alloy tank with some dents, if it will fit in my freezer, we'll see what happens.

I went very light with the temperature on the studs, and just massaged the dents a bit so that now the filler will be just for shaping.
 
Everybody hates to use filler, but you know what,
if done right it will outlast the vehicle.
I think I'm wasting my time pulling out dents to
near perfection to use less filler, I know it won't matter
in the long run, but I can't help myself.
 
It would be interesting to experiment with the ice trick if you had a couple destroyed tank. I would think a few tricks would be, how much water was in the tank and how long you let it freeze, could you control the freeze, say 3 hours and maybe the tank 3/4 full or 7/8. Probably pretty useless but it would be interesting to play with.
 
I think the ice is going to push on the weakest point, but the tank would have to sealed up tight so the ice has no where to go IMO
I know some truck tire guys that use to spray either in the tire after fixing a flat, then light it and put the air to it. It would explode and allow the tire seal and air up. It had to be the right amount of either to get the desired results without any problems.
 
Air pressure in that style tank to remove dents doesn't work well-when I've tried it the tank would change shape and the sides would spread out where it went over the frame so I would think lighting off some starting fluid would do the same-the tank would do the splits LOL.
 
I agree Bob, it seems like anything that expands in the tank will put pressure on the weakest link, and that will not necessarily be the dents.
 
I think using glue on tabs and a Steck Stud Lever would work quite well on MC tanks. I repaired many dented tanks 45 years ago when I worked in the motorcycle shop business. I used compressed air with good results a lot of the time. Then I tried using water pressure and it worked about the same, except for more messing around,lol.

When pressurizing the tank, if it is a saddle type tank that fits over the frame take a couple of small straps and wrap around the tank and snug them up. You won't have the problem of the tank trying to spread.

I wish the glue tabs and Steck lever were available back then, it would have made things faster and simpler - I "think".
 
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