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Fuel Tank Dents

copbike

New member
I have a number of vintage motorcycles that have dents in the tanks. I would like to repair the dents before repainting, but I am unsure how to proceed. Does anyone have suggestions or direct experience with this kind of repair? Would appreciate some insight into this. Also, one of the tanks has rust issues and small (dime sized, or smaller) holes at the top rear. I am a competent welder (mig and gas), but would also appreciate ideas on this kind of repair.
 
You have a couple of options for the dents. There are body shops that offer "paintless dent removal" which is a procedure using special mandrels to push the dents out. There are stud guns that arc weld a stud to the dent which allows you to pull the dent out. Then there are fillers. Holes can be welded, but you can get warping. Holes can also be soldered up, using fine brass screen as a backer. In some cases, the repair is cost effective; in other cases not.
 
A friend took his tank into one of those places that fixes dents from the inside and was told the metal was too thick to get the dent out.
 
When I bought my airhead I was talking to one of the guys that was in the garage and mentioned getting the dents out of the tank to him. He told me he filled the tanks with water and allowed them to freeze, the expanding ice would push the dent out.
Now I am not saying this will work, but the concept makes you wonder if it will work and if it would cause other issues.


I have one of those stud welder dent puller units if the thread author happens to live close by.
 
I would think on the ice freezing option you have little control over where the forces go and there's every possibility that the seams at the bottom would break.
 
I would think on the ice freezing option you have little control over where the forces go and there's every possibility that the seams at the bottom would break.

Yup, that's the first thing that came to my mind.
I think it's a sure fire way to burst the seams.
However, at that point you could pound out the dents from the inside and reassemble the tank.:bolt

Not sure that's a very efficient method of repair, but it would give you something to do over the winter.:)
 
I've heard one can put a couple of straps around the tank to stop it from spreading and use compressed air to pop dents out.
Should be fairly easy to control, I would think.

Steve
 
A friend took his tank into one of those places that fixes dents from the inside and was told the metal was too thick to get the dent out.

I tried this method on a '75 R75/6 tank and found that the metal is too thick to allow it to be moved with the amount of pressure that can be brought to bear on the inside of the dent.
 
I've heard one can put a couple of straps around the tank to stop it from spreading and use compressed air to pop dents out.
Should be fairly easy to control, I would think.

Steve

Seems to me this is about the same as freezing water in the tank. You'd end up with split seams and perhaps a distorted tank.
If these old tanks have a weak point, I'd guess it's at the seams.

It might work with a large, shallow dent; but that's not what we normally see in tanks.
 
Depending on how big & deep the dent is, you can under the right conditions, pull it out...now don't laugh...with a toilet plunger :). Of course,I have NEVER dropped a bike, so I wouldn't know about this.
 
Some of the "paintless" dent removal companies use an adhesive based stud attachment system that allows a pull that works like a stud weld.
They are pretty clever in "messaging" out the dent from the inside with some specially shaped tools.
OM
 
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