Dent in Tank best process

JMPUK

New Member
Hi Guys

I have a dent in my sr250 tank.

I am unsure whether to keep the patina as is and seal or get sprayed.... I will however require dent out.

Is it possible for this to be pulled out or will it have to be filled or similar?

From what I can see the rest of it seems pretty straight..

Cheers

JP
 

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You could pull it, some.

I usually weld. Some studs, and use a slide hammer I made with a drill chuck on it. Tighten the chuck on the stud, pop it out a bit, go to next stud, and on and on until you have it close.
 
Cheers bud

If I decide to go the painted route which I probably would it be best to blast, prime and then fill in that order?

My only concern is that if I ever wanted to bring the tank back to bare metal, if I have the dent filled it I would never be able to is that right?

Cheers

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That's a small dent. You could try vinegar and baking soda. Put a small amount of baking soda in it (1/2 cup), then pour in a half liter of vinegar close it up. The reaction will build pressure and pop it out. There is a risk of spreading the tank tunnel, and if you build up pressure too much, you can pop a seam, but if you're careful it'll be fine. I have yet to pop a seem after 20 or so tanks.
 
Until I read the full message I thought you were having me on haha it started off like an old wives tail!

Although I like the sound of that and would love to give it a go I just cant risk ballsing it up... I will however save this one for the memory tank and strive to try it at some stage!!

Cheers buddy
 
Looking at the dent, I'm not sure the baking soda approach will work. I'd go with the slide hammer route. I use washers gently tacked onto the tank to hook the slide hammer into.

Another method I've used on dented exhausts is to plug the holes and use compressed air to pressurise the exhaust then gently heat the dent until it pops out.


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Karlloss said:
Looking at the dent, I'm not sure the baking soda approach will work. I'd go with the slide hammer route. I use washers gently tacked onto the tank to hook the slide hammer into.

Another method I've used on dented exhausts is to plug the holes and use compressed air to pressurise the exhaust then gently heat the dent until it pops out.


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Thanks Karlloss

Not sure what the first method is but will look into it. Would it not be worth cutting the tank open and attacking from the inside or just filling and being done with it??

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I wouldn't cut the tank, as rewelding will be a pain and will need an extortionate amount of time to get the welds smoothed and the shape of the tank back.

There are some good videos on YouTube that show you how to pull the dents using a slide hammer. You can get a slide hammer from eBay for less than £15 / $20.

You could just fill it, as it won't make much difference to the capacity of the tank. Which ever method you use there will be some filling involved.


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+1 on welding some studs along the crease line and then use a slide hammer to pull out the dent as best you can. It will need filling and I much prefer to use lead lap rather than epoxy fillers. Lead lap is just putting a layer of solder over the area and then filing it back. Lead lap will not fall out in 5 years like epoxy can.
My lead lap is not perfect, but it will only need a little spot putty to get it right.
 

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Seeing how it has a crease in it you won't be able to get that dent out fully without getting a dolly behind it.


Slide hammer with tack welded studs will get you pretty close though. Don't try compressed air or pressure as you will probably balloon the tank.
 
On that note: you can take a length of rod, put a curve on the end of it (like a "J"), then weld a ball or half sphere on the end of it (a wooden ball works too) and use it to massage the crease out. Heat with a torch will make it easier to move the metal.
 
A crease that deep is not going to come out well and will require filler. Problem with a crease that deep is it may have stretched the metal and pulling it out may stretch it more.
 
firebane said:
A crease that deep is not going to come out well and will require filler. Problem with a crease that deep is it may have stretched the metal and pulling it out may stretch it more.
Heat helps shrink stretched metal.

Here's a BMW tank I fixed with no filler:

Before
d6fe2aceebc61c58f90dd0b53c65d5a5.jpg


After (with just a little massaging left)
88683c69e9cf305635919a234a8b1d8b.jpg
 
That is no where near same. The OP is a very hard line crease compared to a soft dent like yours.

Soft dents usually come out fairly easy.
 
firebane said:
That is no where near same. The OP is a very hard line crease compared to a soft dent like yours.

Soft dents usually come out fairly easy.
It has hard creases at the top (chipped paint should inform you) and it had the exact same crease, but vertical, on the other side. I've done this a hundred times. You can disagree if you want, but I've done it enough to know. You have to heat the metal to nearly red hot.

cb1230266f8892675ffae4331ddd0937.jpg
 
That's fairly minor damage. A skilled man can easily render that invisible in an hour needing no filler. That said, easily is determined by skill and experience. If you have less, you might have to take more time and care. Ideally you would weld pins along the crease and gradually pull the dent out with a slide hammer as already noted. A pin welder isn't exactly cheap, but you may be able to get somebody at a body shop to do that bit for pretty cheap as it will only take a few minutes. I would not expect much stretching as more than likely the tank simply distorted very slightly to accommodate the dent, and once pulled back it likely will simply return to its former shape. After that, a hammer and dolly will dress it out, but you'd have to weld one on to a stick to hold it properly inside the tank - again not something most guys will be able to do easily. That is the only way I know if you want to keep a steel finish. However, if you are going to paint, you can simply pull the dent out close and use polyester filler (Bondo) to smooth things out. There is absolutely no downside to using polyester filler. If done properly, it will never shrink, crack separate or fall out and is very easy for inexperienced hands to deal with. Like anything, performance depends on the quality of application. Lead is bomb proof, but has its own problems, is vastly more difficult to achieve the same results with and you are far more likely to have long term problems from flux contamination than any problems you may get with plastic filler. I suggest you avoid any form of pressurizing your tank and/or heating it up with a torch. Both can be used under certain circumstances to good effect but this is not one of them, or at the least is completely unnecessary and can make a great deal of trouble if you don't know what your doing.
 
I don't know where you are located but there's guys that travel round in vans all over the uk that can fix dents in cars without marking the paint. We have one local to us (anglesey) called the dent man, I've seen them called dent doctor also. He fixed a dent in my wing on my car and I couldn't tell. He didn't charge much either. Might be a worth a go


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It has hard creases at the top (chipped paint should inform you) and it had the exact same crease, but vertical, on the other side. I've done this a hundred times. You can disagree if you want, but I've done it enough to know. You have to heat the metal to nearly red hot.

Irk - can you give a bit more information on your technique. Do you seal the tank and pressurise it? Or do you seal and just rely on the heat to increase the pressure in the tank? How do you seal and how much pressure?
 
XS750AU said:
Irk - can you give a bit more information on your technique. Do you seal the tank and pressurise it? Or do you seal and just rely on the heat to increase the pressure in the tank? How do you seal and how much pressure?
Heat is to soften the metal. Then, a bar with a curved end (in the shape of a "J") with a convex cup or ball on the end is fed into the tank to massage the crease out. If you go too far, the sheet metal that's been overstretched (crown) can be heated with a rosebud tip and then quenched with a wet rag. It will cause the metal to shrink back. For small raised bumps, you can heat the spot and quench. For larger raised bumps, massage the metal around the bump in a circle with a planishing hammer and work your way to the center. This will shrink the bump and move the metal to the center where it was thinned out. I say that, because you can also do this for creases if they pop out and become raised.
 
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