Strongest filler

[azr]

I want to paint the tank on my dual sport DR but it's got some pretty big dents in it. I was thinking about having a local guy pop them out but that'll be $150 if he can do it so I thought about filling them. My question is, what's the best filler to use considering I bash the heck out of the thing.

[posplayr]

Prep is key; gpo down to bare metal with a wire wheel, flap wheel or chemical (A/C stripper).
Get off any rust;
Use a metal prep.
final step is scratch a cross hatch using 30 grit cloth (by hand) to give the bond so bite.

Don't use the pink Bondo. It is not water proof.

https://www.amazon.com/272-Bondo-Glass-Fiberglass-Reinforced-Filler/dp/B000VKZ3JM

There is a long strand type as well for massive filling (Kat hair)

[bwringer]

If you're just gonna keep bashing it around off-road (which is good and proper usage for a dual-sport bike) I'd avoid using a filler. You'll just get an even bigger uglier crack in the paint next time you biff. Strip it down, paint it with something very basic, and touch up as necessary later on.

[posplayr]

If you're just gonna keep bashing it around off-road (which is good and proper usage for a dual-sport bike) I'd avoid using a filler. You'll just get an even bigger uglier crack in the paint next time you biff. Strip it down, paint it with something very basic, and touch up as necessary later on.

You must be thinking of pink bondo from the 70's?

[John Park]

Typical fillers are polyester resin based - use a few drops of MEKP as a catalyst - and inevitably shrink somewhat. In thin applications, the shrinkage isn't unacceptable, but most fillers warn against thicknesses greater than a 1/4" or whatever, and that's probably optimistic, especially on a thin and vibratory tank.

I ONLY use polyester fillers as a final deep scratch filler and leveller and use epoxy resins for the main operation. Sure, the cost is way higher and the sandability can be a lot tougher, but the adhesion to metal is better as is the water resistance. You can make your own filler with a good boatbuilding epoxy from West System or Aquaset or wherever; the exact resin isn't critical [I use a product called Cold Cure for most things] by adding micro balloons [glass microspheres] which reduce weigh and add sand ability while adding volume [-$$] and then thicken with polyester minifibers. There may be some ready mix putty available, but the additives are dirt cheap and then the rest of the resin can be for other uses. Busted chairs, what have you.

I remember using this method on a rusted out fender on an old Dodge I had. I sold it, and many years later saw the car still running, but rotted out everywhere except for my repair.

You do have to be careful to follow the directions for the resin ratios, mixing, and pot life which is more involved than just mixing up a dollop of putty from a can and coming back in an hour or two. Epoxies usually take a few days to fully set up and be at their best for sandability, but you can usually work them in a day. Once you've done it you realize why the body shops don't do it this way - unless it's a really expensive car.

If you're planning on keeping something for a long time, epoxy means you don't have to do it twice.

[bobgroger]

I want to paint the tank on my dual sport DR but it's got some pretty big dents in it. I was thinking about having a local guy pop them out but that'll be $150 if he can do it so I thought about filling them. My question is, what's the best filler to use considering I bash the heck out of the thing.

Rob,
You saw the huge dent I popped out of my tank. If you can change valve spring seals you can pop those dents out....You need a high-temp glue gun and one of these https://www.amazon.com/Gliston-Paint...ords=pdr+tools or I used this: https://www.amazon.com/Super-PDR-Bri...ords=pdr+tools The right glue gun and glue are key. You should be able to get it to the point a skim coat of filler will cover it in an hour. Or buy a plastic tank and never worry again

[azr]

Maybe I'll post some pictures up of the dents, they would be considered pretty aggressive I would think, too much for a dent puller but what do I know. GREAT info everyone, I sure appreciate it. If I could get the dents out at least somewhat better than they are I'd be happy and just paint it.

[2BRacing]

It may be possible to bend a steel rod / bar into some kind of "hook" shape and insert it into the fuel filler hole. Then "massage" the dent out from the inside of the tank. If you are patient and take your time, you could get the worst of the dent out.

[posplayr]

If you want to find out about dent pulling, there is something called Google that usually knows.

[azr]

Thanks Jim, I didn't think of that..... Yes I've watched some you tube videos on pushing the dents out, now of course they're all professionals with a huge assortment of rods. Being that there is only one access hole on the DR tank I'm not sure I or anyone else would be able to get at the worst dent. I was wanting to avoid drilling holes to pull out dents but you never know. I have a quote from a local shop to paint it but $500 for a dirt bike tank is crazy in my mind. Like I said as soon as I have a moment off from work I'll throw up some pictures and you guys can see what I'm dealing with.

[posplayr]

Give this guy a call

[metalfab]

The filler is for the most part polyester resin, flox, and micro. The micro makes it light and easier to work, but weakens it. The flox makes it stronger. If you want to strengthen it mix some extra polyester resin and flox into the filler. Aircraft supplies normally sell flox and micro, it can be hard to find.

[Cyrano]

I got some surprisingly good results from using one of these dent pullers for just a few quid.

https://www.amazon.co.uk/d/Shops/Amtech-J1930-Tech-Dent-Repair-Tool-Kit/B0053OJJ7I

Still needed filling and finishing but without the great lumps of filler.

[posplayr]

The filler is for the most part polyester resin, flox, and micro. The micro makes it light and easier to work, but weakens it. The flox makes it stronger. If you want to strengthen it mix some extra polyester resin and flox into the filler. Aircraft supplies normally sell flox and micro, it can be hard to find.

While possible I guess, I can't see any possible benefit in mixing micro balloons into polyester filler. Weight reduction? Better to straighten the metal and if it is such a beater you can't who cares about weight?

Flox? You have a source for carbon fiber cat hair filler or do you mix your own?

[Grimly]

Give this guy a call

Or these guys...

They do a dent-to-order and undent it again. They even leave money.