Thread: Filling welds

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Yo Room - Can anyone help me with grinding and filling ugly welds on a frame - I can grind and re-weld them myself but don't know what to use to fill them so the stress and vibration won't loosen the filler. (WHEW) - What do the big boys use? - Many Thanks - Bill

The big boys use polyester filler (yeah, bondo). Use the high quality stuff (yes there is a difference).

The key is that good welds don't require much grinding, and therefore not much filler. Polyester filler has some flexibility as long as it's 1/8" or less thick.

Word of caution. Do not "over grind" the welds, it will weaken the joint. Only a very small amount of surface roughness should be removed. Your comment makes it sound like the welds are really ugly. That may be the sign of a real problem. If they're "bubble gum" welds, it could be that there is not proper penetration............meaning it's a bad weld. Flexing of the frame will very likely break the weld even without the grinding if it doesn't have good penetration. A VERY bad situation. Have that checked first before grinding anything away.

The best thing to do to fill welds is : First--- Use an oxy-acetylene torch and a metal hanger and weld over existing welds. Second--- Get out a body hammer and a dolly. Third--- Now heat-up the weld and hammer weld a one and a half inch spot flattening out the weld (this also flattens out the weld on the inside) move at this rate till all the welds have been covered and flattened. If you did this method correctly, you will not need any filler at all and the pieces welded together are very strong and will look like a FACTORY connection. If you still want to fill the welds without using this process, I recommend a filler that is waterproof and will never lift like Bondo tends to do. Try using ALL METAL or METAL-TO-METAL these are aluminum based fillers and are guaranteed not to lift or allow any moisture to penetrate through to the metal. Good luck

Well done welds are the key to not needing fillers. A square wave mig welder with argon gas sheilding works great, even my pathetic welding looks good. Slightly overfill and grind down to level.

IF you build a chassis for NHRA or IHRA certification you can't grind or fill the welds in any way. Grinding a weld will weaken it. Personally, I think a proper weld looks o.k. just as it is. Also, magnafluxing the welds is a good idea.

I agree with both DabberDawg and Pro70z28.
The mig with argon gas sheilding does an excellent job on frames. Thats what I used on a camaro that had been totaled in a crash cut off the front and welded on a Iroc front end. When I took it down to have it painted the guy could'nt belive it was the same car he had seen a couple of weeks earlier, he then told me that he could'nt even tell where I had welded it back together. The funny thing is is at the time I had never done this before and had almost no welding experience. I have a friend in las vegas that judges at some of the car shows and he gives extra points to the guys that drive thier cars on the road. And he also told me the he likes the factory look, welds and all. Ask Tech on here what he likes or Bob/Streets what they like to see.
But what It really comes down to is what do you like?
Oh by the way when I traded in the Camaro at the GM dealer they wrote it up as a IROC Hey who am I to argu with GM wright
{MO MONEY towards my new car}And the guy at the paint shop offerd me a job, I declined, too much work. HE! HE! HE!

~ VEGAS ~

PS Magnaflux