rearenginekarts.com

Hi Everyone-
I have a couple of frames that need welding and I've heard that the welding case hardens the metal making it brittle and prone to crack (not good). Is this true and does anyone have experience with welds failing because they didn't anneal.

Along those same lines, is it possible to restore the original flex pattern of the chassis by annealing it? If so, is it a matter of firing up the oxy-acetylene/oxy-propane torch with a big rosette, heating it up and allowing to air cool?

Lastly, does the powder coating process have any affect on the metal or are the relatively low temps (350-450?) negligible.

Thanks,
Dan

There was a series of posts over on Bob's about blasting and powder coating and it was thought that the temps were not to hi to hurt the frame .
Brian

It is very doubtful the time and effort was spent to anneal at frame at the O.E.M. and they seemed to have held together quite nice regardless. You can also find a reputable [SEMA approved] chassis shop in your area and ask them what they think.

Always keep in mind that because of its thickness and 'fill' properties, powdercoat can actually hide cracks and makes repairs a lot more difficult.

R.E.A.R.

Hell Dan;
lots can b said on this topic , but basicly annealing on .125 cro-mo(4130) isnt nessasary post welding ,use a mild rod (tig) I use AWS-E70S-3 or ER80 ,and it will mix with 4130, and wont be a brittle weld. 4130 rod = brittle. Also its good to heat up linseed oil and rotate frame around to coat inside tubing.
My yard Kart Fox needed repairs,I chose not to paint for awhile to keep ck of cracks, I sandblasted it then 3m padded it to a nice shine( its chrome-rite ) after 2 yrs still no paint ,just wash, Gunk&Kero , blow off H2o ,and wipe WD or CRC. I might paint it some day ,but having to much fun driving.
thk/u,gus.

Nils,

The welder that I'm planning to weld the FOX karts that I have uses a soft wire that is numbered ER 70S-6. Do you think that this will be OK?

I'm replacing the front axle on two of the FOX karts I have. I know that we never did anything special after the frames were welded. That's a long time ago but I'm sure they went directly to paint after welding. I worked for FOX in the mid to late 1960's in the engineering dept.

Dick Teal

Dick;
That rod is fine ,anything from 70s-2,70s-9 is fine ;
thk/u,gus

Nils,

Why the linseed oil for the inside of the tubing?

Should it be just in the area of the welds?

Dick Teal

dick; linseed oil is a old aircraft fix for stabilizing rust and prevention , it should slosh around in all main tubes (drill a .125" vent hole in front axcel where it intersects main tubes ).. If the frame is already 40 yr. old and it wants to go 40 more it s alittle insurance in stressed areas,plus welding always leaves alittle scale inside.
thk/u,gus.

Dan,
The primary reason repair welds fail is that they are poor to begin with. A weld made on a
properly cleaned and weld prepped surface will hold up. The inside of the tube should be
cleaned of corrosion as well. Any good TIG weld that is not overheated will be fine. As far as annealing welded or straightened areas you can do it. I turn off the lights and with a rosebud
I heat the area until it JUST shows color, then let it cool. I have found this works amazingly well on some really critical areas of tools I have made. If the welded area cracked broke the user would definitely have been injured. I used this method when I straightened the front axle
on Russ Smiths GK800. I cleaned off all the rattle can paint in the area since it would glow and
hide the color I was looking for.
Mark

Thanks a bunch everyone.
Mark, I will definitely try annealing before I start reefing on the Caretta front axle, it is bent, but not buckled so I am hoping some gentle persuasion will put it right.

Dan