Winter Contest Project #5 Cheap Chinese stainless header repair

My buddy called me up the other day and asked me if I could weld up his cheap chinese ebay header as it has cracked again. I love to weld so I told him to buy me lunch and I'll do it.
Heres before
http://i241.photobucket.com/albums/f...psfa8e9582.jpg

http://i241.photobucket.com/albums/f...ps14ee5725.jpg

And AFTER
http://i241.photobucket.com/albums/f...ps90a71b18.jpg

http://i241.photobucket.com/albums/f...psfc9abc2b.jpg

http://i241.photobucket.com/albums/f...psf9467fbe.jpg

http://i241.photobucket.com/albums/f...psfd2a7b10.jpg

How much force did it take to get the tube back into alignment? Looks like potentially a good repair (depending on what was happening on the inside and what the original cause of the fracture was.)

Did you figure out the cause of the original failure? I'd wager either undercut on the original welds, and/or overzealous use of a die grinder on the inside during "port matching". If you can figure out the cause and correct it, then you can have some confidence that it won't happen again.

The header is super cheap chinese stainless. The flange ports were larger than the tubing and the chinese swedged the end of the tube to fit tight on the inside of the flange. Since they stretched the tube they weakened it. Then on top of that, when they welded it I dont think they used filler rod, just fuse welded it. There were 4 other cracks. 3 of them on the collector where the tubes were joined and 1 up on the same tube I welded back to the flange where the original o2 bung was attached. I cut the tube completely off and refit it so that the tube didnt have any stress on it. I think when it was manufactued they welded the tubes to the flange and didnt get proper alignment to weld up the collector and just forced the tubes together and welded it up at the collector end. Thus putting alot of stress on the tubes and due to expansi9n and contraction it eventually broke.

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I think your repair is as good as it gets! That bead looks very nice, in fact too nice for the rest of the header!. In my experience, production stainless headers can be problematic with stress cracking at the weld areas. They also tend to split at the seams, especially in bends that are sharp.

Obviously heavier gauge material helps, as does really good fit up (no force or stress used), prep work, and weld beads, which is the reason professional header builders get paid so much more for their work than production header companies!

I've actually had to heat a brand new mild steel (production) header up with the torch in order to pry one tube into the correct position (so that it would meet up with the exhaust port). And it wasn't even what I would consider a "cheap" header either!

Did you use shilding gas on the back of the welds?

I cleaned the inside as much as I could with a dremel, then I brushed on solar flux and welded it. Did not use sheilding gas but I did use flux.

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Originally Posted by sw2x

I cleaned the inside as much as I could with a dremel, then I brushed on solar flux and welded it. Did not use sheilding gas but I did use flux.

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How does the inside of the weld look?

What do you mean? You clearly see the weld penetration from the inside as its slightly embossed on the inside.

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I have seen tons of people posting about cheap headers made in china cracking. I have also seen others that don't have a problem with them. Often times the people just weld them up again and they tend to hold just fine.

It probably has something to do with the different manufactures over there. The whole "good China" and "bad China" debate where some people are purchasing the higher quality headers that are made there, and others are purchasing the cheapest header they can find anywhere.

In this case, the stress of the manufacture "force fitting" the header tubes to the flange probably didn't do any good for the header's life. it just shortened the headers life. I've noticed that with low cost street bike and dirt bike exhausts, there tends to be a more issues with the stainless muffler/expansion chambers for some reason. They do seem like they are very thin wall material though. Almost everyone I know with one has had to repair or replace the unit they installed.

Quote:

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Originally Posted by sw2x

What do you mean? You clearly see the weld penetration from the inside as its slightly embossed on the inside.

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Any stainless I have welded without shielding on the back looks like hell on the back. Looks fine on the front but back is not smooth... only way I know to describe it is porous.

Solar flux "B" is a good way to go for shielding the back side with a repair like this, IMO. Nice work!

Thanks. I have seen immense improvement in my welding in the last few months. I think its because ive been welding nothing but aluminum for about 6 months and now my steel welds look really good.

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Quote:

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Originally Posted by sw2x

What do you mean? You clearly see the weld penetration from the inside as its slightly embossed on the inside.

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Both penetration and quality of the weld, lack of penetration will not help structurally nor will the weld if the inside has lack of shielding gas.