? for the welders out there

[souprat]

ok so the winter project for the supra is going to be the DIY catback kit from suprasport. i have a friend with all the welding equipment and know how who is going to help me out with this. i read in Corky Bell's Maximum Boost that if you weld a flange on the end of a pipe(such as the one that goes to the cat) that the flange will warp alittle due to the heat. it also says that the flange would need to be surfaced or else the gasket will not seal and you will have a leak. true?

how do i go about surfacing the flange, do i just take it to any machine shop and have them do it?

should i weld braces on that go from the flange to the piping to make it stronger? any tips and hints are welcome. thanks

 

[IJ.]

I have a big Linisher that I use to surface flanges.
(Think big upside down belt sander on a pedestal)

 

[mullenc525]

If you weld it carefully, it wont warp enough to stop it from making a seal, since exhaust gaskets are soft. Tack weld the pipe to the flange in about 12 places before you start to weld it. Then, weld between two of the tacks, then stop and weld between 2 other tacks on the other side of the pipe. This keeps the heat fairly even and reduces warpage. I didnt surface my Custom DP or catback, and neither leaks anywhere.

 

[jjh]

Thats what I was going to say. Im with Mullenc

 

[souprat]

thanks for the replies guys. so just even welding around the piping. gonna check the flatness with a straightedge and a feeler gauge then. say it does warp, the guy i know also has an acetalene torch, can i heat it up with that and bolt it to something flat to make it flat again?

 

[mullenc525]

You can also bolt it to a flat piece of steel before you start welding it, that will stop it warping. No I dont think heating and bolting to something flat will unwarp it.

 

[Boostedstr8six]

If you weld it carefully, it wont warp enough to stop it from making a seal, since exhaust gaskets are soft. Tack weld the pipe to the flange in about 12 places before you start to weld it. Then, weld between two of the tacks, then stop and weld between 2 other tacks on the other side of the pipe. This keeps the heat fairly even and reduces warpage. I didnt surface my Custom DP or catback, and neither leaks anywhere.

That will do it. Personally, I don't think that many tacks are needed for this application. I would just divide it into four sections, weld one section, hit the opposite side, and then do the same with the last two. Oh, and don't take Mr. Bell's word as gospel.

 

[Adjuster]

Heck, I've welded for years, and just tacked it in 4 places, then welded it up in 3 longer passes right over the tack welds. (Should be the recipie for disaster warp wise, but remember your welding this to a pipe, and you really don't warp the pipe much... the flange can warp, but a few moments on a large flat belt grinder fixes that in a hurry. (Like IJ mentioned.) Most machine shops have one, and don't charge you much if anything to true up a flange if you need it.

I've never needed to on mine, but I use dead soft aluminum gaskets where possible. (Copper works too, but it's more money.)

I also use exhaust gasket paste that you can get at most automotive stores. It cures with heat, but seals up minor leaks and imperfections very well.

Good luck, If I was building another exhaust, I would go with V bands everywhere, but at 25.00 per flange/clamp junction, it can get expensive in a hurry. Figure 75.00 or more materials, but you don't need gaskets, and they work very well if installed right.

 

[NashMan]

if you knwo hwo to weld there will not be prob