cutting a cat

[SwaintaN]

Ok money is tight right now, have a problem with my exhaust. The flange broke at the end of the cat convt. so what im wondering is since we have a dual cat system, if i cut the cat at the end of the straight pipe (piece between to the two cats) and slide on a extended to meet the muffler, what would happen with just one cat on our trucks?

 

[FIND]

assuming you get it to seal, it will be louder and raspier. If you live somewhere that test emissions (I didn't pay attention to where you were from before I responded) you would fail emissions. You may notice a small drop in fuel mileage also.

Why not just go to an exhaust shop and have them weld it back together for you? Seems like you would have just as much or more into your solution. Unless the cat is bad, there is no reason to remove it.

 

[Carguy3J]

I think I know what you're exhaust looks like, if it's the same as my '93 Ranger. My flange was also rotted. You're talking about the part that the spring bolts go through right? If that's the case, and the pipe itself is ok, then it can be saved.

The "flange" doesn't actually do the sealing. The pipe is flared, and that, along with a gasket are what do the sealing. The "flange" is just there so the spring bolts have something to pull against, and pull the 2 pipe together. Before I type any more, is this what you have? Is it just your flange and not the pipe itself?

 

[jake122288]

my 94 X is currently running a temp exhaust i put on it...the flange itself broke and the 2nd cat was falling apart so i cut in between the cats and gutted the first one and added a glasspack to it (its all i had at home) and i havent noticed any drops in mpg it is a bit louder but its getting the job done for mine

 

[Anime]

The two catalytic converters are both part of a system to convert the exhaust gases.

They are not two seperate 3-way converters.

Please, keep them both on there and intact. Having no converter or even just the first one will make the exhaust gases very toxic and dangerous. It is also illegal in all 50 states and the penalty is a few grand and a few years in prison.

An easy fix would be to cut off the rear pipe just in front of the flange, then have new pipe welded on, with a new flange.

This would let you use the same curved sealing washer as stock, assuming the same size pipe is used, and the same spring bolt connectors as well.

It's also possible to just cut off the flange, and use an extension pipe with two exhaust clamps to bridge the gap between the cat and front muffler pipe. This is sometimes how it's done with replacement exhausts done at muffler shops (although it's usually welded rather than using clamps), but I don't think it's as good as the flange/spring bolt system since that flange and the spring bolts allow the rear part of the exhaust to flex without breaking welds or pipe. Still, this would be very simple and cheap, pipe and two clamps, maybe a few bucks, plus the time spent sawing.

If you don't plan on repairing it back to the flange/spring bolt system, you could just have the front muffler pipe welded to the new pipe, and use a clamp to attach it to the rear of the cat, that way it's still removable if necessary.