How do you "gut" cats?

dave6666

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Not that I'm going to do this, but if I wanted to, what's the best way to get the working bits of a ceramic substrate RT cat to vacate the pipe? The thought is to leave everything intact so no fabrication step is needed.
 

Red Snake

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I don't know the answer to your question but I'd think it would be a whole lot easier to just cut them out and put in new pipe. They are hidden by the side sill so noone would ever know. :dunno:
 

got one

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alot of it depends on how the kill went...and what tools you have...are you looking to keep any parts?
 
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dave6666

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I don't know the answer to your question but I'd think it would be a whole lot easier to just cut them out and put in new pipe. They are hidden by the side sill so noone would ever know. :dunno:

With side exhaust that's a little trickier. You have to maintain the other end of the pipe very accurately in a relatively small opening in the sill. If I was rear exhaust then yes cutting and welding would be the preferred route.
 

Red Snake

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With side exhaust that's a little trickier. You have to maintain the other end of the pipe very accurately in a relatively small opening in the sill. If I was rear exhaust then yes cutting and welding would be the preferred route.


Good point.
 

got one

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Uh yeah... The metal pipe... Not the ceramic innards of the cat though.

oh wait...so, you aren't skinning a...um...ya, nevermind.... :rolaugh:

I have heard some folks simply put a long screwdirver in and wallow it around...
 

Chuck 98 RT/10

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With side exhaust that's a little trickier. You have to maintain the other end of the pipe very accurately in a relatively small opening in the sill. If I was rear exhaust then yes cutting and welding would be the preferred route.

On the 2008 Belanger has some sort of adjustment sleeve or something. I should have paid more attention when I saw them being installed but there was some sort of length adjustment to the pipe.
 
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dave6666

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On the 2008 Belanger has some sort of adjustment sleeve or something. I should have paid more attention when I saw them being installed but there was some sort of length adjustment to the pipe.

2001 GTS. All solid welded 'cept for the normal flanges at the Belanger merge collectors.

I have though about drilling small holes and doing the punch/hammer thing. Weld the holes back up.
 

carguy07

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Assuming that by "RT" you mean Random Tech cats? If you can see the honeycomb it's easy. Just ram a big screwdriver through it a few times. It breaks up very easy. Break it up and dump it out.

As a side note, have any of you passed an e-check with empty cats? I punched mine on an 84 Trans Am back in the day (probably around 1989-1990) and passed a California check. It even had an "off-road" chip in it. I remember doing a couple of suggested carb tricks but other than that it blew right through with an empty cat and the chip.:2tu:
 
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dave6666

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Assuming that by "RT" you mean Random Tech cats? If you can see the honeycomb it's easy. Just ram a big screwdriver through it a few times. It breaks up very easy. Break it up and dump it out.

Here's a pic of one of my pipes as I was putting a coat of VHT on it. No line of sight to substrate.

And yes, RT for Random Tech.

You must be registered for see images
 

Big Mac

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One of the "old timers" tricks was to let the car idle with the exhaust partially blocked to get the cats real hot, then shut off the car and stick a water hose in the pipe to "shock" the ceramic while banging on the cat with a rubber mallet. Then they would restart the car with the exhaust unplugged and continue to bang on the cat with the mallet while revving the engine to get the parts out.

There are a couple of drawbacks to this method. First it makes a HUGE mess, and the wet converter material will stain whatever it touches - ie concrete etc. The second is you get pieces of converter in the muffler, that will rattle around for a while and may never come out.

If I was doing it I would cut the pipe right behind the cat, use a crow bar or screwdriver to remove most of the material, and then use one of those small 3m grinding wheels (that look like a hard sponge? - hard to describe) on the inside to remove remaining material. Then I would weld or have someone weld the pipe back up.

I would do this off the car - and use several marks on the pipe (at least 4) so that the welder would get the pipe back in the right place. If you took the pipes to your local muffler shop for welding, it would probably be about $20 a pipe, and I bet they wouldn't care the cats were hollow. A sawzall with a good metal blade would make a clean cut that would be easy to weld up. Also clean any paint/dirt etc off the pipes at least 1" from each side of the place you want to cut before you make your marks and cuts so the weld will be clean. A green scotchbrite pad is good for cleaning. A sharpie marker would be fine for the marks.
 
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dave6666

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The good news is... Actually the good news twice is, that my mufflers are straight through - no traps or baffles - and I am my own welder if I would chose to do it and do it that way.
 

ussjones72

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I think this is how the pros do it...

oh yea, this is a track only car:2tu:
 

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eucharistos

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Here's a pic of one of my pipes as I was putting a coat of VHT on it. No line of sight to substrate.

You must be registered for see images

if you are trying to avoid cutting, measuring, measuring, welding, as they look perfect as they are :2tu:, seems like you could try a flexible auger type of thing (like a roto-rooter, drain auger ) on a drill and bust up the ceramic from the front side and dump to front so nothing gets in the bullets. worth a try before cutting :dunno:

gunna be loud :omg:
 
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dave6666

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if you are trying to avoid cutting, measuring, measuring, welding, as they look perfect as they are :2tu:, seems like you could try a flexible auger type of thing (like a roto-rooter, drain auger ) on a drill and bust up the ceramic from the front side and dump to front so nothing gets in the bullets. worth a try before cutting :dunno:

gunna be loud :omg:

Yup, I could easily drill some holes and patch it up with some welding.

And one of the reasons for just investigating this as opposed to just doing it is, I want to hear someone's car that has done it first. :rolleyes:

The bullets? Ain't nothing getting trapped in them. I don't even know why them call 'em mufflers :D
 

Shandon

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If the ceramic breaks that easy dave as other have said. Just go get a plumbing snake from Lowes or rent one and run it through like you would a drain. They have some serious crap munching bits for those things. If the hand held one wont do, you could rent one of the motorived ones and go clean through (they have 2-3" bits)? Probably eat that ceramic right up? Hey its a thought?:headbang:
Yes I am the posterchild for "REDNECK" but hey I'm proud of it!
 
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WOT!

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I have a question. Do you have to remove all of the substrate, or can you leave say half of it in tack?

This is of course assuming you can see what you're doing as in the pictures.
 

ussjones72

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I have a question. Do you have to remove all of the substrate, or can you leave say half of it in tack?

This is of course assuming you can see what you're doing as in the pictures.

It pretty much crumbled as soon as we hit it with the air chisel so I do not think you could just remove part of the guts... it's all or nothing.
 
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Bobpantax

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Hi Dave. Question. Is there an acid that dissolves ceramic material but does not affect metal?
 

ViperTony

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I think Dimitrios stumbled upon the answer a few years ago. He installed a Roe Supercharger and soon the ceramic bits came flying out the rear of the exhaust. Problem solved.
 

Bobpantax

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The same thing happened to me when I had my Roe on my former 1999 GTS. Along with the ceramic bits went some of my hearing.
 
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dave6666

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Hi Dave. Question. Is there an acid that dissolves ceramic material but does not affect metal?

There are certainly exotic metals that are resistant to acids much more so than what is likely some form of common stainless steel on the cats. Let alone the aluminized steel the rest of the exhaust is made of...

Ceramics in the chemical industry are one of the king of the hill kind of materials when it comes to corrosion resistance. Not universally resistant to everything, but can go where other materials can't especially when you need structural properties..

To answer your question specifically though, anything that can dissolve the catalytic substrate is going to take the stainless can with it.
 

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