1995 Tahoe cat back exhaust fitting issue?

[derekjl]

I bought a really nice stainless steel cat-back exhaust made by Gibson. Couldn't put it on myself, I'm friends with a guy that owns and runs a body shop. I dropped the truck off to have it installed and here is what they told me via email...

"...We’ve had it up for the exhaust. That ended up being a bit more labor intensive because it was already changed once and the flange has been cut off the catalytic converter. It had to be modified to install the new exhaust..."

Can someone explain to me what he meant regarding the flange being cut off? If I understand correctly, that section of the system had been replaced (which I knew already) and to make it fit the shop that did it basically cut the outlet portion of the catalytic converter off. Does this sound right? If I had known this I would have gladly brought them a new catalytic converter or just told them to cut it off altogether. Any input would be appreciated!

 

[drakon543]

behind your catted y pipe it has a flat flange that is supposed to bolt to the flat flange on the Gibson kit. if someone replaced the cats with universal cats or something that rear flange could have definitely been cut off requiring some kind of modification to the exhaust under the truck or to the Gibson kit to make it fit.

 

[derekjl]

behind your catted y pipe it has a flat flange that is supposed to bolt to the flat flange on the Gibson kit. if someone replaced the cats with universal cats or something that rear flange could have definitely been cut off requiring some kind of modification to the exhaust under the truck or to the Gibson kit to make it fit.

Thanks for the reply. Is this all that uncommon? Assuming the previous owner just went to an exhaust shop to have the catalytic converter or tailpipe/muffler section replaced and they didn't exactly do it the "correct" way. The shop that put my exhaust on essentially had to "create" a new flange so the cat-back system could bolt up to the converter. Thankfully, they did not cut the new system, so it still does have the flange on that end. I'm guessing I could just do the Y-pipe modification with a high-flow cat and that would fix the situation?

 

[drakon543]

just as long as you put the correct flange after the cat/cats you can do anything you want before that. is it common, no not really maybe a while ago when the catted y pipe cost more someone could have done it. since yours has the ball flange it wouldn't be much of a hassle. you can buy just that flange but if someone did a diy for a quick fix on a rusted flange they probably would have just cut the flange off and joined the 2 together with a union pipe.

 

[derekjl]

Just an update here. I didn't bother to look at how they actually fitted the new Gibson system to the rest of the exhaust until now. I'm not really pleased about it. As I said, the previous owner took the truck to a shop and for some reason they cut part of the pipe that comes out of the catalytic converter, including cutting the flange. Not knowing this, the shop I took it to had to come up with a way to connect the Gibson cat-back to the rest of the system. It looks like they welded some kind of exhaust sleeve into my really nice and expensive Gibson piping and clamped the other end of it to whatever piping was left over on the rear of the cat. Is this the definition of shoddy workmanship or is it genius? Either way, I don't like that it isn't properly fit to the truck. Very important question, if I want to replace the y-pipe and cat in the future, can this "weld" be taken out of the cat-back portion or does that flange now have to be cut? Basically I do not want to have to modify the cat-back portion of the system at all. Had I known this was necessary I would have just purchased a new y-pipe and have it connect properly via the flange. Not sure what to do here...picture attached.

 

[derekjl]

Is it just me or could they have just used an adapter with a flange on one end? I know I have seen those before, maybe they didn't have one on hand? Instead of WELDING one end of the adapter into the cat-back section, find one that bolts to it! Guessing I'd need one with a 2.5 inch inlet and a 3.0 outlet since that is what the cat-back section is?

 

[drakon543]

if you take that clamp off and heat the pipe you could probably just pull the y pipe out. yes they could have just welded on a new flange. its not too terrible tho that sleeve can be cut back off the flange can be smoothed back out and properly fitted to a new y pipe if you wanted.

 

[derekjl]

if you take that clamp off and heat the pipe you could probably just pull the y pipe out. yes they could have just welded on a new flange. its not too terrible tho that sleeve can be cut back off the flange can be smoothed back out and properly fitted to a new y pipe if you wanted.

Great, thanks. I think I will take it to an actually muffler shop. Lesson learned. Can I keep my existing y pipe and cat even though the flange is gone? I’m assuming they could just weld a flange onto it or just use an adapter with a flange built in? I know Flowmaster makes a direct fit y pipe with a cat for about $190 shipped. Pretty tempting as long as that weld can be taken out. What I DON’T want to do is cut any part of the Gibson section.


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[drakon543]

shouldn't be a problem

 

[pistnbroke88]

Ive NEVER seen a proper exhaust shop use a clamp like that? Why they didn't just weld up a 2 bolt flange is beyond me as opposed to welding a 6$ reducer to the flange face. If i saw that unaware of your story id assume you had some guy of craigslist do it in exchange for a 12pack.