detpac
- December 15th, 2002, 03:25 PM
Lurker, I thought you would need this,
"First off, you'll have to remove the 6 nuts holding the downpipe to the car, and then the one smaller bolt from the exhaust flange. I got really lucky, my car doesn't have a million miles on it, and the previous owner literally never drove it when it rained. So my bolts were not stuck at all, but I have heard that some people have a devil of a time getting them off. At any rate, I put lithium grease on each stud before putting the bolts back on to make future removal easy.
After the downpipe is removed, you can then remove the front cat completely. The rear one I left bolted to the engine, like most people do. The tools to use are simple, an electric drill, 2 drill bits, a 1 inch flat wood bit, and I also used a 3/8 inch metal bit to punch a few holes through the material and weaken it. It's important to note that the precat material you are cutting through is only about 3.5-4 inches thick. You do not need a very long bit to accomplish this, just enough to poke through about an inch. I drilled the holes in the front precat with the metal bit, spaced evenly in a triangle around the center. Then I attacked the center with the wood bit, and punched through the middle with it. When the center of the cat is hollowed out fairly well, you can take a screwdriver to the sides of the cat, and break the seal against the sides of the pipe. It takes time, but on the front precat, it is really no big deal.
Finally, you will start breaking out huge chunks of material, I went back and used the wood bit sporadically here, because it catches on the metal and rips it apart and breaks it up. Once you start breaking out big pieces, your work is almost over. When you are done, I took a 2.5 inch wire wheel with an extension to the insides of the cat, polishing it smooth. You may need to scrape the sides with a screwdriver and hammer to get to this point if it did not get ripped out too cleanly. But, this is easily done. So, with the front precat done... take a break.
The rear cat is a PITA! But, if you love your car enough to even consider doing this, the payoff is worth it.
Using the same tools and technique, I had the rear cat gutted in about 3 hours, polished and ready to go. A lot of people say that after you do this mod, you will hear popping sounds from your exhaust... that is the left over crap that they didn't remove, there are metal filings everywhere. One important thing... you MUST wear eyegoggles, a face mask, and be sure to cover your hair completely. Trust me on this. You really can't do the rear precat without doing this. You will be under the car and this stuff just rains down on you.
Don't worry about damaging the sensor behind the cat, if you use a drill bit that will only extend about 5 inches or so, you will never hit it. Anyway, when the sides are very smooth, (I am a perfectionist, and I was also worried that too many filings would gunk up the main cat down the line) use the wire wheel and polish it out. Then I took a heavy duty shop vac and sucked all the dust out of both cats.
The end result was two very thoroughly gutted precats, with smooth inside walls, and about 15 horses I'd say. You really can feel the difference. I hope this helps anyone planning on doing this. Plan on spending a day for this, longer if you have problems getting the downpipe bolts off. But when everything is bolted back up, and if you have done a great job in removing all the dust and material, you won't hear any "popping noises", just the usual exhaust tone, maybe slightly louder at WOT.
Good luck!"
I found it for you.;)
"First off, you'll have to remove the 6 nuts holding the downpipe to the car, and then the one smaller bolt from the exhaust flange. I got really lucky, my car doesn't have a million miles on it, and the previous owner literally never drove it when it rained. So my bolts were not stuck at all, but I have heard that some people have a devil of a time getting them off. At any rate, I put lithium grease on each stud before putting the bolts back on to make future removal easy.
After the downpipe is removed, you can then remove the front cat completely. The rear one I left bolted to the engine, like most people do. The tools to use are simple, an electric drill, 2 drill bits, a 1 inch flat wood bit, and I also used a 3/8 inch metal bit to punch a few holes through the material and weaken it. It's important to note that the precat material you are cutting through is only about 3.5-4 inches thick. You do not need a very long bit to accomplish this, just enough to poke through about an inch. I drilled the holes in the front precat with the metal bit, spaced evenly in a triangle around the center. Then I attacked the center with the wood bit, and punched through the middle with it. When the center of the cat is hollowed out fairly well, you can take a screwdriver to the sides of the cat, and break the seal against the sides of the pipe. It takes time, but on the front precat, it is really no big deal.
Finally, you will start breaking out huge chunks of material, I went back and used the wood bit sporadically here, because it catches on the metal and rips it apart and breaks it up. Once you start breaking out big pieces, your work is almost over. When you are done, I took a 2.5 inch wire wheel with an extension to the insides of the cat, polishing it smooth. You may need to scrape the sides with a screwdriver and hammer to get to this point if it did not get ripped out too cleanly. But, this is easily done. So, with the front precat done... take a break.
The rear cat is a PITA! But, if you love your car enough to even consider doing this, the payoff is worth it.
Using the same tools and technique, I had the rear cat gutted in about 3 hours, polished and ready to go. A lot of people say that after you do this mod, you will hear popping sounds from your exhaust... that is the left over crap that they didn't remove, there are metal filings everywhere. One important thing... you MUST wear eyegoggles, a face mask, and be sure to cover your hair completely. Trust me on this. You really can't do the rear precat without doing this. You will be under the car and this stuff just rains down on you.
Don't worry about damaging the sensor behind the cat, if you use a drill bit that will only extend about 5 inches or so, you will never hit it. Anyway, when the sides are very smooth, (I am a perfectionist, and I was also worried that too many filings would gunk up the main cat down the line) use the wire wheel and polish it out. Then I took a heavy duty shop vac and sucked all the dust out of both cats.
The end result was two very thoroughly gutted precats, with smooth inside walls, and about 15 horses I'd say. You really can feel the difference. I hope this helps anyone planning on doing this. Plan on spending a day for this, longer if you have problems getting the downpipe bolts off. But when everything is bolted back up, and if you have done a great job in removing all the dust and material, you won't hear any "popping noises", just the usual exhaust tone, maybe slightly louder at WOT.
Good luck!"
I found it for you.;)