remove cat without removing muffler?

[StayGold808]

Hi All,

Is it possible to change the cat without removing the banana muffler? I was wondering if maybe undoing the muffler straps would loosen it up enough so that the cat can be removed.

Thanks for your help,
Adam

[slodave]

It hasn't been a problem for me.

[911mnypt]

You should not have any problems in doing it...

[byfdinky]

I didn't have a problem with it either. Bolted right up to the Muffler. I do plan to switch to SSI's and a new muffler this year but for know just running stock muffler.

[StayGold808]

ok thanks for replies... sounds like it'll be easy...

[McLovin]

It's easy in theory and may be easy in practice on your car, depending on the level of rust and corrosion on the hardware.

Helps a ton to have some kind of penetrant like PB Blaster, a propane torch to heat the hardware up, and some kind of a cutoff wheel for if the going gets tough.

[flatsixjunky]

Since you have to use new hardware and new gaskets anyway, go straight for the angle grinder or a Dremmel tool, and a chisel (for the ones that are hard to reach with the previous tools).

Getting the O2 sensor off the cat will be a challenge. Be careful or have a spare ready.



Good luck.

[rusnak]

I had to use my wrench to break a few bolts in half. Some of them are hard to reach. But once you get the bolts out, the cat comes out.

[StayGold808]

I'll probably just get an exhaust shop to do it...

I'm going to swap my cat, with a dansk pre-muffler from another car. My car is very good underneath, but i know the other one is a little rusty...

[RichHawk]

Originally Posted by StayGold808

I'll probably just get an exhaust shop to do it...

I'm going to swap my cat, with a dansk pre-muffler from another car. My car is very good underneath, but i know the other one is a little rusty...

Good answer! My Cat did not want to let go of the Heat exchanger or cross pipe. Period. I dropped the entire exhaust, took off the muffler with only one broken bolt, and after that the fasteners just refused to come loose. (1987 midwest car)

I tried soaking in PB blaster, I tried heat, I tried busting the heads off with an impact wrench. Nothing going.
I used a cutoff wheel and sliced through the heads of the bolts. So you would think I was done. Right? Not a chance. Two of the bolts were so corroded into the cat, that it took me an HOUR of beating, heating and soaking to finally get them driven loose of the cat.

I replaced them with stainless, and antiseized the hell out of things.

Rust is the enemy!
Richard

[Flieger]

I see no need to remove the muffler, though I think removing the cat will give both better airflow and take a few pounds off the rear end.

But then who will keep the mice from attacking your precious car?

[Wilhelm]

Flieger;

Nice looking cat !

[Geronimo '74]

Originally Posted by RichHawk

Good answer! My Cat did not want to let go of the Heat exchanger or cross pipe. Period. I dropped the entire exhaust, took off the muffler with only one broken bolt, and after that the fasteners just refused to come loose. (1987 midwest car)

I tried soaking in PB blaster, I tried heat, I tried busting the heads off with an impact wrench. Nothing going.
I used a cutoff wheel and sliced through the heads of the bolts. So you would think I was done. Right? Not a chance. Two of the bolts were so corroded into the cat, that it took me an HOUR of beating, heating and soaking to finally get them driven loose of the cat.

I replaced them with stainless, and antiseized the hell out of things.

Rust is the enemy!
Richard

Same story here, I ended up removing the heatexchangers, noticed the black goo in the exhaustvalves....
I am now in the proces of a full rebuild....
You know, while I'm in there....

[wdfifteen]

Originally Posted by StayGold808

Hi All,

Is it possible to change the cat without removing the banana muffler? I was wondering if maybe undoing the muffler straps would loosen it up enough so that the cat can be removed.

Thanks for your help,
Adam

I did just that last fall. I don't know if I could have done it in an afternoon without an air chisel. I didn't touch the muffler. Here is a link with pictures.

Criminal Behavior

[NewfieMZ3]

I got mine off with some effort, heat, liquid wrench, cut-off tool, dremel, hammer chisel, recip saw, hack saw, hammer and punch.

My question is what bolts to replace them with. I am installing a nicely polished Cat Bypass, I would like to use a bolt equally as clean. Is stainless the best I can hope for, and are they strong enough for this application. Also what is the proper spec on the bolt.......is it an M8 x 35. I destroyed mine taking them off.

[McLovin]

The more impt part is the nuts. The factory uses some kind of copper nuts, which makes things much, much easier to remove. They aren't expensive. For the bolts, I don't think they use anything too extraordinary.

[pplkook]

Sorry to bring up an old thread, but I have the same question, and didn't see any replies....what is the best nut/bolt combo for the muffler to cat? I am removing the AC bracket, so I pulled out the bolts, and the nuts do look weird.

Thanks

Jack

[James Brown]

I used stainless steel and bronze nuts like the factory used. Should find them in a good hardware store or a fastener shop.

[pplkook]

OK, so I have thought about this all night, why would using two different metals (SS and Brass) be better than all SS?

-Jack

[James Brown]

Good question, although they are different metals, the softer nuts will never corrode on there making removal easier. You can go with all stainless steel if you like or the original carbon steel bolts and nuts. it's just 4-5 years down the road that will make life easier. Also, use some high temp anti seize on them, most likely they will too hot for the anti seize anyway but you never know.