Bonneville America Forums Forums Technical Forums Exhaust What's in a stock exhaust

I had a set of pipes that got trashed in shipping, so I thought before I chunked them, I'd gut them out and show everyone what is inside them. I should mention that I cut them off with a chop saw in front of the 1st baffle before gutting them.

Working from the exit end in:

This is the baffle that is throughout the pipe- some have three, some have four. On the 1st one you can get to, the through pipe is centered, the rest are offset a bit.


Behind the last baffle is the converter (on the newer pipes- older pipes will not have this). The catalytic converter is the corrugated part in the center(ignore the rest of the photo). On an ungutted pipe, it would not have the indentions. That came from me just (recklessly) beating it out:


Next is the reducer. Where the welds are were a plate just like on the baffles:


There is a mesh screen that sandwiches a wrap of fiberglass matting/batting/wrapping against the outer chromed pipe. The 1st baffle is tack welded to the chrome pipe. the rest of the baffles are welded to the mesh.



The mesh and fiberglass can be removed. That requires getting the backing nuts that hold the mounting brackets on out of the pipes. It isn't easy to do without trashing the pipes. They are of this type, and if they spin, its almost impossible. They have to be drilled out to come out clean. These didn't come out clean, but then again, the pipes were trash anyway.


That should be everything in a stock pipe.

Man , how could it breath with all that stuff ? Good thing for Thunderbike pipes . Stay away from Denver .

That must have been some good anger management therapy...nice show-and-tell.

Good stuff. I've wondered what was in there. Can you tell us how much offset there is for the through-pipe in those second and third baffles? Are they completely off-axis from that first one? And what's the distance between the baffles? Always wondered if you couldn't just drill straight through those other baffles through the hole in the first one.

Cool Stuff! Next time maybe someone can take a stock pipe and cut it lengthwise, that would be cool too.

Soren

An 06.

Happy that those pipes came in handy for autopsy and dissection, Dr. Cowboy!

They sure have complicated things since '05. The older pipes were disc type baffles only. Easy guttin' back then.

Somewhere I saw a set of gutted pipes with the old Speedmaster tapered back ends still intact. That must have taken some skill and patience, and a very long extension.

Really thank you for the show and tell. I didn't know there was catalyst in our stock pipes .... all years?

Appears to be 05 and up, from the pipes I've run across. Chevy605 would probably be a SME on this.

I have done quite a few older sets now and those are easy. I would like to play with a set with the cat just so I could see whats involved to do a clean job I could charge for.

so how do I do this with out destroying them? Is there a way to keep them pretty and take them out?

I have done tons with no cat in them and the answer is yes. There are several different methods.If you do a search you should be able to find all the info you need.

I know this doesn't pertain to stock exhausts but just a quick one about removing baffles again but this time it's with tors. So if I wanted to just take out the last baffle in my tors, there seems to be 2 (or more) trains of thought:

Take off both pipes at the join and one at a time by holding the pipe (in a timber vice protected by rags etc) and vertically looking down, get a whole saw with an extension and start to drill. Seems that this method is the most popular.

The other method is wacking the welds of the end plate to try and dislodge it but that one sounds a bit suspect to me. Any ideas cos I want to do this soon and I don't want to stuff it considering these are the only pipes I have?

put 2 saws on one center. The smaller being the same size as the center pipe that one will act as a center drill and a larger one to cut the baffle out. If all you want to do is remove the last baffle you shouldn't need an extension. Be sure to keep plenty of cutting oil on the saw to keep it cool so you don't risk discoloring the chrome.

The rest of the baffles are just spot welded to the mesh and break away easily with chisel or air hammer.

Great stuff Ian. Sounds like the best method I've heard so far. I might take pictures so others can see how it works.

Staffo
when i drilled out the last baffle i clamped the muffler to a 4" post in the patio useing the muffler support bracket held if tight and firm no drama at all

Cheers Brendan, great tip mate.

Whilst we are at it, how much difference did it make and did it drill out alright using a hole saw. I don't know but I keep feeling like it won't work for some reason.

Make sure you use a metal cutting hole saw. I did most of the ones I did with an air chisel but I know a few that have tried that and didn't have much luck because they caught the mesh behind the first baffle.

That's right chevy605 is a certified forensic pipeologist and theres nothing baffling about that.