Remember how great your car sounded when that straight-through performance muffler was brand new? Over time, though, the fiberglass packing burns out, changing the tone and increasing the decibels. This also has a detrimental effect on performance, as the straight-through design stops emulating a straight pipe’s flow and works more like an expansion chamber.
Round mufflers–like those from Burns Stainless …
Nice muffler rebuild!
I went to the MagnaFlow website to see how this offset muffler was constructed as a straight through muffler was constructed, but all I found was a short animated video of a straight through muffler.
My question is:
What does that muffler look like inside before you packed it full of fluff? Could you actually see through the muffler if you held it up?
Too bad there is no information on how to get the old packing out. I've had motorcycle silencers were the packing was all carboned up and as hard as a rock. It was one solid chunk.
Always wondered about this!!! I have a muffler from a race car that burned out and I have always wondered about re packing it.
A side note - Welding galvanized metal like the electrical block-off plate that was used to close up the muffler in the article can make you feel a bit under the weather. It is actually called Metal Fume Fever. Kind of like a hangover or a mild case of the flue. It is from the zinc burning. I have had this and it sucks.
WIKI >>>https://en.wikipedia.org/wiki/Metal_fume_fever
I am sure you all know this but figured it was worth posting up. Better to go to the other end of the motorsports department at Home Depot and get a 12" square piece of regular sheet metal. It is also sold at most local hardware stores. They have a small rack with miscellaneous pieces of sheet metal and bar stock. While not as cheap as the electrical box cover it is much better for welding.
When I did mine, I sliced the top and bottom off and packed very thoroughly, then spent about eighty pounds of wire welding it back together. Worth it.
Could pack around the front (on right) but getting full wrapping around the rear required slicing the other side.
Honest question: By the time you've bought the supplies, cut, stuffed, welded, and repainted the muffler, and paid yourself for the time cost....couldn't you just have bought a new one? I'm not part of the throw away society where the answer is to buy a new everything but this seems like a borderline exercise for $50 and a whole afternoon of fab time. I just repacked straight through muffler and it was $20 and 20 minutes of time but I don't know I would have messed with this. Hell, I probably wouldn't have even bought a new muffler and just lived with it being louder unless I had to meet some decibel requirement.
In my case, the mufflers are NLA. Racing Beat changed suppliers and the new ones are not the same build quality or sound reduction.
Yeah, depends on the value of your muffler for sure. A good quality stainless one will last forever though, and often are 200 to 300 dollars. But frankly, that looks horrible. I would go thru the top like the other guy did above if you can't do it in the back, no need to mess up the end you see. Also, just find steel that is the same type. Don't weld mild to a stainless muffler. You buy a stainless muffler so it will last forever, if you weld mild to it, it will rust out there eventually, regardless if you paint it. Hit a metal mart/recycler, it's often not that hard to find a little bit of stainless sheet steel laying around places like that. If you get some strips of stainless sheet, you can cut square sections off the top and then use the strips to cover the gaps from your cuts and just weld the same piece back on.
So this packing material can survive being welded? Be carefull what you use for packing material, try and light it on fire before you stuff your muffler with it or you'll make a blazing inferno and engulf everything you just put back in there as soon as you start welding.
In reply to John Prieve :
Try CRC Intake Valve & Turbo Cleaner to "Dissolve Baked On Carbon Deposits"
In reply to dean1484 :
Welding supply stores have masks good for welding galvanized and stainless (the latter to avoid cancer)
In reply to SupraFiend :
Depends a lot on the application. Stainless is a much weaker material than mild and will break. I repacked a Racing Beat muffler because the old ones were mild steel. The new ones are stainless and they crack within one or two heat cycles.
In reply to Pete. (l33t FS) :
Depends on the quality of the stainless. Headers are often made from stainless.
I just meant don't mix metals. If it's a stainless muffler, use a stainless patch, and vice a versa.
In reply to SupraFiend :
Mufflers in particular do not like being made of stainless unless there is a slip fit internally. Otherwise when the outer shell is 150F and the inner perf tube is 1500F the end plates can crack or worse.
Here is a video I did repacking a Borla, but I also talk about other style mufflers like Magnaflow
https://www.youtube.com/watch?v=ODf1T62ziZY
I've read the old rotary race mufflers of the 70's and 80's were packed with crushed lava rock due to the ridiculously high heat of the rotary exhaust. I plan to do this when one of other mufflers burns out shortly.
You can save yourself a bunch of money on repack materials and use standard construction fiberglass batting, minus the paper of course. I repacked an empty Gold Wing exhaust that the previous owner gutted to get that 'bad boy' sound. It has held up well over several thousand miles of highway and back road adventures. Didn't cost anything other than labor 'cause I had some laying around from when the house was built. You probably do too. You may not like the results you get but it worked for me.
This has been a great article because I never even gave this a second thought! I personally would spend the time doing this just because the parts I already have, I am learning something new, and I have no idea what the inside of the muffler looks like, but really wanna! Call it curiosity of the cat or what ever for me wanting to do this, but I won't weld anything galvanized because it can kill the cat...
Thanks for a good read and making the gears in my head turn once again :)
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