My Yosh R77 has 14k miles. Over time the exhaust has lost that nice crisp sound and become boomy. Yosh recommends repacking every 7-10k miles. Don't read a lot about people repacking mufflers so I figure either people found it easy or it's something people don't do. I wouldn't be surprised if many have exhaust systems which might require this service so check your exhaust system if you're not certain.

I consulted a few people on what to do for packing. Some suggested using fiberglass insulation, 3rd party kits, and Yosh's repack kit. After some research I with Yosh repack kit. The main reason is longevity. Found an example where someone used Fly Racing kit (on a dealer recommendation) and it burnt up in a thousand miles. I mean burnt, like the worst burnt toast. Also have read home insulation isn't ideal and will wear out prematurely. That was enough for me, go with OE kit. Plus the OE kit comes with about everything you need, rivets, new name plate (not really needed, but nice), new bands, instructions, correct amount of batting, etc.

Dissassembly

I don't have much experience riveting. At first I thought they meant mark for drilling, but they don't. They mean punch through the rivet center. I hadn't acquired any punches at this point in my tool collection. Don't waste time with improvising screwdrivers or wood handled "punches". I know, normally a screwdriver can be used to beat something into submission. In this case it's just a bad idea. I'll leave it at that. I went to Menards and bought 5 different Wilde brand punches. It's this simple, punches transfer the energy far more efficiently than other tools. Makes things a lot easier, wasn't quite like Yosh's video but a 2-3 hits and done. I ended up using 2 of the punches out of a nail head punch kit. Worked perfectly.

Drilling the rivet is the next step after punching out the centers. Either I have the sharpest $5 set of drill bits on the planet or their instructions are just overly cautious. A few seconds with the drill was all it took to clear the rivets despite them being stainless steel. Very underwhelming I was expecting it to more like drilling into the Nakatomi Towers Vault or something.

I don't know if I waited too long but my muffler core didn't just slide out a with a few taps. I had to beat it out with a 2x4 slamming it to the ground to push it out. It was sort of like the fiber glass had adhered to the can or something. Maybe a couple of quarter horses could've pulled it apart, I don't know. Maybe that's part of the reason they recommend 7-10k miles.

Reassembly
This was pretty much a PITA. It was a pain to get the packing in there. It was a pain to get the end caps lined up. It was a pain to rivet except for the smaller nameplate rivets.

I bought the "heavy duty" rivet gun at Menards. Unless you have superhuman strength this doesn't work well with the 3/32 stainless rivets. I'm sure aluminum rivets would be no problem. THe smaller rivets for the cover weren't any problem. For the 3/32 rivets I ended up just using brute force, at times employing a c-clamp and at times pressing the rivet gun handles against the bench. The 3/32 rivets Yosh includes aren't smooth for some reason, and this adds to them not working well with the rivet gun.

Someone that does this every day this probably really simple. For someone doing this their first time, I don't know. I suppose next time it'll be easier. But I certainly wouldn't blame someone for having this done.

Some suggested using fiberglass insulation,

My exhaust has a mesh tube with fiber packing all around it. It comes out by removing the end cone (3 screws) and loosening the screw fastener for the packing tube. At least I hope it would be that easy after 7 years. I also have a noise reducing insert which is a smaller tube that drops down the center of the main tube. I recall it came with some steel wool looking stuff for packing. Never used it.

* Last updated by: Rook on 8/21/2016 @ 3:42 PM *

what was the condition of the packing when you opened the can at 14 grand ?. was it total burnt toast ?. could it have made it to 20 grand?

My exhaust has a mesh tube with fiber packing all around it. It comes out by removing the end cone (3 screws) and loosening the screw fastener for the packing tube. At least I hope it would be that easy after 7 years. I also have a noise reducing insert which is a smaller tube that drops down the center of the main tube. I recall it came with some steel wool looking stuff for packing.

Yosh exhaust also come with that initial layer of "steel wool". They say to inspect it, but they do not include it in the Repack Kit and it does not appear they offer the replacement parts. Yes, that I understand household fiberglass insulation is not built to stand up to the temperatures required in an exhaust system. I don't know, frankly doesn't seem worth the bother for something that needs done every 1-3 years.

what was the condition of the packing when you opened the can at 14 grand ?. was it total burnt toast ?. could it have made it to 20 grand?

I was expecting it to be darker all around. The ends were the dark/burnt. Overall it reminded me of an air filter. An air filter can look clean but still need changed. Inside the "pillow" (the fiberglass strands) was dirty even if not burnt. One of the main reasons I did this was I could physically feel my exhaust can getting hotter and hotter. Since it's CF I didn't want to chance damaging it. Could I have went 20k miles? Probably. I don't know how loud the thing would've been at that point, probably would've sounded like an old car with a hole in the muffler.

So... are you happy with the results? Did this change the exhaust sound back to what you were looking for?

Yes, I'm satisifed with the results. Hopefully I did it right and it last the 10k miles it's supposed to.