cutting down a carbon fiber muffler?

how is it done? im sure there is a thread on it already but i couldnt find it. how hard is it to do? and how do you do it?

thanks

Joel

Dremel with cutoff wheel. Sand exposed edge with 360 grit wet paper. Don't breath in the particles.

how do i put the end cap back on? just pop rivets?

Theres probably and inner metal sleeve that also has to be cut down, it holds the packing. Then you can pop rivet, or use a high temp epoxy to put the end cap back on. But rivets are better if you plan on replacing the packing anytime later.

4tuneit1 said:

Dremel with cutoff wheel. Sand exposed edge with 360 grit wet paper. Don't breathe in the particles.

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and then brush some catylized epoxy or polyester resin on the cut edge so it doesn't fray, unravel, crack or chip.

THEN re-assemble the can

you guys leave out important steps, like STEEL pop rivets for an exhaust, etc,...

Use caution cutting/modifying carbon fiber parts. Much like intact egg shells CF is a strong material until they're cut, cracked or suffer other damage.

Like Reckon said, any exposed carbon fibers need to be resealed to prevent fraying. Even then pay close attention to the CF breaking down or coming apart.

reckon said:

and then brush some catylized epoxy or polyester resin on the cut edge so it doesn't fray, unravel, crack or chip.

THEN re-assemble the can

you guys leave out important steps, like STEEL pop rivets for an exhaust, etc,...

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I've cut a few mufflers..they don't unravel, the epoxy prepreg or layup prevents that. A simple sanding of the ends with water smooths the carbon and once you put the cap back on, there won't be any fraying. Aluminum rivets work fine, steel even better though.

4tuneit1 said:

I've cut a few mufflers..they don't unravel, the epoxy prepreg or layup prevents that. A simple sanding of the ends with water smooths the carbon and once you put the cap back on, there won't be any fraying. Aluminum rivets work fine, steel even better though.

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I'm glad you don't do this type of thing for a living

I really don't want to start an argument, but this information is just dead wrong.

and no offense, but how do you know the layup was pre-preg? or even pressure cured? it's probably just a simple "brush, lay, brush" layup, with a single layer of BS bling bling CF weave, which after being cut and sanded, is now exposed and ready to soak up all that nice exhaust grime, & oil which can "wick" down into the CF fibers surprisingly far.

so to BE SAFE, just brush .02 cents worth of 30 minute epoxy on the edge and not worry about it ever again.

I never saw anyone argue about doing bullshit amateur half ass repairs, AND THEN STICK TO THAT

god I hope you don't work for randtron, or lockheed.

Why should aluminum (instead of steel) pop-rivets not be used on exhausts? I have used them on a few exhausts without issue, although not for long periods of time.

Thanks.

Here's the yoshimura repack vid:
http://www.yoshimura-rd.com/t-muffler.aspx?v=vid

that's part of the process

-I used a chop saw, to cut straight the muffler section
-driller out the rivets to remove the end cap
-put the rivet band around the remainder of the sleve, marked where the holes should be with a sharpie, then drilled out rivet holes
-reassembled and rivetted the end cap back on

well i used aluminum rivets, i guess aluminum is easier to drill through later on when you need to remove it, and unless you are certain its stainless, aluminum won't rust

reckon said:

I'm glad you don't do this type of thing for a living

I really don't want to start an argument, but this information is just dead wrong.

and no offense, but how do you know the layup was pre-preg? or even pressure cured? it's probably just a simple "brush, lay, brush" layup, with a single layer of BS bling bling CF weave, which after being cut and sanded, is now exposed and ready to soak up all that nice exhaust grime, & oil which can "wick" down into the CF fibers surprisingly far.

so to BE SAFE, just brush .02 cents worth of 30 minute epoxy on the edge and not worry about it ever again.

I never saw anyone argue about doing bullshit amateur half ass repairs, AND THEN STICK TO THAT

god I hope you don't work for randtron, or lockheed.

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Because there's been such a huge rash of unraveling carbon fiber mufflers ENDS causing so many owners such grief because owners like those in this thread DONT WORK FOR LOCKHEED and choose to not to listen to your .02 expert advice...roflmao!! whatever dude You're treating an exhaust tube as if it were a stressed member of a Nasa wing spar and sounding pretty hyper sensational because I didn't AFFIRM you're epoxy on the end of the cut advice. If you prefer that...by all means do it. Epoxy the end cut! Jesus

FYI simply put... A carbon fiber pipe can usually made from three methods for production. A) Filament wound (ie like a fishing pole). B) Autoclaved using a pre impregnated sheet of cut to length/width carbon fiber on a mold with a vaccum setup. C) Hand laid up

Depending on the finish look, you can choose A,B,or C. You wil get huge differences in quality of strength and appearance by doing a wet layup by hand, or by utilizing a mass production method like many of the major muffler brands who simply buy carbon tube and cut it to length. But in all the process' epoxy is impregnated throughout the entire carbon fiber weave, whether the first layer is fiberglass and the final is carbon is irrelevant. High temperature epoxy is consistantly saturated throughout the part and there are no air VOIDS in a properly fused carbon fiber tube for wicking to occur. Secondly, Epoxy by nature is resistant to oils and petrol products which prevents all of those "exhaust products" from turning your carbon exhaust pipe into a potential ticking time bomb as some present. Cutting it cleanly with a Dremel and sanding the edge will not impart ANY weakness in the overall part as I instructed to do, and the edge that is finished cleanly presents a tiny footprint once sealed against the cap of the muffler for anything to migrate into, unless you plan on submersing your pipe in a vat of 20 weight oil for any length of time.

But hey remember... Our expert here didnt also tell you to Epoxy those bolt rivet holes before you re-rivet your end cap on! You know..in case all those frayed ends unravel your Yoshimura on the freeway.

4tuneit1 said:

Epoxy by nature is resistant to oils and petrol products....

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except the fibers themselves do absorb stuff, water in particular.

+1 to the rest of what you said, except with out the e-penis fighting. i use superglue to seal up the edges of CF i've cut if i'm worried about it.

If you have access to a table saw. There's metal cutting blades, like a larger version of the Dremel disc(very thin 1/8" thick). Can get an even cut easily. Lessen the chance to fray the fibers.
Start a scoring pass where the blade only cuts 1/16" depth. Then cut fully through on the second pass. This minimizes tearing the fibers on the exterior fibers the most visible part.

If fraying is a problem. Before cutting put a few wraps of masking tape over the cut line.
After the cut, leave the tape on. Dip the cut edge in a bowl of resin to seal the end. Let dry then remove the tape and sand lightly. Brush on a thin layer of resin to finish.

Reason for dipping into a bowl of resin. The less disturbance of the loose fibers the better. Brushing resin on will no doubt shift the fibers in gaps and bunches. Get it solid then shape by sanding.