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runit3 09-21-2009 09:46 PM

DIY Muffler Delete (JK)
While changing my diff fluid I decided to get rid of the stock junker muffler. I Plan on getting an MBRP cat back down the road but this was a $21.49 investment with a surprisingly good outcome.

Parts List:
x1 2.5" exhaust clamp -$2.50
x1 2.5" 45 degree pipe -$5.99
x1 2.5" x 48" long straight pipe with single side coupling-$7.50
x1 JB Weld classic (good to 600deg F)-$5.50

Tools Needed:
-15mm spark plug socket
-(any size ratchet driver)
-Hacksaw/metal jig/cut-off grinder wheel
-A strong table mounted vise is handy

1) Use 15mm socket to loosen stock muffler clamp, give it a whack or two to shake off the mud/accumulated crap
2) Use a combination of screwdrivers, grease if you have it, and swearing to pry off muffler from rubber hangers - remove muffler and set aside. DO NOT be tempted to salvage the clamp from the stock muffler, it is welded in place, I drilled the spot weld and it still did not come off- just buy the new 2.50 clamp...much easier.
3) mock up exhaust pieces together and position the elbow on exhaust outlet above rear axle. Decide how you want your outlet pipe to be positioned, I chose a left-swept out. Mark your cut-off with a sharpie, the pipe will extend past the bumper, it's unsightly and puts unnecessary strain on the only hanger position in front of the axle, take the time to hack off the extra length.
4) Grind/polish the exit of the elbow for a clean JB weld surface, it will also make the straight pipe coupling slide on a little easier.
5) Apply JB Weld liberally to the elbow exit, hold the elbow in a table vise (or between your feet on the ground) and hammer the straight pipe coupling over the elbow until it has fit completely. Inspect the JB weld and make sure the pipes are completely sealed together. Allow JB weld to set-up for at least 25min before continuing to work.
6) Mock exhaust clamp onto elbow coupling, most clamps will use the same 15mm nut, fit elbow on to stock exhaust outlet, position how you would like, and clamp. Some may swear by muffler/gasket sealant but I don't have even the slightest fume/liquid leak on the pipe, if you feel the need go for it.

If you want a straight pipe out you will need to bend the elbow ~5-15deg depending on what rear bumper system you have in place, best way to do it is with a mandrel but a vise and pry bar will also work.

Sorry about the lack of pics, I only have finished photo.

I'll spray coat it black sometime next week after it's been burned in and I'm sure the JB has set. It sounds a little gurgly but not too loud or obnoxious. Without the muffler there's a small loss in back-pressure, no noticeable difference in performance but mufflers rarely have any on naturally aspirated gas cars. Sounds nice, cheap, and easy.

jgano23 09-22-2009 07:11 AM

did you eliminate the muffler entirely? it is illegal in a lot of states to run a vehicle w/o a muffler.

InfernoGirl 09-22-2009 08:00 AM


Originally Posted by jgano23 (Post 445848)
did you eliminate the muffler entirely? it is illegal in a lot of states to run a vehicle w/o a muffler.

Only if you get caught :D. I don't anymore, but I ran my Tahoe with open headers for a little over a year. Never had even that first glance from a cop. My husband on the other hand, was very nervous everytime he drove it.... Go figure :) The only reason we put a bullet muffler on it, was because he was sooo worried he'd get a ticket. Personally I find it less obnoxious than most the Harley's around here..... JMO.

runit3 09-22-2009 10:38 AM

Yes, the muffler is completely gone. The existence of a muffler is not a requirement by most states, the existence of the catalytic converter is the issue.

The ONLY thing modern mufflers do is create back pressure and baffle sound, they do not reduce emissions. An officer could site you for a sound violation, but the JK doesn't sound any louder than a diesel full ton pick-up flooring it to 6k rpm, and thats when the JK is running at 5k RPM getting on the highway.

Vehicles get an auto-fail at the DEQ if they have any engine lights on, this is usually due to someone modding the headers or cat, I passed DEQ with flying colors. In Oregon they no longer do the tailpipe emissions test, they just plug in an OBD-II Sensor and get a diagnostic readout, not having a muffler doesn't affect really anything other than the sound.

runit3 09-28-2009 12:22 PM

Here's the coating steps:
1) I took the pieces back off after being burned in for ~50hwy miles and some deliberate full throttle take-offs. Cleaned all the pieces with brake cleaner and gave them a thorough scrub down.

2) I picked up some rustoleum matte black high-temp rattle can, rated @1200deg F. VHT high temp primer and matte black were my first options but the rustoleum was cheaper and more available. I can always re-spray later if needed.

3) I sprayed about 3 coats on each side of all the hardware (except the fastening nuts, they're stainless) The stated "to touch" dry time was 25min but I found that it slid off with some pressure and left my fingerprints all over it, the last coats I waited 45-50min each side.

4) When I felt there was ~1/4 of the can left I sprayed inside the pipe, rotating it around while spraying and alternating ends to give the inside as much of a coating as I could. Over-spray really doesn't matter on the inside, no one is going to see it.

5) After the pieces were completely dry (~2hr) I reassembled and changed the mounting angle to curve around the rear springs. I also relocated the fastening nuts to the inside (middle of the jeep) to keep them away from the rear sway bar and body. This way if the pipe catches on the ground on a steep incline nothing will be scratched.

I tightened the fastening nuts to ~150ftlb. It keeps a nice seal and doesn't warp the pipes.

rrich 10-03-2009 09:22 PM

It may not be too loud - in your opinion. But be warned, Federal lands, like Forestry and BLM lands require a spark arrester if no muffler is present. Straight though mufflers, like glasspacks aren't legal either.

Think of the consequences if you start a fire!

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