First time Jeep owner here! Just thought I'd say hi before I told my little story.

Decided to take advantage of the sound-off promotion for the first mod to my 2011 Jeep. I'm a muscle car guy at heart and went with the Dynomax VT catback system. I was encouraged by the video posted by the Dynomax rep in post #2 for this thread https://www.jk-forum.com/forums/show...ecommendations. Thats really the sound I was looking for. However, I was a little afraid of interior drone given I have the windows up about 10 months of the year. Anyhow, on the with the show...

So a buddy and me got it installed this weekend. Neither of us are grease monkeys but between the two of us and a LOT of stuff at our disposal (lift, saws-all, welder, and every craftsman tool invented, we managed it. Install was super easy, except for the dang tail pipe. Probably spent an hour on that alone. We were probably doing something wrong though.

First impressions- VERY quiet. Really couldnt tell much of a difference from inside the vehicle. I noticed it a bit when I did get on it though. Outside the vehicle in Neutral it sounded...ok. A little closer to ricey than I'd like but that is probably just me. My Camaro Z28 has a custom true duel set up with dynomax mufflers dumping about mid car. It sounds...shall we say....angry. Once again I was kinda going for the sound in the video posted above.

Highway- I wasnt expecting any power gains at all...not noticeable ones anyways. But I will tell you this...I drive about 35 mph on the way to work (live on a base). I know exactly how much juice to give it and in what gear I need to be in to get there. This cat back system has thrown that off. I'm having a tough time keeping it under 40 now. Same goes for highway. I'm finding 6th gear isnt quite as useless and 5th gear is even better. There is...as advertised...ZERO drone. Now...I know what some will say. "Its in your head...you didnt really gain anything." Thing is...for it to be in my head...I'd have to hear it. And I dont.

Problem- After putting about 100 miles or so on the system, I started noticing a very annoying and not good sounding rattle when at low speeds...especially when at higher RPM's and shifting. NOW its starting to sound ricey. Certainly not a deeper sound that I was going for. Is this an install issue? I used the clamps that came with it except on the tailpipe....which is now welded since I couldnt figure out any other way to get it on at the time. Not pointing the finger at Dynomax or anything. Its probably my newbish install.

Any idea? Sorry this is so long.

 

first off, the sound clip that you hear is of their rock crawler exhaust system and not what you have. second, regarding your rattle, i would check the exhaust hangers to see if any of them are tapping somewhere. as things heat up, a lot more movement can occur and if i could guess, enough so that a hanger is tapping somewhere. you might also want to check the heat shielding on top of your exhaust crossover. could be that during install, one or more of the tack welds broke and that will definitely cause rattling as well.

 

Yeah I know its not the same system. Was thinking at lower speeds it would be similar but then the drone would kinda fade at highway speeds. At least thats what I saw in a few reviews.

Is the Rockcrawler that different of an animal? If so, I might just have to switch.

 

I have the Rockcrawler and I like it a lot. I also had some rattles, but it was from the tip not being secured. Wrenched it down and it was gone. In addition, I had a problem with the exhaust having some movement around the hangers as WOL mentioned. Moved things around and everything has been great since.

 

On the road right now but we'll get you squared away in no time... sorry for the delay...

 

Preciate it!!!!

 

I just installed this same system last week and had the exact same issue with the exhaust tip (tailpipe). I even called the support line explaining that it just doesn't seeem to fix, if there were any other reported issues, etc. The support rep check the part numbers in the kit and said that everything should be fine. I told him I'd give it hell again and that I'd see what I could find. Well the Jeep has been in the shop for a week so I haven't had a change to mess with it more.

It seemed to me that no matter HOW tight you got the clamp on the tip you can just pull it right off (easily). I was actually considering taking it to a shop to have it welded on. So glad you're having the same problem too as it tells me they mis-calculated or something.

I haven't driven it enough on the highway but also felt that the sound (at the times you wanted to hear it) was much more mild than I expected. The highway was very quiet, as advertised. Again, I haven't had much time to comment on the performance yet.

The last thing I was wondering about, was how the muffler sits. Mine seems to sit higher on the driver's side and slopes down on the right where the tip would go. Does yours sit level in the back or does it slope a bit? I must say that I wasn't thrilled about that either as I think it looks goofy from the back of the Jeep.

 

Alright, back in the office now and can hopefully get you fixed up.

First thing I would check, like WOL said, is the hangers and also where the kickup pipe (the pipe over the axle) is. Since the system is not poke-a-yoked to make sure every installation is exactly the same, there can be variation between setups. This can easily be changed by loosening your torca clamps and rotating the pipe slightly (this will also fix rubi3's issue I believe).

Now, with that in mind and thermal growth in mind as well, depending on the situation you can see roughly 1/2" of thermal growth (increase in length). Please make sure all locations are at least 1" from surrounding components (including the tailpipe where it comes out under your bumper, mine is 3/4" lower and does not make contact even on harsh roads, so you should be good with 3/4" there). This is especially true for the heat shield under the body after the axle. That thing will make noise like crazy if you get into contact with it.

Also, please verify that the tip is tightened down completely (rubi3, I will get to your issue in a second...). Most tips slide on and when the torca is tightened fully, it clamps nicely to the pipe and does not cause rattles.

All torca joints should be sufficiently tightened as well because if they are not, the system could move slightly under vibration from the vehicle on the road and/or the engine vibration. I don't have an exact torque spec in mind, but "good and tight" in this application fits. Please be careful not to shear a bolt though (once the torca comes into contact with the bolt retaining block, you should feel a large increase in resistance as you tighten. I used an impact to tighten mine).

Let me know how it goes...we want everyone to be satisfied with our product so we will do everything we can to help.


As for your tip Rubi3, could you provide a picture of the issue to both myself and "Dynomax" so that we can review the issue here? We have not heard of any fitment issues to this extreme and in my head I am thinking the wrong tip must have been sent to you or something.

As for the muffler sitting higher on the inlet than the outlet, a very small amount of this is necessary for drainage of water. When you burn a gallon of fuel, our rule of thumb here (in OE exhausts) is that you produce a cup of water. Now, if you don't get the exhaust hot enough to boil that water and extract it as steam, it will sit inside the muffler and over the years it will degrade the quality of the continuous roving (the sound deadening material). But, it also sounds like yours is quite extreme. You should be able to loosen the muffler inlet torca and the y-pipe outlet torca and rotate that pipe slightly in the clockwise direction to lower the drivers side down to make it more level. You will definitely need two people as one will typically hold it in place while the other tightens the torca's down. Also, when you do this, you may have to adjust your outlet pipe slightly as well since it will want to be up higher now and I would want to avoid hitting the tip on the bumper and making noise.

As for sound, you guys purchased out VT system which incorporates our passive valve technology. In order to get that "deep" sound you were looking for, you will have to get enough flow rate through the muffler to open the valve. I can attest to this because I have this muffler on my truck (not my Jeep, my truck with a 350 Chevy motor, so don't start yelling at me for calling a Jeep a truck...I know it isn't ). If I ease onto it and take it nice and easy, it will be quiet throughout the RPM band (that is the purpose of this muffler). Reason being is that valve is closed or only very slightly open during these situations. But, once I put the hammer down, it completely opens up fully and sounds amazing! Also, you need to remember that doing "free kicks" at idle puts zero load on the engine, so exhaust flow increase is not as much as if it were driving up a hill and flooring it (under high load percentages at a given RPM, the exhaust flow will be higher than zero load at the same RPM) and the engine can only rev to what, 3500 or 4000 RPM before the ECU overrides you? I can't remember, its been a while since I free-kicked mine...

Hopefully this helps, and if you have any further questions, please don't hesitate to ask.

 

Thanks for the info. I'm not as worried about the sound as I am the fitment of the tailpipe and the look of the slope.

Here are a few (bad) pictures that I took when I got the muffler on. It was dark, and in my garage, but I think it at least shows somewhat of what I mean. You tell me if this is normal.



I will loosen stuff up and wiggle things around to try to re-align the muffler a bit. May just take it to a shop to have the ease of a lift and extra set of hands (my wife isn't going to be much help).

I am going to use an impact wrench on the clamp for the tip to see if it can get any tighter. I will definitely make a video and post it showing how lose it is later today or tomorrow.

One last (stupid) question... how do you suggest I get the paper labels off? They won't burn up if I just leave them on will they?

 

That looks a little extreme on the tilt of the muffler. That would annoy the crap out of me! I would loosen it and reposition it and then tighten it back up like I said before. It should be much closer to level than that.

As for the tip, contact user "dynomax" as he will have further details for you