JCW Mufflers + resonatorectomy
 

So, I know there are a few of us here that have had our resonators removed from the JCW exhaust. I have two sounds that I'm trying to figure out and I'm hoping someone else has/had them too. I think the sounds are either caused from the mufflers or from the piping right before the Y split to the mufflers. Let me explain:

One sound is a vibration from the rear. The only time it can be heard is if the car is in gear, moving and slowing down. So say I'm in 3rd and I take my foot off the accelerator. As I slow down I can hear a vibration of sorts, like a rattling. Very loud internally, not sure if you can hear it at all externally. I got out and shook the exhaust a little. Crawled up underneath to see if anything was touching or loose. Shaking the exhaust around exhibited no sound, and there was nothing that looked to be touching.


The next sound I have been hearing is the popping. After releasing the accelerator, the burbbling is there and sounds amazing. Much better than it used to. Only side effect is this: I (and some others) are getting some popping or snapping sounds with those burbles. With the windows open they are very loud. Sometimes I'm wondering if it is taking away from the classy feel of the Mini. With the windows closed, however, it's much clearer to hear. What I'll hear internally is some nice burbbling and then a pop.

(You really have to sound this out) burbble..burbbleburbble...burbble..POP! POP!

It's like the burbbling is coming out and then it just cuts off quick to a loud tinny pop.

******************

So Sound 1: Vibration on deceleration while still in gear. Sort of tinny sounding.

Possible Cause: After some thought, I began to think that maybe, without the resonator, there was more flow through the mufflers and that it was possible that maybe the insides of the mufflers were rattling around. By that I'm assuming that after 12k miles, the muffler insides would begin to degrade and crumble a little.

Sound 2: Tinny popping from deceleration burbbling.

Possible Cause: At the Y split going to the mufflers, I noticed that they flattened the pipe to be semi oval. Not sure exactly why this was done, but I'm guessing for a different resonation throughout the system. But because of that, I'm thinking the exhaust is being squeezed together and expanded rapidly through the mufflers causing a SNAP.

so what do you all think/recommend me doing?

-Nick

Well, I can tell you what I think I'm going to do - just wait.
I have really been thinking lately of doing this t my JCW and I haven't been too sure how my wife would like it.
I put a flowmaster on my Dodge truck and she hated it, big time. So we sold that and got this Mini and she doen't want it to sound like a Tijuana Taxi.

So, I heard the M7 exhaust is not kaputnik and Randy at WMS is still working on his, and could take some more major time. So, I'm just going to wait.

For you, I would suggest getting the same business that removed your resonator to do a good check on your mufflers, there easily could be a baffle or other small part that broke loose and could possibly be shaken loose and also out once the muffler is removed.

I'm interested in your wife's opinion as well.

Wife?! Not married just yet, I'll be waiting on that :lol:. My girlfriend doesn't know too much about cars and doesn't care too much to learn. So any sound is weird or strange :razz:. Her first impression was that she didn't like the louder burbbling, but for me that's what makes it sound nicer.

Although, I think I will have the shop take a look at the mufflers, or maybe have Mini do it. If Mini complains, then I'll have the shop look at them. I have see what happens.

Thadeus13,
How did you do your resnoatorectomy? Did you cut out the resonator, did you use a piece from the stock exhaust or use that myminiparts straight pipe? I ask because I'm taking my car in tomorrrow to get my resonator removed.

As to your second observation: are talking backfire POW or more like a pronounced sputter? I know, it's hard to convey sounds in print, but I'm curious.

I used a stock systems straight pipe from an MCS.

It's a POW from the burbble. Think about it like a burbble that has more force behind it. So instead of just "lapping" out with a "burbbbblle burbbbblle", it will just SNAP out.

Thanks for the clarification. I'll see if it happens to me an will report back.

That would be great, thanks!

Just got off the phone with the owner of the shop who did the installation. Basically I asked him what the two noises could be or were caused from.

1) Vibrating sound: He said to take a look at the air diverter in the back, that metal shield underneath the exhaust under where the battery is. Since the exhaust moves back and forth when on and off the accelerator, it's possible that it got bent a little during installation and is just hitting during deceleration. I'll have to check that this weekend and let you know.

2)The snapping is basically from this: When letting off the accelerator, cold air is being sucked into the exhaust with the back pressure and when that cold air meets the hot air coming out from the cat it snaps. Just like a thunder clap. Hot air and cold air collide and you get a pop.

Thadeus -

Thanks for the clarification. I have the same two experiences without a resonatorectomy. The popping, I'm told from several sources, is a fact of life with a JCW. Not a very technical answer, but suffices to know nothing is wrong. As for the rattle, I checked the diverter plate and had the dealer do it too. No problem found by either of us. I am convinced it is a broken baffle in one of the muffs, but try to get a dealer to replace the mufflers for an intermittent noise:sad: (PS, is your rattle more likely to happen on short drives but disappear after a lnog drive when the car is good and hot?). I'd be interested in knowing the results of your further inquiry.

Also, please forgive ******* question, but why do a resonatorectomy and what is the downside? Mucho thanks.

First time I've heard it put that way. Interesting.

Its the POW you describe that keeps me from doing this, I don't need another POW from my wife if I do this.

nope, this was done in '05 to accomodate the crossbar added to the cabrio for additional stiffening. the support is not present on the hardtop, but the same pipe is used in both models to simplify the parts inventory.

i doubt the "squish" does anything helpful for the exhaust; i've been looking for a replacement piece to straighten out that passage.

Well, before the resonator was removed I had no "popping". Burbbling yes, but not this popping. If I have to deal with a little snap to make it sound the way I want it to 90% of the time, I'll be fine with it until I make a clear decision on what cat-back I want.

I think my first step is going to be to remove the diverter plate completely and then do a test drive. If I still hear the noise, then I'll start looking around at all the brackets and tightening them again. If it comes down to it, I'll just have a shop look at the mufflers and see what's going on.

When I get home from work, I drive my car from the train station to my house. The vibration occurs during this drive on a day to day basis. Just to test, I took the car out for a drive around town (15-20 minutes) and the noise still persisted. I alternated between in gear and out of gear slow downs. Noise only occurs when the engine is being turned down. So after the acceleration is off and it's just slowing down while still in gear.

I thought the JCW exhaust wasn't aggressive enough for the name. I expected something with a low tone at speed and at idle and nice deep tone while accelerating. I got this by removing the resonator. Cons? Louder and then sometimes you get issues like the ones I'm having, I guess :lol:.

Update from this weekend
 

So this weekend I jacked up the Mini to take a peek underneath and see if anything was loose. I rattled the exhaust around a bit and nothing seemed to be loose. I removed the air deflector and noticed it was bent a little on one side. I took a trip around the block without the air deflector on and it still vibrated.

Afterwards, I bent the air deflector back into shape and put it back on, making sure that it didn't come close to the exhaust pipes. I made sure that the heat shield wasn't touching the exhaust pipes either. So now, happy that nothing was touching, but unhappy that I didn't solve the problem, I just put the car down off the jack and moved it outside.

At that point I took a walk to the back to see the exhaust while the car was on...again. I noticed that the exhaust was actually pretty close to the bumper. I had this issue when I picked up the car. They installed the exhaust before they installed the aero kit, so the aero kit sat only about a half inch away from the tips. I had mentioned this at my last visit to Mini, that the exhaust would rub on the bumper and cause a loud vibration when the car was very low in first gear or reverse (almost about to stall, so everything vibrates more). But now the exhaust seemed even closer, so I've concluded the following:

1) Since the resonator was removed, the exhaust is louder and burbbles a LOT more. This causes the exhaust to shake more. When the engine is turning down and the exhaust burbbles, the vibration occurs. Which leads me to believe that the tips of the exhaust are vibrating a lot more and just "bumping" the...bumper (*sigh*)

2) Either me or Mini will have to adjust the exhaust to make it so that it doesn't rub on the bumper any longer. (Read: I will be adjusting the exhaust, since Mini mechanics said "That's normal, of course it's going to move and hit the bumper.")

And finally...another question for you motoring maniacs!

What's the best way to go about adjusting the exhaust? Is there a way to drop the exhaust down an inch or so? Do I just go and buy new rubber hangers that are longer or is there a bolt somewhere to do this?

Thanks for all the help!
-Thad :thumbsup:

Not trying to hijack it but
I wanna know how to adjust exhausts.
I have Borla Sport which is well known for a lot of adjustability but,
I just cannot loosen the freaking nuts on clamps.

I tried WD-40, spending some time under the car trying to loosen them so I can adjust the tips but crap, they just wouldn't turn..

Yeah I can take it to a shop and pay them but I would rather try to do it myself first.. Any tips on how to loosen the over torqued clamps?

Plus, What size of washers to add on the hangers??

Couple of things...
 

the pop isn't cold air hitting hot air. Put your hand on the exhaust pipe at idle, and you won't feel any suction at all, pulsing yes, but not suction. This popping issue is new to the younger crowd, but for us grey-hairs that know about carbs, V8s and glasspacks, this is nothing new. On carborated cars, it's from unburned fuel getting into the exhaust system that's hot, and it lights off. In fact, any carborated car with a performance exhaust will burble and spit. Just a fact of life. In fuel injected cars, it's from programming to sound like it's a carb under engine braking.

Exhaust clamps are a pain. If squirting them and letting them soak for a day or so doesn't do it, get out the grinder or whatever, and just cut them off. Get some more band clamps to replace what is shot. The temp variation, and all the crap off the road makes this pretty much unavoidable.

For adjusting, loosen, move and tighten. It can help if you have someone looking at the tips as you do your thing, otherwise it becomes more iterative as you make changes, get up and look, ,make changes etc.

And I think powerdyn makes a bunch of urithane hangers in different lengths. But really, if everything is well adjusted, you shouldn't need them.

Matt

Interesting enough, Coca-cola (regular, not diet!) has loosened some hard to break nuts at times. Its something we used to use when all else failed back in Auto shop when High Schools had Auto shop.

Give it a try, might work.

paul

ooo Coke eh?
Well how am I going to do that? since the nut is leaning downward, it will be hard to maintain them on the nut, (they will drop off :sad: ) Gahhhhhhhhh
Thank you for the input! Will try!!

Thadeus - For what it's worth, Tech was finally able to replicate this sound in my JCW and diagnosed a broken baffle in the muffler - at least on my car. TG for the warranty. New exhaust is on its way. Hope this helps you.

Well, it took me a while to find the time, but I put a piece of stock tubing in place of the center resonator section last weekend. I think I understand where the popping complaint comes in. Without the resonator, the sound is primal- it's deep, it spits, it sputters, it goes "popopopopop" when you lift off the gas- all very cool. No droning at any speed or RPM, either. It does, however, sound, a bit tinny when cold (maybe the first 60 seconds), and if you lift off from light throttle, the "popopopop" sometimes comes out as a POP- like a halfhearted backfire. I guess it can be a bit embarassing, but the overall sound is so nifty, I don't really worry about it. My gas mileage has already decreased because I floor it and then lift just to hear the exhaust...

I'm just wondering, does it sound anything like a Tijuana taxi? My wife insists that alot of these muffler mods sound just like that.
Mabe she spent too much time in Tijuana?!?

Paul

God, I hope not. Seriously, though, if you can get your hands on a stock exhaust, all you need to do is hack off a piece and bolt it in. Someone near you has got to have a stock system that they'd beg you to drag away. It cost me 20 bucks and less than an hour under my car. If I get tired of it, I can replace it with my resonator piece at any time. If I had any technical expertise at all, I'd post a sound clip.

FYI: My SA calls the "resonatorectomy" the Rice Krispie mod, because there's nothing you can do to avoid Snap, Crackle and Pop without a resonator in yer JCW. When I say nothing, I guess nothing that the dealership would do. Jury rigging something is always an option.

Thanks for all the responses everyone!

I ended up putting the resonator back in, even though I enjoyed the tone of it immensely. Personal preference for sound. I didn't like that loud backfire-ish pop that was occurring.

So that solved the one sound, the other sound still exists, although not as often. I will be bringing it back to the dealer to have them check the baffles on the mufflers and any possible clearnance issues with the exhaust and the heatshield.

Although, I'm glad that people are actually understanding me! :lol:

-Nick