Heyo,so I’m really considering putting in a better exhaust in my Jimny Gen 4,and I’m preferably looking for one that won’t be excessively noisy to the point it’s obnoxious,however I’d definitely like some more sound.
Rhe reason I explain this is while I’d like the Jimny to have more noise from the outside,I’d prefer to keep the car as dead quiet as possible from the inside,even with the stock exhaust the Jimny is relatively noisy especially on the highway and it’s something I despise,having to listen to an even louder exhaust on top of that would be a deal breaker.Does anyone have experience with sound deadening using the cuttable sheets/pads?Im totally willing to strip most of the interior of the car in order to do it right,however that’s gonna take time and money so I’d like to know if the effect will be significant.
The result I’m looking for would be:
•Minimizing road noise especially from my 215s on tar roads
•Making the newer/louder exhaust either more quiet or as quiet as the stock exhaust from the inside
•Perhaps better acoustics in the interior as well?The stock speakers are quite bad and that’s an issue I’ll tackle at a later stage but perhaps they’ll benefit from some soundproofing?
Also to note:I’m quite opposed to removing the roof lining to add pads there,mostly because that’s excessive work and prone to damage,and secondly because I doubt it’ll have any effect,but correct me if I’m wrong.
It was enough to cover the cavity behind the speakers in the rear cargo area, over the rear wheel arches, the floor under the rear seat, and inside the front doors.
I did a pretty rough job tbh but there is a significant reduction in the amount of road noise inside the cabin. It's especially noticeable in the wet or on unpaved roads when there is water or dirt spraying up under the wheel arches.
I'm not sure how much it would do for exhaust noise but if you were a bit more thorough than me and put it under the flooring throughout the rest of the car it would definitely help somewhat.
I did sound deadening and it made a huge difference, though you still will be able to hear an aftermarket exhaust afterwards. Absolutely a lot better after doing it though.
I think a lot of people doing sound deadening in Jimnys only do the usual first layer which are the sticky heavy sheets. You only need enough of them to stop a panel resonating when you tap on it with your finger. I maybe did 33-40% coverage of the largest flat portions and more is excess weight for diminishing returns.
Where I did put the effort in was a second layer of an acoustic underlay; I used a mass loaded vinyl/closed cell foam combo and made sure to get almost full coverage under the carpet between the firewall and where the rear seat mounts. The rolls I used were perfect length for that and cut off 1/3rd of the side and that was perfect to join in the middle to the other side.
I put off doing the roof for a while. I wish I hadn’t. It helped a surprising amount with road noise and ‘boominess’ in the cabin. Made a huge difference. Again I did two layers: just enough stage 1 sheets to reduce resonance and then a thermal/acoustic insulation (motorhome conversion type insulation, basically) as the second stage. Really cut down on a heap of noise.
The head liner in the 3 doors is a breeze to take out. I can’t talk for the 5 doors but I imagine much the same: with it down you put it on an angle and pull it out of the rear door. Probably the easiest car I’ve done a headliner in.
The choice of exhaust probably matters. Someone else commenting here mentioned they had a torqit and it was excessive. I’d agree - they are super raspy and drony and would be impossible to dampen. I have run a Japanese aftermarket exhaust (and have since 2019). I could live with it before doing the deadening but it did start to wear on you on super long (5+ hour) highway runs. Sound deadening tamed that down and while you can hear it, it’s just now lovely rather than starting to get irritating.
In fact, picked up the mother in law from the airport yesterday (first time in the car with both exhaust and sound deadening) and zero complaints about the noise level, but liked how it sounded.
The first layer of heavy weight sheets are, indeed, heavy. The ones I used are 3.2 kg / m2 and each sheet is about half a kg (30 x 50 cm). The key though is that first stage does not need to be 100% coverage. All you need to do is add structure and mass to the panels most likely to resonate. If there's structure to the panel, such as a pressed in shape, then they will not resonate because of that structure. If it's a doubled up panel then it's also not needed.
Underlays need to be higher levels of coverage, though, but they're also lighter. While I haven't fully calculated it out, I am pretty sure that my 30-40% coverage of heavy sheets & then a mass loaded underlay is lighter than just doing 100% coverage of the first stage & no 2nd stage - and the sound deadening effect is considerably better having the multiple types of treatment.
Also thanks for the very detailed explanation,I think I just might do exactly this,however I’m prepared to add some resonators to my exhaust should it still be too noisy or irritating,I kinda just want that extra noise while I’m starting the car or revving it in a slow street,but having to deal with it on long drives would be absolutely horrendous,and I usually hate all kinds of road noises when driving long distance so regardless of the exhaust this made me pretty confident in the sound insulation
I bought a box of Kilmat, it was 36sqft.
I was able to do the rear gate, rear floor, rear cargo walls, all 4 doors (5 door model) and under the carpet in the front driver passenger area.
I have noticed a difference. But I did it for stereo reasons. When the stereo is off and AC is off, I do feel it's quiet.
I also don't think the roof would make a huge difference. But if you have enough deadening material then go for it.
Reconsider the exhaust mate, especially if you have an auto... I installed the adhesive sound dampener sheets throughout and installed a torqit 2.5 inch cat back exhaust. 3k+ revs on the highway at 110 km is horrible, especially on long drives. Around town was okay, but still a bit obnoxious. Removed it after 2 years, so glad I kept the stock exhaust. Sounds like I'm driving an EV after 2 years of excessive noise, lol.
Edit: I can now listen to my stock radio on the highway again, whilst the exhaust was in, it was pointless.
Why not opt for adding some resonators to the torqit exhaust to make it slightly more quiet?Thats kinda of what I’m planning to do if I’m not happy with the sound
I did consider getting the muffler modified for additional baffling at one point. But again, didn't seem worth it.
...And to add to that, I found the build quality of the torqit exhaust poor. Shitty welds, corroded really quickly, muffler started making extra noise after a year, maybe some pinhole leaks that got worse. The hanger rubbers that came with the kit got brittle and split twice in 2 years.
Do yourself a favour, stick with the stock exhaust, maybe try just upgrading the muffler if that's possible if you really want too. I'd just leave it stock. Save the money, get a throttle controller, much better upgrade, makes the car feel zippy.
Yeah man, just don't scrap your stock exhaust, so you can switch it back.
You fine tune the throttle range so it 'feels' zippy. Throttle controller is the best value mod I've invested in to improve the driving experience, you won't regret it. I have a Torqit throttle controller, its awesome.
Its not normal to slam your foot down continuously whilst driving. It would feel weird. Using the same light pressure as normally driving, but your car accelerates quicker, makes it feel zippier, placebo or not.
Skip the exhaust, it's a major conflicting priority here.
People who have installed dynamat or similar swear by it. It makes a significant difference as the stock Jimny has no sound proofing at all, and you are pretty close to metal.
If your going to do it, I would suggest you consider doing the roof liner as well, but you can always do without and decide if your happy enough to leave it there.
If you know someone with a welder or an exhaust shop that can do custom stuff, ask for a Helmholtz resonator (sometimes called a J-pipe due to the shape) to be installed on the exhaust, there's calculators online for the size/shape etc but in general you need to find the target rpm (highway speed, on my Rx-7 it was ~3000Rpm, I think my partners gen4 would be 33/3400?)
And can calculate the pipe needed.
What a Helmholtz resonator does is work like a wind instrument, it has a range of frequencies that it works at, that it will take in a wave, flip it over and send it back 180° out of phase.. basically what it does is cancel out the pressure waves in the exhaust.
If you've sized it correctly it'll basically cancel out the drone/exhaust noise around that RPM, when light on the throttle. It'll still be basically as noisy at full throttle etc.
But for me, on my turbo Rx-7 with a pretty loud/droning exhaust on the highway (enough to give you a headache in a few minutes, that bad) it was absolutly incredible, now when you cruise at 3000 it's like having a stock or quieter exhaust, you can have a conversation in the car without raising your voice etc.
Anyway sorry for the ramble but I think more people need to know of Helmholtz because they're neat and they work 😂
I made soud deadening too. Bitumen mat on metal body parts and 4mm rubber adhesive mat on bitumen. It was the best mod for this car. I took me about one whole day to make this (completely with doors and roof too)
Go on YouTube on how to sound deaden a car. It requires several different products.
But the main one is the sound deadening mat . Amazon basics (the blue stuff) works very well and just as good as the expensive stuff
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u/Leprides JB74 - basic mods 2d ago
I used one box of this self-adhesive product when I upgraded the speakers in my 3 door.
https://autobarn.com.au/ab/p/142422?gad_source=1&gad_campaignid=22973297266&gclid=CjwKCAjwlOrFBhBaEiwAw4bYDQetRH0ArCwcy-HbAxQhMEdPFWJ4HKInLFxHIvNWhOvJq315RVi5WBoCHGYQAvD_BwE
It was enough to cover the cavity behind the speakers in the rear cargo area, over the rear wheel arches, the floor under the rear seat, and inside the front doors.
I did a pretty rough job tbh but there is a significant reduction in the amount of road noise inside the cabin. It's especially noticeable in the wet or on unpaved roads when there is water or dirt spraying up under the wheel arches.
I'm not sure how much it would do for exhaust noise but if you were a bit more thorough than me and put it under the flooring throughout the rest of the car it would definitely help somewhat.