Well I feel dumb. Or, “finally found the dash buzzing!”

[Clint Beastwood]

Many of us only post our successes - I feel like it’s also important to share mistakes, screw-ups, etc. for general posterity and general “lulz”. So, my story for today:


I am obsessively detail oriented and it’s great in my professional life, but it can stress me out in my day to day. With my car it means I spend an absurd amount of time eliminating noises, hunting down harmonics, the tiniest interior buzz, fixing body panel misalignments, etc. recently a buzz from my fist’s dash has been driving me absolutely bonkers. I spent the first several hours of my Sunday disassembling and reassembling my dash to identify and resolve the buzz. A buzz that is only audible at ~3100rpm, but a buzz nonetheless. I take off my accessport, remove the plastics around the head unit etc. and add mass damping foam to the back of the plastics. Reassemble, test drive, it’s great. I clean up put everything back where it was and head to the store to grab some beer and a tri tip. On the way to the store it’s buzzing again! I get home, remove the access port, and apply silicone grease at all plastics interfaces, tapping the dash with a towel wrapped mallet to find creaks and rattles. Reassemble, test drive. Sounds good! Remount access port, put phone and GoPro mounts back where they go and go for a test drive. Buzzing again! Remove access port, disassemble dash, can’t find *anything*. I grab a tone generator and put a 107hz tone through my stereo and sweep it up and down from 100-120hz and hear a buzzing from the passenger seat. The passenger seat where the access port is. The accessport with the loose faceplate. The loose faceplate that has decided to vibrate and buzz at 107hz. :facepalm: I add a piece of mass damping foam to the back of the AP faceplate and reinstall it. Sweep with the tone generator, no buzzing no rattles. I dejectedly reassemble everything and go for a test drive. Interior quiet as a coffin.

I am generally a pretty clever guy, but today I am not feeling the smartest. Go ahead and enjoy my dumb moment

 

[Clint Beastwood]

I'll take each like as someone laughing at my misfortune

enjoy, you FiSTers!

 

[SrsBsns]

Your threads are always entertaining because I appreciate the level of detail you put into everything.

I've been tracking a buzz in my cabin too. I get it around the same RPM's and it sounds like it's coming from the steering column. It started after I replaced the (wrong) door blend motor and had to take the steering column cowl off, so I'm sure it's something I didn't line up perfectly when I re-installed it.

I'm glad you found your problem, and it's funny/annoying that it was something like the faceplate on the AP. That's a great idea to use the different sound frequencies to find your buzz.

 

[Clint Beastwood]

Your threads are always entertaining because I appreciate the level of detail you put into everything.

I've been tracking a buzz in my cabin too. I get it around the same RPM's and it sounds like it's coming from the steering column. It started after I replaced the (wrong) door blend motor and had to take the steering column cowl off, so I'm sure it's something I didn't line up perfectly when I re-installed it.

I'm glad you found your problem, and it's funny/annoying that it was something like the faceplate on the AP. That's a great idea to use the different sound frequencies to find your buzz.

Yeah I'm pretty obsessively detail oriented

This stuff works great for making cheap interior plastics sound like... not cheap interior plastics https://www.lowes.com/pd/Frost-King-1-in-Foam-Plumbing-Pipe-Wrap-Insulation/3228226

It's like 90%of dynamat for 20 bucks. Also, anywhere you have those plastic pop rivet things, I always lube those with a dab of silicone because I HATE squeaks. The tone generator for hunting rattles was "brain flash" I had one day. The interior any car has a resonant frequency; in the FiST it's ~107hz, which is where you get the worst drone inside when running loud exhaust (or 3200-3400 rpm). It's the frequency that's going to cause the most buzzing and rattles.


The next noise to hunt down sounds like its coming from inside, by the passenger side taillight. My exhaust is causing a rattle in that corner, I think it might be the little pressure relief vents that open when you have the windows down. I quieted the car down a lot lining the spare tire well with that foam stuff I lined above.

 

[OneFord]

I usually just turn the radio up.

 

[Olephart]

Yeah I'm pretty obsessively detail oriented

This stuff works great for making cheap interior plastics sound like... not cheap interior plastics https://www.lowes.com/pd/Frost-King-1-in-Foam-Plumbing-Pipe-Wrap-Insulation/3228226

It's like 90%of dynamat for 20 bucks. Also, anywhere you have those plastic pop rivet things, I always lube those with a dab of silicone because I HATE squeaks. The tone generator for hunting rattles was "brain flash" I had one day. The interior any car has a resonant frequency; in the FiST it's ~107hz, which is where you get the worst drone inside when running loud exhaust (or 3200-3400 rpm). It's the frequency that's going to cause the most buzzing and rattles.


The next noise to hunt down sounds like its coming from inside, by the passenger side taillight. My exhaust is causing a rattle in that corner, I think it might be the little pressure relief vents that open when you have the windows down. I quieted the car down a lot lining the spare tire well with that foam stuff I lined above.

Where have you applied this stuff? What glue?

 

[CB022481]

Hey moron... HEY, MORON!
just kidding. I have ocd to the nth degree and it would drive me nuts as well.

 

[Clint Beastwood]

Where have you applied this stuff? What glue?

Tap interior plastics with your fingertip - if it makes a hollow sound, adding this stuff to the back will make it sound solid. It's great on broad flat planes (I have added it to computer server racks to diffuse vibration across the broad, flat sides of sheetmetal, I have applied it to roll-up garage doors so they don't sound hollow, the inside of door panels (fieros) so they didn't sound like garbage). The stuff is adhesive-backed, but you need to clean/prep surfaces before adhesion. I tried to stick some to the underside of the rear hatch cover... thingy to stop it from vibrating but that stuff is in-stickable.

The best way to describe it... Like, tap the side of a computer case; it sounds hollow and tinny - add the foam stuff and it's more like knocking on a cargo container; still hollow metal but much more substantial. It does add weight, it does smell weird at first, and it eventually dries up a bit and can peel off, so I don't install it inside door panels that are hard to get off. Usually a 1" strip across the middle of a broad flat plane is enough to prevent vibratory "humming".

 

[Clint Beastwood]

Mother of heck! I get everything quiet, then on the drive home it sounds like my vibrant resonator’s baffle came loose. It’s either resonator internal separation or the stock flex joint failed. If I wack the exhaust the flex joint is noisy as heck and it seems really loose but I never paid much attention to it tbh, might be normal.

 

[SrsBsns]

Yeah I'm pretty obsessively detail oriented

This stuff works great for making cheap interior plastics sound like... not cheap interior plastics https://www.lowes.com/pd/Frost-King-1-in-Foam-Plumbing-Pipe-Wrap-Insulation/3228226

It's like 90%of dynamat for 20 bucks. Also, anywhere you have those plastic pop rivet things, I always lube those with a dab of silicone because I HATE squeaks. The tone generator for hunting rattles was "brain flash" I had one day. The interior any car has a resonant frequency; in the FiST it's ~107hz, which is where you get the worst drone inside when running loud exhaust (or 3200-3400 rpm). It's the frequency that's going to cause the most buzzing and rattles.


The next noise to hunt down sounds like its coming from inside, by the passenger side taillight. My exhaust is causing a rattle in that corner, I think it might be the little pressure relief vents that open when you have the windows down. I quieted the car down a lot lining the spare tire well with that foam stuff I lined above.

Awesome. I know what I'm going to be doing, one of these weekends. Thanks for the tip.

 

[Clint Beastwood]

Awesome. I know what I'm going to be doing, one of these weekends. Thanks for the tip.

Just remember that it doesn't stick quite as well as dynamat, but if you thoroughly clean the surface it should stick ok. You don't have to coat every square inch, usually a strip of it is enough to soak up vibration.

 

[Clint Beastwood]

So after quieting everything down i started getting an RPM dependent buzzing from under the car. I pulled off the exhaust and it looks like I had an internal separation of the baffle inside my vibrant resonator. Not the end of the world, but annoying. My car sounds like a vacuum cleaner (no intake or exhaust, just a drop in filter a RMM and a stratified tune) :|

hopefully my 2jr intake ships soon, I would probably be fine with quiet exhaust if i I had the 2j.

 

[dmb]

not many miles on that Vibrant resonator, maybe they will sent you a new one.

 

[Clint Beastwood]

not many miles on that Vibrant resonator, maybe they will sent you a new one.

maybe, it's not a big deal either way.

My car is way too quiet with no intake and no exhaust and symposer delete. The 2j intake was supposed to ship "late march", I'm hoping that's soon, but I can't seem to get a shipping update from them.

If the 2j is absurdly turbo-y enough I might leave the exhaust off, I doubt the 2j will be loud enough from the outside to draw too much police attention.

Since I have the current iteration of my current exhaust off right now I'll probably polish it up and get it all vbanded so it's more modular. I like being able to swap pieces in and out. I might try one of the borla multi chamber race mufflers as the mid since it's a round canister. I just like tinkering - if I weren't messing with FiST exhaust I would be buying more old motorcycles to restore so my wife is fiiiiiiine with me messing with the fiesta this is cheaper and less greasy.



Of note - with the hot-side pipe replacement (from whoosh) the sound it makes is very noticeable with everything else quiet.