Buzzy Vibration at certain RPM's..read before buying!

Maybe there's more than one hanger supplier? I dunno. I was looking primarily between the engine and the rear axle.

I'm looking forward to hearing updates tomorrow to see if the silicone helps.

 

Definitely cheap enough for people to try...really any aftermarket hangers should change it enough to notice.

I'm thinking aftermarket catback helped too.. If the vibration is comeong from the front of the exhaust then any change back pressure(larger pipes, muffler at the back) might change how loud it is up front..many factors to consider.

Definitely try this hanger deal though!

How do you recommend we loosen them up?.. Silicon spray.. Loading them to make them stretch some?

 

Silicon spray yes. I had to use a flat head screwdriver to pop the exhaust out of the mounts. They are kinda honeycomb horizontal chambers. I just used my fingers to get them unstuck from the metal on the truck they attach to. Turned them and slide them on their post after spraying them. They are pretty durable I doubt you could tear them unless you cut them.

 

I drove to work this morning after using silicone spray on the hanger mounts and unfortunately it didn't do anything for me. Still vibing hard at 2100 RPM.

I had a couple Harley's go by me again on the freeway and sure enough it amplified the floor pan vibration way more when they were close. So that still adds points to the exhaust resonance theory. But at the same time I wonder if a new and louder exhaust would make things even worse.

 

Find some way to hang some heavy weights safely on the pipes in the area near the floor pan. See if that makes a difference. I have no idea how to do this but I'm thinking hose clamps with ??? For weight.

And by the way, thank you for all that you are doing to help us 3rd geners trouble shoot this issue. It does not go unnoticed.

 

Also, what is this? This is not the Catalytic Converter, is this an exhuast resonator? This sits directly below the area in the floor that I feel the floor vibes.

 

Sorry it didn't work for you. Maybe it is more related to the install of the cat back. I took a 300 mile trip this morning. Mostly hwy with up and down hills. I intentionally tried to get it to do the vibration. Only time it was noticeable was 2100-2300 rpm on hills. I had my friend drive it and he said he could feel what I was talking about but wouldn't have noticed if I hadn't told him. I can still say a noticeable improvement since the cat back install. Which leads me to think at least for my situation it was exhaust related. I hope this issue gets resolved for those of you with a more pronounced vibration, it's a physical thing so there has to be a fix. I am happy with my truck and I think that if I wasn't keyed in on it I wouldn't notice. Not to minimize your situation, I am sure at best it is very annoying.

 

Does you cat back delete the resonator that I have shown in my picture or does it start behind this?

 

I did see your post. No it connects further back. Almost midway in the truck.

 

Thanks. I wish my under carriage looked that clean...

 

My 2004 4Runner does this too. In addition to my own engine resonance I can feel other cars' exhaust and stereo as well.

I do a lot of shooting reloading and am thinking of melting down some lead and casting it into a small block that will have one side shaped to match the contour of the exhaust pipe. I'll then be able to mount it to the pipe with a pair of hose clamps and be able to experiment with placing it at different points on the exhaust pipe since it won't be permanently mounted.

 

I've decided in general to not participate further in this thread - but I think you are getting warmer. So if other vehicles (bikes, diesel trucks, etc) go by and give a pronounced vibe, you think this points to your exhaust as the main issue? Think about it. Yes, your exhaust may excite a vibe. Just like someone else's. Just sayin.

 

I probably can't get to it this weekend, but I can try adding a weight (essentially mass damper) to the exhaust. A steel clamp and small steel block/weight should be fine.

Its no problem helping, it will be nice if we can all figure this out.

 

Guys, is there a rigid mount/bracket somewhere, like between the exhaust and the transmission that you could temporarily remove? Leaving the backside of the exhaust just on the hangers. Could be interesting experiment.

 

I believe the exhaust does rigidly mount to the transmission, but I'd have to double check.

 

So I turned the truck on and grabbed the exhaust with my bare hands (obviously before it got hot) and I feel the buzz. The more I look at it too, the more the exhaust theory makes sense, I was hesitant before but it makes sense. Vibration accompanied by the drone, vibration at this ~2000 RPM range, buzzing felt in exhaust, no damping along the exhaust (I don't believe) except for the rubber hangers, and I've seen a couple sources state that exhaust drone exists around 140 Hz, which just so happens to be roughly the same frequency a cell phone vibrates at.

Current plan is to:

1. Scavenge Home Depot or an accessible source (if I can't find suitable stuff at Home Depot it will be from McMaster-Carr) for a "mass damping" setup. Will start with 2 hose clamps, an L bracket and some sort of steel weight (possibly steel rod with a bolt through it and the L bracket). I'll be keeping all materials steel (regular, stainless, whatever I can find) to keep thermal expansion similar to the exhaust pipe.

2. I will start forward of the muffler, but behind the joint where an aftermarket system would bolt on. I will test every 4-6" or so and probably some variety of weight.

3. This might take me a bit to test since I will have to wait for the exhaust to cool each time a position or weight configuration doesn't work and I just don't have all day, or even every day, to test this.


I should note, I am not expecting this to completely cure the problem. I am looking for a change in behavior, theoretically, a change in RPM where the issue occurs. In an ideal world, this would pull the resonance frequency out of the engine operation range so it would never hit resonance, but this isn't a Disney story. Or if i happen to make a tuned mass damper, it will cancel out the resonance. Also, this is can be a tougher way to try and fix this. It can take a lot of trial and error.

If I notice a drastic change I may consider an aftermarket exhaust system to try to cure the issue. If an aftermarket exhaust system would fix the issue, I would recommend people do the same. If an aftermarket exhaust wouldn't fix the issue for us, then we are stuck with showing Toyota our findings and hoping for a proper mass damper TSB or permanently modifying the exhaust ourselves (not my favorite option). Unaccounted for resonance frequency (I call it unaccounted for because not everybody has the issue), while it is unlikely to pose any immediate issues, can significantly lower fatigue predictions, especially on welded joints. I would not say this will be a guaranteed problem, but I plan to keep the vehicle a long time and would rather be safe.

Ok everyone, let's hope for results.

 

I commend for your efforts! The exhaust system drone/resonance/harmonic frequency is exactly what I think it might be. Because you can lightly tip in and out on the accelerator pedal in the dreaded rpm range and hear/feel it come and go. I really think your on he right track, at least testing/diagnosis needs to be done to rule the exhaust system out. Thanks again for trying to diagnosis.

 

I don't think it does, or I didn't notice when I was under the truck. But even if it did, I think it would improve(?) the vibration situation since the exhaust wouldn't be free to vibrate on it's own. It would have to shake the entire engine.

It's interested in seeing how this turns out. I looked into making a tuned mass damper but after some research it didn't so easy.

I've done some audio captures, my drone exists between about 85Hz and 120Hz, which corresponds to the exhaust pulses between about 1900rpm and 2500rpm. I've looked quite a bit into building a Helmholtz resonator(s) and will probably tackle that during the summer.

I had a loaner 2nd gen Taco and I noticed it had none of the drone (wasn't looking for vibration at the time). I'm curious to see a 2nd gen stock exhaust and/or see if it would bolt up to the 3rd gen.

I'm looking forward to hearing about your results.

 

Sorry for my stupid or uneducated comment but what about adding sound proofing material to the cab or floor of of the vehicle. Maybe it's not the vibration that is bad but that it can reach the passenger of the truck. There are people on here that have added material to sound proof for normal noise but I wonder if it has helped for vibration as well.

 

It could certainly help with vibration, but despite what Dynamat says, you need to significantly change the mass of the panel to change it's resonant properties, especially when a bunch of amateurs are adding a few layers by eye-balling it.