Vibrations at certain RPM

[Chadd7]

I see that you take it for a good reason as an exhaust drone. But it might as well be the heat shield near the exhaust. I wouldn’t know how to separate those noises as they would have the same sort of origin (Natural frequency of one component)

I will check the heat shields, but I've had loose heat shields before (Subaru STI). Sounds different

 

[AMD66]

Same v slight vibration/resonant frequency at 1800 rpm or so on early diesel N1 5 seater but not enough of an issue to be an ”issue” (vs erratic heating) and in same general folder as not an issue footrest etc

N1 Diesel 5 seat, exactly the same as above.

 

[Chadd7]

I checked the heat shields, in the engine compartment, around the exhaust muffler, and the insulation under the hood/bonnet and everything looks tight with no obvious points of contact with other metal parts. I truly think this is an exhaust design issue that causes drone at very specific speeds and RPMs. It's not a vibration I hear. It's more of a deep bass humming at throttle while going 60-70mph on the highway.

 

[Krabby]

I checked the heat shields, in the engine compartment, around the exhaust muffler, and the insulation under the hood/bonnet and everything looks tight with no obvious points of contact with other metal parts. I truly think this is an exhaust design issue that causes drone at very specific speeds and RPMs. It's not a vibration I hear. It's more of a deep bass humming at throttle while going 60-70mph on the highway.

Do you have the, ahem,. premium sound system? Could it be that subwoofer somehow?

I ask because I cannot remember anyone else sharing a similar issue.

 

[Chadd7]

Do you have the, ahem,. premium sound system? Could it be that subwoofer somehow?

I ask because I cannot remember anyone else sharing a similar issue.

I do have the premium sound system and I originally thought it was the subwoofer, but it was not. I turned off the music and the drone would still come back. We'll see what happens as the car and exhaust system "break in". I'm no expert on the topic but have owned many cars in my lifetime, several with aftermarket exhaust systems, so I'm familiar with the typical troubleshooting steps. I hope this drone goes away. I can see it inducing headaches on long drives. Otherwise the sound insulation and build quality are awesome, and the Gren is as quiet as my LC200 in local driving.

 

[Krabby]

I do have the premium sound system and I originally thought it was the subwoofer, but it was not. I turned off the music and the drone would still come back. We'll see what happens as the car and exhaust system "break in". I'm no expert on the topic but have owned many cars in my lifetime, several with aftermarket exhaust systems, so I'm familiar with the typical troubleshooting steps. I hope this drone goes away. I can see it inducing headaches on long drives. Otherwise the sound insulation and build quality are awesome, and the Gren is as quiet as my LC200 in local driving.

Gotcha.

I did see that the company in Tennessee selling the Urban sidesteps also offers a cat-back exhaust system - that could be a potential problem solver down the road.

MILLTEK

 

[Chadd7]

Gotcha.

I did see that the company in Tennessee selling the Urban sidesteps also offers a cat-back exhaust system - that could be a potential problem solver down the road.

MILLTEK

Haha yes, but I'm not looking for more rumble overall. I'm getting to that age.....

 

[Krabby]

Haha yes, but I'm not looking for more rumble overall. I'm getting to that age.....

I was thinking it might not drone though - my F150 Coyote 5-0 droned some until I swapped it out for a Borla system. Yes, it rumbled a little more, but that was not detectable in the cab whatsoever. It will be interesting to see if other NAS owners have the same experience.

 

[Chadd7]

I was thinking it might not drone though - my F150 Coyote 5-0 droned some until I swapped it out for a Borla system. Yes, it rumbled a little more, but that was not detectable in the cab whatsoever. It will be interesting to see if other NAS owners have the same experience.

Gotcha. Let's monitor this. Maybe you can resurrect the meetup in S NJ and I can give you a ride.

 

[Chadd7]

I went underneath this morning to take a look at the area to the bottom right of this picture. The heat shield is making contact with the black metal protective plate. It's hard to access because the black metal plate is installed over the heat shield, but I pushed a small wooden shoe horn in there to bend some of the heat shield away from metal contact, but I don't think I got it all. Will report back later on whether this helps with the drone.

 

[Chadd7]

Just reposting pictures from rovie, who seems to have made similar adjustments months ago.

 

[Chadd7]

The drone is still there even with some of the heat shield adjustments I made. My passengers say it's not bad and sounds normal for a "truck". Maybe my ears are too sensitive? The last vehicle I had with similar issues straight from the factory was a Toyota minivan. Wondering if the shape of the cabin contributes to it, being so cavernous inside.

 

[Krabby]

The drone is still there even with some of the heat shield adjustments I made. My passengers say it's not bad and sounds normal for a "truck". Maybe my ears are too sensitive? The last vehicle I had with similar issues straight from the factory was a Toyota minivan. Wondering if the shape of the cabin contributes to it, being so cavernous inside.

Do you have the carpet floors or plain “rubber?”

 

[Chadd7]

Do you have the carpet floors or plain “rubber?”

Carpet floor mats over rubber.

 

[rovie]

The drone is still there even with some of the heat shield adjustments I made. My passengers say it's not bad and sounds normal for a "truck". Maybe my ears are too sensitive? The last vehicle I had with similar issues straight from the factory was a Toyota minivan. Wondering if the shape of the cabin contributes to it, being so cavernous inside.

Take a look at the heat shield at the rear. There are a few places that vibrate and hit somewhere.

 

[Chadd7]

Take a look at the heat shield at the rear. There are a few places that vibrate and hit somewhere.

I think I found the culprit. On the passenger side of the rear skid plate, if you peek through the last slat you can see a heat shield in there. That piece was not secured tightly. It has some movement. I could probably remove the skid plate and tighten that bolt so the heat shield doesn't move around, but for now I jammed in some aluminum foil so that the heat shield wouldn't wiggle anymore. will report back.

 

[MrMike]

The drone is still there even with some of the heat shield adjustments I made. My passengers say it's not bad and sounds normal for a "truck". Maybe my ears are too sensitive? The last vehicle I had with similar issues straight from the factory was a Toyota minivan. Wondering if the shape of the cabin contributes to it, being so cavernous inside.

By drone, do you mean something like you get when traveling by jet when the pilot backs the throttle off, you get a certain harmonic vibration?

 

[Chadd7]

By drone, do you mean something like you get when traveling by jet when the pilot backs the throttle off, you get a certain harmonic vibration?

Not sure I know what jet drone is. But there are many youtube videos on the topic that explain it well

 

[gkhaldi]

Good question. Has anyone with a B58 petrol reported a vibration issue in the 1850-2000rpm range?

The B57 Diesel and ZF 8HPxx transmission are well proven in BMW vehicles. In the Grenadier we have a different mounting arrangement plus the addition of a transfer case, which adds length and gearing, and reportedly an upgraded torque converter. All of that should be common to the B58 petrol - except for the transmission which for petrol is 8HP50 and for diesel is 8HP76. I wonder if the upgraded torque converter is common to both?

@NQ94 enlightened us on the different natural characteristics of diesel versus petrol engines and I speculated earlier about diesel exhaust pulses or droning. To me this vibration is engine rpm and load sensitive, not road speed sensitive. Try it for yourself. Very lightly adjust the throttle pedal while in the vibe zone and you can feel it fade in and out with load and small rpm changes.

It just occurred to me that my brother in law is a PHD Engineer and a University Lecturer in this stuff. He runs a business that specialises in structural acoustics monitoring and analysis and vibration minimisation. It's time I got him over again for a BBQ

Hi, I have the B58 petrol and I have some vibrations coming in 8th gear around 95km / hr and again around 110-115 km/hr. The vibrations aren’t very hard but it’s there. They remind me of similar vibrations on my LR110 TD5 I sued to have. The vibrations are accompanied with an increase of noise (sounds like diff whining) but once you get below or above these speeds it‘s gone.

 

[Chadd7]

I think I found the culprit. On the passenger side of the rear skid plate, if you peek through the last slat you can see a heat shield in there. That piece was not secured tightly. It has some movement. I could probably remove the skid plate and tighten that bolt so the heat shield doesn't move around, but for now I jammed in some aluminum foil so that the heat shield wouldn't wiggle anymore. will report back.

Just a follow-up. That heat shield tightening definitely made a difference. I still hear a faint droning but not as irritating.