tldr; If you are unhappy with the amount of noise that filters into the cabin then this DIY should help reduce cabin noise, especially from the front suspension.

So this is likely my OCD, but it did start to bother me as none of the other EVs that I have driven, with the exception of the Model Y, seemed to have such a noisy suspension. And then I also seem to get bothered by the little sounds that filter into the cabin and they rob an otherwise nice in-cabin experience. Primarily these three:

1. Very loud suspension thuds and groans as the vehicle encounters a bump or pothole. I think the suspension is just fine, actually it is quite good; my problem is that it feels just too noisy for my liking. That's not how a suspension should sound, especially in a Mercedes.
2. The sound of the friction brakes grinding as they start to engage. I can hear them at crawl speeds, with my foot off the gas pedal when trying to bring the car to a slow crawl.
3. The coolant circulation motor starting and coolant gushing through during the first few seconds of starting the car along with a few other clicks, clacks, and squeaks.

So with my goal of making the cabin quieter, I started reading a few forums and came to the conclusion that getting an engine hood damper would be most straightforward and least 'invasive' way of going down this path.

Mercedes does not ship any EQB variant with a hood damper. But because the hood on the EQB is the same as the one as on the GLB, my thinking was that there might be one for the GLB. And sure enough, there is. While the GLB250 does not come with a hood damper, the AMG GLB 35 does. There is an interesting discussion on this over on the GLB forum: GLB 250 Hood Sound Liner or Not

So I ordered the part A247-682-28-00 from mbonlineparts.com: https://www.mbonlineparts.com/oem-pa...ood-2476822800
along with a set of fasteners A001-988-03-25 from Amazon: (no affiliation to either)

The parts fit perfectly and I was excited to take the car out for a drive and feel (hear) the difference. So while there was some noise reduction, it was not to the level which I had hoped for. So I could still hear the brake noise, suspension noise could still be heard though reduced, and a bit of the coolant sloshing as the circulation started at startup.

I figured that using a sound damping sheet could help in reducing the noise level further. I had some 2mm sound damping sheets, attached 2 of them together using automotive tape, then cut out the outline of the damping hood liner, and punched (cut) holes at the spots for the clips.

Now, I did not want to glue the damping sheet to the hood. They are a mess to take off due the sticky butyl rubber which leaves a lot of residue behind and I did not want to spoil the hood, lest this turned out to be a 'failed' experiment. And, so I did not remove the backing paper protecting the glue on the sound damping sheet.

Then I put the damping sheet over the hood liner and attached them to the hood with the clips, sandwiching the damping sheet between the hood and the hood liner.

Took the car for a drive and the results were immediately apparently.

1. The suspension now feels much quieter. No more loud noises as you hit a pothole, just a muted well rounded thud which feels more like 'one and done' than the sharp 'fall out of the chair' feeling previously.
2. Most of the noise now seems to come from the bottom and rear of the car vs the front of the car.
3. Cannot hear the friction brakes engaging anymore.
4. Coolant motor starting and coolant sloshing at startup is much reduced and is only audible if you are paying attention.
5. Road noise is also contained. I have now reduced the radio volume by a point as the cabin feels perceptively quieter.

Biggest validation was when better half (who drives an ev herself) and 12 yo got into the car this Sunday for a drive to the local theater and remarked how my car felt noticeably quieter now!

So finally, I feel I kind of achieved what I had to set out for. The cabin definitely feels much quieter ; more like how a Mercedes should have been in the first place. Actually, I would love to say it feels like a different car now, but definitely much better.

The only negative so far seems to be that the damping sheets are a bit heavy (2 kgs) as compared to around 300 - 400 gms for the hood liner. The clips seem to be able to support the weight of the damping sheet + liner just fine so far. We'll see how they hold up. Here are a few pics of the setup.

The hood damper as received.


Damping sheet cut to the outline of the hood damper and holes marked.


Checking the alignment of the damping sheet with the hood damper and punching holes (damping sheet is below the liner).


As installed.

 

Nice work. Where did you buy the damping sheets?

 

Thanks for sharing. As someone who enjoys an ultra quiet cabin, I appreciate your summary. Could you use your phone to do a db reading at highway speed? For the $65, I think I'll do this upgrade regardless, but would be nice to know the db improvement.

 

Got them from an audiophile friend. Nothing special about these, I believe any 2 mm Butyl car damping sheet should work.

 

Thank you!

Unfortunately, I do not have any before/ after readings. But I did take some manage to take some readings using my phone on a short drive today.

In garage, with hvac on and car in P. 49.5 - 51 db
Bitumen road, 50mph/ 80 kph. 60.5 - 62 db
Concrete road, 50mph/ 80 kph. 62 - 65 db

I believe the cabin noise also depends on the tires the car came with, so YMMV. Mine has Bridgestone Turanza T005 RFTs, which are pretty average on noise and poor in terms of ride comfort (as are most RFTs and I plan to switch to tubeless soon).

 

I've got the original Continentals on mine/ with only 4000 miles on the odometer. I'll take db readings and report back here.

 

I am surprised that lining the hood made that much of a difference in the cabin. Good to know.

 

noise is one of my biggest pet peeves too