Hi fam,

Recently I started to notice an interesting grinding noise when I drive at 65mph on highway, when going over uneven surface. Like, the car jumps a little bit, and made a very quick and sharp grinding sound when sitting down.

Car is w205 c63s, running Zito 20 ZF01 in 20”. Currently only observed this in comfort suspension mode, and this noise is more likely to happen when I got passangers.

Initially I though it was the wheels, but the tiers and fenders do not have any sign of rubbing. Also the sound is more like a short metal grinding instead of rubber. The sound mostly come from the rear of the car.

I also have aftermarket IPE exhaust, but the muffler seems to be high enough it it’s impossible that it will touch the ground.

Anybody else experiencing this issue? Any thoughts on the likely cause and how should I investigate?

Thanks!

p.s here are two pics of the baby

 

Did you changed your wheel lugs?

 

Yes, I did. Could this be the problem?

 

Just a hunch at the moment, but judging from your pictures, those rear wheels look too wide. Are they sticking out past the fender? If they are not rubbing on the outside, then I'm guessing they are rubbing against the suspension on the inside. Have you looked for signs of rubbing on the inside of the wheels/tires? Since it happens in comfort mode more and with passengers that would indicate rubbing when the suspension compresses to a certain point. With S and S+ the suspension doesn't compress as much, so less or no rubbing might occur. BTW, that's a W205 C63S. The 206 is the next generation

 

Sorry, 206 was a typo, meant to write w205.

The rear tires are almost flush with the fender, but I will check the inside of tires to confirm.

 

Yes, your lugs might be slightly too long in the rear. Jack up your rear. Put in neutral and spin your wheel. If your lugs is too long, you will hear clicking noise lugs hitting your parking brake.