Strange whirring noise when decelerating 2013 C63


Is it a situation where the sound changes pitch as the car slows down?


How about a wheel bearing?
When I test drove my car 6 weeks ago it was raining in Vancouver and traffic was a ***** so getting it up to highway speed was impossible. I bought the car - it was a swap for a CLA45 AMG - and later that day found it had a noise that started at 100kph as a harmonical sound that increases in frequency and disappeared at 125kph. I suspected a wheel bearing.
I had the car checked completely by my trusted tech and the left front wheel bearing was on its way out. He changed both fronts under warranty.


You should try to narrow down the range from the lowest speed you hear it to a point where you can no longer hear it.
My front bearing experience was interesting. As the car was turned left it got noisier. To the right it went quiet at the speeds I noted earlier. If it is a bearing they will change the whole hub assembly of course but try to argue they do both sides given one has failed under warranty. I didn't even have to suggest that to my guys.
The other thing that is bugging me is you say it comes on when you take your foot off the gas. Perhaps it is a drive shaft issue with the rear disc.
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See post #1


We have no idea as to how fast he might have been going either
You would think if the force was a high as is being suggested something would have come up bent or seriously misaligned when he had it checked.
Perhaps we need the OP to tell us more of the circumstances. I guess it would also be wrong to assume he had a 4 wheel alignment done to check the thrust angle etc. in the rear after his excursion.
As for the impact itself, I do know how much force is required to pop the beads on a tire... I've done it twice on a track car when either the front or the rear slid sideways over the curbing and into the ground on the outside. In both cases there was other damage - snapped tie rod, ball joints and bent control arm on the front, and snapped drive shaft, wheel bearing and damage to the LSD on the rear. While suspension and drivetrain components are designed to take bumps vertically, they are not designed to have much flexibility laterally so a reasonably strong whack sideways certainly has the ability to damage other things.




I have had 2 off track excursions at high speeds (100+mph) that have damaged suspension components and not popped a bead on a tire
I have also had the misfortune of an off-track mishap with no issues at all.Having a tire come off the wheel/popping the bead can be associated with significant suspension component issues.
Any chance that there is 'dirt/grass' in the tire from the off track excusion? i.e. did you just have the tire remounted without removing it from the wheel completely?


As for the impact itself, I do know how much force is required to pop the beads on a tire... I've done it twice on a track car when either the front or the rear slid sideways over the curbing and into the ground on the outside. In both cases there was other damage - snapped tie rod, ball joints and bent control arm on the front, and snapped drive shaft, wheel bearing and damage to the LSD on the rear. While suspension and drivetrain components are designed to take bumps vertically, they are not designed to have much flexibility laterally so a reasonably strong whack sideways certainly has the ability to damage other things.


