James_

Earlier today, literally out of the blue the car developed a faint but noticable rhythmic thrum through the steering wheel, most noticeble between 40-70mph.

I've checked the air pressures, that is fine. I'm maybe thinking a wheel spat a weight off it and it needs balancing... but going around the car I noticed a piston looks to be coming up short on one of the rear rotors/discs (im UK but know my american friends prefer rotors ) .....

Could the brakes be causing the vibration? TO be fair, the brakes don't pulse or vibrate, but I know they are tired and will need doing sooner rather than later.

Any other thoughts on what might be causing the vibration - are more than welcome

cheers

Ludedude

That's called "knockback" and is not uncommon. It's a bad surprise when you're looking for brakes right now on track but shouldn't be causing any vibration. First thing to check is wheel/tire balance. If you haven't done that yet, there's nothing to talk about.

James_

Excellent - exactly what I wanted to know tbh. I've got it booked in tomorrow to get both of those looked at. It's just the way my head works that it has to know every damn possible cause asap, it's a **** trait

chrisridebike8

Is that a picture of the rear caliper? You wouldn’t feel rear brakes through the steering wheel. Check the wheel balance.

James_

Yeah that's a rear - now you've said it out loud, yeah how would that even work haha... it's been a long week.

G_Money

Bent wheel or warped rotors maybe?

James_

Yeah I don't think that can be totally ruled out... but I didn't really do anything of note from it all being fine, to it not being, so it's the cause im struggling to attribute. I'll get the balancing done first, maybe it just spat a weight off, then go from there. The rotors all round are living on borrowed time, so if I have to bring forward changing them all then it won't be too traumatic

AMG6.3

Balance wheel and or inspect wheels for cracks. A small crack in rim will cause vibrations

James_

Okay so I had all my wheels balanced this morning, apparently they were out by a bit. They are also 'mildly' buckled - that's MB's 19s fo you, at least they weren't cracked.

BUT... the slight vibration, and its really slight - I just I know it wasn't there a few days back - is still present.

As they had the wheels off I could look at the front rotors properly and the inner face of them had; to use the tyre shops own words; 'fallen off'

So next job is to replace the front rotors, and see if that stops the annoying vibration.