I'm being a little lazy hear and have not really done any specific troubleshooting yet. I'm wondering if any Focus ST owners or pro mechanics have come across this before.
A week or so ago I noticed my Focus making a squealing noise on the highway. Intermittent. Getting off the highway, it was much more pronounced. It changes with starting/stopping, hitting a bump, turning - especially tight turns, and braking. No difference with engine rpm or clutch actuation. It's rather loud and piercing. Not pleasant.
So seems like a brake dust shield or something rubbing. I did a quick look and saw nothing. Haven't yet jacked it up and taken off the wheels.
Any wisdom?
Frozen caliper slider pin?
Brakes would be my first guess. How many miles? Ever had the brakes done?
It's a 2018 and it has only 20K on it. I worked at home before it was cool...
Never done any brake work on it.
The caliper slider seems like a good starting point. Do these normally get greased?
Caliper guide pins should be sealed to environment by rubber boots. Not saying it isn't, but it's unlikely.
do you brake like a madman? Maybe it's a pad wear indicator?
AngryCorvair (Forum Supporter) said:
do you brake like a madman?
Um, no? I do my best to not snap the necks of any of my children.
I do autocross this car a little but no track laps or anything.
Yep, sounds like the brakes.
As an easy check, make sure you don't have something getting stuck between the dust shield and caliper. My old MINI got a chunk of rock floating around inside the disk hat and it would occasionally get caught in the shield. Probably not it, but looking is free.
If the braking system doesn't give you any hints, take a look at the seals for the axles on both sides. I had a hub to axle seal fail on my Integra that made some terrible noises but the fix was rather easy.
Ok, after "enjoying" the banshee-squeal all day yesterday, today I made a little time to investigate. I jacked up the passenger's side first because it was closest to the gate and still in the shade.
Took the wheel off, took a look in behind the rotor with a flashlight. What might that be?
Bad pic of the obvious foreign object lodged between the rotor and the dust shield.
A minute of prying with my longest broken screwdriver yielded this:
One very durable, very noisy-ass wood chip. Who knew?
Just the right shape to randomly lodge between the rotor and shield, then bounce around in the middle for a while, then get lodged again. Just heat resistant enough to not burst into flames. Just strong enough to not get shredded.
Haven't driven the car yet, but if that wasn't the issue I'll be terribly surprised.
