Symptoms
- Squeal, click, or grind heard only sometimes, not on every stop
- May correlate with weather, time of day, or how the car is loaded
- Noise unpredictable enough to be hard to reproduce for a mechanic
Likely causes
- CommonMoisture or light rust forming between drives, cleared after a few stopsSimilar to cold-weather squeal, but can happen any time humidity is higher.
- CommonA pad wear indicator only contacting the rotor at certain positionsDepending on design, some indicators only make noise during specific parts of rotor rotation.
- PossibleLoose hardware that only rattles or clicks under certain vibration frequenciesSpeed, road surface, or load can affect whether a loose part makes noise.
- PossibleDebris that moves in and out of contact with the rotorA small piece of debris can shift position and stop causing noise, then start again.
What to do
- Keep a simple log of when the noise happens: weather, time since the car was last driven, load in the car, road type.
- Check if the noise is worse after the car has been sitting for a while.
- Check pad thickness and general hardware condition even if the noise isn't happening at the moment.
- Bring the log or notes to a mechanic to help them understand the pattern.
- Ask the shop to test drive under conditions similar to when you've noticed the noise, if possible.
- Have any loose hardware, debris, or worn components addressed even if the noise isn't reproducible on demand.
When to call a pro
See a mechanic and share detailed notes on when the noise occurs, since intermittent noises are often solvable once a pattern is identified.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.