Hi all, I have a 2009 Prius at 77,000 miles, been driving it since August with no (mechanical) issues. About four days ago I noticed a soft grinding sound from the front wheels when I pressed the brakes, always only on the first 1-3 times braking after startup. Braking in Drive or in Reverse, it doesn't matter -- the brakes will make the noise those first few times, then after I've started driving for over 1 min there won't be any noise braking at any speed, fast or slow. This happens regardless of how long I wait after turning it on: whether I put it in gear right away or let the car warm up for 5 min. If I run short errands, the brakes will not grind after I start it up again: it only happens after it's been sitting for a while (2+ hrs). Is this a normal thing? I don't remember it happening anytime before and I feel like I would have noticed. The sound is a little disconcerting but doesn't sound too horrible, and it's not really squeaking either. Thanks for your help!
Most likely you are getting some surface rust on the rotors due to the increased humidity this time of year. This will cause some brake grind noise on startup. Before you start out in the morning, try looking through the rims at your rotors. You may need to use a flashlight to see in there, but I would bet there is a small amount of rust on them. They clean off after a couple stops, especially in reverse. I drive a school bus for a living and they really squawk as the weather changes. Hope that is all it is.
Sometimes. But you won't know for sure until you have a shop inspect them. Often the rotors get a light film of "rust" on them overnight and without some hard braking effort that never goes away completely......and you hear it again the next morning. That is really nothing to worry about. But there also is a "wear indicator" built into the brake shoes which can make a similar noise.
So...it's either completely normal, or a sign I need to replace brakes, and those two scenarios produce the same noise? xD Thanks for the help! Hopefully it's not a major concern, but I think I'll still take it to a brakes place to check.
Those two situations may produce a SIMILAR noise......in addition to just needing the dust cleaned out around the brakes. Keep in mind that a "brake place" is in business to SELL BRAKE JOBS. Brakes are usually inspected when tires are rotated. How long since your tires were rotated ??
Agree with Sam Spade; shops are in it to sell you their wares. Good to have an independent voice/opinion. If you are somewhat handy with tools, consider getting your front end up on jacks and remove both wheels to see how far along the breaks are. Also bring along a can of break cleaner to rinse off rust debris. Eyes on the object will give you and us a greater understanding of what we are up against. Hope its just the dust at initial start up.