J-Lung

On a recent trip to the "Tail of the Dragon" my car made a bad squealing noise from the front right corner, but only after hundreds of hard turns and only under hard braking. I had the same thing happen one other time during the trip, also on a hard left turn. The noise stopped when I backed off. Thoughts?

Rgarcia

My guess would be brakes.

hbrakes

Yeah I'd second that - sounds a lot like brakes. Not necessarily the screech of them getting low, maybe contaminated, or just hot.

DesmoSD

Do you have non-OEM brake pads? If so, you'll need to re-bed them

https://pages.ferodoracing.com/produ...s/pad-bedding/

J-Lung

Thanks guys - I was thinking it was the brakes, but not sure why it only happened after a lot of repeated build up. I had somebody else suggest the sound is like rotor flex touching pads. He suggested I check the wheel bearing for play.

Petza914

I was going to say that same thing. The wheels load laterally on the opposite side when you turn right vs left which is why it only makes the noise when you load it in a left turn and not a right turn. If you got the brakes hot enough to create that squealing noise, I would also suggest a brake bleed to get that fluid out of the calipers. If the rotor looks bluish, it's also glazed and needs to be sanded then cleaned with red can brake cleaner and same.wirh the pads, then rebed the brakes.

What causes the noise is oscillation between the caliper piston and the back of the brake pad carrier. To eliminate it you'll need to do something to restick the pad to the caliper pistons either with new OEM pad dampeners - these are the adhesive rubber pads with metal prong that lock them into the caliper piston or with a liquid anti-squeal product from CRC or Permatex.

Bruce In Philly

2009 C2S 179K miles

Sounds like a classic hot brake. When I first tracked my car, I was freaked by the noise... you almost never hear that squeaking and grinding and metal-on-metal awfulness on the street. To test this out, you can make your brakes get hot on the street by finding a road and do rolling hot accelerations and hard stops. You can get them hot enough to squeal. There is nothing wrong with a squealing hot brake. It is what they do.

Peace
Bruce in Philly (now Atlanta)

J-Lung

179K miles with track experience! Thank Bruce for the feedback. I was thinking it could be a hot brake squeal . . . I haven't tracked the car, so haven't heard that noise before. In thinking about it, on public roads, I feel I can take a left turn harder than a right, since a head on collision could result if I over cook a right as opposed to an "off" with a left. Not good to overcook a turn either way I guess . . . .

Petza914

Sorry, but I disagree. The reason brakes squeal is because of oscillation. It's usually race car brakes that we're used to hear do it so we correlate hot track brakes to the squeal noise, but it's because those pad compounds are much harder so they oscillate more than street compounds. If street pads are squealing, it's because the vibration dampeners are no longer working and to get street pads hot enough to squeal like race pads, the car is either on a track or the driver is over-braking the car. Street cars brakes don't start making noise even when running ridiculous speeds through Tail of the Dragon and similar curvy mounting roads. If they've gotten hot enough to make that noise, they're now glazed and regular braking will be compromised until that super hard fused layer is removed.

If he runs racing hardness pads, then the above doesn't apply and then it's just normal brake pad noise from those super hard pads designed to work optimally and high temperatures, but if running racing pads, he'd likely know this already and the speeds in the video aren't high enough to create that kind of heat, especially with the acceleration time between corners

J-Lung

I appreciate it! It sounds like a worthwhile effort to get the brakes services as you recommend.

cbredesen

I've got pretty chronic squealing from my OEM pads and rotors but haven't nailed down where it's coming from but it's LOUD. Starts happening when they are up to temp but not hot (i.e. no hard driving). I'm going to try and deglaze them again but the fronts are entirely new and installed by a reputable shop. Rears are not new so it's possible they are to blame. More investigation needed but my car sounds like a dang school bus!