Is my GFs car eating brakes?

MonkeyBusiness@lemmy.one to Cars - For Car Enthusiasts@lemmy.world – 10 points –

SUV breaks have been an issue, ever since the 2022 May inspection, in which Rotors and Pads were replaced. Just the fronts were replaced.

The brakes started sqeaking at first, and then the car started to shake mildly when breaking. This eventually got worse.

The car was taken to the shop sometime around September, and the Rotors were sanded down. This fixed the issue for about a month.

The brakes being squeaking again. The car was taken to the shop again, but they didn't hear it when taking it for a test drive.

Car started shaking again.

I didn't bring it up during the May inspection in 23. The Rotors were then replaced around June of 23.

The car has started to squeak again when breaking, but only at around 50 mph or above.

13

You are describing a car with overheating brakes. Brakes squeaking is from "glazing", which causes a high frequency slip and grip that "rings" the rotor like a bell. Wet finger on the rim of a glass is the same idea. Some squeak is normal, just annoying. The shake can be caused by a few things, but since we are talking brakes, the rotor being warped is most likely.

Why the brakes are overheating are usually due to two factors, caliper issues or improper use of the brakes.

Caliper issues can be things like a sticking piston or sticking slide pins. The technician who did the brakes should have cleaned the pins as well as the hole they go into and lubed them. The grease that the pins use to slide can gum up and cause the caliper to stick and seize, resulting in the pads not retracting away from the rotor, just like you were riding the brakes. The "saddle" that the pads sit in can also be a sticking point due to rust or improper brake pad hardware installation. The tech should have cleaned up the channels that the pads ride in and lightly lubed them. A sticking piston will have the same result, the pads riding the rotor too much and excessive heat and wear results. Too much heat cause by either issue can result in both issues being observed.

Improper use of the brakes is usually riding the brakes, like in heavy traffic, or hard braking habitually. Long braking periods of light pressure can also cause excessive heat to build.

I am not saying the shop did a bad job, but that is as likely a possibility as bad braking habits from where I am sitting with the information available.

And since hard braking isn't always optional, it's important to know how to avoid leaving significant pad deposits. Try to avoid completely stopping by leaving a little extra space to keep rolling slowly. Obviously it's not always possible due to traffic conditions, but I haven't had a "warped" rotor in about 10 years that hasn't been caused by a sticking caliper.

Rotors are almost never truly warped but rather have sticky spots from transferred brake pad material. The shaking comes from the sudden higher braking force of the sticky spot coming around again, forcing the car's momentum to try to pivot around that one wheel. A truly warped rotor doesn't change the braking force much as long as the floating caliper is free to slide. If they do get deposits, you can also try cleaning them with the "brake bedding" sequence used for new pads. It's a mix of high speed and hard/moderate brake applications followed by a 10 minute steady speed cool down drive. Just remember: don't fully stop

Could also be bad brake hoses. Some vehicles are prone to them getting restricted.

True. Technicians letting the caliper hang by the brake hose can also cause a failure of the hose in any vehicle with some miles on it.

'SUV' are big cars. Most are pushing 2 tonnes or more, so will naturally wear brakes out faster. That goes for all unsprung components such as tyres, bushings, and all the other wear items in the suspension.

Some cars are notorious for being under braked for their size, especially 'SUVs' that share platforms with standard sized counterparts so that contributes to it as well.

That said, brakes shouldn't judder/shake under braking during normal operation, even when worn. Juddering is due to something either not being right or very, very heavily and dangerously worn brakes. It may be warped disks/rotors (from cooking them due to overuse), pitting (if the car hasn't been driven much) or something else. The squeaking can be anything from debris caught between the pad and disk, a hard point on the pad or the wear indicator (called a squealer). The former 2 generally clear themselves out.

Without knowing how and where you drive or perhaps even the car itself it's difficult to say where the problem lies. A set of pads and disks can easily last 10s of 1000s of miles. But it depends on many factors.

  1. Brakes. Rotors.

  2. Its an SUV, so the weight it needs to stop is higher than a small car. People who don't know how to drive heavier cars cook brakes pretty easily on them.

  3. Is she a lead-foot? Ride the brakes downhill? Two-footed driver? Is she an attentive driver, or does she constantly get distracted doing other things like makeup? Is she constantly speeding?

  1. Thank you, my spelling ain't the best

  2. She had the SUV for maybe three years before this started happening, and it was bought used.

  3. She's a slower driver, and doesn't ride or slam the brakes, at least when I'm with her. There are occasions when she's stuck in stop and go traffic coming home from work, which probably puts more wear on them

Bring it to a NEW shop or do the brakes yourself. It's about the easiest repair you can do. Basic tools are needed and tons of videos on YouTube walk you through the process. And the cost will be a lot less than bringing it to a shop - maybe as low as $200 for the front rotors and pads and secondary parts you will need. (The cost will vary greatly depending upon the specific vehicle)

Also while the front brakes do do most of the braking, so they will wear out before the rear brakes, don't forget that the rears will need servicing eventually.

Squeaking usually comes from not lubricating the pads when you put them in. Or it can come from not lubing the caliper components.

Shaking usually comes from rotors that have warped from heat. And braking your car produces a LOT of heat. You mentioned that the rotors were sanded down. I hope they weren't sanded down. They should have been turned down on a lathe. That will give you a smooth even surface for the pads to grab onto. But the problem with turning down the rotors is that they are now thinner, and thinner materials tend to warp. Usually it isn't worth turning down rotors. The mechanic might charge you about $50 to turn them down, but new rotors would probably cost only about $100, so you are far better off replacing the rotors instead of turning them down.

Sometimes shaking comes from the pad material leaving small bits and pieces of itself onto a hot rotor. That happens when the pads haven't been "bedded-in" properly. I'm not going to explain that - there are plenty of videos that explain bedding-in brake pads you can watch.

3 stop start isnt great but it wouldnt wear them out super fast, the easiest way to utterly fuck brakes is frequent heavy braking or riding them.

What kind of car is it SPECIFICALLY (year, make, model and badge)