Piston Slap: That Gritty Feeling in Your Brakes?

TTAC Commentator 1500cc writes:

Hi Sajeev,

I have an odd problem with the brakes on my 2014 Cadillac ATS 2.0 AWD. It has 35k miles on the clock and the Brembo brakes up front. It started happening last spring: when I’d apply the brakes I’d feel (more so than hear) a grinding or gritty feeling through the brake pedal. The odd part was that the brakes were nice and smooth when cold, and only started to act up after I drove a little bit and the brakes warmed up. Also, it only seemed to do this in the final few feet of a stop, say from 10 mph down to zero (or maybe I just couldn’t detect it at higher speeds). The grinding was proportionate to how hard I pressed on the pedal, but pulsed a bit with the rotation of the wheels as if the rotors were warped.

So the first thing I did was pull the front wheels (for some reason it felt like it was coming from the front) and while the rotors were good and rusty, there was lots of meat left on both the rotors and pads. But just to be sure, I installed new front rotors and pads (a shop said the rotors were too gnarly to turn). Didn’t help. Okay, let’s look at the rears, then. They actually were worn to the point of needing replacement, so on went new pads and rotors there, too. But the problem is unchanged, including the pulsing sensation.

Searching the internet, I’ve seen a few forum threads with pretty much the exact symptoms (fine when cold, grindy/gritty when warm) on everything from Explorers to pickups to Porsches. Unfortunately I couldn’t find one thread that actually had the answer. There were some left-field suggestions like an overfilled master cylinder (I took an ounce or so out of mine just to be sure), but nothing fixed it. What could it be?

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Piston Slap: A Fusion of Malcontent?

Casey writes:

Dear Sajeev,

I love your column! Anyway long story short I’m an idiot. When I met my wife she had a 2003 Ford Explorer Sport Trac that was in ROUGH shape inside and out, cosmetically and mechanically. She liked her truck though and it worked for us for a few years. Recently we (I) was tired of it. So I traded it in on a 2006 Ford Fusion SEL V6. It’s a beautiful car, black on black, lots of power and nice ride. I paid $7,200 for it with 108,000 miles.

The problem is, only about 5 months into ownership and 4,000 miles later several issues have revealed themselves.

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  • Kjhkjlhkjhkljh kljhjkhjklhkjh *Why would anyone buy this* when the 2025 RamCharger is right around the corner, *faster* with vastly *better mpg* and stupid amounts of torque using a proven engine layout and motivation drive in use since 1920.
  • Kjhkjlhkjhkljh kljhjkhjklhkjh I hate this soooooooo much. but the 2025 RAMCHARGER is the CORRECT bridge for people to go electric. I hate dodge (thanks for making me buy 2 replacement 46RH's) .. but the ramcharger's electric drive layout is *vastly* superior to a full electric car in dense populous areas where charging is difficult and where moron luddite science hating trumpers sabotage charges or block them.If Toyota had a tundra in the same config i'd plop 75k cash down today and burn my pos chevy in the dealer parking lot
  • Kjhkjlhkjhkljh kljhjkhjklhkjh I own my house 100% paid for at age 52. the answer is still NO.-28k (realistically) would take 8 years to offset my gas truck even with its constant repair bills (thanks chevy)-Still takes too long to charge UNTIL solidsate batteries are a thing and 80% in 15 minutes becomes a reality (for ME anyways, i get others are willing to wait)For the rest of the market, especially people in dense cityscape, apartments dens rentals it just isnt feasible yet IMO.
  • ToolGuy I do like the fuel economy of a 6-cylinder engine. 😉
  • Carson D I'd go with the RAV4. It will last forever, and someone will pay you for it if you ever lose your survival instincts.