2017 Jeep Renegade - Deep grooves in front rotor, but why?

[wavinwayne]

Late last week, my father in law pointed out to me that my son's Jeep Renegade had some significant grooves in the driver's front brake rotor. I hadn't noticed this, so I have no idea how long it took to happen. Basically just that one front rotor (sorry I didn't get pictures) looked like someone has spun the wheel at 100mph and held a chisel to the rotor at 3/8-1/2" increments from near the hub to the exterior diameter of the rotor. The pedal feel when braking was completely normal which is one reason I didn't know anything was wrong. All of the other rotors were very smooth, and the pads have plenty of meat on them. Took it to my local shop today, and he's replacing the front rotors and pads, but no clue what caused this. Any ideas?

 

[John105]

I’ve always heard something embeds.

Imagine on one of our cars if we park on a stone driveway and quickly drive away, rocks get flung and they have landed inside the rotor hat and make a rattling sound. So I imagine depending on vehicle (heard that happens on Audis) things can go where they should not. Think about this one, calipers are in different positions on different cars, front and rear. My .02

 

[JustinH]

someone ran it metal to metal then pad slapped it?

 

[Oillover]

I’ve always heard something embeds.

Imagine on one of our cars if we park on a stone driveway and quickly drive away, rocks get flung and they have landed inside the rotor hat and make a rattling sound. So I imagine depending on vehicle (heard that happens on Audis) things can go where they should not. Think about this one, calipers are in different positions on different cars, front and rear. My .02

Certainly possible, but you'd think the driver would hear significant brake noise, no?

 

[Donald]

Need to know history of the brakes.

 

[wavinwayne]

Need to know history of the brakes.

We bought the Jeep used in summer 2022 and my son has put 15k miles on it in 1.5 years. The brake pads had plenty of meat on them when we bought it and it didn't have the grooves in the front rotor. What was done on the brakes before we bought it is unknown. My mechanic didn't find anything odd when he inspected things this morning, just that grooved rotor. Said he didn't know what might have caused it, the pads weren't worn out.

 

[wavinwayne]

Certainly possible, but you'd think the driver would hear significant brake noise, no?

To the best of my knowledge, my son never heard any strange sounds and never felt any vibrations.

 

[The Critic]

I would not have replaced the front brakes since braking performance was satisfactory. Certain operating conditions can cause the rotor to wear differently.

 

[demarpaint]

Is it possible you bought it that way and didn't notice?

 

[wavinwayne]

I would not have replaced the front brakes since braking performance was satisfactory...

I might not have either, but my wife insisted since our son drives it. If Mama ain't happy...

 

[wavinwayne]

Is it possible you bought it that way and didn't notice?

Thinking back, it is possible. The grooves were possibly there but not nearly as pronounced and it just didn't seem memorable. Oh well, Jeep's got new front brakes and rotors now.

 

[demarpaint]

Thinking back, it is possible. The grooves were possibly there but not nearly as pronounced and it just didn't seem memorable. Oh well, Jeep's got new front brakes and rotors now.

It certainly is possible, you solved the problem, and I'm sure you'll be checking now.

 

[Gasbuggy]

Can be a metallurgy issue with the rotor.

 

[someonesomewhere]

Can be a metallurgy issue with the rotor.

Had this thought. Or maybe an improperly blended pad compound on the one pad? Can that happen? Compound batch swap on the line, like how mystery flavored Dum-Dum suckers are made?

 

[wavinwayne]

Can be a metallurgy issue with the rotor.

That's as good a guess as any. With the new rotors (not sure what brand the shop used), if it happens again, we'll have to dig into the issue more. Hopefully just a one off problem.