New Brake Pads, New Issue

[RandomNerd2000]

So, I got enough of the black dust accumulating on my wheels on my 2000 every 200 miles, to the point they'd be black, and got brake pads for it. Didn't do the rotors since mine were in good shape, no warping or grooves or deep wear. Anyhow, I've done the pads, I went with ceramic pads, which changed the feel of the truck entirely, also no more dust. However, babbling aside, I noticed on the drivers side rotor, about center, about half an inch wide, the entire way around, there's a nice strip the pad isn't touching, like a perfect circle. Anybody seen this before? It okay or I need to change the rotor? I'm having ZERO issues stopping or anything so it's thrown me for a loop why it's doing that.

 

[fast_dave]

I noticed on the drivers side rotor, about center, about half an inch wide, the entire way around, there's a nice strip the pad isn't touching, like a perfect circle.

Without seeing a picture, it sounds like you are describing a "perfect circle" low spot, somehow scribed/scored on to the rotor.

If that's the case, you should gradually see the pad "grow" a high spot that matches the low spot on the rotor.

If you do have a low spot on the rotor, I'd replace both front rotors before the driver's side outer pad is ruined - but that's just me.

Brakes are a safety issue and in CA I've had to make more than a few high-speed panic stops. I know the value of a set of well performing four wheel disc brakes that stop STRAIGHT and in a SHORT DISTANCE.

Sounds like your concern is your little voice inside is talking to you...

What caused the rotor to get scribed/scored - I don't know...

Rock Auto has rotors at a very reasonable price ;-)

 

[koda2000]

This is what can happen when you install new pads w/out getting the rotors turned. The new pad will eventually conform to the uneven surface, not to worry. BTW - Do you break-in your new brake pads, or just start driving normally on them?

 

[toypaseo]

BTW - Do you break-in your new brake pads, or just start driving normally on them?

When I replaced my fronts with new NAPA polymer coated rotors and new NAPA Adaptive One ceramic pads, I was told to drive easy with no hard braking.

After six months...

 

[koda2000]

Whenever I've changed brake pads I've always broken in my pads by making 3 hard stops at 35 MPH, 45 MPH and then 55 MPH (letting things cool between each step). I find this has made a big difference in braking power and feel and has never seemed to cause any damage.

 

[fast_dave]

bbling aside, I noticed on the drivers side rotor, about center, about half an inch wide, the entire way around, there's a nice strip the pad isn't touching, like a perfect circle. Anybody seen this before?

A pic of the rotor/brake pad interface wouldn't hurt and would help us to get a better understanding of your particular situation.
With the wheel off - one or two pics from the side - around 70 to 80 degree angle - so that we could see the width & depth and thus get a better idea of what is worrying you.

 

[J_C]

Turn (if enough material thickness remains) or replace the rotors. If you have a micrometer [or some designs of caliper] then you can get an idea if enough thickness remains by measuring yourself in that thinnest area. The minimum thickness should be stamped on the rotor.

Eventually the rotor and pad will wear to a matching state, though they'll probably wear faster and you might end up with some noise, though less since they're ceramic.

If it stops fine, noise isn't excessive... it's not our money, easy to tell you to do something that requires more labor and expense, or if they wear faster it's still going to be cheaper to wait till next time for new rotors. If hauling loads, towing, or driving a lot of long, steep hills then I wouldn't wait.

 

[imp]

...........If it stops fine, noise isn't excessive... it's not our money, easy to tell you to do something that requires more labor and expense, or if they wear faster it's still going to be cheaper to wait till next time for new rotors. If hauling loads, towing, or driving a lot of long, steep hills then I wouldn't wait.

@J_C
Back in the days of drum brakes, occasionally I encountered rivet-scoring. If the drum had already breen bored, and the grooves not excessively deep, I ran the new linings right on the old drums. Linings wear to conform to the drum shape. Next guy, however, will encounter difficulty pulling the drums off, unless shoes are backed off.

 

[koda2000]

@J_C
Back in the days of drum brakes, occasionally I encountered rivet-scoring. If the drum had already breen bored, and the grooves not excessively deep, I ran the new linings right on the old drums. Linings wear to conform to the drum shape. Next guy, however, will encounter difficulty pulling the drums off, unless shoes are backed off.

When you think about, you actually got a little better braking due to the increased surface/contact area once the shoes worn in.

 

[imp]

When you think about, you actually got a little better braking due to the increased surface/contact area once the shoes worn in.

@koda2000
Ha! Something I never thought of! I like your ability to analyze stuff. imp

 

[koda2000]

@koda2000
Ha! Something I never thought of! I like your ability to analyze stuff. imp

Analyze or rationalize?

 

[imp]

Analyze or rationalize?

@koda2000
I suppose rationalizing occasionally helps "keep the peace" amongst some of us argumentative old farts!

 

[J_C]

You might end up with greater contact surface area but it could vary. The coefficient of expansion is higher for (iron) rotors than brake pads so they're not going to fit together the same cold as hot.

 

[imp]

You might end up with greater contact surface area but it could vary. The coefficient of expansion is higher for (iron) rotors than brake pads so they're not going to fit together the same cold as hot.

@J_C
We could get into the Physics of frictional surfaces, as you mention area could vary. Depending on the characteristics, smooth on smooth, smooth on rough, etc., the area of contact often makes little or no difference. In the case of something having "teeth", however, like rubber tires being scrunched down into pavement (which really isn't "smooth"), the contact area makes a world of difference, though in theory it should not. 'Nuther example of "rubber is magic". imp

 

[RandomNerd2000]

It's gone away now, took 200 miles and it's fine now, it stops a world better compared to the dirt cheap pads on it before, it'll stop on the spot almost now, and still no black rims, dust is the least of my issues now. The reason I was asking was I though it'd break in to be perfectly fine, I don't have any pulsations or issues stopping, nor was this exactly a groove or scoring, the rotor appeared perfectly flat and I didn't notice anything abnormal on the old pads, nor do I tow, but two heads generally work better than one. Also, to respond to the question, I do break in my pads, helps with the stopping ability generally.

 

[swshawaii]

Thanks for follow up. I had the same issue with my drivers rear, except the 1/4" "rust ring" was on the outer edge.
After following the bedding in procedure, the ring appeared. After about 200 miles of normal driving it disappeared.

 

[RandomNerd2000]

Thanks for follow up. I had the same issue with my drivers rear, except the 1/4" "rust ring" was on the outer edge.
After following the bedding in procedure, the ring appeared. After about 200 miles of normal driving it disappeared.

Yeah, mine was in the dead center of the rotor, tad strange of a place but I don't have normal issues generally. I'm so happy I did the pads though, it's like driving an entirely different vehicle.

 

[koda2000]

Yeah, mine was in the dead center of the rotor, tad strange of a place but I don't have normal issues generally. I'm so happy I did the pads though, it's like driving an entirely different vehicle.

Yeah, I find the ceramic pads work a lot better than the semi-metallic pads and keep my wheels clean. I use C-MAX ceramic pads (or whatever brand AutoZone is currently selling to replace them). AutoZone has always replaced brake pads for free (no questions asked, as long as your in their computer ) so that's where I get them. My current vehicles all use the same calipers/pads I guess I could just have bought a single pair and just keep saying they're for that vehicle, though that's a dishonest.