Pad Imprint on Front Brake Rotors, WARPED?

[DRACO A5OG]

Hey Fellas,

So I have an issue with my front brakes, maybe someone can guide me, purty please?

I replaced my Rotors and Pads all around. My front rotors developed what I can best describe as "Pad Imprints" residue. It is just enough to emit vibration noise on the freeway when I have to slow down for an off ramp. Today, a low tone hum developed when driving off from a stop ( sticky piston???, will diagnose tomorrow )

Not my car but from the web:


To the touch, the residue is definitely higher then the rest of the surface of the rotor and I put a brass wire wheel to it. It got better but the imprint is still there and I still hear the vibration but not a pulsating feel like a warped rotor.

So my questions are:

Will this "pad impression" wear off over time or do I need to machine service/turn my new Zimmermans? Pads are Porterfields R4S.

Did I not bed these pads correctly? I was very gentle for the first 200 miles and never sat at a stop with my brakes depressed. Very Strange.

TIA,

Jim

[sc_rufctr]

I wouldn't do anything except keep an eye on it. After a few spirited drives it will probably disappear.

It's probably moisture related.

[DRACO A5OG]

That's what I was thinking, never had this happen to me before so I was a bit concerned.

Time to go to the canyons But better be safe and do an A/X to burn it off. She brakes on a dime so it should be fine.

The pads look fine too.

Thanks for your post Brother Peter!

[DanielDudley]

3M Roloc disk on a drill, or the Harbor Freight equivalent. The red ones work well. What you want to do is deglaze your rotors. You let the rotor spin while you are using the drill on it with the roloc disk almost flat to the wheel. You pull the caliper and do the inside surface as well. When the roloc pad looks filthy, swap it out.

Lightly sand the brake pads on a flat surface and then go out and bed in the pads. If you do this, your brakes will be as good as new or better. Rolock is like Scotchbrite. I suppose you could take the rotors off and scrub them, but I have always had super results with the rotary approach.

This is a fairly common procedure, and I have used it many times. I learned it from a pro 30 years ago. The Rolock pad makes the surface of the rotor the perfect texture for bedding in. This works very well on glazed flywheels too, if they are not badly scored.

[Bill Verburg]

Originally Posted by DRACO A5OG

Hey Fellas,

So I have an issue with my front brakes, maybe someone can guide me, purty please?

I replaced my Rotors and Pads all around. My front rotors developed what I can best describe as "Pad Imprints" residue. It is just enough to emit vibration noise on the freeway when I have to slow down for an off ramp. Today, a low tone hum developed when driving off from a stop ( sticky piston???, will diagnose tomorrow )

Not my car but from the web:


To the touch, the residue is definitely higher then the rest of the surface of the rotor and I put a brass wire wheel to it. It got better but the imprint is still there and I still hear the vibration but not a pulsating feel like a warped rotor.

So my questions are:

Will this "pad impression" wear off over time or do I need to machine service/turn my new Zimmermans? Pads are Porterfields R4S.

Did I not bed these pads correctly? I was very gentle for the first 200 miles and never sat at a stop with my brakes depressed. Very Strange.

TIA,

Jim

Just drive it, it will be fine

[Lapkritis]

If you have contamination on the surfaces, you can get spooky brake performance. I would recommend removing the pads and hitting those and rotors with a brake cleaner spray bath.

[Porsche 2]

Could be slight rust from the last time you washed the car.

[DRACO A5OG]

Rolock? Interesting, I guess as long as I do not cut into the rotors.

Well, before that I will try the bedding process one last time. 6-8 50MPH down to 5MPH with 15-30 second cool downs then another 6-8 30MPH to Stops with cool downs.

Per Jack's findings:

I drive them to the track and they seem good to go.

However, I found this in a search:

Quote:
Originally posted on http://www.porterfield-brakes.com/performancefaq.htm

- Is there a bedding in procedure for your pads?

Yes. The Carbon Kevlar pads have a bedding in procedure.

Make light to medium deceleration stops to slowly heat up disc. This must be done slowly to avoid thermal shock to the disc. Make a series of hard stops, allow to cool slowly.
__________________
Jack Olsen
1972 911

[jjeffries]

Bill Verburg is the gold standard for brake advice. This happens to cars (daily drivers) every day in places where there's moisture. John in CT.

[brighton911]

Like others have said, Jim, no worries, just drive it. One trick I use to avoid this is: after washing the car, I drive it around it around the block and use the brakes lots to heat the rotors and drive away any moisture. Keeps the rotors looking like new.

Dave

[DRACO A5OG]

Thanks fellas!

I took everything apart to insure all moving components are clean and managed to duplicate the low harmonic tone, when I just slipped the cleaned pads back in place and I did not press the pedal. The pads were lop sided, but once I pressed the brakes and pads aligned to the rotor, it stopped the harmonic tone Weird

I have not attempted to re-bed yet. As Bill Verburg suggested, I will just drive her, burn it off over time and use.

Funny thing is, after our rare SoCal rain last week, I did let it sit for couple of days so I have to assume it must have been some rain rust residue. Hmmm????

The imprint is getting lighter and lighter though That does not concern me but the vibration noise does from freeway slow down using the brakes.

JIm

[DRACO A5OG]

Update:

All good, just took a bit of time to burn those imprints off :-)

Thanks to all and especially to Master Bill Verburg!