Notch in Front Brake Rotor

[CharBaby]

So, last May 2011, I purchaced from Rock Auto and installed 4 brand new Centric Rotors w/Black E-Coating and Centric Posi-Quiet Ceramic Pads on my daughters Mazda3.

3-4 months later(after Centric's 90 day warranty), we noticed brake pulsation. I called Rock Auto(whom I still do business with and don't hold anything against them) and mentioned this issue and they unfortunatly told me that Centric's Warranty had expeird but, doesn't cover warpage anyway just MFG defects. At this time, I hadn't noticed anything wrong with the rotor(s)

While living with the pulsation(which is mild) now for over 1 year, I decided to measure both rotors/runout and the driver side Front rotor is where the problem lies.

This warped Centric Rotor(driver front only), has a long notch(Oh, 3"-4") along the top of the Vented area in which I have never seen in 40 years of doing brakes. The other(pass front) does not.

This morning, I did an AAP online purchace(discount code) for their WearEver Rotors(only bought 1) and it was ready when I picked it up.

Dontcha' know it? This Rotor also has a machined groove cut along the top of the vent(~2"-3"). I asked to see another box(same WearEver part #) and this other/rotor DID NOT have the groove along the top of the rotor.

My question is: What is up with the groove/notch cut along the top of the rotor(s) and some do not???

I was told that it's for extra cooling! Huuuuh?
Why one and not the other? Is is just Mazda3's?

 

[exranger06]

I recently replaced the rotors on my Ranger with Napa Ultra Premiums and I noticed the same notch on one of the rotors. I figured that was just the way it was made and I didn't bother checking the other rotor to see if it had it.

 

[KrisZ]

My guess is that this is done to balance the rotor.

 

[Eddie]

The knotch is to allow one to remove & or replace the brake pad from the caliper.

 

[CharBaby]

Originally Posted By: Eddie
The knotch is to allow one to remove & or replace the brake pad from the caliper.


Not on anything that I own! The Calipers still have to be lifted(remove bottom slider bolt and lift up). This knotch isn't large enough to allow the romoval of pads from the caliper!

Originally Posted By: exranger06
I recently replaced the rotors on my Ranger with Napa Ultra Premiums and I noticed the same notch on one of the rotors. I figured that was just the way it was made and I didn't bother checking the other rotor to see if it had it.

Did you have any issues with that Rotor?

I have never heard what I have been told by the clerk/mgr at AAP(extra venting) although they claim it's true!

 

[CharBaby]

I've been google'ing the snot out of these rotors and can't find a thing! Not a picture, not a mention...Nothing!

I'm starting to think that it's a manufacturing defect; that the machine work has remained in one place too long!

 

[exranger06]

Originally Posted By: Char Baby

Did you have any issues with that Rotor?

It's only been installed for less than 2k miles. No issues so far.

 

[mechanicx]

Originally Posted By: KrisZ
My guess is that this is done to balance the rotor.


I think that is the case. The notch was to balance the rotor.

The warranty not covering warpage allows them to get out of the warranty. The rotors probably aren't even warped but may have had thickness variation because the rotor had run out. The question is does the rotor have excessive run out because of the hub or rotor. They don't even investigate that.

 

[stephen9666]

Why don't you post some pics?

 

[Texan4Life]

Does it look like this?

http://i50.tinypic.com/x4n5ab.jpg

these are normal IMO. I assumed they were from balancing the rotor.

 

[mechtech2]

Balancing - it's a good thing.

 

[CharBaby]

Originally Posted By: Texan4Life
Does it look like this?

http://i50.tinypic.com/x4n5ab.jpg

these are normal IMO. I assumed they were from balancing the rotor.

Yes, it looks exactly like this. The Centric groove is a bit longer and the WareEver is a bit shorter.

For balancing hmmm?
I buy that more than for better air flow/ventilation as the guy at AAP said!

This Centric Rotor is the first rotor that I have ever seen that was like this and it's the first rotor that I have ever had that cuused me issue in 3-4 months...Especially for a "BETTER" rotor not an economy rotor

 

[HTSS_TR]

This is the first time I saw a rotor with a notch like Texan4Life's picture. From original to many aftermarket brands.

 

[Kiwi_ME]

That seems like a good way to remove material for balancing, which would be essential.

 

[CharBaby]

I believe that the longish groove in my one Centric rotor, is what caused my pulsation issue as I stated above...1st time I have ever seen this...1st time any(ANY) new rotors that I have purchaced, has developed this pulse issue sooooo soon!

I mean, the earliest issues that I have ever had with rotors was 1.5 years, not 3-4 months!

 

[mechanicx]

That groove is from balancing as mentioned earlier and wouldn't cause brake pulsation. Thickness variation causes brake pulsation. You said you measured excessive run out on the rotor and that's the source of the problem.

 

[CharBaby]

Originally Posted By: HTSS_TR
This is the first time I saw a rotor with a notch like Texan4Life's picture. From original to many aftermarket brands.

This is why I am so concerned. I have just never seen this before!

 

[Eddie]

I was assumed the "knotch" was on the edge of the diameter which is to remove & replace pads. My bad, as I didn't understand. Ed

 

[edwardh1]

must have some serious metal density variations in the casting to require a balance notch like that. The variations probably indicate poor rotors that in turn warp quicker,

 

[Texan4Life]

I have noticed these are many rotors. Never paid much attention so so hard to guess how many on the ones I have handled, at least half maybe..... the rotor in my picture was one I took of our 04 neon. they are the original OEM ones.