Need help with new brake rotors. Interior surface machined off?

[sceptre]

Hey guys,

I just got back into a 4runner after selling my 3rd gen 15 years ago. This 4runner is for my sons and me to fix up and eventually for them to use.

I started by ordering brakes/rotors and front calipers (Upgraded to larger sport ones) since the front ones were all rusted. Ordered them from Callahan Brake Parts via Amazon.

When they arrived I've noticed that the rotors had areas machined off on the inside of the rotors.

Can some who tell me if this is normal? The only reason I can think of is balancing the rotors? If not, wouldn't this throw off the balance of the rotors?

Here are some pictures of what I'm talking about. Thanks in advance.

Front - Both of the rotors has it. Different lengths

Rear - Only one of the rotors have it. This one is about 12 inches long.

UPDATE: Got a response back from Callahan, and indeed it was for balancing purposes. Learn something new every day. Thanks for the responses all.

 

[Inv4drZm]

Looks like they are for balancing.

https://www.google.com/search?q=bal...bvcAhUBjq0KHXWlCYAQ_AUICygC&biw=2560&bih=1307

 

[Doozi]

Yup... that’s from balancing.


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[Terminator03]

That would be my guess as well, but I’ve honestly never seen rotor that were balanced before. In theory that’s probably a good idea that most replacements don’t bother doing.

 

[Morphyne]

Wow. Balancing rotors. That's quality. Might have to start buying from Callahan.

 

[Rodtheviking]

Wow. Balancing rotors. That's quality. Might have to start buying from Callahan.

How do you know the guaranteed fairy isn't some crazy glue sniffer... He sneaks into your house once and that's all it takes. Next thing you know, there is money missing off your dresser and your daughter is knocked up! I've seen it a hundred times.

 

[sceptre]

Yup... that’s from balancing.


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Thanks for your response.

Have you seen this with other rotors before?

 

[Morphyne]

How do you know the guaranteed fairy isn't some crazy glue sniffer... He sneaks into your house once and that's all it takes. Next thing you know, there is money missing off your dresser and your daughter is knocked up! I've seen it a hundred times.

LOL that took me a second.

 

[Rodtheviking]

Thanks for your response.

Have you seen this with other rotors before?

I have some new Max Brake rotors and they have it too.

 

[sceptre]

Response from Callahan

Thanks for all the responses. It was indeed for balancing purposes. Thanks for your responses all.

Here is their response:

"From what you are describing, it is completely normal. Every single one of our rotors is balanced. If it is out of balance our machine will mark it with a groove and then rechecked for balancing. Customer satisfaction is our priority, if you would prefer we reship a new front set we will gladly ship it."

I have to say they are very responsive and I would rate their customer service pretty high. Once I install the brakes and use them I'll update. But so far, happy with their customer service.