Has anyone replaced with cross drilled and/or slotted rotors?

[Jcera304]

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[BourbonRunner]

Be wary of "cross drilled" rotors, especially inexpensive ones.

Unless you're getting into Brembo or Willwood upgrades they're almost always strictly for looks, are made like garbage in some Chinese factory and prone to cracking under pressure. The drilling process can weaken the rotor and creates microscopic fractures that over time grow bigger until they catastrophically fail due to heat cycles. On a street car there is little to no value aside from aesthetics.

Slotted is better for most street vehicles but be ready to replace pads more frequently, the slots bite into them.

Your brakes and tires are two areas you should NEVER skimp on.

https://www.brembo.com/en/company/news/5-differences-perforated-and-slotted-discs-brembo-brakes

 

[SgtT11B]

As Bourbon says, if you get cross drilled rotors don't cheap out. To be honest I wouldn't bother with this on a BS. I am getting the BAER cross drilled rotors for my Mustang but its the Eradispeed not their cheaper sport ones. They are going to run $1800 for the set.

 

[BourbonRunner]

As Bourbon says, if you get cross drilled rotors don't cheap out. To be honest I wouldn't bother with this on a BS. I am getting the BAER cross drilled rotors for my Mustang but its the Eradispeed not their cheaper sport ones. They are going to run $1800 for the set.

Forgot Baer in my post above, thanks. And I bet that 'stang will stop on a dime when you're done!

For 90% of the driving public, OEM rotors and pads with quality brake fluid will be more than enough. Upgrading pads will help but increase brake dust and noise so there is that.

OP: My recommendation would be to flush the system and use a good high heat tolerating fluid, then bleed them every year. Install stainless lines if they're available and get a good, high quality brake pad from Hawk, EBC, or Stoptech. Forget about the rotors, OEM is more than adequate.

I personally run Hawk HP+ on OEM BMW rotors on my e46 and though they are noisy, they stop on a dime. My next full brake job in the spring will replace the current OEM rotors with EBC slotted.

 

[Bucko]

Totally agree with not going the cheap route when it comes to brakes.

Slotted rotors are supposed to help dissipate the hot gases produced with braking, and provide a better brake action. Used on sports cars and trucks that pull heavy weight.

Wonder if it would eliminate the rear brake squeal that some complain about? Ford would want to bypass this option as it would be an expensive recall if it is found to work.

 

[BourbonRunner]

Totally agree with not going the cheap route when it comes to brakes.

Slotted rotors are supposed to help dissipate the hot gases produced with braking, and provide a better brake action. Used on sports cars and trucks that pull heavy weight.

Wonder if it would eliminate the rear brake squeal that some complain about? Ford would want to bypass this option as it would be an expensive recall if it is found to work.

Depends on the chemical compounds in the brake pads and rotors. Might actually be a bit louder since the surface is interrupted by the slots.

Mentioned above I run Hawk HP+ on my e46 on factory discs. Noisy is an understatement. I’ve taken the system apart and regressed components, cleaned, etc multiple times. Still squeaks and I’ve just accepted it. Changing them in the spring but it is what it is.

 

[sajohnson]

Car & Driver tested: OEM brakes; aftermarket pads (Hawk); and a couple big brake kits on a WRX years ago. The results were that:

* The Hawk pads with OE rotors were a slight improvement (but with increased dusting and pad wear). As I recall, the stopping distance was less but not dramatically so.

* The big brake kits were essentially no better for the first and maybe second stop, but as the number of stops increased, the OE brakes (with stock and Hawk pads) faded badly, while the big brakes' stopping distance remained consistent.

Of course "big brake" kits require larger wheels and tires -- so $ thousands total, for next to no improvement in normal driving.

On a street driven vehicle -- especially something like the BS (i.e., not a muscle car or sports sedan) -- unless there is some obvious problem with the stock rotors and/or pads I'd stick with them.

Repeated hard deceleration/stops from high speed with a short cool-down period are usually only seen on a track. It can be tempting to think that if something works on a race car then it will be great on a street car too. In reality, it's usually a waste of money and may even be worse -- e.g., pads that must be hot to work well (actually worse at lower temps); or are noisy/dusty. Or aggressive pads that eat rotors and need to be replaced in ~20,000 miles.

Ask me how I know.

 

[BourbonRunner]

I recall that test, Marc. And yes, generally speaking on higher performance vehicles the setup from the factory is still adequate for everyone except those of us that throw them around tracks or cones. And then there's the other part of the equation- the tires. Stickier rubber = faster stops but also less tread life.

On a CUV/SUV like the BS I don't think there would be any difference unless you went to a soft compound tire.

I had a MkIV VW that I aggressively auto-x'ed back in the day. I did find that the OEM setup, even if it was an "upgrade" faded out to the point of whacking the cones. I tried many combinations of replacements to get it "right" and finally settled on ECS slotted rotors, SS lines, high temp fluid and a litany of pads until I found the Hawks were the best all around street and course option. To this day Hawk is still my preference for street performance and weekend track days.

 

[RSH]

They could be a benefit if you were trying to use the BS for spirited canyon driving in which it isn't a great canyon carver or if frequently driving or living in the mountains. Other than those situations, I'd save my money.
I guess there's another situation, you just want to have them because they look sweet, sometimes that's all it takes.

 

[Jcera304]

I just wanted to see some pics lol. But thank you all for the info. I will definitely keep that in mind when I change rotors in the future.

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