If you were to ask me the straightforward question of, “what’s the first modification that I should do to my car?”, the answer would be equally as simple – brakes. Whether you’re looking at this from a safety angle, or are keen on optimizing the dynamics of your car, brakes are crucial. If you can’t stop right, then what really is the point of doing anything else? But, are drilled and slotted rotors better?
This is an argument that’s raged on for a long time now, as far as any brake-related mods go. While it may be quite simple to recommend you brakes as the first path to go down when tuning up your car. It’s a whole other matter to dive down the rabbit hole of which particular brakes are better. Carbon ceramics, performance brake pads, or gargantuan brake calipers. So, how about those big rotors?
As you press the brake pedal, it’s the brake rotors – or discs – where all your car’s momentum will be scrubbed against. Hence, slowing you down. When you’re looking to maximize your car’s dynamic or athletic potential, those minute differences – such as the varying types of brake rotors – can make a lot of difference. In this regard then, are drilled and slotted rotors better, or are there alternatives?
What Are Brake Rotors, Anyway?
There’s an important question that we have to answer before we discuss are drilled and slotted rotors better… Just what are brake rotors, and what do they do? The brake rotors are among the most vital aspects of a car’s braking system. When we speak of “rotors” or “discs”, these are those round saucer or plate-like objects that you can peer through your wheel spokes. Big or small, those are the rotors.
Their purpose is simple, to reduce your car’s speed by converting its motion into heat and friction. Its process first begins – step-by-step – with the press of the brake pedal. This input, via your feet, would make its way through the braking system by way of pressurized, hydraulic brake fluids. The pressure will subsequently actuate the brake calipers, which are the fork-like things sticking out on the side.
In effect, the brake calipers will squeeze, clamping down the brake pads against the rotors. As your brake pads rub and grind against the rotors-slash-discs, heat and friction will be generated. All that energy lost was converted from the kinetic energy of your car moving around. In layman’s terms, the braking system converts that kinetic energy into heat and friction, thus slowing your car down.
Brake rotors are typically made out of steel. It’s deemed to be an efficient material for being able to quickly absorb and simultaneously release all that heat effectively. However, they’re not the only compound that rotors-cum-discs are made of. Steel may be commonplace among most vehicles, but they’re not alone. Typically, rotors can be made out of six different types of materials…
What Are Brake Rotors (Including Drilled And Slotted Ones) Made Of?
- Cast Iron – The first brake discs ever made were cast iron. They’re an old-school option, usually found in classic and vintage cars. Many earlier race cars also used cast iron brake rotors. There’s one major downside in their design though, as iron is pretty heavy. Consequently, this would affect handling.
- Steel – They’re the most common ones you’ll find on most cars today. Tweak their design a bit more, and even racers often favor steel. They’re not only lightweight (owing to their thinner construction and reduced density), but they also manage heat quite well.
- Layered Steel – There is, unfortunately, one flaw with straight steel brake rotors. Apply too much heat and wear, and they can warp. This is where layered steel discs come in. Its design includes laminating together layers of steel sheets, making them more robust. Alas, they’re quite hard to find.
- Aluminum – It’s an intriguing material to use since aluminum has a lower melting point than every other material here. The upshot is that it dissipates heat very rapidly, is incredibly light, and could last for a long time if used modestly. They’re most commonly found on motorcycles.
- High Carbon – Despite what the name might suggest, they’re essentially iron rotors underneath. But, with a lot of carbon added into the mix. This enables them to withstand high heat, and dissipate that heat quickly. Moreover, they prevent cracking under duress, as well as reduce vibrations and noise.
- Carbon Ceramic – As good as high carbon brakes are, they’re expensive. As a result, carbon-ceramic brakes have stepped in to bridge the gap. They can tolerate more heat than most, dissipate heat, as well as anyone, could, and maintain even braking force and pressure.
Are All Brake Rotor Types And Designs Drilled And Slotted?
As you can imagine, brake rotors undergo an immense amount of strain anytime you even tap at the brake pedals. They have to absorb a lot of heat. And we do mean loads of high temperatures. Under regular use, you can expect your brake rotors to heat up to a toasty 392°F. If that’s not high enough, consider that with aggressive and hard braking on a track day, they can heat up past 1,000°F.
It’s for that reason why many people are wondering are drilled and slotted rotors better. For the heat to dissipate as efficiently as it can from the brakes, not all rotors have smooth surfaces. Some, though it’s mostly found on performance cars, have ribs or grooves on their rotor surface to help move the heat along. In other words, are drills and slots carved into the rotors. But is this necessarily any good?
To best find out are drilled and slotted rotors better, we ought to look at all the options available. You can find four different rotor types. Here’s how you can tell them apart…
- Blank And Smooth – The brake rotor’s surface is smooth and plain, without any drilled holes or slotted grooves engraved into them.
- Drilled – You can spot these quite easily with a series of holes drilled and punched into the surface of the rotors in a set pattern.
- Slotted – You’ll remark the slots, or straight lines carved into the rotor’s surface, placed at a set angle and distance away from each other.
- Drilled And Slotted – A combination of the latter two, you can notice both drilled holes, surrounded by slotted markings.
As you can imagine, different types of brakes and their surface finishing have varying pros and cons. Here’s a quick summary of the four here…
1. Blank And Smooth – Best All-Rounder And For General Day-To-Day Use
- They’ve been refined for hitting that fine balance between good performance and being affordably priced. Since they’re inexpensive, you won’t have to worry too much about having them replaced.
- As simple as they may be, they’re also among the long-lasting types of brakes here. Lacking complex designs like drill holes and slotted grooves means that there’s less of a chance of cracking or warping.
- Endurance race cars typically have blank and smooth rotors. While they can’t dissipate heat as well, they wear slowly, which is perfect for a race that can last up to 24 hours.
- In general operation, they provide an even amount of braking feedback that works well in any car or situation. On top of that, they’re also fairly quiet and don’t provide too much brake dust.
- While they’re able to dissipate a sufficient amount of heat, they’re not the best performer out there. Should you like to drive your car hard (but not long), there are better options.
2. Drilled – Best For All-Season Performance (Especially Good When Wet)
- The drilled holes allow for moisture to seep through. This makes drilled rotors a must-have for those who live in rainy climates. To that end, it performs and bites down well, even with a lot of water.
- Speaking off, the initial brake “bite” (or how long it takes for maximal friction to be had) is better on a drilled rotor. Once again, this has a lot to do with how well moisture can escape the discs.
- When used in racing applications or under hard driving, the extensive (very high) heat exposure can wear drilled rotors unevenly. If you’re too harsh on them, they might also crack under pressure.
- Similarly, they’re not a great fitment on race cars or if you’re enthusiastic during track days. Drilled rotors can’t withstand the continuous heating and cooling cycles, which lead them to premature wear.
3. Slotted – Best For Heavier/Larger Vehicles, And Competition Cars
- They’re incredibly effective at braking performance, but also reducing the friction made by the brake pads. Their slotted design can shave through brake pad material, exposing their fresher contact pads.
- Besides top-notch braking performance, this also has the side-effect of making sure you’re able to use more out of a set of brake pads. You can thus rely on both the rotors and pads for optimal braking.
- They’re able to maintain braking performance as well as braking feel and initial bite consistently. But, it’s crucial that you pick quality slotted rotors that were machined well, or else they may wear quickly.
- Owing to their best-of-its-class braking performance, this makes slotted rotors a great option for heavy-duty vehicles. That includes SUVs, pickups, off-roaders, trucks, as well as race cars.
- While its capabilities are all well and good, slotted rotors do wear out much quicker than most of the brake discs here. On top of that, you’ll start wearing your brake pads faster, too.
- As you’re coming to a halt from higher speeds, the slotted design can cause the rotors to rumble and shake a bit. This is normal and needn’t be concerned about, but the noises may be discomforting.
Okay, So How About Are Drilled And Slotted Rotors Better?
We’ve saved, of course, the best for last. So, are drilled and slotted brakes better? As that’s the topic of discussion today, we’ll be diving into greater depth of its many benefits, and some downsides. In a nutshell, its drilled and slotted surfacing is meant to optimize improved cooling of the rotors, as well as disperse away heat. High-speed braking and race or performance cars are their prime target.
So, have they succeeded? Now, remember, drilled holes and slotted grooves don’t magically make a car stop better through heat transfer. Drilled and slotted rotors aren’t that much better at that than just drilled, or merely slotted rotors. However, the use of grilling and slotting on the rotors do help significantly in evacuating moisture, on top of brake just, and hot gases or fumes from the brakes.
By clearing out as many obstacles as possible between the surface of the rotor and the brake pads, what you end up with is a tighter contact patch. In other words, it can enhance the friction between the rotors and the pads, thanks to those drills and slots. Altogether, are they worth the compromises and complexities? Here’s a quick round-up of their pros and cons, to help you find out…
Pros Of Drilled And Slotted Brake Rotors
1. Excellent Brake Performance During Weather Climates
A continuation of the point we made earlier, drilling holes through the brake rotors aid in removing any water or moisture from getting in between the discs and the pads. Thus, you can expect them to work fantastically in stopping your car when the weather and roads get rainy. The addition of slotted grooves also helps the drilled holes to evacuate moisture that bit more effectively.
2. Works Wonders For Heavy-Duty Or Competition Vehicles
When we say heavy-duty, we mean large trucks, SUVs, pickups, 4×4 off-roaders, or any vehicle that’s carrying a lot of mass that needs stopping. Or, the benefits of superb braking performance go to competition racers, too. One caveat is that you should be attentive towards the finish of the rotor. The outer and inner finishing on the surface needs to be done just right to prevent premature cracks.
3. Makes Sure Your Brake Pads Don’t Glaze
Glazing is what happens when the brake pads heat up too much, to a point where the contact pads harden into a glaze. Because of this, they can’t adequately create a smooth contact with the rotors. Some of the brake pads materials may also fuse with the discs. Drilled and slotted brakes not only exhaust heat better to prevent the pads from overheating but also actively shaves off the glazing.
4. Consistent Braking Pressure And Feedback
This is most noticeable if you’re daily driving, for example. As brakes get used, constant heating and cooling can affect how they feel. With drilled and slotted rotors, they instead have a consistent amount of friction going out all the time. Additionally, the bite you feel as you tap on the brake pedal is firm and even. This ensures that you can feel more confident behind the wheel.
Cons Of Drilled And Slotted Brake Rotors
1. They’re Often Subject To Premature Wear And Tear
Drilled and slotted rotors can sometimes wear unevenly across their entire surface area. This means two things. First, you’ll have to replace them more often, and have a shorter shelf-life than other types of rotors. Moreover, repeated exposure to high heat can enable them to develop cracks over time. This is most typically seen with performance cars, or for those who drive a bit too enthusiastically.
2. The Wearing Pattern Isn’t Even
Because of its design, drilled and slotted rotors wear out in concentric patterns. This may cause them to look rather ugly, but the aesthetics aren’t the primary concern. As these rotors age, the patterning will get deeper, resulting in some vibrations felt over the steering wheel under braking. This can, at least, be somewhat prevented with higher-quality rotors that have staggered drill holes.
3. Its Usable Life-Cycle Is Rather Short
As we’ve explained already with slotted brakes, the grooves can wear out both the rotors and pads much sooner than anticipated. Should you be too hard on them, it’s possible that you may need to replace the rotors as frequently as you do with the pads. A rough estimate would be somewhere in the neighborhood of every 25,000 miles. This figure will decrease the more you brake.
4. They Can Be Louder Under Braking
Since all brakes have direct contact between the rotors and pads, you’ll of course expect there to be some noise. This can be heard as a squealing sound. With drilled and slotted rotors, however, you’ll get to hear a new sound, a sort of rumbling. This is caused by the brake pads running over the slots and holes. While this doesn’t create an issue safety-wise, the noise may be unpleasant.
5. Cooling Effects Are Questionable At Best
True, drilled and slotted rotors can evacuate some of the hot bits, such as gases, away from the pads and discs. It can also run cooler too since there’s less direct metal-on-metal contact with the brake pads. Nonetheless, its cooling effects don’t work with every car. As drilled and slotted rotors have fewer metal compounds in them, they could heat up faster than most. Too much, and it can warp or crack.
6. You Can’t Resurface Drilled And Slotted Rotors
Resurfacing is the process of shaving off the top layer of the rotors. This is a good alternative to simply replacing them, as reconditioning the rotors can be done if there’s only minimal wear or damage. It works well to restore its functionality in a pinch, but not on drilled and slotted rotors. You can’t easily resurface the drilled holes and slotted grooves, without negatively impacting its performance.
Should You Get Drilled And Slotted Brake Rotors?
Now, we finally come to the million-dollar question… Are drilled and slotted rotors better? My reply to that would be Yes, and also No. They’re certainly better in some regards compared to most other rotor designs. As far as performance goes, they perform brilliantly in wet climates, as well as helping to provide strong and consistent braking performance. Plus, they work with heavier vehicles, too.
There’s also the downside, whereby the upkeep is both expensive and complicated. While they work well under normal conditions, get them too hot, and they can warp or crack. Under use, they can be a bit louder at times, with subtle vibrations felt on the wheel. Worse of all, you can’t resurface them if they’re only slightly worn. Furthermore, you’ll have to replace them (and the pads) quite regularly.
In layman’s terms, DO consider upgrading to drilled and slotted brake rotors if:
- You drive a heavy-duty truck, SUV, pickup, or off-roader that needs good stopping power.
- A luxury car is what you own, where you pride consistency and evenness.
- You’re driving around a performance car that would benefit from better braking.
- The weather around you is typically damp, wet, and rainy.
Otherwise, DON’T even think about drilled and slotted brake rotors if:
- You go out for aggressive, hard, and lengthy track days that could heat up the brakes too much.
- The budget you have is a bit too short to support regular upkeep and replacements.
- You’re sensitive towards aesthetic wear, as well as slight rumbly noises and vibrations.
- The prospect of repeated trips to the workshop for a replacement is too inconvenient.
Final Thoughts On Are Drilled And Slotted Rotors Better?
Generally, you can find drilled and slotted brake rotors for around $150 for a pair of them. Although, more performant versions can be expensive. Sometimes, you’ll find these brakes going for between $1,000 to $2,000 just for a set of two. Do the benefits justify the cost of upgrading your current set of brakes to these. After all, the question of are drilled and slotted rotors better show that they are.
In truth, if you’re not planning to use your car any more than you already do, and the brakes there are working just fine, then don’t bother. Your car likely has a set of blank and smooth rotors, and they’re already pretty decent at what they do. They present a good balance between upkeep costs, wear and tear, as well as performance. It’s remarkable to see just how much brakes have evolved.
Therefore, you have to assess whether or not you even need these potent rotors in the first place. If your car manufacturer recommends you to use the OEM brakes, then there are few reasons to deviate. With that being said, and if you find yourself wanting a bit more. Or, if you’re feeling that your car’s brakes just aren’t up to snuff, then drilled and slotted rotors could be a good next step up.
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