Are drilled and/or slotted rotors worth the money?

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BlackRoseRacing
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Are drilled and/or slotted rotors worth the money?

Post by BlackRoseRacing » Tue May 22, 2012 10:28 pm

I'm not sure if this topic has been covered or not so.....
I'm looking to upgrade the brakes on my 2500 Ram, started to google search as I've been always the first person to say that a drilled or slotted rotor helps with braking due to technical reasons and I stumbled across this topic online that may be a good read....I'm on page 3......
http://honda-tech.com/showthread.php?t=1437513
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Post by dvon17 » Tue May 22, 2012 10:36 pm

I always thought they just helped with keeping the brakes a little cool-er (ish) idk.

I'll be watching this to learn more, definitely.
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Post by BlackRoseRacing » Tue May 22, 2012 11:02 pm

I just read through all 7 pages and they brought up a good point, brake pad material is not what it used to be when they used asbestos. So the whole theory of the gas build up between the pad and rotor may not exist anymore which is what the drilled rotor is supposed to get rid of. So from what I can gather based on the reading, a good set of pads with OE rotors will provide better braking force as compared to a drilled or slotted setup due to more of a surface area.
So, I should get OE replacement rotors with a set of descent pads(EBC,Hawk,etc) and it will provide me better braking force than using drilled and slotted. It basically shows the old theory of the new drilled and slotted rotors are a waste of $ and there is no real gains next to looks of using them.
I've always recommended for years to use the drilled or slotted setup to help get rid of brake fade due to the gases building up between the pad and rotor and apparently with the new pad design the gas build up no longer exists. So, with that said, I'm going to turn my rotors on a lathe and install a set of new High quality pads Vs OEM...
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Post by OB » Tue May 22, 2012 11:42 pm

Slots, dimples, and drilled holes are all beneficial in cooling. They are also more expensive, sometimes introduce noise, and thru-drilled rotors have been known to crack under extreme use. I prefer dimpled to thru drilled for this reason, but that's just me. Beyond that, the effective differences are minimal. At speed, surface area related frictional losses are easily made up for in performance by the cooling effects of the above designs. A completely flat contact between the friction material and the rotor causes a hot spot, which increases the chances of warpage under heavy use. This is why stock and OEM style designs, though quiet and good for regular street driving, can quickly warp and overheat when used for spirited driving.

All in all, like almost everything, it comes down to the use of the vehicle. If weight and heat are an issue, look at the options out there. Otherwise, stock is perfectly fine. Be sure to use OE replacement pads, aggressive pads on stock rotors can cause some issues as well.
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Post by dvon17 » Wed May 23, 2012 12:08 am

hmm...

Although I like the way the D/S rotors look, I guess I'll stick with my Duralast Gold pads & Duralast rotors for now. :roll: .
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Post by r/tguy02 » Wed May 23, 2012 8:16 am

yes, you hit the nail on the head when you said "more surface area" the more area those pads can contact the better, thats why a lot of people upgrade to PT brakes or SRT brakes. the slots and holes are great for cooling but they also reduce surface area, which do you want more? i personally went back to oem after having drilled and slotted rotors for some time.
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Post by Dranz » Fri May 25, 2012 12:26 pm

When pads are manufactured, they are divided into several groups. The two most common are "flash" molded and "positive pressure" molded. We'll go over flash molded first.

Flash molding is a process where a mold of the brake pad friction material is placed on the backing plate and the friction material is forced in via a duct. This method requires a high resin content to allow the friction material to flow into the mold. The shape of the finished product is acheived by cutting off undesired material. Which in turn is redeposited into the mix. This can result in hard spots or uneven braking pressure.

Positive pressure molds use tons of force to press the pad material onto the backing plate. This process uses significantly less resin and the finished product is achieved in fewer steps. Some companies use virgin friction material which is not recycled friction material.

Less resin=better. When resin is heated to a high temperature(such as spirited braking) is turns into a gas. This process is called "outgassing". This also consequently shortens the life of the pad significantly. This also happens to create a disgusting film on your wheels and sometimes glazes your rotors causing further loss of braking performance. Positive molded pads last longer, outgas less due to a lower resin content, and keep your wheels cleaner.

So basically, outgassing is still an issue no matter what pads you use. Performance rotors are better for people who are brake heavy. They allow this outgassing of resin to escape from the pad while cooling the friction surface of the rotor.

drilled>blanks
dimpled>drilled
slotted>dimpled

Now this is only my opinion on which rotor is better. It is true that drilled rotors crack when overheated. Dimpled rotors are basically just polkadotted versions of a slot. Slots carry away gas and heat much quicker due to the surface area. The only downside to the slots that others don't have is lifespan. Due to decreased friction surface area, slotted will wear the quickest under the same conditions, except when those conditions would require the slots to adequately cool the brakes.

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Post by stairmaster3001 » Fri May 25, 2012 1:31 pm

they can warp easier becuase it has less stability with holes in em.
I bought a set for 180 off ebay for my srt4 and they work great and 8k miles and no warppage. i got all 4 drilled and slotted rotors and ceramic pads. it stops a lil better than the oem set up but not a great difference but there is some improvement. for 180 bucks to me it was a good buy. it would have cost about 190-200 at the parts store for oem type setup but we all know part store rotors are thin and dont last long worth shit so i went with ebay!
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Post by Dranz » Fri May 25, 2012 1:34 pm

The stability comes from a combination of the quality of metal used and the type, quantity, and quality of the cooling veins inside the rotor itself. There was some aftermarket issues with rotors where the veins were directional and aftermarket companies only copied one side. Needless to say, having a comeback for vibration on only one side rotor all the time was quite confusing...
Last edited by Dranz on Fri May 25, 2012 1:39 pm, edited 1 time in total.

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Post by stairmaster3001 » Fri May 25, 2012 1:35 pm

Dranz wrote:The stability comes from a combination of the quality of metal used and the type, quantity, and quality of the cooling veins inside the rotor itself.
well yeah like a ebay set wont last as long as a actually brand name like brembo or wilwood lol but they work good enough for my cheap ass! :rockon:
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Post by darthroush » Tue May 29, 2012 6:42 am

There's also a difference when the rotors are drilled after they are cast, and actually casting the holes into the rotor. Regardless, I always understood the drilling/slotting to help primarily with cooling; not outgassing.

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