Rotors, please explain the difference

tommyguns · 02-13-2011, 08:05 PM

Could someone please explain why when purchasing rotors some will get cross drilled some will get slotted and some will get the combo. I ask because I intend to change my rotors in the near future and need to be educated before making a purchase.
Thanks in advance,
Tom

Baer383 · 02-13-2011, 08:16 PM

Cross drilling and slotted rotors is b/c it gives the gas/brake dust an area to escape kind of like a passage most people buy them cause of the looks but if it is cross drilled and slotted it will release heat quicker than stock.

Hope some of this helps.

tommyguns · 02-13-2011, 08:29 PM

Quote:

Originally Posted by Baer383

Cross drilling and slotted rotors is b/c it gives the gas/brake dust an area to escape kind of like a passage most people buy them cause of the looks but if it is cross drilled and slotted it will release heat quicker than stock.

Hope some of this helps.

Yes that I do understand, I actually have them on my FX, but to be honest I did it for the looks. So I ask this, then why do they offer an option if the combo is the best way to go. I also notice that not all race cars use just the cross drilled /slotted. I have seen all 3 types out there

Baer383 · 02-13-2011, 08:42 PM

Quote:

Originally Posted by tommyguns

Yes that I do understand, I actually have them on my FX, but to be honest I did it for the looks. So I ask this, then why do they offer an option if the combo is the best way to go. I also notice that not all race cars use just the cross drilled /slotted. I have seen all 3 types out there

I'm not exactly sure but by having them cross drilled could also be for lightening to keep reciprocating mass down but having all of them would give the most benefit,slotted is generally to get rid of expanding gases but does also keep weight down too.

tommyguns · 02-13-2011, 08:55 PM

Quote:

Originally Posted by Baer383

I'm not exactly sure but by having them cross drilled could also be for lightening to keep reciprocating mass down but having all of them would give the most benefit,slotted is generally to get rid of expanding gases but does also keep weight down too.

Thanks for the info.

cossie1600 · 02-13-2011, 09:36 PM

It's all for looks on a street car, makes no different when you drive from IKEA to Home Depot

spearfish25 · 02-13-2011, 09:46 PM

There are more reasons. To touch on all I can think of:

1) aesthetics
2) weight reduction (though minor)
3) ventilation (minor)
4) increased initial bite...this is a big draw for the slotted rotors

Keep in mind that drilled rotors may crack under high temperature applications. From what I've read, the best overall braking force is obtained with non-drilled, non-slotted rotors. Slotting and drilling can both increase pad bite by shaving off the brake pad surface and exposing fresh material.

tommyguns · 02-13-2011, 09:56 PM

Quote:

Originally Posted by cossie1600

It's all for looks on a street car, makes no different when you drive from IKEA to Home Depot

The car will be at the track this summer for sure.

wilsonp · 02-13-2011, 11:21 PM

Considering the heat issues the 370Z has with brakes, you shouldn't do either one - having more mass provides more heat sinking for the discs.

RockStarKick · 02-14-2011, 11:11 AM

Quote:

Originally Posted by wilsonp

Considering the heat issues the 370Z has with brakes, you shouldn't do either one - having more mass provides more heat sinking for the discs.

And what are the heating issues with the brakes ? Wouldn't the drilled holes
or slots make the weight lighter (slightly) ? The drilling and slotting would also release the hot gas therefore making the rotors/pads cooler..?

Just curious..

CFZ · 02-14-2011, 11:45 AM

Cross drilling give the rotor more surface area, which in turn helps the rotor cool down more quickly. Slots on the other hand gives the pads a way for the gases from the pads to escape. Also it shaves the pad surface as your braking, letting the contact surface of the rotor and pad to be fresh and help prevent hazing.

But here is the real deal with them.
Current pads do not release a gas. So slots for that purpose is deemed useless. Now I do get the slots to resuface the pads but its just a placebo effect for me (I just like looking cool)

The cross drills on the other hand may actually work. but the tradeoff is much worse. This is why I stay away from crossdrilled rotors and so should you guys. Cross drilled rotors are very prone to cracking. In fact one session at a track day is all it takes for them to really crack.

I am not saying none of the other rotors crack. In fact most my rotors crack because of the aggressive pads I use on the track. But Cross drilled rotors are just plain scary how easily they crack. Also just to get the information straight for you guys, neither crossdrilled or slotted rotors are made to save weight. The better more performance oriented crossdrilled rotors have double the number of veins inside the rotor to not only strengthen them, but also to further help with cooling, causing the rotor to be even heavier than the stock.

Hope this helps.

RockStarKick · 02-14-2011, 12:19 PM

Quote:

Originally Posted by CFZ

The cross drills on the other hand may actually work. but the tradeoff is much worse. This is why I stay away from crossdrilled rotors and so should you guys. Cross drilled rotors are very prone to cracking. In fact one session at a track day is all it takes for them to really crack.

Would cross drilled and slotted be ok for daily driving..? I don't have any plans of tracking the car..

ChrisSlicks · 02-14-2011, 12:28 PM

Quote:

Originally Posted by RockStarKick

Would cross drilled and slotted be ok for daily driving..? I don't have any plans of tracking the car..

Yes, you'll be fine for street driving. The stress cracking only occurs from the heat cycling at the track.

RockStarKick · 02-14-2011, 12:41 PM

Quote:

Originally Posted by ChrisSlicks

Yes, you'll be fine for street driving. The stress cracking only occurs from the heat cycling at the track.

Thanks for the reply.

I would be in it more for the aesthetic aspect of the brakes..

CFZ · 02-14-2011, 12:47 PM

Yes you'll be fine for dd. I generally put on slotted rotors for dd. But again this is also more prone to cracking than the stock blanks.

02-13-2011, 08:05 PM	#1 (permalink)
tommyguns Track Member Join Date: May 2009 Location: New York Age: 65 Posts: 914 Drives: 370Z/Sport/Black/MT Rep Power: 17	Rotors, please explain the difference Could someone please explain why when purchasing rotors some will get cross drilled some will get slotted and some will get the combo. I ask because I intend to change my rotors in the near future and need to be educated before making a purchase. Thanks in advance, Tom __________________ 09 Sport / MB / 6sd / Nismo"R" Intake / Eibach Pro Kit / Z1 25 row cooler / JWT LW FW / New Short Block 3/11/11 /H&R 15fr 20rr/DBA 4000/FI CB with 12"res./Morel/JL/"Division"mod/SPC/EcuTek/M370/ZEX C SHOT/ART's/NRG

02-13-2011, 08:16 PM	#2 (permalink)
Baer383 A True Z Fanatic Join Date: Aug 2010 Location: Lawrenceville,Ga Posts: 4,293 Drives: My foot up your azz Rep Power: 30	Cross drilling and slotted rotors is b/c it gives the gas/brake dust an area to escape kind of like a passage most people buy them cause of the looks but if it is cross drilled and slotted it will release heat quicker than stock. Hope some of this helps. __________________ 2013 ZL1 754 rwhp 747 rwtq

02-13-2011, 09:46 PM	#7 (permalink)
spearfish25 A True Z Fanatic Join Date: Mar 2009 Location: Naples, FL Posts: 4,117 Drives: to work Rep Power: 1856	There are more reasons. To touch on all I can think of: 1) aesthetics 2) weight reduction (though minor) 3) ventilation (minor) 4) increased initial bite...this is a big draw for the slotted rotors Keep in mind that drilled rotors may crack under high temperature applications. From what I've read, the best overall braking force is obtained with non-drilled, non-slotted rotors. Slotting and drilling can both increase pad bite by shaving off the brake pad surface and exposing fresh material. __________________ 2013 Cadillac V-Wagon, RIP Z

02-13-2011, 11:21 PM	#9 (permalink)
wilsonp A True Z Fanatic Join Date: Jul 2010 Location: Virginia Posts: 1,134 Drives: 2009 Touring Sp Nav Rep Power: 17	Considering the heat issues the 370Z has with brakes, you shouldn't do either one - having more mass provides more heat sinking for the discs. __________________ 2014 Cayman S PDK Sport Chrono White/Black Was 2009 370Z Touring Sport+Nav 7AT Metallic Black/Persimmon Was 1991 NSX Auto Black/Black

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02-13-2011, 09:36 PM	#6 (permalink)
cossie1600 A True Z Fanatic Join Date: Jun 2009 Location: californee way Posts: 5,380 Drives: 370, Leaf Rep Power: 30	It's all for looks on a street car, makes no different when you drive from IKEA to Home Depot

02-14-2011, 11:45 AM	#11 (permalink)
CFZ Base Member Join Date: Jul 2010 Location: F-Town Posts: 134 Drives: 2010 370Z Rep Power: 234	Cross drilling give the rotor more surface area, which in turn helps the rotor cool down more quickly. Slots on the other hand gives the pads a way for the gases from the pads to escape. Also it shaves the pad surface as your braking, letting the contact surface of the rotor and pad to be fresh and help prevent hazing. But here is the real deal with them. Current pads do not release a gas. So slots for that purpose is deemed useless. Now I do get the slots to resuface the pads but its just a placebo effect for me (I just like looking cool) The cross drills on the other hand may actually work. but the tradeoff is much worse. This is why I stay away from crossdrilled rotors and so should you guys. Cross drilled rotors are very prone to cracking. In fact one session at a track day is all it takes for them to really crack. I am not saying none of the other rotors crack. In fact most my rotors crack because of the aggressive pads I use on the track. But Cross drilled rotors are just plain scary how easily they crack. Also just to get the information straight for you guys, neither crossdrilled or slotted rotors are made to save weight. The better more performance oriented crossdrilled rotors have double the number of veins inside the rotor to not only strengthen them, but also to further help with cooling, causing the rotor to be even heavier than the stock. Hope this helps.

02-14-2011, 12:47 PM	#15 (permalink)
CFZ Base Member Join Date: Jul 2010 Location: F-Town Posts: 134 Drives: 2010 370Z Rep Power: 234	Yes you'll be fine for dd. I generally put on slotted rotors for dd. But again this is also more prone to cracking than the stock blanks.