Are Slotted Rotors Worth It? - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 21 Old 11-16-2010, 01:13 AM Thread Starter
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Are Slotted Rotors Worth It?

I have a 1998 Cobra and was going to put on some new high performance pads. I was wondering if new slotted/drilled rotors would be a benefit on a mostly street driven car?

If they would, where would you suggest I shop for some at?

Thanks.


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post #2 of 21 Old 11-16-2010, 04:56 AM
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post #3 of 21 Old 11-16-2010, 07:36 AM
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lol.

Rotors that are drilled/slotted are of little benefit on a street car. They're of some value on a race car...unless you enjoy swapping on new rotors often.
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post #4 of 21 Old 11-16-2010, 09:11 AM Thread Starter
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Ok - I wondered if all of the DD cars that have them are just for the "look" factor. Now I know they just have more money to spend them me. haha.

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post #5 of 21 Old 11-16-2010, 02:49 PM
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Originally Posted by Cobra_Kid View Post
Ok - I wondered if all of the DD cars that have them are just for the "look" factor. Now I know they just have more money to spend them me. haha.
Drilled are actually less durable.I would never use them for track days.

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post #6 of 21 Old 11-17-2010, 07:32 AM
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Any DD that has them has them for the bling factor. "Look, I'm driving a race car!"
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post #7 of 21 Old 11-17-2010, 07:52 AM
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When they're the next step up price-wise from two sets of Brembo plain rotors that were pure crap dimensionally, slotted rotors start to make a little sense (ATE's, in this case). They also don't seem to score/groove quite as rapidly in street driving.

Drilled rotors used to have a purpose. I guess they still do if it's an outdated/obsolete race car that you want to emulate.


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post #8 of 21 Old 11-17-2010, 10:57 PM
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I have slotted and drilled for street use, but switch over to good ol napa rotors and race pads for HPDE. The regular face rotors are least likely to crack as the drilled ones and are much cheaper.

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post #9 of 21 Old 11-17-2010, 11:38 PM
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Mines are mad tight but they were on the car when I bought it so there they sit. When its time to replace I'll just go with regular blanks I think.

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post #10 of 21 Old 11-18-2010, 06:34 PM
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I have plain faced rotors on my race car. I tried slotted and they wore out pads quicker, and were more prone to cracking. So its a double no for a DD. I can still lock up the fronts on my AI race car so having more pad bite isn't going to do a dam thing for you.


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post #11 of 21 Old 11-18-2010, 08:00 PM
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I'm trying out some slotted and zinc washed rotors from http://www.rotorpros.net/ for my fox sn95 Cobra upgrade. Great price shipped and sometimes they have performance pad packages too. I've had these on my car for a couple of months now and have run it up to triple digits, and hauled it down without any drama in the sense of imbalance or other issues. Not certain how they'd hold up in a track environment, but for the street they seem priced more than competitivley.
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post #12 of 21 Old 11-19-2010, 05:28 PM
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if you wana replace rotors constantly yes. I use brembo blanks on carbotech xp10 xp8(Rear) and i like it

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post #13 of 21 Old 11-21-2010, 01:44 PM
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I wouldn't bother with a slotted or drilled rotors on a tracked car. They don't make any difference is stopping power and the small spaces of less material have been theoretically linked to warping and cracking. Although as far as I know no actual specific testing has been published.

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post #14 of 21 Old 11-21-2010, 01:52 PM
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i have some before and after pics from brand new and then 1 track outting the drilled holes cracked pretty bad have to upload pics to photobucket before i can link them to here


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post #15 of 21 Old 11-21-2010, 08:36 PM
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I've been driving OT and AutoX events for years with Eradispeed+ rotors. Never had one crack. The cheap stuff cracks, not the good stuff.

Those who think upgraded rotors won't improve stopping distances might want to have a look AT THIS.

There are lots of objective test results out there that demonstrate that slotted/drilled rotors do, in fact, reduce stopping distances.

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post #16 of 21 Old 11-21-2010, 09:40 PM
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At the track, seems most people there just go with blanks. Less cracking and way cheaper. And you can have a set of street blanks and track blanks plus a set of extra just incase, cheaper then drilled / slotted.
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post #17 of 21 Old 11-21-2010, 10:11 PM
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Quote:
Originally Posted by TazCobra View Post
I've been driving OT and AutoX events for years with Eradispeed+ rotors. Never had one crack. The cheap stuff cracks, not the good stuff.

Those who think upgraded rotors won't improve stopping distances might want to have a look AT THIS.

There are lots of objective test results out there that demonstrate that slotted/drilled rotors do, in fact, reduce stopping distances.

OK let me just say right away that I think those rotors are an extremely nice piece and totally worth the money! They are not junk, I would love to have a set.

But I am not buying that they contributed to the shorter stopping distances.
I'm not an engineer but I do know it's against the laws of physics.
I believe the Hawk pads were the sole factor in the shorter stopping distance.


I'd still love to have a set of those DBA rotors though especially since it's nearly impossible to find plain Brembos anymore for the 13" Cobra application.

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post #18 of 21 Old 11-21-2010, 11:01 PM
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But I am not buying that they contributed to the shorter stopping distances.
I'm not an engineer but I do know it's against the laws of physics.
I believe the Hawk pads were the sole factor in the shorter stopping distance.
I think the idea was that the combination of pads and rotors contributed to the shorter stopping distance. The slots are supposed to help with cooling, etc. I have the Wilwood Big Brake setup on my 1995 GT and I can tell the difference between the slotted and the plain face rotors when pushing my car hard at Hallet. My car is not a DD, so I don't have any issue with going through pads quickly - I generally change them more due to age than wear.

Now, that being said, I cannot tell the difference when running on the street or doing SCCA SOLO events.

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post #19 of 21 Old 11-22-2010, 08:05 AM
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Quote:
Originally Posted by JimmySidecarr View Post
I'm not an engineer but I do know it's against the laws of physics.
I believe the Hawk pads were the sole factor in the shorter stopping distance.

Which laws of physics would that be, Jimmy? Because I studied a little physics back in my college days, and it seems to me that a surface's coefficient of friction increases as you improve its aggressiveness, which is exactly what slotting/drilling does. That's why, with the same pads, you get a lot more dusting with slotted/drilled than with blanks. It's the increased coefficient of friction that causes it.

Yes, the more aggressive pads certainly contributed to the improvments demonstrated in that video, but I've seen other tests in which only the rotors were exchanged, and the stopping distances were improved, not as dramatically, but significantly, nonetheless.

Improving the aggressiveness of the rotors' surfaces WILL buy you improved braking. The downsides to slotted/drilled are their propensity for cracking if you go cheap or greatly increased price if you don't, and the increased dusting.

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post #20 of 21 Old 11-22-2010, 11:51 AM
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I'm a little more inclined to think that what slotting does is do a better job of keeping the pad surface fresh and give stuff like brake dust, water, etc., some place to go initially.

Once you can reliably lock up the wheels, further brake torque is not really useable. But there can be differences during the transition from zero to maximum braking.


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post #21 of 21 Old 11-22-2010, 12:05 PM
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Slotted and drilled rotrs will "degas" the brake pad. When you stop there is a gas created and the slots and holes relieve that gas between the rotor and brake pad making for better pad contact. They also scrape the pads clean. You will get more pad wear and rotors will have a greater chance to crack with drill rotors. A cheap rotor will most likely crack. A high quailty rotor will be less likely to crack.

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