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Old 05-15-2003, 07:04 PM   #46
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Quote:
Originally posted by SkylineUSA
I read that article, you are suppose to safety wire them. Are mine, no. I did use Loc-tite. The way the Apex 2 piece rotors are made, you would have to have all 10 bolts fall out, before they would become unsafe. I would hope I would notice something before then
LOL, yeah, I mean it would take A LOT for just one or two let alone all 10 per hat to fall out. But the Loc-tite should be just as well as the safety wires.
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Old 05-15-2003, 07:14 PM   #47
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This pic below is what I was talking about with the reversing of the rotors when slotted. The rotors on the car in the pic are put on so the slots turn AGAINST the caliper, so that the outside edge of the slot reaches the caliper first verses how you have your rotors put on, which is also how mine are on right now. An advantages/disadvantages to having the slots in this direction?
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Old 05-16-2003, 12:39 AM   #48
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Quote:
Originally posted by SkylineUSA
You might want to rethink that statement. It has nothing at all to do with surface area. Its the mass of the rotor and its ability to dissapate heat, not surface area.


I didnt say anything about heat disapation. A solid disc exposes a greater surface area to the pad than a drilled or slotted disc, and so theres more friction and greater braking force, but of course at the expense of more heat.
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Old 05-16-2003, 03:23 AM   #49
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So,

Where was I wrong in what I posted?
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Old 05-16-2003, 02:30 PM   #50
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Just to stick my nose up in this, both are right. You DO need something that will disipate heat better and quicker (larger rotor) but you also need/want something that'll let you slow down quicker (solid surface area). Thing is, I really have yet to see a big brake upgrade kit that offers say like "13 solid blank rotors. Look at all the popular big brake kits from Baer, Wilwood, AEM, Brembo, ALL come with slotted if not x-drilled rotors. Defeats the whole purpose of a larger brake, doesn't it?

Let me bump something else into the equasion here, what does THIS kind of brake system do for a car in terms of braking ability?
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Old 05-16-2003, 04:36 PM   #51
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Of course the surface area will be a player in the scheme of things, but that is not what stops your car.

Those brakes, where did you find those, or better question who in the hell would make them
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Old 05-16-2003, 06:27 PM   #52
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Quote:
Originally posted by SkylineUSA
Of course the surface area will be a player in the scheme of things, but that is not what stops your car.

Those brakes, where did you find those, or better question who in the hell would make them
LOL, I thought those might perk a comment or two. I company called "The Brake Man" makes them. They are called buttercup rotors for their distinct shape of a buttercup flower. These are definitely show of course, and when I first saw them on a car in Super Street I think it was, I didn't think you could actually drive with them, but apparently you can.
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Old 05-17-2003, 04:18 PM   #53
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Quote:
I didn't think you could actually drive with them, but apparently you can.
Ya, you can drive fine with them, you just can't stop.
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Old 05-17-2003, 04:40 PM   #54
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Quote:
Originally posted by SkylineUSA
You might want to rethink that statement. It has nothing at all to do with surface area. Its the mass of the rotor and its ability to dissapate heat, not surface area.

I do not see in any part of your statement that proves what I have been saying is wrong, or missed the point?

I will admit, that everything else you have written is very true.

As for the direction of the slots, ?

I'll post some pics when I get a chance.
Hello,

Great thread..

You're partially right - a xdrilled rotor may have less mass than a blank while at the same time its surface area measured on all axis still being roughly the same due to the holes increasing the surface area on the z-axis (assuming you are looking at the hat of the rotor).
However, decreased mass will result in a lesser ability to distribute heat energy thoughout the rotor, thus making it less "efficient" at dissipating heat, which results in increased rotor/pad temperature and reduced breaking performance as well as risking structural integrity - it all goes downhill from there..
When moppie refered to "surface area," I am assuming that he meant the surface area on the x and y axis - the axis that matters the most. The larger the surface area on the x and y axis, the more friction can be generated between the surface of the rotor and the brake pad, and greater enegry transfer (stopping power) can be obtained. A smooth surface will also help insure that more of the pad surface area is in contact with the rotor.
As moppie mentioned, the only time xdrilled or slotted rotors will _really_ make a difference is if you increase the size of the rotor to compensate for the removed surface area on the x and y axis of the rotor. BOTH for heat distribution AND breaking power.
Some may argue that because some surface area on the xy axis is removed, that there will be less friction, and therefore less energy transfer in the form of heat, which in turn compensates for the lesser mass of the rotor. In either case, you are making your braking system less efficient at doing what it was designed to do.

I'm with moppie on this one.. Unless you're upgrading to bigger rotors, xdrilled or slotted rotors are a waste of money if your goal is decreased stopping distance. The best upgrade you can do on a stock-sized rotor is to upgrade your brake bads.


As for the direction of slotted rotors, they should flow away from the caliper. In the same fashion that the vents in the middle of the rotor create a centripidal fan which sucks air in from the middle "hat" of the rotor and pushes it out the sides, you want the slots to do the same.

"Your milage may vary.."
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Old 05-17-2003, 06:52 PM   #55
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tarmac165,

Very well said, and I totally agree, in theory





Quote:
When moppie refered to "surface area," I am assuming that he meant the surface area on the x and y axis - the axis that matters the most. The larger the surface area on the x and y axis, the more friction can be generated between the surface of the rotor and the brake pad, and greater enegry transfer (stopping power) can be obtained. A smooth surface will also help insure that more of the pad surface area is in contact with the rotor.
Moppie said that crossed drilled had less surface area, but you mentioned it increases surface area (which it does), how can the cross drilled surface areas of the holes creat more friction, when they are not in contact with the pad?

As for the way the slots should face, I really do not think it matters. But, the way explained it, the pic that SilverY2KCivic posted, you are saying is correct?

My hole point was more mass for the rotors, I guess I did not explain myself that well, sorry guys.

Like I said, I totally agree with your post, tarmac165.
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Old 05-17-2003, 07:21 PM   #56
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Quote:
Originally posted by SkylineUSA
Moppie said that crossed drilled had less surface area, but you mentioned it increases surface area (which it does), how can the cross drilled surface areas of the holes creat more friction, when they are not in contact with the pad?
SkylineUSA, I believe you may have misunderstood me.

Cross drilling may increase the OVERALL surface area, but it does in fact decrease the surface area in contact with thre brake pad. Again, when moppie made his statement, I am assuming he was refering to the surface area in contact with the brake pad, and as I (and moppie) stated before, crossdrilling or slotting your rotor will reduce its ability to do its job unless compensated by increasing the diameter of the rotor to increase the surface area in contact with the pad (big brakes upgrade).

However, as you said, surface area is not the only variable, MASS is very important as well.. It takes much more energy to heat a large item than it does to heat a small item... With any good heatsink, the larger the surface area, the more efficiently it can dissipate heat. While drilling/slotting your rotors will increase the rotors ability to dissipate the heat, it is also of smaller mass and therefore heats-up quicker, and has to store more heat in a smaller space... It's all a tradeoff.. The key is to find the best compromise.

Quote:
Originally posted by SkylineUSA
As for the way the slots should face, I really do not think it matters. But, the way explained it, the pic that SilverY2KCivic posted, you are saying is correct?

My hole point was more mass for the rotors, I guess I did not explain myself that well, sorry guys.

Like I said, I totally agree with your post, tarmac165.
That particular setup would work great if you were going 100MPH in reverse.

It is my belief that the rotor installation illustrated in the picture posted by SilverY2KCivic is incorrect and may be for show purposes only.

Correct installation is as follows:


Although I have never tested a slotted rotor in the "reverse" direction to be able to tell you for sure if it makes a notible difference or not. I can tell you that logic would indicate that there is only one proper way to install sloted rotors. You want the slots in the rotors to begin on the inside and work their way outward with rotation. This is because you want any particles that come off of the pad to be propelled off of the surface outward with rotation, and not inward.


-Alex
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Old 05-18-2003, 02:02 AM   #57
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When I read you post, it was 1 am in the morning, and I had a few pints from the local pub too boot.

I believe everything you have just posted, is the same thing I have been saying all along.

So, we all agree, that Cross-Drilled rotors really do not help, unless they are physically bigger.


tarmac165,

Thank you for posting the clarification on the slots as well.
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Old 05-18-2003, 02:25 AM   #58
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Quote:
Originally posted by tarmac165


Although I have never tested a slotted rotor in the "reverse" direction to be able to tell you for sure if it makes a notible difference or not. I can tell you that logic would indicate that there is only one proper way to install sloted rotors. You want the slots in the rotors to begin on the inside and work their way outward with rotation. This is because you want any particles that come off of the pad to be propelled off of the surface outward with rotation, and not inward.


-Alex
That's a very excellent point there. But there's gotta be something to reversing their direction. Maybe it's not something to do in street applications, but I have pics (from the June '03 issue of Car & Driver magazine) of SCCA World Challenge road racing cars that use slotted rotors, and they are reversed like in the pic I posted. Maybe when they are used the amount those cars use their brakes, and at the speeds they use them at, maybe reversing has a better effect of the slots than running them in the normal direction that draws the air away from the center of the hat like in the pic you posted.
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Old 05-18-2003, 03:29 AM   #59
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OK, not having read this theread here's my opinion:

1)cross-drilled helps dissipate heat better, it's proven
2)cross-drilled cracks easier, it's proven
3)if cross drilled correctly (i.e. chafered holes) they will hold up almost as well as solid rotors
4)slotted is ultimately just a compromise
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Old 05-18-2003, 07:09 AM   #60
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Quote:
1)cross-drilled helps dissipate heat better, it's proven
Really? Please show us.

Of course, if you are talking about the Swiss cheese rotors that Porsche uses, I wonder how much they cost?


For the record, I am in complete agreement with tarmac165, on all subjects:sun:
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