brakes: slotted or cross drilled rotors?

i have a 2000 tacoma prerunner looking to upgrade the stock rotors (which are warped) to either slotted rotors or cross drilled rotors. which one is better? anybody with experience using either type? i heard cross drilled crack and damage very easily. i will either go with El Prototypes cross-drilled rotors or Rod Millen gas slotted rotors. and yes, i am upgrading the pads also.
thanks in advance
laters
chris
 

Crayfish

Well-Known Member
Cross drilling helps with warpage and the slotting pulls the gas that builds up under the pads away. I know cross drilling and slotting rotors is popular on street rides and track cars but I don't know about in the dirt. My wife has cross drilled and slotted rotors on her Audi A4 and she autocrosses and does track events regularly, she loves them and hasn't had a single problem.

Hope that helps
 

ntsqd

Well-Known Member
Slots and holes both do that same thing. They offer any pad-heat generated gas a place to go. Most modern pad compounds don't outgas very much. Older pad compounds do. Something that slots offer that holes (when done right) don't is a mild 'cutting' edge to clean glazing off of the pad surface.
Something else to think about: slotting, and to a greater degree drilling, actually reduce the surface area of the rotor under the pad. This means for the same heat generation the rotor & pad will heat up faster. Granted, it may cool faster too. One way you can take advantage of cross drilling is to use a pad that otherwise might be a little too high temp for the application. All pad compounds have a temp vs. coefficient of Friction curve. Findind that pad with the best curve for your application will yield far, far better results than throwing money at gee-gaws like slotted or drilled rotors.
It's pretty rare that rotors warp anymore. B4 you do anything, have a brake shop take the lightest skim cut they can on the rotors. See if that doesn't clear up your pulsation. Some compounds and rotor materials build up pad material on the rotors unevenly. Don't really know why, they just do. That uneven build up will give you the pulsation that makes most think the rotors are warped. To give you an idea of how small this varience in build up is, you can't measure it w/o some extremely expensive tools. A micrometer MAY catch it, probably not.

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 

Dave_G

Well-Known Member
RE: "It's pretty rare that rotors warp anymore"

Toyota's are notorious for that! My wifes Camry and her old Celica all warped the rotors. My partners MR2 did it and also my parents Saturn. I just mount them in the fly wheel grinder and check them with a dial indicator while rotating. The worst I've seen is .028 on the wifes Camry. I grind one side to cleanup and then the other and it always takes care of the pulsating problem. Don't know why Toyota's do it the worst but it is a problem in some new cars.

Dave

"I know it all, but I can't remember most of it..."
 

Kritter

Krittro Campbell
I have noticed that warped rotors are usually due to the driving style. Just about every girl I know has warped her rotors becasue they hammer on the brakes at the last minute ALL the time.

Kris
<A target="_blank" HREF=http://www.dmsrace.com>www.dmsrace.com</A>
"Jesus loves you, everybody else thinks you're an A-hole"
 
RE: Toyota's are notorious for that!
same with my supra, and it happened when i was driving like a jerk one day.

victor fabian
<A target="_blank" HREF=http://www.stuck-throttle.com>www.stuck-throttle.com</A>
CARCO RACING 5-1600
 

DougM

Well-Known Member
On my Jeep Grand Cherokee I upgraded to STILLEN cross -drilled rotors since the Jeep rotors are notorious for warping. They are just too small for a 4000# SUV. It also doesnt help that I have rear drum brakes and single piston calipers up front!

The only issues Ive had with Stillens are that NO ONE will turn the rotors since the champfered holes catch on the cutting blade!

im soon going back to Autozone rotors at $25 a pice since the Stillens I have are gone after 2 years and at $80/piece, are just to pricey and benefits are only non warping, not better stopping.
 

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motoxscott

Well-Known Member
What about rotor material or design? Do any of the aftermarket companies that make "bolt-on" rotors use better materials or change the design slighty to help out?
 

WeldnFab

Well-Known Member
I WORK FOR STILLEN AND WOULD AGREE THAT THEY'RE STUFF IS PRICING AND THE DIFFERENCE BETWEEN X-DRILLED AND SLOTTED IS NO DIFFERENCE AT ALL. BUT THE ROTOR MATERIAL DOES!
JUST MY TWO CENTS!!
 

Dave_G

Well-Known Member
RE: "Just about every girl I know has warped her rotors becasue they hammer on the brakes at the last minute ALL the time."

Kris,
Actually, my wife is just the opposite. She's the type that gets off the throttle two miles before she comes to a stop sign so she doesn't have to use the brakes. Pi**es everyone off including me when I'm riding with her. She does get about 75K out of a set of pads though but can't get away from warping those rotors.

It's just a fact of life that women and cars wern't meant to get along. :-0

Dave

"I know it all, but I can't remember most of it..."
 

jeff

Moderator
The stock rotors on my 2000 Dakota sucked. They warped at 2000 miles on the odometer and the dealership turned them... 3000 miles later the rotors warped again. Dealership replaced them this time because they were already past their minimum thickness (no idea how much they took off the first time but it must've been a bunch). Rotors warped 2500 miles later and this time the dealership blamed it on my driving style and wouldn't fix the problem. I knew it wasn't my driving style because even after 100,000 miles of brake intensive driving my S-10 never once warped a rotor. I finally replaced the front pads but left the stock S-10 rotors as they were... all of this living in Lake Arrowhead and Lake Tahoe. I told Daimler-Chrysler a thing or two and bought a set of Powerslot rotors online for pretty cheap, less than $40 per rotor. I've put over 58,000 miles on these rotors with the SAME driving style and this includes a bunch of towing and hauling that the stock rotors never saw. If you think your brakes suck I suggest a slotted rotor and some upgraded pads to go with them. The biggest advantage I've found over the stock pads is an almost complete elimination of nasty brake dust buildup on my front wheels. Upgrades are without a doubt out there and they do work.

I think most stock rotors are trash. If you are one of the lucky ones to have a fairly new vehicle with a good brake system consider yourself lucky...

Aloha
 

Dave_G

Well-Known Member
RE: "Does she drive with both feet draging the brake?"

Nope.

Dave

"I know it all, but I can't remember most of it..."
 

ntsqd

Well-Known Member
I knew I should have waited to reply later instead of making myself mildly late to work. It's been my experience and observation that while rotors can and do warp, most of the time they do not. Modern pad materials actually transfer some of the pad material to the rotor's faces. You can't see it with the naked eye, but it's there. For reasons unknown some rotors or rotor/pad combos transfer material at an uneven rate. Lincoln Mk VIII's are notorious for 'warping' rotors. My boss has one that he used to rally (think Starlight) and has done a thorough investigation into what is happening, at least on his car. This uneven transfer is what happens with them, and no pad he's found behaves any better. So about every 10k or so he takes them off and has them lightly cut. Then the shimy under braking goes away for another 10k or so.

My advice is if you think you have warped rotors to have them turned the barest minimum that they can. The boss' would sometimes come back looking like they hadn't even turned them unless you looked really closely. Lightly scuff the pads and try it again.
If you have a vehicle that warps rotors regularly, I would suggest you look into a cryo stress relieve process.

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 

Dave_G

Well-Known Member
RE: "Modern pad materials actually transfer some of the pad material to the rotor's faces"

I'm not sure that pad material transfer or build up is what I've seen in the rotors that I have had to resurface. I do them on a fly wheel grinder and if I was grinding on brake pad buildup material I don't think I would be seeing a consistent spark color or pattern while grinding on the cast iron rotor. On a brake lathe it would be hard to tell as there are no sparks generated in that type of operation.

Do the newer pad compounds like to transfer material more because of the higher metalic content?

Dave

"I know it all, but I can't remember most of it..."
 

rdc

- users no longer part of the rdc family -
Front brakes on my 90 Blazer (full-size) only lasted 6 month, about 10,000 miles. The pads are gone and the rotors are heat checked and warped. The last time I replaced everything, I had the rotors and pads Cryoed. I am now running 37" GSA tires and have over 10,000 miles on everything and the rotors are straight. My feeling is that the Cryogenic Freezing helped solve the problem. Check out www.cryoscience.com or email the owner Roger Young roger@cryoscience.com and tell him Ramsey sent you.
 
i am a guy, but my driving style is what effected my rotors. i used to deliver pizzas for 2 years 5 days a week and the hard city driving is what killed the rotors/brakes. el more toyota (blows goats) resurfaced the rotors a few times under warrenty and then they decided it was my driving style and stopped replacing my rotors, so now i need a better braking system. oh yeah, in the winter i go to big bear about 2-3 times a week, so downhill mountain driving kills my brakes also, even when i downshift to 2nd.
laters
 
so are you running stock rotors and pads using the cyroscience? or did you upgrade to slotted/crossdrilled rotors and then apply the cyro?
their prices are very reasonable.
 

ntsqd

Well-Known Member
No, it sounds like you're getting bonifide rotor warping. .026" worth of build up would be pretty obvious.
I believe, but do not know, that it is the chemistry of the organic compounds in the pad material that cause the transfer layer. I think the analogy of certain amine's affinity for binding to metals (ala 'Slick 50' etc.) may be a decent model of the process, only in this case we're trying to increase the cF, not decrease it. There isn't much metal in most of the pads we sell, at least not metal that is obvious to the naked eye.

"I'm not sure that pad material transfer or build up is what I've seen in the rotors that I have had to resurface. I do them on a fly wheel grinder and if I was grinding on brake pad buildup material I don't think I would be seeing a consistent spark color or pattern while grinding on the cast iron rotor. On a brake lathe it would be hard to tell as there are no sparks generated in that type of operation.

Do the newer pad compounds like to transfer material more because of the higher metalic content?"

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 

Timmah

Well-Known Member
I see a lot of quite interesting theories in here regarding "rotor warping". Rotor warping is what seems to be a universal term for a pedal pulsation and which is often accompanied by a steering wheel shimmy. It may seem like a warpage if you only check one side with a dial indicator and it may have started as a slight warpage, but due to the warped high spots eventually being worn off the rotor by the pads, we get what is called thickness variation and that is what causes the feeling at the steering wheel and pedal.

Most production single piston calipers are of a free floating design and center on the rotor while sliding on pins. This means that they can actually move with a mildy warped rotor, but when thickness variation is present, the caliper piston pushes back on the fluid in the lines causing the pedal to move up and down too!

Our research has shown that most recurring brake problems of this type can be minimized or eliminated by USING A TORQUE WRENCH to tighten your lugs! Also, if you do have to machine the rotor, don't take it off the car and machine it to some unknown center. Use an on-car brake lathe and turn them on the car so that they are concentric with the bearing races or hub that they mount to.

Well, there's my 2 cents!!

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