North American Turbocoupe Organization

Slotted/drilled rotors?
jangus Offline
Senior Member
Can any one point me to a source for these? Economical if possible.

88TC 5speed, 160,000+, ranger roller, Evergreen T3, cone filter, manual boost controller.
One parts car still waiting to be taken apart.
Waiting in the garage: SC throttle body, SC intercooler, graphic equalizer, among other things.

firstsvo Offline
Senior Member

This is what I paid:

Ordered: 1 Shipped: 1 KDbrakeparts 1988 Thunderbird T Coupe F/R rotors D/S zinc plated silver + F/R Posi Quiet Pads $175.00

I ordered full set-ups for 2 cars at the same time, so I'm not sure of the shipping cost for just the TC. It was $54 for all parts for both cars, so probably about half of that.

I've dealt with them before and never a problem. The guy I dealt with was Kit Davis. Whatever price he gives you, knock it down some. I was at $450 for everything and told him "$400 sounds better" and he did it. Shoulda said $350. lol. Problem these days with heavy stuff is the shipping. I would definitely reccomend them.
White '88 auto mostly stock, Black '88 5 speed nowhere near stock

V6TBird87 Offline
Posting Freak
I run cross drilled and slotted rotors, and honestly, I would say save your money. I actually run a set from R1concepts, but I'm using Mark VII stuff to go 5-lug.

They make no actual difference in braking power.
2018 Mustang GT
1988 Turbo Coupe, 5-speed

aka Tbird232ci

firstsvo Offline
Senior Member
I don't agree. I have them on all my cars and would not go any other way. The biggest problem with "regular" rotors is that in no time I would get that pedal pulsing. I don't know how much better they actually stop, but I hated that shaking and shuddering when on the brakes, especially at higher speeds. Both my Mustang GT's and both my TC's would shake when braking with the factory rotors. I have drilled/slotted rotors on my one TC for about 4 years and on my '01 GT for probably over 5 years and not a shudder since and they both were terrible with the stockers. #2 TC had all new stock rotors and pads and within way less than a year the shake was back. I just put the D/S on TC #2. I would never go back to stock. How much cheaper are stockers? I didn't think $175+shipping for 4 rotors and all pads was that bad.
White '88 auto mostly stock, Black '88 5 speed nowhere near stock

ILoveMyTC Offline
Senior Member
You should buy drilled rotors for appearance purposes only. Don't expect them to offer better braking performance or lifespan, because they will offer the opposite. A car is stopped by heat/friction and the purpose of a rotor is to absorb that heat and dissipate it. Removing surface material from a rotor is contrary to both of those functions.

If you really feel the need to spend the extra $50-$100, your money is better spent on good pads than trick rotors.

Quote:Darrick Dong; Director of Motorsports at Performance Friction: "Anyone that tells you that drilling makes the disc run cooler is smoking crack."

Power Slot: "At one time the conventional wisdom in racing circles was to cross-drill brake rotors to aid cooling and eliminate the gas emitted by brake pads. However, today’s elite teams in open wheel, Indy and Trans Am racing are moving away from crack prone, cross-drilled brake rotors in favor of rotors modified with a fatigue resistant slotting process."

Stop Tech: "StopTech provides rotors slotted, drilled or plain. For most performance applications slotted is the preferred choice. Slotting helps wipe away debris from between the pad and rotor as well as increasing the "bite" characteristics of the pad. A drilled rotor provides the same type of benefit, but is more susceptible to cracking under severe usage. Many customers prefer the look of a drilled rotor and for street and occasional light duty track use they will work fine. For more severe applications, we recommend slotted rotors." (Note that even though Stop Tech sells both drilled and slotted rotors they do not recommend drilled rotors for severe applications.)

Wilwood: "Q: Why are some rotors drilled or slotted?
A: Rotors are drilled to reduce rotating weight, an issue near and dear to racers searching for ways to minimize unsprung weight. Drilling diminishes a rotor's durability and cooling capacity."

From Waren Gilliand: (Warren Gilliland is a well-known brake engineer in the racing industry and has more than 32 years experience in custom designing brake systems ...he became the main source for improving the brake systems on a variety of different race vehicles from midgets to Nascar Winston Cup cars.) "If you cross drill one of these vented rotors, you are creating a stress riser that will encourage the rotor to crack right through the hole. Many of the rotors available in the aftermarket are nothing more than inexpensive offshore manufactured stock replacement rotors, cross drilled to appeal to the performance market. They are not performance rotors and will have a corresponding high failure rate"

From Baer: "What are the benefits to Crossdrilling, Slotting, and Zinc-Washing my rotors?
In years past, crossdrilling and/or Slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads...However, with today’s race pad technology, ‘outgassing’ is no longer much of a concern...Slotted surfaces are what Baer recommends for track only use. Slotted only rotors are offered as an option for any of Baer’s offerings."

Grassroots Motorsports: "Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the '40s and 50s, not a whole lot. Rotors were first drilled because early brake pad materials gave off gasses when heated to racing temperatures, a process known as "gassing out." ...It was an effective solution, but today's friction materials do not exhibit the some gassing out phenomenon as the early pads. Contrary to popular belief, they don't lower temperatures. (In fact, by removing weight from the rotor, they can actually cause temperatures to increase a little.) These holes create stress risers that allow the rotor to crack sooner, and make a mess of brake pads--sort of like a cheese grater rubbing against them at every stop. Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it...Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean the face of the brake pads over time, helping to reduce the glazing often found during high-speed use which can lower the coefficient of friction. While there may still be a small concern over creating stress risers in the face of the rotor, if the slots are shallow and cut properly, the trade-off appears to be worth the risk. (Have you looked at a NASCAR rotor lately?)
Nick Johnson

JohnL Offline
Senior Member
This is well established, just take a look at forums if you want to see a lot of discussion on it. The holes are nothing more than a reduction in surface area and a propagation point for stress cracks. Overheated fluid is more often the cause of fade. Pulsation is due to the pads temp range being exceeded causing it to leave uneven residue on the rotor. Get a better pad if you have problems with pulsation/"warped" rotors (they're rarely actually warped).

Also get a good fluid, Valvoline or Ford brake fluid, and flush the system well and again after any hard use. The fluid absorbs water and then the boiling point is substantially lowered. Even better fluids exist for more money, Motul RBF600, ATE Super Blue, and many others.
John Lewis
88 TC, 87 XR, 84 SVO
Currently deciding which is worth my time.

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