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Avid Track Day peoples.... slotted vs crossdrilled....

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There are reports on the interwebs that cross drilled rotors might crack with lots of track use. I was wondering if you have seen this on the 986s boxsters... The 986s has thicker spec and larger rotors than the 986 used normally (I don't know if spec boxster uses the s rotors or not...

I tracked my car on a shorter 'technical track' (lots of 2nd,3rd, and some 4th gear) for about 10 hrs last year (1 daytime event, 4-5 evening events)...

I need new street pads and rotors soon. I have Hawk noisy track oriented pads that I swap out for trackdays. I also have track rubber this year to use. I plan to go to 2 daytime events with 2-3hrs tracktime/day and probably 3-4 evening events with 1-2hrs of tracktime per evening

I like the look of the cross drilled rotors through my street wheels, but wonder if I should switch to slotted rotors for both track and everyday use.

I found a company up here in Canada that takes rotor blanks (read - probably from China) and then slots or crossdrills them... Price is very good... about $635 for 4 rotors and pads...

First trackday is 2 weeks away... need to order soon.



Edited 2 time(s). Last edit at 05/07/2019 08:10AM by Petee_C. (view changes)
Yes, they will develop cracks at the holes over time, and therefore generally do not last as long as non-drilled or slotted rotors. They may also wear out the pads more quickly. Slotted rotors work better.

However, drilled rotors do work, and if you are diligent about inspecting them thoroughly you can avoid a last minute surprise that gets in the way of a track day. Just be sure to really check both sides of each disc, and rotate it fully so you can inspect the entire surface. When a small crack develops into a long one, odds are it won't be in the area that is visible by peeking through the wheel spokes.
Any noticeable difference for a beginner trackday driver?

There's a cdn company that has plain fronts for $80 cdn pesos... They cater to the autosport crowd...
Nothing wrong with any of the rotors, really. Drilled are just most prone to early replacement (i.e. before they are "worn down" to minimum thickness) due to cracks emanating from the holes. The other types of rotor can still develop tiny "crackles" that lead to cracks, but it takes longer for the cracks to become worrisome. Among the SPB racers, I don't hear people discussing performance differences between $ and $$$$ rotors. People tend to get cheaper ones. (Slotted version for those who prefer it.)

Here is a nasty crack (on a slotted rotor, unrelated to the slotting) that was concerning to discover! When you see this, you think, "How did I not find that before? Or did it suddenly happen? Relieved that I found it before it got worse!" The smaller crackles all over the surface are normal but at this state probably signal the disc could be replaced (even without the crack appearing). You can see from the slot channel still being there that there is plenty of material remaining (slots are not much deeper than the wear limit depth).





Edited 1 time(s). Last edit at 05/07/2019 06:39PM by Trygve (Oakland, CA).
(view changes)
The sales rep emailed me and informed me that the $80 rotors were infact crossdrilled like OEM...

DBA front rotors for my car are $200..... That's a 150% increase in cost....

I looked at the rotors with the wheels still on last night and can not see any cracking on my stock rotors (yet)

1st trackday of the year is 2 weeks away.... I would like to order soon...
... when it's cooling. If you run hard on the track and then park it, you can hear a ticking sound coming from the rotors.
Those tics are cracks developing.
In order to minimize the cracks take at least 2 cool-down laps without using the brakes before you park it.
Happy Boxstering,
Pedro

Pedro Bonilla 1998 Boxster 986 - 290,000+ miles: http://www.PedrosGarage.com
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
Does this end up warping the rotors?

Current: 07 Carrera S Cab - Midnight Blue/Sand Beige Previous: 01 Boxster - (formerly boxtaboy), 86 944 https://www.instagram.com/carreralicious/
It's practically impossible to warp a Porsche rotor.
The thickness of the metal plus the construction with the vented slats make it super sturdy.
What most people refer to as warped rotor is generally pad deposits on the rotor from leaving the brake depressed with a very hot rotor.
Every time after that, when the pad passes over that mark it grabs a little more than over the rotor surface and you can feel it on the steering wheel as if it was warped.
Happy Boxstering,
Pedro

Pedro Bonilla 1998 Boxster 986 - 290,000+ miles: http://www.PedrosGarage.com
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna


Current: 07 Carrera S Cab - Midnight Blue/Sand Beige Previous: 01 Boxster - (formerly boxtaboy), 86 944 https://www.instagram.com/carreralicious/
I do do some cool down driving in the paddock before parking it after each session.... generally don't really get a cooldown lap.... maybe only get 1/3rd of a cooldown lap on the track after the checkered flag...

I do park it in 1st without parking brake applied, and coast to my chosen parking spot without any brake pressure...

Some in the spec boxster forum consider brake rotors disposable items, and they go for the cheapest...

so many decisions....
Don't forget, they sell a lot of handbags, sun glasses, movie DVDs, etc. on the street just like OEM at considerably less money, too, but it is not OEM at all. To me, brakes are such a important safety feature, not sure i'd risk it. But, that's me. Now, maybe some bling items would be worth it, but for safety and reliable needs, not so much. Are you talking rotors that are manufactured by a reputable company that supplies quality auto parts? Then, again, maybe worth considering.
Just a follow up to my comment above. With brakes, I always think back to my first Nascar night race at Richmond, a fast, 3/4 mile oval. You sit in Turns 1 or 3 when it gets dark, and you wouldn't believe how bright orange the rotors get from the heat due to braking after the straights. Richmond doesn't have long straights, either, but at 800 horses, those boys do carry some speed going into the corners.
... it happens at Sebring on a lowly Boxster too.

[pic]https://ibb.co/F0M88XM[/pic]
PCA 48_1203 (135) (Large).jpg

Pedro Bonilla 1998 Boxster 986 - 290,000+ miles: http://www.PedrosGarage.com
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

Racecar spelled backwards is Racecar
"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"
"If you wait, all that happens is that you get older"... Mario Andretti
"Being second is to be the first of the ones who lose" ... Ayrton Senna
Sure it's not just part of your branding/color scheme?
Thx everyone.

I decided to try pagid rotors up front and raybestos rotors in the rear.... Cross drilled like stock....

A decent deal $400 including woe stop tech pads shipped to my house, north of Guenther.
Followup : rotors from rockauto
Petee_C - Yesterday at 1:06:41 pm
https://peterchang1.blogspot.com/2019/05/raybestos-96965-brake-rotors-on-2001.html

(Pagid rotors were fine, Raybestos rotors had a minor hiccup....)

I will be installing the street pads in the next couple days and taking my super loud hawk pads out....
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