drilled / slotted / solid ??

[wicked68]

back in the day when it was all the rage to be cool and have cool looking discs I put drilled and slotted rotors on my front spindles.

I have learned that if you are going to do a lot of road racing - this is not recommended due to the drilling weakening the rotors.

Slotted is recommended. Doesn't look as cool but apparently is better for strength.

[rrunner68]

I spoke to the Wilwood guys about that at RTTC, and they said the same thing. Drilled is really just for looks.

[Gitter Dun]

I spoke to the Wilwood guys about that at RTTC, and they said the same thing. Drilled is really just for looks.

Slotted is the way to go if you are going to road race, drilled rotors develope stress cracks in between the holes after road racing with them. I have seen sets of drilled rotors that developed stress or fatigue cracks in them one time at a Global West track day and that was enough to convince me.

[ProdigyCustoms]

back in the day when it was all the rage to be cool and have cool looking discs I put drilled and slotted rotors on my front spindles.

I have learned that if you are going to do a lot of road racing - this is not recommended due to the drilling weakening the rotors.

Slotted is recommended. Doesn't look as cool but apparently is better for strength.

If I remember correctly. Your issue is not drilled or not drilled, it is the small diameter and thin rotor you have. For the street, a occasional Autocross, even mild track driving just a couple laps, no problem. Start pushing it and you need a larger diameter / thicker rotor set up.

You need to step up to a 13 ' or 14" (6) piston Superlite set up.

[Cannon]

drilling doesnt weaken the rotor, it only allows places for stress cracks to form after heating and cooling of the rotors over time with hard use. They use to use drilling to help keep brakes cooler in racing but as pad materials got better, it was no longer needed. slotted is the best way to go for street/track use, because the slot cleans the pads from normal road use. if its a racecar just a blank rotor is actually best, unless you race in the wet.

[wicked68]

If I remember correctly. Your issue is not drilled or not drilled, it is the small diameter and thin rotor you have. For the street, a occasional Autocross, even mild track driving just a couple laps, no problem. Start pushing it and you need a larger diameter / thicker rotor set up.

You need to step up to a 13 ' or 14" (6) piston Superlite set up.


I have the largest rotors that will fit on my 17 inch wheels. They are not thing by any means.

they are drilled though. I have not had any isues with them but some of the top guys at wilwood looked at them and made the comment that they are not best suited for road racing past some parade laps. They recommended going to slotted only.

As far as the calipers go - yes larger calipes would be nice one day. for now with what I am doing at the moment - the ones I have are working fine. I will find out this season as we do more road course and less drags. I suspect I will be changing out by the end of the season.

[ProdigyCustoms]

The guys at Wilwood told you that because they are thin, only .81 thick rotor on your set up. You need at least 1.10 to 1.25 anyway.

You may very well clear a 13" set up under those wheels.

[wicked68]

The guys at Wilwood told you that because they are thin, only .81 thick rotor on your set up. You need at least 1.10 to 1.25 anyway.

You may very well clear a 13" set up under those wheels.

I will measure tomorrow and let you know.

thanks :)

[wicked68]

The guys at Wilwood told you that because they are thin, only .81 thick rotor on your set up. You need at least 1.10 to 1.25 anyway.

You may very well clear a 13" set up under those wheels.


measured it and it is .87

I am going to run it for a while since I am not racing the car a lot this year but will see how it goes.

I suspect I will upgrade down the road though.

[ITLBTU]

Don't tell the engineers at Chevrolet... They have drilled rotors on the Z06... I guess they're mostly grocery getters... :naughty:

[The WidowMaker]

Don't tell the engineers at Chevrolet... They have drilled rotors on the Z06... I guess they're mostly grocery getters...

arent those the same guys that only built one directional rotor for the front and one directional rotor for the back? :hmm: so one side of the car is always backwards.......

even with that, the guys that track them, crack them. i really wanted a set of d/s for the z06 brakes, but ended up with the slotted dba's from tobin.

[JEFFTATE]

Slotted DBA's are the way to go.
I'm gonna upgrade my Z06 with slotted DBA's and Carbotech pads someday..

Then apply that experience and knowledge to my '69

[wicked68]

Don't tell the engineers at Chevrolet... They have drilled rotors on the Z06... I guess they're mostly grocery getters... :naughty:
its apparently all about the looks these days - with the new materials and vein designs as well as new calipers heat rejection is not dependent so much on drilled rotors

[ITLBTU]

Well, I picked up new rotors yesterday for the Z06. They are cross drilled and slotted GM durastop rotors. They are listed as high performance. They look pretty good. The holes are all countersunk with a nice round radius. I think they have a 12,000 mile guarantee. We’ll see, since I’m off to Thunderhill for a track day next Friday…

[Apogee]

Don't tell the engineers at Chevrolet... They have drilled rotors on the Z06... I guess they're mostly grocery getters... :naughty:

It's important to keep in mind that just because the manufacturer did something doesn't mean that it's necessarily the highest performance solution to the problem. The manufacturers are typically trying to optimize for many factors, not the least of which include marketing, cost, customer complaints, etc.

The C6 Z51 rotors are left hand, curved vane rotors front and rear. The C6 Z06 front rotors are similar to the Z51's, however the rear rotors are a pillar vane design that would be non-directional if it weren't for the directional drilled hole pattern. The advantage to directional/pillar vane rotors is that they tend to be more dimensionally stable than similar straight vane designs. As such, they are less likely to experience harmonics and generate noise which has historically been the number one brake reason Corvette owners bring them into the shop. The cost implications are obvious since you only have one casting each for the front and rear applications. Drilled finish gives them the bling-bling finish that makes them easy to sell. The decrease in thermal efficiency is relatively small and offset with mass to keep temperatures in check.

Anything more aggressive than a "FF" pad compound and you should be able to crack your OE C6 Z06 rotors pretty quickly in a track environment. The more aggressive the pad and the driver, the shorter I would expect them to last. You haven't said what pads or tires you're running, but Thunderhill can be a demanding track, so enjoy it and let us know what you learn.

Tobin
KORE3

[ITLBTU]

Thanks for scaring me Tobin... I have Hawk HPS pads and the rotors are ROTOR ASM,FRT BRK (PERFORMANCE). All the rotors are corner specific, although I haven't looked to see if the vanes are directional yet. And pathetically I don't know what my tires are... I know they aren't the stock Goodyears, but I don't remember what they are.

[Apogee]

Greg, no worries. Worst case scenario is that they crack...not the end of the world. The HPS pads will be much more forgiving than an HP+ or something more aggressive. Besides, cracks are not really a significant safety issue until they reach the outer edge of the rotor, which usually takes some time and abuse.

Would you happen to have the part numbers of the rotors you're running...I wasn't aware of a corner specific rotor being offered by ACDelco/GM for the C6 Z06 (or Z51) application.

Tobin
KORE3

[MrQuick]

Baer needs to put out dimpled/slot rotor kits.


Vince

[jknight16]

Baer needs to put out dimpled/slot rotor kits.


Vince

Agreed. I'm very curious to see how the drilled Baer rotors I have hold up to a track day. They have significantly more meat on them than the factory C5/C6 rotors or the drilled aftermarket replacements. I'm thinking they may hold up to the abuse better, but can't say until I get to beat on em.

[MrQuick]

We had done the Eradi Speed rotor upgrade on a C5 and it held up very well, but that was only after 2 races at Willow and about 30K miles of street driving.

vince

[lsxfirstgen]

just thought i would post these pics that i have taken over the years. I dont think i would call Porsche out on using drilled rotors especially since most privateers have factory cash and engineers working with them. On the other hand look at the factory C5R - solid, and 911 GT1 24 hour car - solid, just my $.02

[Bryce]

the last two solid pics are carbon? i think?

[LateNight72]

the last two solid pics are carbon? i think?
Yup.

Carbon rotors are an apples-to-oranges comparison.

[lsxfirstgen]

well either way, there are a lot of posts saying that drilled rotors are not for competition use. the first pic, the 911 gt3 rs, kinda disproves that...like i said before, i wouldnt question the engineers on using drilled rotors.

[JRouche]

The old drilled or not issue...... It will go on and on. The folks that say they arent for track use have some legit concerns. Then there are ALOT of manufactures that are using them on race cars. And will continue to without regard for the nay sayers.

The way I see it is yes, there MAY be a concern with cracking. But that small concern doesnt seem to hold back racers using them.

And for the semi race, mostly street guy. I dont even see a concern.

But... This long lasting drilled or not drilled rotor thread will out last me. JR