72Vega

05 Z51 coupe, advanced HPDE driver, Toyo R888s, stainless steel pistons, DRM brake ducts, Motul 600, Hawk DTC60/HT10 pads, Konis, SKF, VBP Extreme Springs, aggressive track alignment.

Need to replace all 4 oem rotors and pads and I am seeking your thoughts and experience.

Other than weight savings (35+ lbs for all 4), are there any advantages moving to 2 piece rotors and are they worth the cost ($350-400 each)?

If so, should I just invest in the fronts only or do the rears also? Need to preserve parking brake and 2 of the options I an considering will do that.

Also, any thoughts on pad replacements? Should I go DTC60 or 70 both front and rear or DTC70 Front and DTC60 Rear?

I am also considering forgetting the upgrade and just replacing with new GM rotors and spending the money on track time. Advanced HPDE is as far as this car is going.

Thanks in advance for sharing your thoughts and experiences.

Paul

stevensa

There is lots of debate on this topic. I run the Performance AFX 2-piece Coleman front rotor setup on my C5z and love it. My first set lasted ~2 years before I finally cracked one, I would go through about 4 OEM sets for every one set of the 2-piece, which doesn't justify them economically. However knowing that I have reliable rotors and not worrying about having to change them during a track day more than makes up for the slight price increase IMO. Just depends what you are looking for.

So basically you have to decide, do you want to save ~$200-$300 every 1-2 years on rotor costs, or do you want to spend a bit more to save some weight and hassle?

Racingswh

So debatable.

For me personally I went with the 2 piece Wilwood setup. I really liked it as all the torx screw heads were drilled for .032 stainless safety wire which I took the time to do. Seems safe to me which was important. They are expensive. 4 times as much as a cheaper replacement rotor. One point that I have heard about a 2 piece rotor that may have merit is that not as much heat is transferred to the hub. I have no way of knowing whether or not that is true. It did make a little sense to me at least.

I run Carbotech pads I got from Adam, XP12 in front and XP10 in the rear. I know there are guys a lot faster than me running 10's and 8's. Also I will say that the brake dust wipes right off the wheels, both the chrome and the gray. I have found the Hawks to wreck a wheels finish in no time.

I guess if the 60's work and there is some savings there that's what I would run. I don't know about the balance of the car thing or if I could even tell the difference. I know of my one friend running 60's all around and I was following him recently and he is plenty fast and has said his setup works great. I am pretty sure the 70's are more brake than the R888's need and if the operating temp of the 60's are similar then the 60's all around should be fine.

My .02

RX-Ben

Depends on how much you track the car.
2 piece setups last longer, so less replacing cracked discs (which could cause you to miss a session as they crack when cooling).
Keeping the hub temps down are a huge benefit as well.

The fronts are the most important, rears not so much.

Obviously a no brainer if you are going for lap times, as the 35lbs savings is a big benefit.

TKOGTO

As I am the same boat as you, Advanced HPDE only, I'll tell you what I did. Bought Centric Premium's. They are inexpensive, not drilled and are well reviewed by many here on the CF. Keeping heat out of the bearings is the downside but how much depends on several factors, the track you go to, your braking style, your tires, etc. For me, the issue is minimal.

Experience with how long 2 piece rotors last vs. OEM or Centrics, etc, varies greatly. For some the cost difference is only a few hundred, for others it is several times that. At several times that, I figure I'll just use that cash for the new bearings, if even necessary. As the Centrics are cheap, I bought 2 sets. I take the extra set with me in case one cracks. Small price to pay to prevent missing a session.

Rob Willis

I really like my Coleman/DRM front 2pc 14" rotors.

I use stock OEM rears.

Adam@Amp'dAutosport.com

We have found no problem running the Centric rotor, if you feel the weight savings is a big deal, I would look at the Dba 5000 rotors and some Carbotech pads. I will be happy to help you. XP12 front and XP10 rear would be my start.

sperkins

Huge unsprung weight savings though.

argonaut

I think the weight savings depends on which 2-piece you are talking about. Before installing my Hardbar/AP Racing rotors I weighed them and compared to the NAPA style rotors I previously had and they were only a couple lbs lighter. The reason is the rings are much more heavy duty - thicker vanes and more of them. So, although I'm not seeing a big weight savings on the front, I am seeing far higher heat capacity and my butt-o-meter is telling me better consistency in braking (but that is also influenced by the AP calipers).

mountainbiker2

My C5 2pc. front rotors were only about 2lbs. lighter then stock type rotors each. The rear 2pc. rotors with ebrake 3lbs. lighter each.



Steve A.

Bill Dearborn

Really hard to say. Last year I went with the AFX/Coleman rotors for my 08Z. Previous to that I had been cracking stock rotors about every 5 days using Hawk HP Plus pads. Rears would crack about as often as fronts. Previous to the rotors I had already added WA6 calipers to the front that ran with the stock rotors. With the Wilwoods my pad choices are pretty much limited to Wilwood pads so I went with the H pads. One of the front rotor rings lasted 7 days. This year I replaced both rings on the front and one of them only lasted 5 days. I have two heavily heat checked rotors that maybe I could run but I will have to get some bolts to put the one rotor on the hat. The rear rotors held up well with 7 days last year and 13 days with several autocrosses in addition so far this year. Slots are worn off the rotors and they are within a half millimeter of minimum thickness (drop about .1 millimeter per day). Probably can get a couple more days out of them if I decide to push them that far.

At $240 each delivered to the front door the front rotor rings aren't worth the cost compared to stock rotors that are $95 each delivered to the front door. For $165 each plus shipping the rear rotor rings are a bargain compared to the stock rear rotor $95 price and since they lasted 20 days have paid back the extra money I spent on the initial purchase with the hat included. Definitely have gone past the break even point in that area. Bob at AFX says my front rotors are running too hot and I should get more cooling to them. I added Quantum brake ducts from the stock ducts to the spindle, I modified the stock duct to take a 3 inch hose instead of the 2.5 inch opening it originally had, I modified the stock duct to Y in more air from the fog light area and replaced the fog lights with brake duct intakes that funnel the air from the front fascia directly into the stock duct. I still have the air coming in from under the bumper. Use my 150 mph leaf blower to check the ducts and they do move air through the rotor. Rotors are still overheating and I am boiling brake fluid even though it has a 570 degree dry boiling point and I am using titanium pad spacers when there is enough space to get them in. Only thing left to do is add the Wilwood thermock pistons but that doesn't help the rotor heat and cracking issues.

Bill

0Todd TCE

Bill brings up a good point and I've seen this on other vehicles as well.

The cost/value relationship of having 2pc vs the stock ones can be hard to justify. Even if the 2pc lasts twice as long they generally run 3x or more money. Granted they 'might' run a bit cooler and be slightly more effective at the extreme end of things but for the majority of folks the "disposable rotor" formula seems to remain the more cost effective method.

Last C5

I was only getting 3 days out of an OEM rotor and I get 15 to 17 out of the Stoptech Aero 2 piece rotors so I'm saving money and doing a lot less wrenching in the pits. I just went to a Stoptech BBK with 14" rotors so I have my 13" Aero rotors and some new backups to sell.

0Todd TCE

Apples to oranges here to an extent; you're not comparing the same size parts. And if you took off the 13" stuff with stock calipers, pads and all to replace it with a full on 14" kit that's not an equal comparison.

Last C5

That's not the comparison I was making. I went from 13" OEMs to 13" Stoptech Aeros with the same SSBC calipers and XP10 pads and got five fold the performance. The 13" 2-piece Stoptech Aeros I was using are a direct replacement for the stock rotor.

After the initial outlay for the hats, the Stoptech Aero rotor replacement rings are $150 ea.compared to spending $250 on five NAPA or what have you OEM type rotors.

0Todd TCE

Ahh, miss understood your post. A five fold would be a pretty good value.

72Vega

Very enlightening discussion. Although there seems to be no right answer, here's what appears to my non-technical brain to be some common themes:

1. Spending the extra $$ for 2 piece rotors MAY be justified to reduce weight and improve cooling of mainly hubs. (Glad I already replaced the oem with the SKFs.)

2. However "saving weight" with a 2 piece rotor varies widely based on the specs of rotor ring. Rotor rings that weigh less than oem may not always be a good thing. Less mass may = thinner (than oem) firepath/friction area = may need to be replaced more often = may cost MORE in the long run. There's a reason that GM made oem rotors really thick and really heavy! (Maybe I'm stating the obvious to all the engineer-types out there.)

3. Maybe vendors who promote the 35 lb+ weight reduction is marketing the 2 piece rotors to drag racers who want to reduce weight to improve ETs and don't need the types of brakes we use on road courses. Or maybe they are trying to sell to the street racer/tuner crowd who want to impress with boy racer-type parts. Dunno.

4. Tires, different road courses, driving/braking style all enter into the equation. Although wringing my car's neck is exciting, I tend to take it relatively easier than most on my car mainly because A) there aren't any trophies or points awarded for HPDE and B) I've got the drive my car home!

Thanks for all the responses to my questions! I appreciate all who took the time to post. If anyone has any additional thoughts, please feel free to add them!

See you guys down the road!

Paul

db2xpert

Running the Hardbar 2-piece front rotors, Carbotech XP10's on front of my '07-Z06.
Rotors saved 10# each vs stock, about 12 track days, on second set of
XP10's and rotors are fine. I run the XP10's on the street too.

drivinhard

I gave up on chinese rotors (after cracking a million) when I cracked a nearly new chinese POS during the warm up lap of a NASA race. I threw my whole race away.

For NASA nationals 2011 I started using 2 pc rotors on the front, and 1 year later, they same ones are still on the car. In the last year I have done 4 W2W races, 1 practice DE day, 18 TT days, and many taxi cab laps hauling passengers around. That's about 100x longer than I ever had any chinese POS rotor last. The old canadian NAPA rotors did ok for the money ($25) but those are long gone.

I probably do it for safety as much as anything, trusting one of the most important parts of your race car/safety to a crap, pot metal chinese rotor? hmmm.

JeremyGSU

Bill, have you tried a different pad combo? I haven't heard of too many people cracking the 2-piece rotors like you have been. Wonder it if it's not the pad?