mikymu

I converted my CCM rotors to RB steel rotors last year (http://forums.corvetteforum.com/c6-z...onversion.html) and been very happy with the much improve brake performance but like to have lighter weight rotors for better handling and acceleration on the track. My Porsche GT3 Cup has front steel rotors that weigh 23 lbs compare with RB's 28 lbs front - but GT3 Cup use a smaller 380 mm diameter rotor with much thinner and smaller brake pad contact space compare with stock CCM's massive 390 mm diameter and 85 mm brake pad width. I contacted Warren at RB performance brakes and discussed the possibility of a true light weight steel rotor setup. Warren was great in accepting this challenge and came up with a light weight steel rotor setup for both front and rear with an ambitious goal of Front: 390x32mm, estd wt = 22.8 lbs and Rear: 380x30mm, estd wt = 19.6 lbs. After couple anxious months of waiting they have arrived and did not disappoint!

Here is a chart demonstrating the difference in weight between CCM vs RB direct steel rotor replacement vs RB light weight steel rotors



Thunderhill raceway recently completed their new 2 miles west side addition which is full of tight turns and hard on brakes and perfect to test out the light weight rotors. So let's get started with the install

New front and rear light weight rotors ... look super nice with black front rotors from factory and modified 72 mm wide RB XR70 brake pads. Lighter weight was immediately noticeable with handling





next to my Z06 carbon and my high tech jacks



front rotor - just below 23 lbs so it's 5 lbs lighter than heavier cousin and 10 lbs heavier than CCM.





same 390 mm diameter



Thickness comparison with heavier counterpart





Here is my Porsche GT3 Cup rotor - thinner and smaller and yet RB was able to deliver a 390 mm rotor with larger brake pad contact space and thicker and still weight the same as a GT3 Cup rotor! Great job!!





Here is the light weight rear rotor came in at a whopping 19.6 lbs which is only 3.5 lbs heavier than CCM thanks to light weight center hat compare with OEM heavy steel hat



brake pad contact width



thickness compare with heavier counter part





front and rear rotors installed







After bedding - black coating on front rotor is all gone and no brake fades during bedding procedure



off to Thunderhill West for brake test and also took the oppertunity to fine tune the suspension. Couple glory shots on trailer and at the raceway - it was breezy and hot in the mid 90F





praying mantis keeping me company



Brake performed very well on the track and handled harsh frequent short burst braking without issue. I only need to apply gentle firm brake pressure to slow down the car and ease on brakes to modulate as needed. There were no brake fades and pick up and go and directional change were noticeably improved with lighter steel rotors

Here is the video from the track test



One thing worth mentioning is RB's XR70 brake pads. These things are pretty amazing for steel rotors. They last a long time and has minimal tapering compare with OEM brake pads and not super harsh on rotors.

Here is what front brake pads look like - 72 mm wide XR70 for light weight rotors (top left pair) compare with stock size XR70 (top right single pad) vs OEM on bottom. Notice the caliper piston contact points on the brake pads



Caliper piston contact points are biased toward inner side of the rotor on all three sets of brake pads. OEM brake pads have horrible tapering at the outbound side (outer edge of rotor) which is much thinner than inbound, This is likely because rotors spin much faster as you move to the outer edge hence more wear. maybe this is why Brembo offset caliper piston toward the center of the rotor to help even out brake pads wear.

tapering of OEM brake pads



which is also seen on stock size XR70 after 4-5 track events but much much less than OEM



tapering not noticeable on 72 mm XR70 after one track test



I use stock size XR70 brake pads for rear which is slightly wider than the prepared surface. It does not upset the car on the track and perform well





Very happy with RB's light weight steel rotors setup and it definitely improve performance on the track. Look forward to hammering it hard at Thunderhill again soon

mikymu

update

Had another chance this past weekend at Porsche club event running with couple fast Porsche GT3 and twin turbo and really test the brake performance on the 5 miles Thunderhill long course. We were the fastest car of the day and I was riding right on the rear end of the twin turbo so I have to totally trust the brakes as not to hit the car. Brakes performed flawlessly without fade and modulation with XR70 brake pads is just fantastic.

Here is the chase video. For some reason Aims data recorder tun off on it's own and I had to turn it back on manually 2:30 into the video. The first GT3 is a 3.9L beast from sharkwerks and the black twin turbo 911 is a highly tuned beast - both cars are track prepped with experience drivers



hanging out with my Porsche friends



The XR70 front brake pads are 1.68 mm thicker than OEM because light weight rotors are thinner than CCM so you can fit thicker pads in brake caliper

XR70 front brake pads thickness





vs new OEM fronts

Z-Stallion

Awesome! Just awesome! You're a very dedicated racer.

phipp85

Nice driving!! That's a long track
What size slick do you run up front?

mikymu

Thanks! This track thing is totally addicting. Glad we have cars that can keep pace with the fasted European sports car at 1/3 the running cost - that's the best part!

Thanks. I will be at the HOD corvette day at Thunderhill next month so you should come and check it out. I run 305 front and 325 rear conti slicks - too much over steer with this setup. Working hard trying to dial out the over steer so back end don;t step out so easily especially on the low speed turn in second gear on the west side

phipp85

I'm going to try some of the pirelli slicks in those sizes. I have heard good things about them. If it's just mild oversteer you could try a little bit stiffer front bar.

I'll get out to Thunderhill and Laguna one day but the 2500 mile drive makes it tough.

mikymu

yes, that is a long drive but well worth the trip

I been told as far as slicks goes Michelin>Yokohama>conti>Hoosier>Pirelli> Toyo and I only tried Michelin, Yoko, Conti and Hoosier. Let us know how Pirelli perform on the track

vette ruminator

Really interesting brake setup. Many of us will be interested to hear what the initial price was and how the cost of running your setup compares with OEM. I understand that your motivation was brake feel and not cost savings but that info would be helpful to those of us considering your setup...

mikymu

OK, will go over some price numbers - from RB website under C6 ZR1 light weight rotors http://www.racingbrake.com/category-s/7129.htm

*** keep in mind these are estimate figure from RB website - final price need to be confirm with RB since listed price on rotors are discounted already ***

Front rotors with XT910 (street pads $305 a set) $2175 or $1870 without pads
http://www.racingbrake.com/Iron-Two-...rbo-p/2390.htm
front replacement rings $949
https://www.racingbrake.com/ProductD...de=D601-11-381

Rear rotors with XT910 (street pads $197.75) $1892.75 or $1695 without pads
http://www.racingbrake.com/RB-380x30...cin-p/2372.htm
rear replacement rings $932.25
http://www.racingbrake.com/GT-R-R35-...601-04-381.htm

Total front/rear rotors cost with XT910 (street pads) $4067.75 or $3565 without pads and average to about $891.25 per rotor

OEM CCM rotors - best price I could find is about $1200 front and $1400 rear which add up to $5200 a set of four and average $1300 each. So RB light weight rotors are $1635 less than CCM and replacement rings are less than $500 each. Better modulation and consistent braking across temperature range aside These light weight steel rotors have wide range of GTR spec size brake pads to chose from for street and track. For example excellent GTR size track pads like Hawks DTC 60 are about $274 a set for front and $249 rear compare with the best track pads from endless for CCM which cost all the way up to $1000+ for front set ONLY (W007) and that's with less brake performance compare with steel

DUMAN

Mike tired to PM you my # for some pictures of the trailer. send me a pm please

LGK-SD

Awesome post, great info and videos. My coffee went down the wrong pipe when I got to the part that you own a GT3 Cup.....

mikymu

sorry man! my inbox was full

here is how I tied down front wheels. You can order the hardware from MAC





We sure had tons of fun at Thunderhill including the convoy home



Glad you enjoy the post

DUMAN

I would love to see the video of the caravan home. It's was a good weekend. I will be making some changes to the car for the next outing.

mikymu

I did not tape the convoy - too busy trying to keep up with Rich. He tow his trailer like he is still on the track

dizzy8085

I've been following your build closely because I am building my grand sport up to be an hpde toy as well. Although, a lot slower. You don't waste any time!

I've been trying to figure out where I'm going to go with up grading my brakes for a little while now.

I've thought about the zr1 calipers and iron rotors like you're running.

My question is, at 4k dollars in just rotors. Wouldn't it have been more advantageous to just go ahead and go with a stoptech trophy or AP racing full kit? For a few thousand more it seems those kits would prove better performance, lighter weight, and a tad big cheaper consumables.

mikymu

yes, stoptech and AP racing are both good options. which ever one is cheaper and black Friday sales will be coming up soon so you should get a good deal