08-27-2004, 12:33 AM
Officially Welcomed to the 'Fest
Location: Irvine, CA
Join Date: Aug 2003
Mein Auto: Rogue E46 M3 Wagon
Rotora Brake System Performance on BMW M3 Racer Car
SUBJECT: Rotora Brake System Performance on BMW M3 Racer Car.
I thought it would be a good time to share some race and testing notes with you regarding the Rotora brakes I put on my race car. This is a pretty long post but if you are considering spending the money on a brake upgrade or if you want some insight into brake testing and race car preparation it's worth the read.
I installed the Rotora BBK Front and Rear brakes on my modified E36 M3 race car. The kit consists of 355mm rotors and 6-pot calipers up front with 330mm rotors and 4-pot calipers in the rear. The E46 M3 kit is the same but comes with 355mm rotors front and rear. The kit comes with all the brackets, hardware, brake lines and pads. I chose the H6 (race) pads rather than the (H2) street pads. Initial fit and finish are excellent and the red calipers look awesome through the race wheels.
A little background… Half-way through this season I finally had my car well sorted and started to win races (overall). The aero package, springs, remote reservoir dampers and the slicks all really started to work well together. The slicks are amazing and offer so much more grip then the other R-compound tires I was using that my old AP Racing brakes no longer seemed powerful enough for the application. I was also getting a bit of fade nearing the end of sessions.
I had AP Racing Brakes on the car an was a bit hesitant at first to take them off and replace them with a different brand. I didn't want to have to get larger (Tilton dual) master cylinders to accommodate a huge brake upgrade. The front and rear Rotora BBK brake packages were the perfect solution because they do not require a master cylinder upgrade. Also, the huge AP Racing or Brembo Brakes would have literally cost thousands of dollars more in addition to the cost of the new master cylinders.
Below are race and testing notes from the first few times the brakes were used the track. These notes were taken from e-mails I sent to my Rotora contact. I've been working with Richie Ho who seems to be 1 part marketing, 1 part R&D and 1 part engineer. He has come through for me every time I needed something and is a very sharp guy.
There is a group buy going on now for the E46 M3. Details on that can be found here… http://www.m3forum.net/m3forum/showthread.php?t=32691
If you have further questions for me about my experiences with Rotora brakes, please feel free to contact me at firstname.lastname@example.org I have beat the hell out of them and they had stood up well in extreme racing environments.
Event #1 - BMW Oktoberfest Event July 2004
The car finished 3rd overall out of 40 cars at BMW’s Oktoberfest event at Fontana despite being 50hp to 100hp down on power to many of the front runners.
The brakes performed very well. Proportioning to my old brakes (AP Racing) was similar. Only minor changes to the proportioning and application needed to be made depending on fuel load and rear wing angle.
The pads broke in fine with little to no gassing out and no sensation of uneven pad transfer during break in. Initial bite seemed a bit soft. I like harder pads in general for racing but the softer pads did make it easier to trail brake and the braking "feel" was excellent which gave me confidence. The pads did firm up nicely after the first session.
After the event was over and many sessions on the track, the rotors show no sign of wear - amazing. I will measure the pads for you and report back but I can tell just from looking at them that they have worn down a bit. The way they feel and the wear of the pads make me consider them a soft pad – which isn’t always a bad thing. They were quiet and consistent through the temp range.
The front rotors did have very slight normal and acceptable stress cracks – the rear rotors had no stress cracks at all. This is probably due to the fact that the front not only got hotter but that they were cooled with brake ducts which creates stress as the rotors go from very hot to cold so quickly and often.
Rotor temps were very low – like “really” low. I did not get a reading over 500 degrees all weekend with the laser pyrometer. I used tempilaq thermo-graphic paint at it indicates a max of 900 degrees – which is nothing (especially for California Speedway). I did have the brake ducts installed up front but will probably pull them for all other tracks other than Buttonwillow and Laguna (the harder braking tracks). When I took my E46 M3 street car to California Speedway last year I got brake rotor readings of 1200F with the stock brakes on the car - yikes!
I will install a set of Thermax stickers and report back actual caliper temps after the next weekend of racing if you’d like.
The Rotora 6-pot front brakes are a bit heavier then the AP Racing 4-pot I was running. They are of course much bigger (something has to give). I’m wondering if the fronts are actually too big for my application. My car only has 280hp and weighs just 2400lbs. The E46 M3 cars have much more power and much more weight so they would benefit greatly from this huge brake kit. If I remove the brake ducting to get the temps up I wonder what the pad wear will be like?
I think the brakes over all did pretty good in a very tough environment. Fontana is very tough on brakes not only because of the 4 hard brake zones per lap but because you are off the brakes all the way through the oval and by the time you need them most going into turn 3 they have cooled significantly.
Event #2 - Testing at Willow Springs with Beverly Hills Motor Car Club
I instructed at the Beverly Hills Motor Car Club Event last weekend and took the car to test - and to toy with the exotics with (it's so fun to beat up on Ferraris). It took a few laps in the morning to reset brake bias as I have recently switched to even bigger rear slicks and wanted to make them work for me by pushing some of the brake bias to the rear of the car. I also took off some rear wing as well to help with straight line speed.
The front rotors never got above 425F as the brake temp paint did not change color from the prior event. I ran the car with no front brake cooling ducts as WSIR is easy on brakes. Again pedal feel was excellent and is important there as the braking for turn 3 is bumpy and the braking for turn 9 is, well… “check your balls time”.
I was easily under 1:30 there but didn’t have a drafting buddy and didn't want to push it too much at a school. I did have fun playing with the Evosport E46 M3 race car driven by the company co-owner Brad Otoupalik. We always have fun together on the track when there is open passing - I trust his driving. He was on lesser rubber and stock brakes (testing for Grand-AM later this year) and I was able to pass him under braking anywhere I wanted. "Go Rotora" but the slicks and my lesser weight gave me the advantage as well.
As far as pad and rotor wear is concerned there was very little at that event. There was less dusting this time as well - almost none. I was only on track for about 2 hours total. Total pad thickness in front was .653 with a starting thickness of aprox .663 – so again, very little wear occurred.
Event #3 - California Speedway - Touring Car Club
I was back at California Speedway this weekend for a Touring Car Club race against Ferrari's, Porsches and Vipers. I did have the front brake ducts hooked up as it was a hot day. I was going to take them off as a test but didn't want to take any chances as there was little time to test at this packed event and didn't want to potentially waste a session.
I had to start last as I skipped the qualifying race to do a family thing. I worked my way through the pack and finished 12th out of 40 cars. A mid-race yellow helped me catch up to the leaders who got quite a lead as I was tending with slow traffic on the opening laps. I totally snaked a Viper and Porsche on the restart - good thing I did because the more I moved up the more difficult it was to pass the faster cars. I'd love to get a chance against those guys at Buttonwillow - they'd fall like a house of cards.
Brake rotor temps approached 1000F – which is about right for that track and is a bit higher than the event done there about a month ago.
Rotor wear continues to be negligible - which still blows me away. At the rate I'm going I'll never have to replace the rotors!
I ran the car aprox 125 miles total for the event at full-tilt-bogy. I was doing 1:48s which is my best effort by a second.
The starting thickness of the pads was .653” this is the thickness taken after the first event with those pads from Willow Springs. The ending pad thickness measured out to an average of .610” so the car used .043” of pads. The rear pad wear is as expected much less. Overall pad wear is not bad all considering it's the toughest track I know of on brakes short of Sebring.
I hope the information I’ve been providing you has been helpful.