Porterfield rear pads, available in R4S for fast road use or R4 race compounds, as used on the Whifbitz Time Attack cars.
The R4S fast road compound:
For high performance and heavy duty street conditions the Porterfield R4-S compound remains a top performer in the realm of street/performance brake pads. With the R4-S compound giving a friction level up to .41. This is an amazingly fast stopping brake pad. Simply put, they will give you an impressive increase in stopping ability with very minimum amount of pedal effort. Perfect for prolonged everyday street driving while also being capable of enduring the most severe use without fade. It is also disc friendly of course.
Porterfield have gone to great measures to ensure that the R4-S compound has the absolute lowest noise and dust levels possible, far below O.E.M. equipment or any other high performance brake material. The R4-S compound which has an overall win in the Baja 1000 is available for most models of cars and trucks. Superb stopping power under heavy use. Great for occasional track days, off road events and rallies. Perhaps one of the overall best performing, clean and quiet everyday high performance driving brake pad ever made.
The R4-S compound is available for virtually any vehicle sold across the world. Also for rare vintage cars and special applications for street touring.
The R4 race compound:
For over two decades, the Porterfield R4 Carbon Kevlar brake pad has given racers abroad a definite world class friction material suitable for virtually any racing condition. Designed specifically for heavy duty motorsports, the Porterfield R-4 brake pad was our first and is our original Carbon Kevlar brake pad. Being able to maintain an average of a .50 friction level within a very wide temperature range gives the R-4 pad astounding versatility and makes it very suitable for a wide array of various track conditions.
With use of the latest ceramic technology, the Carbon based semimetallic R-4 materials allow the pads to absorb tremendous amounts of heat and dissipate it at a very even rate, while at the same time insulating excessive heat from calipers. Another inherent characteristic of our carbon kevlar material is how quickly the pads warm up to race temperature which is quite helpful during restarts, and when track time is limited.
Optimum R-4 operating temperatures are 450ºF and above. When used with cast iron and steel alloy rotors, the R-4 compound requires minimal bed-in period. Throughout the entire heat range, the Carbon Kevlar material will give extremely consistent modulation and predictability smooth release characteristics up to threshold. Another benefit of our R-4 compound is that even with the high friction levels and broad temperature ranges, the unique properties of our compound allows the rotors life to be extended to the maximum. This is truly the most rotor friendly racing brake pad material ever. Road courses, oval track, rally, vintage racing, autocross, club events or professional racing events. Tested and raced in countless types of competition vehicles, the R-4 compound from the outset has established its reputation as a Championship winning brake pad material.