The R-4 brake pad was the first and original pad from Porterfield made from Carbon Kevlar.
Being able to maintain an average of .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. The Carbon Kevlar allows the pads to warm quickly up to race temperature, ideal for restarts and when track time is limited. The R-4 Compound requires minimal bed-in and optimum operating temperatures of 450F – 1200F and able to maintain an average of .50 friction level within a very wide temperature range.