BRAKES YOUR QUESTIONS ANSWERED
This month we ask Dan Newton, boss of PB Brakes, your questions about brakes.
direction as we found this doesn’t decrease the strength as much without affecting the function. Braided hoses comprise of a Teflon inner wall, with strands of stainless steel braided on the outside for increased durability. One advantage is that they expand less than your OEM rubber hoses, which allows you a firmer brake pedal. A firmer brake pedal means more feedback and ultimately better braking. The other big advantage is safety – They’re almost bulletproof! Useful if you have problems with people sabotaging your brake lines as you sleep. Glycol-based brake fluid is hydroscopic which means that it loves to absorb moisture, which is always going to find a way into the brake system via micro pores in the cap, lines and seals. This is a bad thing since it dramatically reduces the boiling temperature of the brake fluid – 3 percent water in DOT4 fluid can reduce the boiling point by up to 50 percent! That’s dangerous because bubbles are compressible, which causes at best a spongy pedal feel, and in extreme cases it may go all the way to the floor without actually stopping the car! One word – Torque! When you increase the diameter of the disc, the amount of braking torque also exponentially increases. So in theory the bigger the disc, the faster you’ll stop. However, there is a limit to how big you can go. You’re limited by how much grip your tyres allow, once your discs are over a certain size you’ll brake so hard that the ABS will initiate in order to prevent the tyres from losing traction, and whatever gains you made are out the window. Brake pads can also be a limiting factor as your bog-standard street compound will just melt if subjected to more torque than it can handle. You also need to consider that brake discs are fairly heavy items, and increasing the weight that each wheel needs to rotate is going to have an effect on your acceleration. This maximum recommend size of discs depends on the car, but generally speaking, heavier cars require larger discs for effective braking, and lighter cars can get away with running smaller discs. It all comes down to cost really. Your bog-standard OEM discs are usually cast in one solid piece as this is most cost effective way to manufacture them. One-piece discs are fine for normal use and the odd spirited drive, but push them too hard or take them on the track and they will fade within a couple of laps at race speed. When you’re flying down the straight at 130mph and you hit the brake pedal, the last thing you want is for it to sink right down to the floor because of fade. One solution is to upgrade to a set of two-piece discs with billet aluminium centre caps. The contact area between the actual disc and centre cap is minimal, which greatly