Technical page: Brakes

Choosing a brake pad

Some points to know:

• The different compounds that you can see might mention pre-heating need, or a temperature range. That's because the pads can't be designed to optimize braking at every temperature. During strong braking, like in competition use, the pads can reach 700°C, and that's why some sets that are specifically designed for heavy use need pre-heating. They brake hardly anything when cold, but behave optimally at that high temperatures. Take care with that, because even knowing that if you brake hard the pads can heat fast on a long braking at high speed, as you don't count with it it's easy to break a front bumper in your first early morning traffic light braking!

  So it's smart to choose pads that give some grip at low temperature and don't go for the ultimate racing set for a daily use...

• Performance sets usually will wear faster that standard ones, as they're softer.

• The greater braking effort is made with the front brakes, so those are the ones worth improving. During any strong brake the rear brake limiter will reduce the effective fluid pressure that reaches the rear pads, so it doesn't make much sense to try to improve the rear braking upgrading the rear pads, but actually, to be a perfectionist when you change to a front performance pad set, you should install the same model at the rear or readjust the brake limiter to set again the braking relationship.

Fading

Brake discs become very hot if used hardly. They're prepared to dissipate a lot of heat (vented discs are much better for that, and that's why the GT Turbo front discs are so), but there is always a limit.

The problem with the heat is that the brake fluid starts boiling and introduces air into the brake lines. Then we start talking about fluid 'fading', a progressive brake efficiency decrease that's also perceived as a sticky sensation at the brake pedal.

Another effect of the excessive heating is the pad 'fading', when the working temperature of the pads is exceeded (depending on the compound used, of course) and they reduce their friction coefficient. In this case you also note a decreased brake power, but the pedal feels hard this time. Besides, the pads can get to crystalize, what would ruin them forever.

Choosing a brake fluid

Take into account that:

• As a rule of thumb, brake fluid types shouldn't be mixed.
• A brake fluid quality increases with its compression resistance, and boiling point. DOT 4 means better quality than DOT 3, and then DOT 5, designed for ABS-equipped vehicles, is even better than both of them.
• There are fluids intended only for competition use (550, 600 series). Their characteristics are very good, their boiling point is extremely high... but thy must be changed after each race because they are hygroscopic: they tend to absorb humidity and they get worse and worse quickly. If you don't plan a brake fluid renewal monthly, I wouldn't suggest using them.