Motorsport Plumbing Systems: Sizing
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Sizing
02.34
| 00:00 | While the sizing of braking master cylinders, calipers and rotors varies significantly for different applications, the size of the brake lines is almost completely standardised and not something used to change the brake performance. |
| 00:15 | That's because well designed brake systems rely on pressure rather than fluid displacement, and while line size will influence the pressure generated and fluid displacement for a given pedal effort, the master cylinder and its ratio to the caliper piston size will have much more influence. |
| 00:33 | We also don't have to deal with any pressure drop from restrictions in our brake lines since the pressure is so high, small changes have a negligible effect. |
| 00:42 | 99% of brake lines on road cars and in motorsport applications are 3 16ths of an inch or dash 3 sizing for the hard lines and flexible hose, which is sometimes referred to as its metric equivalent of 4.75mm. |
| 00:59 | You're likely familiar with the formula for calculating the area of a circle, and this also applies to our plumbing where the cross sectional area equals pi multiplied by the radius squared or 1 over 4 multiplied by pi multiplied by the diameter squared. |
| 01:16 | Basically what this means is that the cross sectional area and therefore volume of our plumbing increases exponentially with changes to the diameter so a seemingly small change moving from a 3/16ths ,or dash 3 line to a 1/4 or dash 4 line, is more significant than you might think and stepping up again to dash 5 is an even bigger change to the volume. |
| 01:40 | So, if we consider this, then any swelling to our brake lines causing compliance will worsen by the use of larger plumbing. |
| 01:49 | And saying that, there are some applications that do make use of 1/4 inch or dash 4 brake lines, one being vintage trucks with big drum brakes, not something usually involved with performance. |
| 02:02 | Some vehicles with very large callipers can also make use of a bigger line as they'll require a significant amount more fluid displacement, but this needs to be considered with the rest of the brake system design. |
| 02:14 | The key takeaway point here is that the brake line sizing isn't generally used as a tuning tool to influence brake performance. |
| 02:22 | In almost all applications, the best size brake hard line and flexible hose to use is 3/16ths of an inch or dash 3. |
