Brake System Design and Optimization: Brake Bias Bars
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Brake Bias Bars
02.53
| 00:00 | - The ability to adjust brake bias to suit different conditions is an essential part of getting the absolute most of a motorsport brake system. |
| 00:08 | The mechanism that makes this possible in almost all cases is what's known as a brake bias bar. |
| 00:15 | Also known as a brake balance bar. |
| 00:18 | Brake bias bars are used in twin master cylinder setups where each brake circuit has its own master cylinder. |
| 00:25 | By making adjustments to the bias bar, we can vary the proportion of brake pedal force that's applied to the front and rear master cylinders, therefore affecting the hydraulic bias. |
| 00:38 | While the exact implementation of a bias bar can vary between manufacturers, the basic layout is always the same. |
| 00:46 | There's a bearing that sits in the brake pedal and all the force that the driver applies to the pedal is transferred through this bearing. |
| 00:54 | The bias bar sits in this bearing and at each end of the bar there's clevis that connects it to each of the master cylinders. |
| 01:01 | That is the mechanism that transfers the force from the brake pedal to each of the master cylinders. |
| 01:07 | The brake bias bar is generally threaded and it's a mechanism that allows it to be rotated to adjust the brake bias. |
| 01:16 | As the bias bar is rotated, the bearing moves one way or the other depending on the direction the bar is rotated. |
| 01:24 | By bringing the bearing closer to either the front or rear master cylinders, the proportion of the force each master cylinder sees is subject to changes. |
| 01:33 | If the bearing is moved closer to the front master cylinder, the front master cylinder receives more force, the rear master cylinder receives less force and as a result, the hydraulic brake bias is moved towards the front axle. |
| 01:49 | The opposite is clearly also true. |
| 01:51 | To increase the rear hydraulic bias, the bar is rotated, bringing the bearing closer to the rear master cylinder. |
| 01:58 | It's most common for the bias bar to have a cable mounted to the end of it. |
| 02:02 | This allows the driver to turn a knob at the other end of the cable, rotating the bar. |
| 02:08 | This mechanism will also incorporate a lock or detent system to prevent the cable and the bar rotating without driver input. |
| 02:16 | Electric or electronically adjusted systems are also becoming increasingly common. |
| 02:21 | The mechanism is essentially the same as the manually adjusted bias bar, except that a motor will be rotating the bias bar either directly or via a cable. |
| 02:32 | To summarise, a brake bias bar allows the hydraulic brake bias to be varied by the driver in dual master cylinder setups. |
| 02:41 | It does this by changing how much force is apportioned to each master cylinder. |
| 02:46 | The adjustment of the bias bar can either be mechanical or electrical. |
