Motorsport Plumbing Systems: Routing & Heat Management
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Routing & Heat Management
04.17
| 00:00 | Hot brakes in motorsport are a timeless duo and it's not surprising as the main function of the braking system is to transfer kinetic energy to heat energy. |
| 00:09 | This means the brake fluid and our plumbing gets hot as a result, and while some components of our brake system like the calipers, pads and discs will work best with some amount of heat, we really want to minimise the temperature of our plumbing and the brake fluid. |
| 00:26 | As we've discussed already, boiling brake fluid needs to be avoided at all cost, as this will quickly reduce our ability to transfer force from the brake's pedal to the brake calipers and therefore brake effectively. |
| 00:41 | Sticking with the theme of our previous discussions, let's cover this from the perspective of heat transfer mechanisms. |
| 00:48 | With the severe amounts of heat at our brake discs and pads, it's inevitable that some of this will be passed through the calipers and pistons to the fluid via conduction. |
| 00:58 | This is the primary source of heat transferred to the fluid and there's a lot that can be done to manage this in regards to our braking package, including changes to the thermal mass of the brakes, disc vane efficiency as well as ducting and airflow. |
| 01:13 | This is a big subject and is far outside the scope of this plumbing course, but if you're interested in learning more about heat management and braking systems, and much more, check out our Motorsport Braking System course. |
| 01:26 | So, what can we do from a plumbing perspective to manage the heat in our brake lines? Brake lines are very small and this low thermal mass means they come up to temperature very quickly. |
| 01:38 | Simply put, if they're exposed to heat, they'll get hot and so will the fluid inside, regardless of the material used. |
| 01:45 | What's important is to avoid external heating of the plumbing and components, making the situation worse. |
| 01:52 | If we consider the routing of the brake lines to each corner of the vehicle, which is usually outside the cabin underneath the vehicle, having the lines exposed to the fresh airstream can help transfer heat away via convection. |
| 02:06 | Otherwise, the usual considerations apply. |
| 02:09 | Where we want to avoid running the brake lines near heat sources like exhaust manifolds and turbochargers, and in cases where this can't be avoided, it's best to use heat shielding and insulation to prevent radiant heat transfer. |
| 02:23 | A final consideration on this topic of routing is that we don't typically have to deal with any pressure drop from the restriction in our brake lines. |
| 02:32 | Since the pressure is so high, small changes are negligible. |
| 02:36 | What we're more concerned with is the compliance seen in long lengths of flexible hose that's prone to swelling with internal pressure. |
| 02:45 | The greater the length of hose in this case, the greater the total volume change and therefore the poorer the compliance. |
| 02:52 | Similarly, as always, it's going to be ideal to minimise the length of the lines in general for weight along with the amount of fittings as possible failure and leakage points. |
| 03:03 | We still need to ensure our plumbing is routed clear of any suspension components, including the wheel and tyres to prevent any rubbing. |
| 03:11 | Taking into account the suspension articulation and steering. |
| 03:16 | A good method of checking this is removing the suspension spring and bump stop and disconnecting the anti roll bar if present. |
| 03:24 | This will allow us to easily move the suspension through its travel and check for clearance. |
| 03:29 | To achieve this, it's common to have fixture points for the flexible lines on the suspension arms or struts. |
| 03:36 | So, with that covered, let's summarise. |
| 03:38 | Heat is a key issue in the braking system, resulting from the brake's primary function. |
| 03:44 | While there's a range of heat management considerations for braking system, in regards to the plumbing of the brake lines it really comes down to avoiding heat sources and using shielding and insulation where possible. |
| 03:57 | As always, minimising the length of the plumbing is beneficial for weight and reducing failure points and while restrictive lines and resulting pressure drops aren't a big issue for brake lines, poor compliance will come from excessive flexible hose use as it's prone to swelling. |
