Motorsport Plumbing Systems: Materials
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Materials
06.33
| 00:00 | The material requirements of our brake plumbing system are comparable to other automotive plumbing systems, although with some specific considerations. |
| 00:08 | Naturally, safety is our main priority as brake failure due to issues with our plumbing system will almost completely eliminate our ability to slow the vehicle, which comes with some obvious consequences. |
| 00:22 | The internal pressures of our braking system can reach up to 2000 psi and beyond. |
| 00:28 | So, plumbing materials need to be specced with this in mind. |
| 00:32 | This is also related to compliance which as we discussed previously, we want to minimise, especially in performance applications. |
| 00:41 | For this reason our plumbing needs to be stiff enough to resist swelling with these high internal pressures. |
| 00:47 | While this is relatively easy for hard lines, the key area of concerns is really with our flexible lines that allow for movement with the suspension and steering of outboard brake callipers. |
| 01:00 | Further to this, flexible hoses as well as hard lines are usually run through the engine bay, underneath vehicles, around the suspension and out to the wheels. |
| 01:09 | All of which are abusive environments to say the least. |
| 01:13 | For this reason our plumbing needs to have good resistance to abrasion and corrosion, as well as chemically resistant to any external fluids it may come in contact with. |
| 01:23 | Brake lines will need to be able to withstand exposure to high temperatures when run through the engine bay but it's also important to minimise heat transfer to the fluid. |
| 01:33 | The final brake specific consideration we'll discuss is that the system needs to be sealed as most brake fluid is hydroscopic, meaning it'll absorb moisture, which lowers the boiling point and leads to potential compliance issues. |
| 01:48 | Moisture damage can occur even when the car's braking system has remained completely sealed. |
| 01:54 | This is due to diffusion, where the moisture can pass through some materials like plastic fluid reservoirs and rubber based calliper seals. |
| 02:03 | Leaks in the system will also introduce air bubbles into the fluid which has similar results to moisture and also the inability to transfer hydraulic pressure. |
| 02:13 | It should be obvious that leaks in any automotive plumbing system should be avoided. |
| 02:18 | As always let's discuss the materials commonly used in OEM through to motorsport applications. |
| 02:25 | Starting with hard lines, steel is the common offering for most lower end factory vehicles. |
| 02:31 | Whereas more modern and higher end vehicles often use stainless steel lines for the added corrosion resistance. |
| 02:39 | Stainless steel is a great option for replacing old corroded steel lines but naturally comes with a higher price tag. |
| 02:46 | An alternative option is to use copper nickel which also offers good corrosion resistance but is generally cheaper and a lot easier to work with when it comes to flaring and bending the lines. |
| 02:58 | Just be sure to use copper nickel specifically offered as brake lines as this will have sufficient wall thickness to provide the required strength. |
| 03:07 | Aluminium, however, is not an option for brake lines as it's simply not strong enough for the high internal pressures seen and more susceptible to cracking and failing. |
| 03:17 | The size of these hard lines will be discussed in a coming module but for now just know that it's almost always 3/16ths inch. |
| 03:26 | For flexible hoses in the OE world, most brake lines you'll come in contact with will be rubber based, but in the motorsport industry, braided stainless steel lines are the go to. |
| 03:37 | The rubber based hoses are chosen in the OE world primarily for cost reasons, and they do have some downsides we'll discuss shortly. |
| 03:46 | Brake hoses will generally connect to the solid brake lines somewhere near the inner wheel well and provide the flexibility required to the outboard brake calipers. |
| 03:55 | This helps to minimise the length of the flexible hoses in the system, which we want to do for a few different reasons. |
| 04:03 | Solid steel lines are going to be more damage resistant than flexible hoses in most cases, meaning we should be using them whenever possible. |
| 04:12 | However, from a function perspective, compliance is also an important factor. |
| 04:18 | Rubber based hoses expand a lot more than a hard line does in response to internal pressure. |
| 04:25 | This is why braided stainless steel brake hoses are so important in motorsport, as they expand far less due to the pressure, giving us less compliance overall. |
| 04:34 | We wouldn't usually discuss the fittings here, but there are some specific considerations when it comes to the brake plumbing so let's cover that before wrapping up. |
| 04:44 | To allow the solid brake hard lines to be joined to other components, we'll generally find tube nuts at each end. |
| 04:50 | This is a nut that slides over the line where the end of the line has a flare on it. |
| 04:55 | The nut screws into the component, pressing the flared end into the matching part of the component, thereby creating a seal. |
| 05:03 | The flare is used to add strength and integrity to the connection and provide the seal. |
| 05:08 | There are a few different types of flares and although single flares do exist, they shouldn't be used for brake lines and are actually illegal for road use in most countries, as they aren't able to withstand high pressures and will crack and leak easily. |
| 05:23 | 45 degree double flares, also known as SAE or inverted flares, create a much stronger, more secure sealed connection. |
| 05:33 | Bubble flares, which are also sometimes referred to as ISO or DIN, are also commonly used for success. |
| 05:40 | However, a double flare is still a more durable and reliable option and is therefore the go to for brake hard lines in motorsport applications. |
| 05:49 | To summarise, our hydraulic brake plumbing system consists of hard lines and flexible hose. |
| 05:55 | In most performance applications, 3/16th stainless steel or copper nickel hard lines are used, where aluminium isn't suitable for brake lines due to the extreme internal fluid pressures. |
| 06:07 | These hard lines are flared with 45 degree double flares and connected with tube nuts. |
| 06:13 | Flexible hoses on the other hand, while usually simple rubber based parts in most OEM road cars, should be upgraded to stainless steel reinforced variations for performance in motorsport applications to reduce compliance and increase abrasion resistance. |
