Brake System Design and Optimization: Step 2 - Planning & Implementation
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Step 2 - Planning & Implementation
05.21
| 00:00 | - By now, we've got an understanding of the shortcomings of our existing setup or if we're starting from scratch, we know what we're trying to achieve. |
| 00:08 | Just like how we used the HPA calculator for the analysis stage, we can also experiment with new setups in the calculator to find the best way forward. |
| 00:18 | Let's first discuss how we would work through this when designing from scratch and then use this as a reference to discuss how we might plan to address the shortcomings of an existing system. |
| 00:29 | This typically starts with working to maximise the front disc size using the biggest item we can fit with a calliper under our wheels. |
| 00:38 | While this comes with a weight penalty it's far outweighed by the advantage in thermal capacity and brake torque. |
| 00:45 | We then need to find a suitable calliper for this disc size and the piston size of the calliper also plays an important role in the brake torque but we'll come back to this in a moment. |
| 00:56 | Calliper choice comes from a range of other considerations like staggered pistons to reduce uneven pad wear as well as weight and stiffness among many other things. |
| 01:07 | Likewise, when choosing pads we need to consider factors like the ability to work from cold but more specifically, the coefficient of friction and its stability with temperature. |
| 01:18 | With the calliper piston, disc and pad information, the calculator can find the hydraulic pressure required to achieve our target brake torque. |
| 01:27 | We want this pressure to be in a reasonable range, say between 500 and 1500 psi, although this isn't a hard rule as there are many setups that work well outside of this range. |
| 01:39 | If the pressure requirement is very low, say under 500 psi, we've probably just over specced our calliper, meaning it'll be unnecessarily heavy and likely expensive or our pad could also be too aggressive, leading to expensive maintenance. |
| 01:56 | If the pressure is too high though, we probably need a calliper with more total piston area, or a more aggressive pad as the high pressure can damage components in the hydraulic system and require too much pedal effort or leverage to generate. |
| 02:11 | We'll also know this by the master cylinder size that's recommended where we'd typically use between a 5/8th of an inch and a 1 1/8th inch master cylinder. |
| 02:21 | If we're recommended sizes outside this range, then it's likely that we need to rethink our calliper or pad we intend to use. |
| 02:30 | With an idea of the front brake sizing we can move onto the rear, choosing a disc and calliper appropriate for the bias and thermal requirements. |
| 02:38 | The relative sizing of the front and rear brakes is always a bit of a balancing act to get the bias correct and the hydraulic systems balanced so when we then choose the master cylinders, we can avoid excessive bias bar tilt while getting reasonable values for the pedal effort and travel. |
| 02:56 | Our plot can then give us a clear visual understanding of how the suggested brake bias, based on these components will stack up compared to the theoretical ideal and we can experiment with changes to find the best way forward. |
| 03:10 | For an existing system with known faults, we can use the same method of experimenting with changes to components, be it the brake discs, callipers, pads, master cylinders or even pedal ratio or aerodynamics to address the shortcomings. |
| 03:26 | If we've found issues from other means like excessive front brake temperatures, leading to fade, then we can also use the calculator to see how changing the pad compound or disc annulus would have an impact on the system as a whole. |
| 03:42 | Or alternatively, we might need to just look at improving the ducting. |
| 03:46 | If you're hazy on the details here, a revisit to the troubleshooting module should refresh your memory. |
| 03:52 | With our plan finalised, it's time to move away from the theory and put our practical skills to work. |
| 03:59 | While master cylinder and brake pad changes might be simple enough, installing new callipers and changing disc sizing might require making a new calliper mounting bracket ourselves if there are no off the shelf offerings available. |
| 04:13 | While the actual fabrication and/or CAD work is out of the scope of this course, there are a few important things to remember such as ensuring the edges of the pad are lined up with the brake disc and the calliper is centred on the brake disc and aligned perfectly. |
| 04:28 | This will help reduce pad and disc wear issues as well as compliance problems. |
| 04:33 | If we're starting from scratch, there's also a good chance we'll need to be making brake lines as well to connect all our components. |
| 04:41 | After this, a quick check of the bias by hand on the hoist or axle stands can provide a quick sanity check to make sure we're at least in the ballpark. |
| 04:51 | The final thing to note here is that it's worth considering adding pressure or temperature sensors or alternatively disc paint or calliper stickers at this point if we don't already have them. |
| 05:02 | It's definitely possible to get good results from testing and tuning without these items but they'll give us a much deeper and clearer understanding of what's really happening. |
| 05:12 | With our changes made, the next step will be getting out on track or in a safe location and testing our work. |
