Wheel and Tyre Fitment: Brake Clearance
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Brake Clearance
03.56
| 00:00 | Although not a performance metric directly related to the size of the wheels themselves, the size of the braking package naturally has a significant impact on its performance, and this is limited directly by the fitment of the wheels. |
| 00:14 | Factory brakes are usually one of the first things to give us problems when we take the car out on track, and upgrading them is therefore one of the most common changes to performance focused vehicles. |
| 00:25 | Increasing the brake disc size for more thermal capacity and brake torque, or changing to a larger caliper with more pistons and piston area for more brake power and performance pad availability, among many other things, will most often require more space inside the wheel. |
| 00:42 | For this reason it's not uncommon to have to change the wheels when upgrading our braking package, or alternatively, if we're just changing the wheels without upgrading the brakes, it's important to understand how much clearance we need for our current braking package. |
| 00:58 | Brake clearance has been discussed to some extent in the wheel structure and diameter modules, so we'll keep things brief in these regards, and then you can check back to these modules if you need a refresher. |
| 01:10 | As we hopefully understand by now, there are lots of elements of the wheel to determine the brake clearance. |
| 01:16 | In the radial direction, the diameter of the wheel and the profile of the barrel are the key players. |
| 01:21 | A larger diameter wheel and having the drop centre away from the brake location generally allows for more clearance for a larger disc. |
| 01:30 | In the axial direction, the design of the face makes the most difference. |
| 01:34 | Here, a greater pad height and spokes that extend further outwards will tend to allow for a larger caliper. |
| 01:42 | This is going to of course depend on the hub design of the vehicle and the type of brakes as well, as some vehicles and brake calipers require a lot more brake clearance than others, even if the disc is the same size. |
| 01:55 | In some cases we might be able to get away with a small spacer to get the clearance we need without causing other issues around scrub radius and wheel to guard clearance. |
| 02:05 | But in other cases, we just simply won't be able to use the wheels. |
| 02:10 | Some wheel suppliers will be able to confirm if a particular wheel will fit our vehicle with the factory brake option, but if not, we'll need to make some educated decisions based on our research. |
| 02:22 | Alternatively, if the wheel supplier is able to provide a cross section drawing of the wheel, then this can be cut out to the correct size and used to check clearance on the hub to the brakes. |
| 02:33 | We'll cover the use of this method to also check the wheel clearance to the rest of the wheel well later in the course. |
| 02:41 | An opposite method is also possible if we already have our wheels and are looking to upgrade the brakes. |
| 02:47 | Most off the shelf big brake kit suppliers can provide a template that we can print out to scale and cut out to check the clearance to the inside of the wheel. |
| 02:56 | Alternatively, if we've modified the design for a custom caliper disc and mounting bracket in CAD, it's possible to make a template ourselves to perform the same check. |
| 03:07 | Or even if we use a model of the wheel to check for clearance. |
| 03:11 | In summary, when changing the wheels or braking package on a vehicle, we need to consider the internal clearance of the wheel for the brakes. |
| 03:19 | The diameter and profile of the barrel govern the diameter of brake discs that we can run, so if we want to increase this, it's not uncommon to have to step up to a larger diameter wheel. |
| 03:30 | The pad height and design of the wheel face are also important in the axial direction, as well as the location of the brake disc and caliper relative to the hub of the vehicle. |
| 03:41 | In some cases, the wheel will be approved by the supplier for fitment on our vehicle. |
| 03:46 | But in other cases, it might be possible to use a template to check for clearance before committing to a purchase. |
