Ooh right! ;-)
OK, well there are basically two types of handbrake arrangement when a car has rear disc brakes.
The first is unofficially known as “drum in hat”. In other words there is a small drum brake positioned inside the hub of the rear disc. Drum brakes make a good static brake because they have a self servo action. When the brake is applied, the shoes try to wrap around with the drum until they “sprag” or jam it - like throwing a wedge under a door. Additionally, as the brake cools, the drum shrinks and applies even more force.
Mazda have opted for the other type on the CX-3. This is where the pads are used to clamp the disc. Now disc brakes are excellent dynamic brakes but they don’t make particularly good static brakes. The pads are better suited to motion and there is no self servo effect - they rely purely on how hard the handbrake lever is pulled. They are used because they are relatively simple and cost less. In this case, as the disc cools, the pads can lose grip of the disc. The best ones have electric motors (EPB - Electric Parking Brake) and these apply a very high clamping force with a follow up spring brake to compensate for any shrinkage or cooling effects. For you CX-3 guys, brute strength is the only option and make no mistake, the lever should be pulled firmly if parking is to rely purely on the handbrake.
Now in relation to what is happening with these above cases of Peter’ and Fun’s, well you have to give them chance to start with. Friction materials respond to temperature very well. “Bedding" or “burnishing" as the US brake industry calls it, is a two stage process. The first and most obvious stage is that the pad and disc conform to each other and 100% contact can be seen on both surfaces. The second and less obvious stage is that the friction material becomes “conditioned” by temperature. This is where some of the resin content of the pads is burned away to expose the friction element which is usually abrasive of which silica sand is an example. This second stage MUST see heat and those of you tootling round and getting 100,000 miles from your pads will never achieve it. What does it mean in terms of handbrake? Well the rear brake is already under utilised because of weight transfer and the fronts get all the heat. The designers try to offset it by giving the rears a smaller area (which gives more pressure per unit of area) but it is still not easy to force some heat into the rear brakes.
So! In summary, the pads themselves need heat which may not easily (or ever) happen. The handbrake is at a disadvantage until it does PLUS that lever needs to be pulled quite firmly. Having said all that, the legal approvals only require the parking brake to be about 12.5% efficient so by design (although it will be higher to provide a margin of safety) it need not be that powerful and may struggle to fight the engine even in tip top condition. To get the best from friction materials, don’t be afraid to get them working quite hard - they are excited by temperature. Under these conditions, they will wear out quicker but they will give the best performance. Discs should also always look bright and shiny like mirrors.
I’ll attach some info on the CX-3 parking brake so you can see pictures!
Currently CX5 SportNav 2.2 diesel automatic and AWD.
Formerly CX3 SportNav 1.5 diesel automatic and AWD.
All advice is given in good spirit and taken entirely at the readers own risk. WORK SAFELY. ©2018 anchorman
“.........and another thing"
Last edited by anchorman; 05-20-2016 at 12:35 AM.