Drum brakes are the great forgotten, although they have never died out and may now have a second youth. We explain why and what you should watch out for.
If you ask anyone if they prefer disc brakes or drum brakes, a priori they will choose the first ones, since they have a better reputation, they are more attractive, you see them in racing cars… Motorcycles and bicycles also show them with pride. And there are even simulated baby strollers!
But, if the drum ones were so outdated, why are they being mounted now even in 300 hp plug-in cars? Is the same technology valid for a bus, a Seat 600 -which never had discs-, a normal utility vehicle on its rear axle? Interestingly, yes.
Why can drum brakes have a second youth?
Currently, there are drum brakes, disc brakes and electric brakes (which is not that they give the order in a non-mechanical way for the first and/or second to act, but rather, they directly retain the axle from the brake system itself). propulsion -motor and transmission- so that the desired deceleration occurs).
That is why, for more than half a century, the most recommended configuration was to mount disc brakes on all four wheels or, at least, front (and rear, drum), since when braking, the inertia that a vehicle carries makes that all the force moves forward, due to which the most powerful brakes must be mounted there.
And more, in models with more acceleration, speed, tire dimensions and heavy braking, because the performance of the drums fell short as there was more friction surface and greater risk of overheating and loss of effectiveness (fading).
The rear wheels must also be equipped with their own brake system so that the distance covered when stepping on the pedal is not dangerously long. However, for less heavy cars (urban, utilitarian) and for which sporty driving was not required, such powerful elements were not needed.
If you made sure that the drum brakes complied behind in these circumstances, manufacturer and user could benefit from its qualities: greater savings in assembly and maintenance, since it was traditionally calculated that in a conventional vehicle with a mixed system, you had to change its discs for every other time you replaced his pads.
But if a sports car now relies continuously on electronics to act on the whole with the engine brake, a lot of work is taken away from discs, pads, shoes and drums. So drums can be a good idea in these times of dizzying changes in mobility, forced electrification and maximum cost savings by all manufacturers in the world…
The return to the drums behind lacks logic… unless it saves production costs in a system a priori more sophisticated than that of the discs. So be careful with the replacement periods and their costs: if traditionally shoes and drums were more expensive to change, imagine if they now have electronic energy regeneration systems, or less durable materials.