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Does it really matter how fast your bike is if your brakes down work? I thought so.
If you’ve ever been curious about what it is that actually makes your bike stop, this episode is for you.
Tune in to discover:
- The differences between disc and drum brakes
- About something DEADLY that might be in your drum brakes
- The differences between DOT 3, DOT 4, DOT 5, DOT 5.1 brake fluids – and the one type suitable for modern motorcycles
Transcript
Hello and welcome to 30-minute motorcycling, a podcast for new, aspiring, and returning riders, we’ll you’ll learn something new about motorcycles and other two-wheelers in 30 minutes or less.
And this week, I’m afraid I have some bad news for you. It doesn’t matter how fast your bike is – sooner or later, you’ll have to stop.
And without brakes, that’s an impossible task.
So, therefore, in this episode, we’re talking about brakes. Specifically,
the differences between disc brakes and drum brakes,
Whether you should put DOT 3, 4, 5, or 5.1 brake fluid in your brake fluid reservoir
And about something that might be in a drum brake that could kill you slowly if you’re not careful.
Before we start, however, I have one little caveat.
For this episode, I’m only going to focus on hydraulic brake systems – i.e. braking systems that use some kind of liquid to transfer the braking power to the brakes.
So in other words, I’m not going to cover mechanical brake systems at all – although I might do a future episode on that.
So with that out of the way, let’s start with disc brakes.
Disc brakes
Back in 1969, Honda introduced the CB750 – the first motorcycle to be equipped with a disc brake as standard.
Since then, disc brakes are common on most modern two-wheelers, especially for the front brake.
The reason for this is because when compared to drum brakes, disc brakes are much better at dealing with heat, and also require less maintenance
A disc brake consists of a caliper, which acts as a housing for the brake pads and the brake pistons.
A rotor, or “disc,” which connects to the wheel hub,
And a pair of brake pads, which press against the rotor when you apply the brakes, which in turn brings the motorcycle to a stop.
Because the brake pads grind against the rotor, they will eventually thin out, and have to be replaced – generally when their thickness is below 3 mm.
If you continue riding with brake pads whose thickness is below that, you might hear a loud screeching sound the next time you apply the brakes.
As you probably realized, this is not a good thing – this screeching sound indicates that the metal inside the brake pad is grinding against the rotor, which can cause the rotor to break.
So that’s a basic overview of disc brakes. Now, let’s move on to drum brakes.
Drum brakes
Drum brakes were common on motorcycles built in the 1950s and 1960s. Some moderns motorcycles, mopeds, and scooters still use them, although usually for the rear wheel.
The reason for this is because disc brakes are very powerful – if you have a rear disc brake and you apply it too hard, you could lock up the rear wheel, lose traction and have a crash known as a “high-side,” where you get thrown off.”
Anyway, a drum brake consists of
A pair of brake shoes
And a wheel cylinder
When the brakes are applied, the brake shoes expand, which brings the bike to a stop.
When the brakes are released, the brake shoes are returned to their original position by a small metal spring called the “return spring.”
The drum brake is a simple mechanism, although it’s more prone to overheating than a disc brake, and need more frequent servicing.
Furthermore, if the drum brake is on an older motorcycle made in the 1970s or before, you might have to contend with asbestos.
Yes – you heard that right – ASBESTOS.
In case you didn’t already know, asbestos is a substance which is toxic to inhale and causes life-long breathing problems and even complete suffocation.
Most reputable brands stopped using asbestos for their brake components in the 1990s, but if
you have an older motorcycle with drum brakes – be VERY careful when you disassemble them.
– wear protective gloves and a face mask or some kind of anti-asphyxiation device to prevent inhaling asbestos spores.
Brake fluid
Regardless of whether you’ve got disc or drum brakes, there’s another thing your brake system needs. Remember what I said at the beginning about how a hydraulic brake system uses liquid to transfer the braking power to the wheels?
That liquid is known as brake fluid.
Now, with such an important task, the brake fluid must have
a high boiling point of at least 230 degrees Celcius or 446 degrees Fahrenheit.
a low viscosity rating, especially if your bike has ABS.
And the ability to withstand high temperatures without affecting the viscosity,
Just for the record, viscosity has to do with how thick a fluid is – the higher the viscosity, the thicker the fluid will be.
Brake fluid comes in four main categories, all marked with DOT; you’ve got the DOT 3, DOT 4, DOT 5, and the DOT 5.1.
The best and easiest choice is DOT 4, since most modern motorcycles are built for this type of brake fluid.
DOT 3 has a low boiling point, and DOT 5 is not suitable for motorcycle use, mainly due to its high viscosity rating.
As for DOT 5.1, it tends to attract more moisture over time and needs to be replaced more often than DOT 4.
If you’re unsure, check the cap on your brake fluid reservoir, it should say what kind of brake fluid you should use.
And as a final note – you should never mix glycol-based brake fluids like DOT 4 with silicone-based brake fluids like DOT 5.
And those are the difference between motorcycle disc and drum brakes, and a basic overview of brake fluid.
If you’d like to learn more about disc and drum brakes, as well as differences between glycol and silicone-based brake fluids, I’ve put a link in the shown notes to an article on The Dual Wheel Journey about this topic.
I hope you enjoyed listening, and above all that you learned something new.
Until next time, keep your helmet on and your eyes on the road. Bye!
