A few months ago in Nairobi, I was at the Uhuru Highway-Haile Selasie Avenue roundabout waiting for the green light before proceeding onto Mombasa road. Being on a motorbike, I was at the head of traffic, giving knowing looks to the other motorbike riders alongside me hoping that one of them would be interested in a race once the light turned green.
Being a competitive but unfair soul, I set off just as the light turned orange and something totally unexpected happened just as I was halfway out of the roundabout: a policeman launched himself onto the road, right on my path as he inexplicably tried to stop the traffic coming from my side of the road. I braked hard and the next thing I knew, I had hit the tarmac, knee first, bike falling to one side and me right on the path of the other bikes I had left behind as I took off.
This was terrible and very undignified.The policeman did not even give me a second look, he kept on doing his thing. I could see matatu drivers having their sides split with laughter and some woman in a Mazda Demio quickly rolled up her window. A pair of sweating handcart guys came to offer me some advice but I could not understand anything they were saying.
When I had collected myself and at home licking my wounds, I got to thinking: Ordinarily such hard braking would never have resulted in the front wheel suddenly locking causing the bike to skid. What could have happened? Well ladies and gentlemen, I give you brake fluid.
About a week before the embarrassing incident, I had been riding as usual and under very routine braking the front wheel had seized momentarily. Everything returned to normal and I didn’t give it much attention, I thought it was my fingers that had grabbed the brake handles a little over zealously and so I forgot all about it. But that was a sign that my brake fluid had lost its effectiveness because it could not apply a consistent force to the brake pads. Another sign, now that I can think about it, was that I needed to pull hard on the brake handle for the bike to stop. If it were a car, the brake pedal would feel “spongy” and it that would require the pedal to be pushed little harder to stop the car.
So to save you from driving into the back of a lorry, I shall give you a few facts about brake fluid. Change your brake fluid after one year, but don’t exceed two years if you are late. It does not matter that you own a Ferrari F50 and you only drive it on Christmas Eve, brake fluid is hygroscopic and this means that over time, it will absorb moisture, which will lower its boiling temperature (yes I said boiling) thus reducing its effectiveness. I fear that I will bore you with words like hygroscopic, poly-glycol and silicone but bear with me as this will help you choose the type of brake fluid to buy when it is time to change.
Yes, it boils
It will be clearly indicated on your car’s brake fluid reservoir cap that you should use Dot3, Dot4, Super Dot4 or Dot5.1. All these Dots are poly-glycol based, the only difference between them being the temperatures at which they boil. The general rule here is this, the faster your car goes, the higher the Dot it requires. Very fast road cars and racing cars would use Dot 5.1. Ordinary cars and bikes will do well with Dot4. Super Dot4 has the advantage of boiling a little later than Dot4, but they are essentially the same thing. If your car or bike demands nothing but Dot3, I suggest you sell that old bucket of rust! Dot3 is an older standard but still in use and in some cases interchangeable with Dot4. I will not bother you with the details of the rarely used silicone based fluid called Dot5. Just know that it is quite different from all the other Dots and you should never use it when not specified.
You need to know what you are doing!
Do not attempt to change the brake fluid on your own if you have no idea what you are doing, or if you don’t have patience. If I could borrow Jesus’ words, it is easier for a camel to pass through the eye of a needle than for brake fluid to be correctly replaced in a brake system. What you must do after draining the very corrosive and poisonous fluid, is to fill the reservoir with the new fluid and do something that sounds a bit gory – bleeding. Bleeding is the expulsion of air bubbles from the entire brake system. The bad news is that there are millions of air bubbles and that makes bleeding one of the most arduous jobs in car maintenance if you do not have tools such as vacuum pumps to make the work easier.
Besides brake fluid there could be other wrong things with your braking system such as worn out brake pads, leaking master and slave cylinders, punctured brake lines, broken seals or damaged brake callipers. The thing I must emphasize is that you should treat matters to do with brakes with extreme caution.
All diagnosis, maintenance or repair of any component in the brake system must be handled with utmost caution and preferably by someone that actually knows what they are doing.
This article first appeared on www.onemanspanner.com.
The author, Bill Mike, is a motorcycle and classic car enthusiast. He often writes about his riding and amateur mechanic escapades, interlacing it with events from his seemingly unfortunate life.