Brakes
Brakes
It's been a while since I did a 'tech' article, mostly they are not 'tech' though, mostly just how I deal with and react to things that either go wrong or maybe need improving.
Today it's brakes, recently on a trip up to Santa Pod via the M1 my front brakes failed on the ZZR110, this produced a bum gripping moment of epic proportions, as I topped a rise the traffic ahead was all stationary, I squeezed the handlebar lever and it just came straight back to the bar.
Pumping the lever had no effect at all, so I headed for the hard shoulder whilst dabbing the back brake (so as not to lock it up) and slamming down through the gearbox, eventually (seemed like hours…) I came to a stop. Putting the bike on the centre stand I took a quick look, no obvious leaks and all seemed fine, I pulled the lever in and it worked, not well, but with a couple of pumps it was back up again. Proceeding carefully I arrived safely at Santa Pod, pitched my tent and started taking the master cylinder apart, aside from a few specks of dirt in the fluid it looked good to me, I put it back together and forgot about it.
Until a couple of days ago, when it failed again as I came up rather rapidly behind a car in Kennington, I ended up having to go around him on the wrong side of the road.
The pistons in the slave cylinders push against pads that come into contact with the disc creating a massive force of friction; this slows the disc and the vehicle by converting the forward motion into heat energy. Some systems may have up to six pistons per disc (3 each side); mine has two, on Saturday I stripped down the complete front braking system to try and find the problem, it turned out to be a stuck piston in one of the slave cylinders when the cylinder got hot, this was unbalancing everything. Because one piston was not moving the others had to take up the pressure, which meant they had to move further and this caused the pad to twist and get stuck in the caliper, once the caliper cooled it moved again clearing the fault. Both times this happened was on hot days, so the logical conclusion was that temperature was a major factor in when the fault occurred. I cleaned up the pistons in the slave cylinders, which were caked in road dirt, and all seems fine again, everything now moves freely and taking it for a blast in the hot sunshine gave no problems at all.
We can spend a lot of money tuning and servicing our engines, yet we do tend to neglect our brakes, until they fail or have problems, check your pads on a regular basis, one side can wear faster than the other and change the fluid every couple of years, brake fluid is hygroscopic and will absorb moisture from the surrounding air, if moisture gets into the fluid then when you brake the fluid heats boiling any moisture in there, this will lose you your brakes. The tiniest amount of moisture can cause this, if you have a weird problem with fading brakes I'm will to bet its moisture in the fluid.
Pumping the lever had no effect at all, so I headed for the hard shoulder whilst dabbing the back brake (so as not to lock it up) and slamming down through the gearbox, eventually (seemed like hours…) I came to a stop. Putting the bike on the centre stand I took a quick look, no obvious leaks and all seemed fine, I pulled the lever in and it worked, not well, but with a couple of pumps it was back up again. Proceeding carefully I arrived safely at Santa Pod, pitched my tent and started taking the master cylinder apart, aside from a few specks of dirt in the fluid it looked good to me, I put it back together and forgot about it.
Until a couple of days ago, when it failed again as I came up rather rapidly behind a car in Kennington, I ended up having to go around him on the wrong side of the road.
Have you thought about how your brakes actually work?
Motorcycles (or any propelled vehicle) have a lot of kinetic energy once get moving, to retard the vehicle you have to lose that energy, this is done, partly, by using the brakes, what is not commonly realised is that the brakes convert the kinetic energy into heat, this is why your brakes get hot when you brake and the harder you brake the hotter they will get. Braking turns the kinetic force into heat by friction. Now to bring a 400lb motorbike to a stop just using your hand would not be possible without the hydraulic effects of the master cylinder / slave cylinders. When you squeeze the brake lever the effect of squeezing the fluid down a narrow tube increases the power of that action by large multiple of the original effort.The pistons in the slave cylinders push against pads that come into contact with the disc creating a massive force of friction; this slows the disc and the vehicle by converting the forward motion into heat energy. Some systems may have up to six pistons per disc (3 each side); mine has two, on Saturday I stripped down the complete front braking system to try and find the problem, it turned out to be a stuck piston in one of the slave cylinders when the cylinder got hot, this was unbalancing everything. Because one piston was not moving the others had to take up the pressure, which meant they had to move further and this caused the pad to twist and get stuck in the caliper, once the caliper cooled it moved again clearing the fault. Both times this happened was on hot days, so the logical conclusion was that temperature was a major factor in when the fault occurred. I cleaned up the pistons in the slave cylinders, which were caked in road dirt, and all seems fine again, everything now moves freely and taking it for a blast in the hot sunshine gave no problems at all.
We can spend a lot of money tuning and servicing our engines, yet we do tend to neglect our brakes, until they fail or have problems, check your pads on a regular basis, one side can wear faster than the other and change the fluid every couple of years, brake fluid is hygroscopic and will absorb moisture from the surrounding air, if moisture gets into the fluid then when you brake the fluid heats boiling any moisture in there, this will lose you your brakes. The tiniest amount of moisture can cause this, if you have a weird problem with fading brakes I'm will to bet its moisture in the fluid.
Your brakes are an integral and important part of your bike, look after them.
Jake
