Get better brakes:
It’s the lifeblood of your braking system so keep it fresh for the best stopping power
Change your fluid
1 Be warned… brake fluid is evil
Brake fluid makes a suprisingly efficient paintstripper so cover bodywork and have a stash of paper towels handy. Defend the area around the tank and handlebars against any possible spillage. Changing the fluid makes sense because it degrares over time, reducing braking performance. Check in a workshop manual for the intervals for changing, and the exact type of fluid your bike needs: Dot 4 , Dot 5 etc.
2 Gloves on, lid off (but carefully)
Wear protective workshop gloves from now on. Remove the reservoir lid, sometimes they are retained with a screw and locating bracket so make sure this is undone. When removing the lid do it slowly making sure the diaphragm isn’t going to drop off. Sometimes it will remain in the reservoir, if this is the case gently ease it off and have that paper towel to hand to catch any drips.
3 The need to bleed
Identify the size of the spanner needed to fit the bleed nipple. Remove the rubber grommet protecting the nipple. Ideally use a ring spanner and place it on the nipple so it can be loosened a few degrees without hitting anything. Now fit the pipe from the bleed kit to the exposed nipple. If the pipe won’t reach the floor, hang the bottle from an indicator.
4 Get cracking
Crack the bleed nipple and apply positive pressure to the brake lever as if braking gently. Tighten the nipple and let go of the lever, then repeat. When you see a clear stream of fluid with no bubbles in the tube, you can just pump the fluid out without stopping to tighten the nipple every time. Watch the reservoir – don’t let the level drop out of sight.
5 Pour in fresh fluid
You will notice that each time you pump the lever there will be a visible reduction in the level, so keep it topped up. Sometimes the process can be sped up by having your brake lever span adjusted out to its maximum. Don’t be tempted to move the lever itself too quickly or else it could pop the bleed pipe off and spit fluid everywhere.
6 Repeat on the other side
When you see a change in colour in the fluid through the transparent pipe tighten the nipple up, check the fluid level is OK and release the lever. With a couple of sheets of paper towel scrunched up, remove the bleed pipe and catch and mop up any stray fluid. Most bikes have twin discs on the front, so the opposite caliper will need the same technique.
7 Top up and check
With both calipers flushed with new brake fluid, pull the lever in for a final time, hold, crack the nipple and observe that there are no bubbles or air in the tube, then re-tighten. Do this for both calipers. Top up the reservoir to the correct level. Refit the cap with the diaphragm, making sure it is seated correctly. Finally, make a visual check of both calipers, and give a wipe around with paper towel for any unseen spillages.
8 Turn to the rear
The same technique can be applied to the rear brake. Quite often you will need to remove a side panel to gain access to the reservoir. Again use the bleed kit, and pump out the old fluid while adding fresh. Note that many rear calipers are fitted with two bleed nipples, if this is the case make sure you flush them both out one at a time. And of course make sure they are both used to bleed out any air.
No sniggering as Bruce tweaks the nippleé
O Brake fluid bleeding kit from you local autofactor O Correct grade of brake fluid (always use a freshly opened bottle)
Spanner for bleed nipple TOOLS