Brake Hose & Fluid Replacement
Keeping with the theme of braking systems, this month I will explain how to upgrade your brake hoses and then replace/bleed the hydraulic system.
Standard brake hoses on most bikes are adequate enough for the job (they make you slow and stop). However, you can vastly improve your machine’s braking efficiency by replacing the rubber factory hoses for metal braided lines. Goodrich and Hel are leading manufactures for braided hose systems for bikes. The kits are well constructed, comprehensive and include all the lines, washers and Banjo fixings you need to completely overhaul your machine.
Standard brake hoses are constructed from reinforced rubber. This is adequate if you own a brand new machine. However if you are like me and cannot afford £9000 on a new Kawasaki ZZR1400, then a brake hose overhaul is the best way to modify your bike and at the same time improve your stopping power.
Standard brake hoses derteriate with age/use and become supple and weak. Although you won’t be able to see it with the naked eye; old hoses expand (balloon) in weak areas when you press the rear brake pedal or pull the front lever. This defect vastly reduces your braking power because fluid pressure is lost in these inflated areas rather than being directed efficiently to the brake pistons and pads.
Braided hoses are constructed from thin rubber pipes with woven metal wire (braid) and then covered with a thin coating of plastic. The metal braid reinforces the brake hose and does not allow the pipe to expand under extreme braking.
Replacing the brake lines is very easy:
After purchasing the chosen kit for your particular make and model, it is then a case of identifying the correct length of hose for the line you are replacing.
A word of caution: Always start by choosing a hose that is lowest to the ground. I mention this because after cracking open one of the joints to the chosen line, you can then place the hose end into a container and drain the whole hydraulic system. If you don’t do this, you then run the risk of splashing the corrosive fluid all over your paintwork each time you start on the next hose. When changing brake fluid, remember to have clean water close to hand because water neutralises brake fluid.
Fill the front and rear brake master cylinders with new DOT4 brake fluid and move onto the brake bleeding process.
The tried and trusted way to bleed brakes is to use the conventional press and lock method.
If using the press and lock method, purchase a brake bleed kit from any good motorist shop and place the rubber end of the see-through pipe onto the bleed nipple of the left calliper (furthest calliper way from the front master cylinder). Also make sure the bleed bottle is filled slightly with new brake fluid.
Using a ring spanner (normally 8 or 10mm) crack open the bleed nipple slightly and pull the brake lever slowly until it stops. It might be worth getting a friend to work the brake lever whilst you concentrate on the bleed nipple and bottle. When the lever is operated, you should see fluid and air bubbles travel from the brake calliper and into the bleed bottle.
At the end of each pull on the lever stop with the lever all the way in and then re-tighten the bleed nipple. This will prevent air being sucked into the system again when the lever is released.
When the nipple has been locked off, release the lever.
Whilst putting slight pressure on the brake lever, slacken the bleed nipple again and repeat the above process.
After three pulls on the brake lever, check the master cylinder for brake fluid because it will to be topped up, if you don’t top-up, you run the risk of sucking air into the system again via the empty master cylinder.
Keep on with the bleed process until you see no further air bubbles in the transparent plastic piping.
Once the left calliper has been bled, move over to the right calliper and repeat the whole process.
After you think you have removed all air from the front brakes, ensure both bleed nipples are tight then check the pressure on the lever. The pressure should feel solid with no creeping feeling.
Now the front part of the system is done, repeat the whole process on the rear calliper however instead of operating the front brake lever, use the rear foot brake. The master cylinder for the rear calliper should be located just above the foot brake under the seat cowling.
Once completed correctly you should have a braking system that is sharper than my wife’s tongue and tighter than my Inspector at the mention of the word “overtime”.