Disc brakes on older motorcycles often produce a "squeaking" noise from the brake caliper when braking. Normally, there should be no noise, and that is a good thing. However, there are times when the noise is heard or a chattering sensation is transmitted to the brake lever during brake control. In the case of old motorcycles, some parts have already been replaced, so no matter how much maintenance you do, you may not be able to achieve what you want. This may be the will of a Sunday mechanic. Regardless of whether there is noise or not, let's take a look at some "extra" maintenance around calipers that should be done whenever possible.
Small accumulation of brake noise that disappears
Here, I incorporated the Daytona "red pads," the standard brake pads of the 80s. There's a lineup for models from the 80s onward, as well as for models from the 80s. Here, I installed Daytona red pads for Kawasaki 70s brake calipers.The package is for the Z2/Z1, but they can also be used for the W3 and Mach series larger models.
Basically, it is a part that can be installed as it is, but by chamfering the edges of the contact surface of both the pushing pad and receiving pad, I tried to prevent the rotor from dragging or generating burrs at the beginning of use. By chamfering the edges of both the pushing and receiving pads, it is possible to prevent the rotor from dragging and causing burrs in the early stages of use. This is not limited to single piston calipers with round pads, but can be done with square pads as well.
If there is no fluid seepage, external cleaning will be effective.
It is advisable to change the brake fluid at least once every two years. During the rainy season, when the motorcycle has been driven in the rain repeatedly during daily use, the fluid should be changed after the rainy season, regardless of the length of use. When performing caliper maintenance by draining the fluid, remove the piston seal from the caliper and remove any impurities that may have accumulated in the seal grooves. After removing the impurities with a special tool or pickup tool, brush the inside of the grooves with an unnecessary toothbrush, then clean with parts cleaner and blow air.
Check the elasticity of the removed piston seal and replace it with a new seal if there is fluid leakage when disassembling. When installing the piston seal, apply rubber grease to your fingertips and pinch the seal with your fingertips to apply a thin layer of rubber grease.
Smooth operation without piston seal is important.
When the caliper piston is removed from the brake caliper body, remove any dirt from around the periphery of the piston and check for any point rust. Make sure there is no point rust. If there is any rust on the piston, it will cause oil leakage when the rusted part goes over the piston seal. Also, be careful because point rust can cause damage to the piston seal.
Once the pistons and caliper body have been cleaned, try to put the parts together in a "completely dry situation" without applying any grease or fluid to any of the parts. Do the pistons in the caliper cylinders move back and forth smoothly and rotate smoothly? It is important to check this without any piston seals or fluid.
Caliper mating surfaces must be "flush".
Even with single push piston calipers, calipers developed in the early 70's used a two-part body. If there is any debris or burrs in the mating area of the body, the caliper rigidity will be reduced and the braking performance will be greatly affected. In order to increase the rigidity of the assembly, the tightening surface of the caliper body and the caliper bracket should be cleaned with an oil stone to make the tightening surface flat.
If you have any braking discomfort....
If you notice any chattering around the front end when braking, or if you feel any kickback to the brake lever (slight vibration to the lever) when braking, you should suspect a distorted or unevenly worn disc rotor. Rotor distortion can be checked by using a dial gauge while the rotor is installed on the wheel. When reassembling the rotor, mark the tightening area on the wheel hub, remove the rotor, apply oil stone to the tightening surface on the hub side and rotor side, and then clean with parts cleaner. Reassemble the rotor in its original position. If you still feel any discomfort, rotate the rotor 180 degrees to fix it, and check the driving again. Check the brake feeling after the change.
- Point 1・When replacing the brake pads, try to choose the product based on many user reviews, not just the genuine parts.
- Point 2・When assembling the brake pads, chamfer the edge of the contact surface with the rotor. Also, apply a thin layer of pad grease or anti-squeal grease to the piston sliding area on the back of the pad.
- Point 3・Check the condition of the caliper piston seal and apply a thin layer of rubber grease when assembling. On the cylinder side, remove all the impurities from the seal groove.
- Point 4・After degreasing and cleaning the caliper pistons and caliper body, insert the pistons in a dry state and check that they operate smoothly back and forth and rotate.
- Point 4・If you get a small chatter from the front area when braking, or if you feel a kickback to the brake lever, try rotating the tightening points on the rotors.
Comparing the parts that appeared in the early days of hydraulic disc brake systems before the 1970s with the calipers for genuine manufacturer disc brakes that appeared in the 1980s and later, the level of perfection and ease of handling have absolutely improved. Even with very general maintenance, the calipers that were introduced in later years are able to perform as they should. On the other hand, calipers for hydraulic disc brakes, which were introduced in the early 70's, were still in a transitional stage in terms of technology and were not easy to maintain. However, compared to the disc brake calipers of later years, they often require a certain amount of skill and familiarity to maintain, such as the tendency for the pads to drag when pushing and walking, or the tendency for the brakes to squeal.
If the flaring pipe, which is a "metal pipe" that tightens the oil line directly to the brake caliper, is installed incorrectly or the tightening procedure is not followed, the pipe will bend (deform) and become peculiar, and this peculiarity will affect the operation of the caliper itself, preventing floating operation. This can affect the operation of the caliper itself and hinder the floating operation.
Calipers for hydraulic disc brakes made in the 1970s and earlier, while having the same single-push structure, had a separate caliper body on the front and back sides, with a single fastening bolt. The caliper body of the caliper is a separate structure on the front and back, and is integrated with fastening bolts. In addition, there were calipers with a floating guide for the fastening bolt. This structure can be called a technological legacy from the dawn of the hydraulic disc brake system for motorcycles.
With the recent boom in the popularity of old machines, many Honda CB750K series, Kawasaki air-cooled Z series, and 2-stroke models such as the Sampachi and Mach have returned to the road, but some of these machines are suffering from worn parts and poor condition, causing the pads to drag and the brakes to make noise.
What we're practicing maintenance on here is the caliper itself for Kawasaki's first generation hydraulic disc brake system. Specifically, the brake calipers that were standard equipment on the large two-stroke triples from 1971 to 1977. To ensure that the flaring pipe does not affect the floating operation of the caliper body, the pipe must be bent carefully, the guide bushes in the caliper support bracket must be maintained regularly to prevent rattling, and even then, the pad edges must be chamfered when the brake pads are replaced. Even so, when replacing the brake pads, chamfering the pad edge, applying anti-squeal grease on the backside of the pad where the caliper piston touches, and various other precautions have been taken in maintenance practice. Thanks to the maintenance, the braking performance was perfect, however, sometimes dragging occurred, squeal noise came out just before stopping, and so on. It is not only the brake system, but also the fact that maintaining the condition of an old motorcycle requires some getting used to and some tricks. Even so, it is important to keep your motorcycle in good condition as much as possible by following the usual maintenance and procedures.
Effective counter-flow air vent for fluid filling
When maintenance is performed with the brake fluid completely drained and the part is restored, new brake fluid will have to be filled. In such a case, you can fill the syringe with brake fluid and use the air bleeder on the caliper side to "back-fill" the fluid without wasting any fluid. Once the fluid has risen to the reserve tank of the brake master, you can tighten the bleeder and operate the brake lever in small increments to bleed the air around the master, then use the normal air bleeding method to bleed the air from the caliper bleeder. You'll be amazed at how fast it works. Once the air has bled out, turn the steering wheel to the left, hold the motorcycle on the side stand, and leave the plake lever gripped with a tie wrap or loop of tubing overnight. This method is surprisingly effective. This method is called "no-good air venting", which allows small air particles in the brake hose to rise to the reserve tank.
