Overhaul to Find Out the Cause of the Dragging Noise from the Brakes

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The master cylinder body was increased in size by installing a W-disc kit. In addition, the brake lines were replaced, and the lever touch changed to suit my preference. However, after a while, I started to notice a dragging noise from the brakes. The only solution was to disassemble the caliper to find out what was causing the noise, but then I remembered that some genuine Kawasaki brake pads had a "shim plate" caulked to prevent squeal.

The chattering sound when you grip the lever is bothersome.

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After the engine overhaul, the Kawasaki air-cooled Z no longer emitted white smoke from the exhaust system, and the motorcycle was riding very smoothly and strongly. Although we had greased the pads and guides thoroughly, we couldn't help but notice the noise. So I decided to install the brake pad shims for Z1/Z2 that were available at Doremi Collection. It is true that in the early days of disc brakes, many Kawasaki models had shims riveted to the back of the brake pads.

Check the installation position of the pad shim

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When installing the pad shims, make sure that the leading side of the pad is on the "missing" side of the shim. The leading side of the pad tends to hit the pad harder, so the purpose of the shim is to release that. After setting the position of the shim, mark the fixed position with a marker pen. Since the direction of the pads is different between the left and right calipers, the direction of the shims is also different between the left and right calipers.

Screw rivets to secure shims

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I remember the stock Kawasaki pads from the 70's that came with these shims as standard equipment, and there were several different ways to secure the shims. In this case, we decided to use brass screw rivets to secure the shims. Screw rivets can be found in the bolt and hardware section of any home improvement store.

Hole processing on the base plate of the pad

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The thickness dimension of the pad base plate was carefully checked and its depth was marked on the drill blade. I clamped the pad in a vise and drilled the holes with an electric drill. I used a drill that was 0.2mm thicker than the outer diameter of the screw rivet tip. If the thickness of the drill is the same, it will not be able to fix the rivet firmly.

Securely hammered in place with a pin punch

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After finishing the drilling process, set the shim on the back of the pad while fixing it with screw rivets. The rivets are thinner than the fixing holes for the shims, so I hit them in with a pin punch, being careful not to displace the shims. In the days when these pad shims were installed as standard, there were "left and right" stock brake pads, and they were not common parts. I hope these shims will reduce the uneven wear of the pads and eliminate the noise, but I also want to remember that the cause of the noise may be elsewhere, unrelated to the pads.

 
POINT
  • Point 1・The presence of pad shim may not be the cause of brake squeal, so it is essential to maintain the basics first.
  • Point 2・ Since it is maintenance and processing of important safety parts, practice DIY work at your own risk. If you are a beginner in maintenance, please consult an experienced person.

 

When you are driving, the traffic light ahead turns red and you start braking. Whether it is disc brake or drum brake, you may hear a "squeak" brake sound during such braking. Most of the brake squeal is caused by so-called "chattering", which often resonates and can be heard. In the case of brake caliper, when the brake piston pushes the brake pad, there is a small gap between the piston surface and the back of the pad (due to uneven wear of pad), which is often heard as chattering and resonance sound.

In such a case, pad grease is used. The viscosity of the grease fills the gap between the back of the pad and the piston surface and prevents the sound from ringing. In some models, a backup plate is installed on the back of the pad to prevent heat conduction and resonance. There must be some Sunday mechanics who didn't notice the existence of the plate when they replaced the pad, removed the old pad, and installed the new pad (it was still attached to the back of the pad), but after the work was completed, they noticed the existence of the plate and removed the pad again and re-installed the plate. I'm sure there are some Sunday mechanics who have experienced this.

On the other hand, what about drum brakes? In most cases, applying pad grease or heat-resistant grease (silicon-based grease) will eliminate the resonant sound. The points to apply grease are the brake cam bearings, the area where the brake cam lifts, and the area where the two brake shoes are pressed together and set. Whether it is single or double leading, it is effective to apply a thin layer of pad grease to the shaft and cam surface that receives the brake shoes. Of course, when disassembling the brake parts, the first thing to do is to clean them and blow them dry before applying the pad grease.

The pad shim installed here is a part that reduces uneven pad wear by preventing the brake piston from pressing on the chipped area = less pressure on the pad. In any case, it is important to apply pad grease to the back of the pad where the brake piston meets. Too little or too much pad grease will not have the desired effect, so it is best not to apply too much.

See Accessories of DOREMI COLLECTON
See KAWASAKI Moto Index Page
See Accessories for KAWASAKI Z1 (900 Super Four)
See Accessories for KAWASAKI Z2 (750RS, Z750 Four)

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