A flat surface can be reproduced by grinding and reproducing an uneven disc rotor.!!

How to

When you're tinkering with your bike, you might think, "Oh, it's already expired (time to replace it).!?I wish I'd known about it sooner so I wouldn't have lost it.!!In many cases, you will notice things like "I'm not sure what I'm doing. By paying attention to such trivial things, you can make your motorcycle tinkering life more enjoyable and fulfilling. If you are a Sunday mechanic, you want to lead such a motorcycle life. In order to reduce unnecessary expenses, regular parts inspections are a must. "Hey!!?The condition of your bike can be improved by simply asking questions such as, "What's wrong with my disc brake rotor? Let's take a look at the condition of the disc brake rotor.

Rigid rotors can be polished and regenerated.

In the early days of disc rotors, the most common type of disc rotor was the "rigid rotor", which consisted of a stainless steel outer rotor riveted to an aluminum inner rotor. These disc rotors were not prone to wear and tear, but in many cases they had deep bumps due to excessive use of brake pads. A feature of rigid rotors is that they can be polished and refinished, and the touch on the lever and the braking performance will be completely different after polishing.

There's a reason it's "rain or shine.

The front side was at the "I'd like to polish it soon" level, while the back side was in a "complete tacky situation". Some areas were burned and completely zapped. Since the rotor is sandwiched between two brake pads, it is important to check the front side of the rotor as well as the back side. When driving in the rain, rainwater mixed with gravel can bite into the rotors and cause unnecessary wear. A bike that has not been used in the rain can also be judged by the condition of its disc rotors.

Surface grinding or lathe grinding to restore quality!!

Chuck it on the outer rotor side to eliminate rotor collapse at the fastening flange surface with the wheel hub. Using a dial gauge, once set up, the runout should be 1/I was able to keep it within 100mm. We started by cutting the back side of the rotor. The cutting was 0.Feed amount of 05mm. The discolored area where the pad was reduced and pressed against the steel plate base was clearly visible. The part where the steel plate base was pressed and burned into the rotor was very hard and squeaky.

Accuracy improvement = Machining without runout is the most basic of all.

A large lathe is set to chuck a claw called a raw jaw, and the raw jaw is machined to match the shape of the outer rotor to be clamped. It is better to clamp the outer rotor than to hold it by the inner clamping part. The burn line disappears and the disc rotor looks like a new one.!!Rotor polishing is frequently performed on four-wheeled vehicles, but now there are machines that can polish disc rotors without removing them from the vehicle body.

The rotor is turned over face down, and the dial gauge is used to eliminate collapse before chucking firmly. The surface is finished beautifully by cutting in the same way. The surface, which had few steps, was 0.The flat surface was achieved by cutting 15mm.

Literally, if it's a flat disc, you can use a flat grinder.

The disc rotors introduced in the 80's were completely flat for reasons of weight reduction and productivity, and many of the large models of the 80's were of this type. Flat disc rotors can be beautifully finished with a surface grinder.

The surface grinder has an electromagnet bed, and if the rotor is made of iron or stainless steel alloy, it can be magnetically attracted and polished. Inoue Boring's surface grinding is done with a grindstone and finished in 1000 minutes. Gradual polishing makes the unevenness of the rotor obvious. The part where the line remains is a deep wear groove. When it is completely removed, the minimum thickness is reduced to 0.It was a situation that exceeded about 2mm, but this time I had the wear thread removed by polishing.


  • Point 1: Floating, non-disassembled outer rotors cannot be reground, but rigid rotors can be reground.
  • Point 2. Even if you replace the disc rotor with new pads with uneven wear, the pads do not have enough bite and the brakes do not work well.
  • Point 3・ When you have practiced rotor polishing, you should replace the brake pads with new ones to experience the original braking performance.

One of the good traditions of Japan, where we live, is the "mottainai" spirit. If a pencil breaks, it can be sharpened and reused, but this is not the case with a mechanical pencil. For example, if a pencil is dropped from a desk and the pipe at the tip is bent, all is not well. Naturally, you can buy a new pen at ......, which is the norm.

Let's take good care of our parts.!!If we follow the spirit of the "Mere Old Man", it is not too late to dispose of them after sucking them to the bone. If it can be reused, I would like to think about repairing it before replacing it with a new one. By chance, I found a disc rotor in the trash at the garage of a motorcycle friend. When I took it out and stared at it, I found that the surface of the rotor was covered with many uneven lines, like a so-called "record disc". Looking at the back side of the rotor, we found that some parts were deeply burnt. This could be due to the fact that the brake pads were worn out and the rotors were pressed against the steel plate. I told the owner of the garage, "I think you can still use them.?When I asked him, he replied, "It's worn and burned so much that it looks like it will exceed the minimum thickness when I grind it. If there is any distortion, I can give up without crying, but even if it looks badly worn, I can't tell until I actually grind it. In fact, I thought the rotor was "still manageable?The conditions were like this.

Even if polishing and regeneration is possible, it is dangerous to make the rotor too thin. However, even if the rotors are thinner than the minimum thickness, they are not physically useless if you keep track of the brake pads and change them before they are completely worn out.

When the brake pads are running low, the braking performance and lever touch become less than ideal, so it is only natural for motorists to replace them as soon as possible. As a side note, when driving in the rain, the rotor surface tends to wear like a vinyl record because of the gravel that gets caught in the gravel. This is one of the reasons why "unused in the rain" vehicles are so popular.

Brakes are an important safety component, so it is essential to make a careful decision. If you combine the polished rotors with new pads, you will notice a clear difference in the way the pads work and feel compared to before.

cooperation in photography:iB Inoue Boring

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