Brake master cylinder overhaul #4

I disassembled the brake master cylinder again I repaired on the other day because the behavior of the piston seemed to be not smooth enough.

When I removed the piston at the last time, I checked the condition of the rubber and it looked good. Therefore, I reassembled it without replacing the rubber.

However, again I disassembled the brake master cylinder’s piston and checked its condition carefully in order to reassure myself.

I disassembled and cleaned the piston and the spring.

The condition of the original rubber was not bad, but I replaced it once with the rubber part of the repair kit.

Again, however, I felt that the quality of the rubber parts of the repair kit (left one) seemed to be poor….

I also assembled the piston into the cylinder as a trial, however, the tight contacting feeling was not enough.

As my conclusion, I judged the condition of the original rubber parts were good enough and decided to reuse them.

So, I reassembled with the original rubber parts again.

When I was reassembling the brake master cylinder, I felt very slight resistance in the movement of the piston.

I checked the inside wall of the cylinder with my finger very carefully and found there was a very small step in the smooth surface.

I honed the inside of the cylinder again and polished with #2000 sand paper to make the surface flat. Then, the movement of the piston became very smooth.

I thought now it should be okay. I would try a test drive with this, if it would be not good, I would replace it with a new part at that time.

(My original blog was written on 25th Jun 2009)

Comments

Tip to repair rubber parts

I disassembled the rear axle before. There had been no progress on it because I started the repair of the fuel tank during my summer holiday. While painting the fuel tank , I repaired the torn rubber boot of the parking brake wire. I guessed it didn ’ t cost high because it was small rubber part. But I wanted to try the repair method I read on the magazine article before. This was the condition before the repair. The rubber was torn apart and separated almost. I used this self-adhesive type butyl tape. I pasted lots of small pieces of the butyl tape on the back side of the rubber boot. As time goes by , these tapes would melt and stick together. After this I applied plenty of adhesive “ Super X Black ” on the rubber boot. On the magazine of MOTO MAINTENANCE , I read the article that the motorcycle seat was repaired with this method. So , I wanted to try it. After drying 1 day , it became like this....

Clutch master cylinder overhaul #3

I was still struggling with the sticking piston of the clutch master cylinder. I thought I should give up and look for the new part for the replacement. And to for my curiosity , I started to destroy and disassemble the clutch master cylinder piston by drilling. When I was drilling the piston halfway , I didn ’ t have any specific idea , however , I thought to tap the piston to make the thread. I started to turn the tap handle , and I felt the feeling that the piston was moved. So , I tried to pull it , and then suddenly the piston was removed from the cylinder. Finally I could extract the rusty piston! I observed the extracted piston. It looked there was no risk of the leakage of the fluid because the hole I made in the piston was not penetrated. Thinking the function that this part only holding the rod connected with the clutch pedal , it could be reused if the hole would be filled by the hard material. However , be...

Clutch master cylinder overhaul #2: tough match

I disassembled the removed clutch master cylinder. And I found that the piston was heavily rusted. I tried to hit it with a hummer , Pushed the piston using the vise clamp like this. However , the piston was heavily sticking by rust and it could not to be moved today. The brake master cylinder was replaced in the past , however , the clutch master cylinder was not. Therefore , the condition of the clutch master cylinder might be worse. Tentatively , I would spray the rust-penetration lubricant from both sides of the piston and try again in a few days. If it doesn ’ t work , I would give up the overhaul and order the new part. ( My original blog was written on 2nd July 2009 )

The day my "onboro ALFA" would revive

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