Master cylinder kit

[Kharville]

Has anyone ordered the Newstar MC rebuild kit and found blemishes on the piston? I just opened mine and found the anomalies send in the photos below. my bore of the cylinder seems very smooth so I was going to skip honing it and just replace the spring parts and rubber. This piston looks like it would do more damage than good if I use it like this.

 

[texas30cal]

Looks like it's just a tiny ding, knock it off with a small file, the piston is softer than the cast iron master cylinder it won't scar it and really shouldn't touch the bore anyway.

 

[rustystud]

Has anyone ordered the Newstar MC rebuild kit and found blemishes on the piston? I just opened mine and found the anomalies send in the photos below. my bore of the cylinder seems very smooth so I was going to skip honing it and just replace the spring parts and rubber. This piston looks like it would do more damage than good if I use it like this.View attachment 704360View attachment 704359View attachment 704357View attachment 704358View attachment 704361

I wouldn't skip honing it. Just give it a little bit. You never know what is lurking inside that bore.

 

[texas30cal]

Right, those quad rings won't tolerate imperfections like the original seal did. Rusty is there any source for the original cup type seals?

 

[Kharville]

ok. Thanks for the advice. I'll hit it with the hone a little and then take an emery or file and get those burrs off the piston. I only decided to put the kit in since I had the MC off trying to fix some seepage and connections to the remote reservoir. There was some fluid in the rubber boot so I decided to put the kit in since I had it.

 

[Kharville]

I wouldn't skip honing it. Just give it a little bit. You never know what is lurking inside that bore.

Rustystud, what do you recommend for lubricant in the bore while honing? Engine oil? Or something else?

 

[rustystud]

Rustystud, what do you recommend for lubricant in the bore while honing? Engine oil? Or something else?

This is a good oil. Though any honing oil will do. Most all Automotive Stores will carry a good honing oil.

 

[Kharville]

View attachment 704508 This is a good oil. Though any honing oil will do. Most all Automotive Stores will carry a good honing oil.

I ended up stopping at another store and looking at the packaging the brake hones come in and the instructions stated to use brake fluid as the "honing oil". I used that. Of course the guys in parts stores these days know very little. I asked where the brake "hones" were and he said he only knew what brake "hoses" were not "hones".

 

[rustystud]

I ended up stopping at another store and looking at the packaging the brake hones come in and the instructions stated to use brake fluid as the "honing oil". I used that. Of course the guys in parts stores these days know very little. I asked where the brake "hones" were and he said he only knew what brake "hoses" were not "hones".

If you use "brake fluid" then be sure to clean off the part and the hone every time you stop honing, and add some clean brake fluid. Honing oil will hold the particles in "suspension" while brake fluid will not.