Is it possible to get any seeping from the piston (plunger at the pedal) if one applies brake pressure beyond anything used while driving? I've been having caliper leaking issues so been pushing the pedal hard to test.

My guess is the MC should be bone dry, but just want to verify.

I have a spare 914Rubber MC with barbed supply lines and watched Ian's video (thanks Ian) and have a few questions for those that have done this.

1) Is it possible to do this with the gas tank installed? It appears yes, but don't want to discover this with brake fluid lines exposed.

2) Has anyone just unmounted the reservoir and left the supply lines attached? or do they have to be detached to get enough freedom to disassemble?

3) If the lines have to be detached, I'd like to replace the cloth braided tubes between the reservoir and plastic tubes. Does anyone have the specification for that tube?

4) In the video all the lines appeared empty. I plan to empty the reservoir with a turkey baster, but is there anyway to empty the plastic lines or just be ready when I disconnect them.

5) I can't push the reset button on the 914Rubber MC I have. It seems solid and not a button. Does there need to be brake pressure before the button can be pushed in?

I did this a couple months ago. So, you can do it with the tank still in. Also, in Ian's video, he also has the steering rack removed (thanks Ian)

But yeah - I disconnected the reservoir with lines still attached. There was barely enough slack to work down there.

And yes, I just had a bowl ready to catch the fluid.

The only other advice I can give is to not over tighten the fittings on the MC with the little o-rings. I did and now there's a small slow leak. 914 rubber was kind enough to send me some new ones free of charge - but for now, I think I can live with a drop of brake fluid seeping out now and then. That's how much i DON'T want to get under there and mess with it again.

Good luck.

mike

I see what you mean about over tightening the top fittings. Just by hand I can see the o-ring push out and not seal.

Has anyone replaced the rubber o-ring with copper gasket?

What is the proper tightness with the rubber o-rings?

@Mikey914

Lube the o-ring so it won't grab and twist. Not much room to tighten the hose clamps and the rear barbed fitting is very close to the metal wall the pedal cluster bolts to. As stated above the existing hose is barely long enough. If my tank weren't full I'd have pulled it for sure.

Thanks. Does one lube with motor oil, brake fluid or perhaps a sealant?

Should the nipples just be hand tight?

Any opinion on replacing the o-rings with copper washers?

I tried a copper washer after my first attempt with the oring failed on one fitting. It leaked too, and I had to bail because of time so am going back under the car this weekend. Don't have a new plan yet and am dreading it.

You could use a dab of brake fluid. Snug would be a good description. Pretend your wrench handle is only 2" long. These aren't pipe fittings and the only pressure upon them is the weight of the fluid; mere ounces.

Could I do any harm if I put a teflon sealant like Loctite 565 on the threads?

Possibly, if any got into the system. But why would you? The O-ring is what provides the seal. The threads aren't tapered so they do not play a part in sealing. You''re going to bench bleed the MC before installation so play with it to see. You can stick a couple of lines on it then fill them to the brim and check for leaks. It's quite simple and after one install you will be an expert like the rest of us.

Thanks members for all the input.

One more question. I've read that bleeding the brake lines with the "buddy" method can damage the master cylinder. Although I understand the basics of how a dual piston MC works, what is exactly being damaged? Does damage only occur if the pedal is pushed to the floor with excessive force?