Tried many searches, asked a couple people... getting ready refill my brake system. The larger section of the two in the brake fluid reservoir is currently connected to the rear brakes. I hooked my hoses up like the pic below (items 11 & 12) when I put on my new master cylinder. Is the reservoir larger because the volume of the rear brake system holds more fluid? Or am I backwards? Or does it not matter?

BTW - I know they are connected this way because I just sent my rear calipers out to Eric Shea for refurb and rear lines were left disconnected = brake fluid on the floor when I forgot to cover the reservoir with plastic to prevent the fluid from leaking out (no mysterious leaks / problems on the front brakes).

Click to view attachment

assemble it just like that picture and you will be fine.
BTW - the only _real_ way to keep fluid from draining is to keep the pedal depressed, and even then you'll probably drain the lines and the proportioning valve - but at least it won't drain the reservoir and MC...

Strangely enough, the pedal was (and still is) depressed using a couple pieces of wood between the seat rail and pedal. I read on another thread that the vented cap will still allow a leak unless the plastic wrap is placed under it.

And, I like that assembling like the picture = OK, but still am curious why one part of the reservoir is bigger than the other.

Bump...

Common guys - someone has to know this one.

I don't know but i tend to agree with you that it's probably because of the overall larger volume of fluid needed to get to the rear brakes.

I think the big reservoir feeds the front brakes. And further, this is because since the front brakes have bigger pistons, and do most of the braking and thus wear more, they have a bigger reservoir requirement.

The picture shows the big reservoir feeding the front chamber of the MC.

The front chamber of the tandem MC feeds the front brakes. (That's not shown on this picture, tho) But it's that way so that if the back brakes fail, you're still left with fronts. The rear piston compresses the front.

BTW - if your reservoir drained with the pedal depressed, I'd be concerned about the integrity of that system's piston seals...

The large chamber is on the "back" of the reservoir, connects to hose 12, which is connected to the back chamber of the MC?

I was just going from the picture - in which it appears that the 'Hose 11' side of the reservoir is bigger.

I'll have to go look at an actual reservoir tonight.

You are saying that the big end of the reservoir contains the small chamber ?

Interesting...

I had a rear caliper explode on me once under hard braking and the brake pedal instantly went to the floor with *no* braking going to either circuit at all. Immediate loss of all braking ...

Just looked at mine, the front section seems smaller when you look at it from above thru the cap. Maybe it's one of those "which line is longer" games
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by Porsche engineers (meaning they are the same volume - and we're back to the it doesn't matter answer)

OK in this case, the drawing is the way it is suppose to be. . . the front of the reservoir is for the front brakes. . . that lower plastic line goes through the body hole that is towards the passenger side, and curves back to the front of the master cylinder. . . so the rear of the reservoir , for the rear brakes, and it's lower plastic hose goes through the hole on the drivers side and curves to the rear port on the master cylinder. .

Virtually all cars will have larger brakes on the front, thats where all your stopping power comes from. With this in mind, the larger portion of the reservoir typically goes to the front brakes. Now on a 914 with a remote resevoir, you have so much brake fluid stored in the feed lines, you would be hard pressed to run into a problem with low brake fluid and getting air in the system. I would still hook the larger side to the fronts no matter what the picture shows. Mike