Brake Caliper Reservoir

[jjacob12345]

I'm doing some brake work on my 75 vette. My master cylinder has 2 reservoirs’ of which only one has fluid. I was told that the 2nd reservoir is supposed to stay empty. In my Chilton's manual they said the front reservoir is for the front brakes and the rear reservoir is for the rear brake. I'm confused now. Are both of the reservoirs supposed to have brake fluid in it?? I was trying my best to bleed the brake system this weekend, however I could not get any fluid to come out of the rear calipers. I am beginning to think that both reservoirs should have fluid. Can anyone confirm this? I plan to be back in the garage next weekend.

[Hib Halverson]

Originally Posted by jjacob12345

I'm doing some brake work on my 75 vette. My master cylinder has 2 reservoirs’ of which only one has fluid. I was told that the 2nd reservoir is supposed to stay empty. In my Chilton's manual they said the front reservoir is for the front brakes and the rear reservoir is for the rear brake. I'm confused now. Are both of the reservoirs supposed to have brake fluid in it?? I was trying my best to bleed the brake system this weekend, however I could not get any fluid to come out of the rear calipers. I am beginning to think that both reservoirs should have fluid. Can anyone confirm this? I plan to be back in the garage next weekend.

You've been told dangerously wrong. Both reservoirs should be full. Whomever is telling you one reservoir stays empty may be trying to kill you.


Seriously, if you have one half the master cylinder empty, there is a serious brake leak somewhere, probably at the brake calipers which, on a C3, are prone to leakage caused by corrosion of the caliper piston bores.

To safely perform brake service you need good mechanical skills and accurate service data. I suggest the factory service manual for instructions on how to service your brakes.

[brusso]

On cars that have a combination of front disc and rear drum brakes, one reserviour level may be lower than the other. This is because, as the disc brake pads wear, the caliper pistons move out to make up for pad wear. The pistons do not completely retract. Unlike drum brakes, that have springs pulling the shoes/pistons fully in. That is why drum brakes periodically need to be adjusted, to make up for shoe wear. Never, in any case, should there be an empty reserviour.

[Culprit]

Howdy jjacob12345,

Welcome to CAC!

Yes, the front reservoir contains the brake fluid for the front brakes, and the rear reservoir for the rear brakes. It's designed like this so that if one caliper blows a seal then you don't lose all braking capability. If the rear is empty then you've been driving around on the front brakes only. Check your rear calipers like Hib says - that's where you're likely to find the leak.

The fluid level in both reservoirs should be approx 1/4 inch below the top of the sides.

You're most likely going to end up rebuilding or replacing a caliper. Whatever you do, do it to both rear calipers to keep them the same - even if you only think one is the culprit. And spend a few extra bucks to replace the rubber brake hoses back there as well. They can look great on the outside, but be clogged up like a sink drain on the inside.

Semper Fidelis,
Culprit

[SteveG75]

If the reservoir is empty, you will need to bleed the master cylinder (bench bleed) before you bleed the calipers.

[Vette/Berlina-coupe]

-actually, if he prefers, he can empty the front/rear-systems of brake-oil entirely; --only thing is, he will just need to find a master-cyl. with a 4-ft. stroke to allow for a rather spongy feel facilitated by the fluid medium known as Air!!! --Hope this explaination is helpful in showing why oil is preferred over air in your Brake-reservoir.... ~Bob vH