Vacuum Master Cylinder

[gnonyx]

I finally switched over from powermaster to vacuum brake system, both brake line fittings are the same, so would it make a difference if the rear brake lines is attached to the front master cylinder, or should the rear brake lines be connected to the master cylinder fitting closest to the firewall?

[Steve Wood]

the front disc brake calipers require more fluid for operation than do the rear drum brakes.  this means the larger m/c reservoir is meant to be connected to the front brakes.


On our cars, it appears that the front bowl is for the rears and the rear bowl is the rears...as noted further down this page.  It's hard to tell on our cars' reservoir which is the largest....sor ry for the confusion created by my initial post.

[gnonyx]

the front disc brake calipers require more fluid for operation than do the rear drum brakes.  this means the larger m/c reservoir is meant to be connected to the front brakes.

Thanks for the info Steve

[john robertson]

I finally switched over from powermaster to vacuum brake system, both brake line fittings are the same, so would it make a difference if the rear brake lines is attached to the front master cylinder, or should the rear brake lines be connected to the master cylinder fitting closest to the firewall?

If I recall, they can only go on one way. The hex is the same, 9/16", but one fitting is larger than the other.

[gnonyx]

I finally switched over from powermaster to vacuum brake system, both brake line fittings are the same, so would it make a difference if the rear brake lines is attached to the front master cylinder, or should the rear brake lines be connected to the master cylinder fitting closest to the firewall?

If I recall, they can only go on one way. The hex is the same, 9/16", but one fitting is larger than the other.

You may be right, but both brake lines fit right into the vacuum master cylinder
When I was gravity bleeding the passenger rear wheel the front/larger master bowl was running low. This means my master cylinder brake lines are backward. My photo shows the brake fittings are backward. This weekend I have to replace the passenger rear drum brake wheel cylinder. I'm also going to replace all of the brake bleeders with Russell Speed Bleeder.

[john robertson]

I finally switched over from powermaster to vacuum brake system, both brake line fittings are the same, so would it make a difference if the rear brake lines is attached to the front master cylinder, or should the rear brake lines be connected to the master cylinder fitting closest to the firewall?

 


If I recall, they can only go on one way. The hex is the same, 9/16", but one fitting is larger than the other.

You may be right, but both brake lines fit right into the vacuum master cylinder
When I was gravity bleeding the passenger rear wheel the front/larger master bowl was running low. This means my master cylinder brake lines are backward. My photo shows the brake fittings are backward. This weekend I have to replace the passenger rear drum brake wheel cylinder. I'm also going to replace all of the brake bleeders with Russell Speed Bleeder.

The picture you submitted shows that the front fitting is larger than the rear fitting as they are on all G-body master cylinders. You can't reverse them.

[gnonyx]

the front disc brake calipers require more fluid for operation than do the rear drum brakes.  this means the larger m/c reservoir is meant to be connected to the front brakes.

Hi Steve,
Today I tried to reverse the MC brake line but those lines are not reversible.
I believe I would have to get a shorty brake line with a coupling in order to make it right
What are your thoughts

[Steve Wood]

I have done several and everything fit with no mods. Let me go out to the shop and actually look at a car

[Steve Wood]

the fitting with the larger tube (also has the pigtail closest to to the master cylinder) goes to the front.  I forgot these units are hard to tell which reservoir is largest.  Been working on mopars too much, I guess


this is probably what Phil has been trying to tell us LOL

[nocooler]

I seem to remember there was difference in the master cylinders between G/B bodys. I think the B body master fits but the line sizes are reversed in sizes. I bought adapter fittings to correct it.
Ignore this post.

[gnonyx]

I seem to remember there was difference in the master cylinders between G/B bodys. I think the B body master fits but the line sizes are reversed in sizes. I bought adapter fittings to correct it.

When you claimed you bought an adapter fittings to correct it, what do you mean?
Is it because the front bowl of the MC is for the front, and the rear bowl of the MC closer to the firewall is the rear brakes?
Right now when removed the powermaster the brake lines are connected as photo, but when I started to bleed the rear the front bowl of the MC started to go down. Is this where the adapter fittings comes in to play?

[nocooler]

If you have it like Steve’s it’s right. 

[Steve Wood]

I must have been thinking of the older style mc.

[john robertson]

I seem to remember there was difference in the master cylinders between G/B bodys. I think the B body master fits but the line sizes are reversed in sizes. I bought adapter fittings to correct it.

I use B-body master cylinders on all my cars because I upgraded all of them to LS1 brakes. Fitting align the same as with the stock MC.     I didn't use any type of adapter.

[john robertson]

The picture you submitted shows that the front fitting is larger than the rear fitting as they are on all G-body master cylinders. You can't reverse them.
THIS IS CORRECT!