Dumb master cylinder question.

[moparmat2000]

I am almost 100% sure i am right on this, however with a 2 bolt master cylinder, is the rear chamber for the front brakes? I know it is on the cast iron disc brake masters, but then again its easier to see inside the reservoir on one of them.

Thanks
Matt

 

[Dana67Dart]

Typically I have seen the reservoir closest to the firewall is for the front brakes regardless if disk or drum.

 

[67Dart273]

Yup

 

[AJ/FormS]

Hyup, except Willwood seems to buck the trend

 

[Garrett Ellison]

Yep, large chamber to front braes and small to rear.

 

[moparmat2000]

Yep, large chamber to front braes and small to rear.

Yes i know large chamber to front brakes, however you cannot see very well inside of a 2 bolt master. Reservoir is black plastic with 2 small round caps. Wanted to be 100% sure before i go and plumb any lines. I kinda figured it was probably this way because of manufacturing, just wanted to be sure.

Thanks everybody

 

[Garrett Ellison]

Yes i know large chamber to front brakes, however you cannot see very well inside of a 2 bolt master. Reservoir is black plastic with 2 small round caps. Wanted to be 100% sure before i go and plumb any lines. I kinda figured it was probably this way because of manufacturing, just wanted to be sure.

Thanks everybody

Okay thank you for the heads up on the sight issue, I have been planning on the MP cylinder myself when I do a set Wilwoods on the front.

 

[moparmat2000]

Look into a Dodge Diplomat M body aluminum master cylinder. Bore is 1&1/32" bore. Piston has a groove for a manual brake pushrod O ring, and uses SAE fittings. Rock auto has em. Get a 2 bolt to 4 bolt adaptor plate from doctor diff. About $38 comes w replacement pushrod o ring. I will be using a GM combination valve and plumbing it all myself. If your going 4 wheel disc, you can buy a GM 4 wheel disc combination valve, and might need a residual pressure valve for the rear brakes.

 

[Dana67Dart]

. If your going 4 wheel disc, you can buy a GM 4 wheel disc combination valve, and would need a residual pressure check valve going to the rear wheels. This residual pressure check valve is unneeded if going w rear drums

Isnt that reversed? Disc dont use a rasidual check valve but drums do to compansate for the drum springs.
Am i missing something? I did a 4 wheel disc conversion back in the late 80s on a 56 F100 and all research then called for removing the risidual check valve from the forward cir of the master cyl (ie former rear drum)

 

[kursplat]

lots of mixed info out there. i've seen "use a 2lb on front and back for disks", don't need any for all disk", and "just do the rears for 4 disks".

 

[TrailBeast]

lots of mixed info out there. i've seen "use a 2lb on front and back for disks", don't need any for all disk", and "just do the rears for 4 disks".

And even some opinions that they are not needed at all unless your master cylinder is lower that the brake calipers or wheel cylinders.
I put them front and back both on another vehicle when I switched it to power brakes just to help keep the pedal up nice and high on the first step.
They don't seem to drag the brakes or anything noticeable like that.

 

[kursplat]

And even some opinions that they are not needed at all unless your master cylinder is lower that the brake calipers or wheel cylinders.

yup...

 

[moparmat2000]

I may have that backwards. I have to plumb a 4 wheel disc car and a disc/drum car.

 

[moparmat2000]

Did some more research. If master cylinder is on the firewall and not below the floorboard, a residual pressure valve is not needed. I am going to use a GM type combination valve for both cars. I was able to buy one set up for 4 wheel disc, and one set up for disc/drum. One car is a 4 wheel disc setup with cordoba big brakes in the front, xploder rears, dippy master cylinder. Other car is cordoba big brakes in front, cordoba 10x2.5 drums in the rear, dippy master cylinder.

The GM combination valve meters and proportions the fluid all in one simple compact unit. The mopar one with exta piece and crossover tube for disc brakes is double the money, and looks like an effing science project to me.

 

[moparmat2000]

Here is how the GM disc brake valve is plumbed. Pretty simple actually. Plus it has 2 nice built in mounting lugs. On GM trucks its mounted to a bracket attached to the master cylinder.

 

[moparmat2000]

Last evilbay deal i got, i was able to pick up two 3/16" tubing kits with 25' of line each kit with enough correct SAE fittings and gravel guard to plumb each car for $19.99 each, and 2 GM style combination valves for $39.99 each. One for disc/disc, one for disc/drum. Neither car has any remnant of the original brake system except for the pedal, neither one is a valuable numbers matching car, so they are clean slates. Next junkyard trip i will have to get some low brake pressure warning plugs out of a few GM trucks.