Dual Brake MC Upgrade Issue

[fotoroadie]

I'm in a state of confusion. I'm in the middle of a master cylinder upgrade to my '65 Bus.
'm getting different advice from just about everyone i contact.
I followed a tutorial that had me acquire a '72-'79 dual MC and a Volvo reservoir & had me make a spacer and to use longer bolt/nuts, all of which i did.
My MC is a Remanufactured Ate - the box is marked:
Wagner Brake Products
Import Master Cylinder R96379 and other numbers on the label like
24D2 DCB2115 & 11-1560
& a separate sticker Inspected by: HS
DCB2109 12836YR 1560
Don't really know if this is a MC for a '72-'79 or not, but have to assume it is.
My confusion lies in the fact that i've been instructed to run the front brake lines to the two rear ports and the rear line to the front drivers side port and the brake sensor to the pass. side front port.
Here's my question:
When i look down into the ports i see that the openings on the front two (closest to the plunger) are the same size, but when i inspect the two rear ports, the pass. side is the same as the fronts but the driver side is about half that size. ????
Why would i want the two front brakes fed by two different sized ports?
Also i'm told i cannot reconfigure and hook the front brakes to the front ports because this MC is designed for the front port to service the rear brakes.
Bottom line here i guess is why is there a port that's different from the other three?

confused but determined

bobby

[cru62]

I won't bother refering you to the vaunted "BENTLEY" manual as it does not include ANY information about the '67 only MC and brake lines. I'm sure it exists on this site somewhere, however.
In the meantime, I can say with almost unwavering conviction that the two front lines are fed from a brass "T" screwed to one of the crossmembers and fed by a single line from the MC. The rears are set up similarly with the "T" on the DS rear fork and splitting to each of the rear brakes.
I would imagine that this is why the ports are of differing diameters. My '67 MC has a sensor for the front and the rear portions of the MC. You may have to bend up your own hose to connect to the front brake "T". The lines from there to the wheelwells are available from WW but do require that you bend them to fit.
Good Luck!

Here is a pic I found in the Gallery-

It might clear up some of your confusion.
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Jokes about German sausage are the wurst.

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[Eric&Barb]

http://type2.com/library/brakes/dualmas.htm
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[Culito]

I didn't have to use the "T" for the fronts. I'll have to look and see how the lines are routed, but I think I just used the two front ports for the brakes and only used one switch.
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Copyright CJ Industries, Inc.
'64 standard w/2.0L type 4
'62 bug

[fotoroadie]

It seems you are saying that the fronts are fed from a T - and the rears are fed from a T - and that's why the ports are different. ? Why? And which should be the smaller and why.
Is it true that i cannot attach my front brakes to the front ports? And why?
Of course, a '65 does not have a T at the front, which means if i have to feed the frony brakes from the rear ports i will have a pretty major brake line project (at least for me) running hard lines and the T. That's not what I was led to believe.
Right now I have my front brake driver side attached to the front left side of the MC and the front brake pass. side attached to the front right side of the MC. I have the rear line attached to the rear pass. side and the sensor attached to the rear left (which is the port with the smaller dia. opening) as seen in my photo. This way I can use existing hard line configuration but I can't bring myself to try it out until I understand this more.
My logic said that since only one port was different it must be for the sensor. ???

[Split 66']

I did this conversion a while back. If I remember correctly, the smaller diameter fitting acted as a proportioning valve.

The front brakes are about 80% of your braking capacity, therefore you need the most pressure up front. If your rear brakes were to lock up as much or more than your front brakes, you would lose the rear end in a hard braking scenario. The smaller diameter fitting would control the flow, or pressure in that way.

If I am wrong, someone will be along shortly to let us know.

EDIT: I have mine setup like Culito, two separate front lines and no T up front, with only one stop switch.
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[fotoroadie]

In Eric & Barb's tutorial they say to reroute the front brake line to the port at the 45 degree angle since, with a sensor there, you can't get your belly pan on. But doesn't this then defeat the purpose of the proportioning valve since it's the one on the driver's side rear, where they end up putting a sensor.
Which begs the question - if their setup works fine then why couldn't I leave my setup the way it is with the front attached to the front of the MC?

[Split 66']

I am not running a pedal pan on my '66, couldn't bring myself to cut the OG pan.

Here is how my DCMC is setup:

This is the diagram I used:

I changed the stop switch to the other side, so I could use my existing hard lines.

I can't remember if I had two smaller diameter openings for the rear brake line, or just one. Either way, this configuration has worked for me for nearly two years now without issue. I definitely purchased a '72 Bus ATE DCMC though.

Hopefully someone can you give you better advice here, as mine is limited.
_________________
"OG = Original German" -- TheSamba.com dictionary

[Culito]

^^ That's how I'm running mine. Easy-peasy.
_________________
Copyright CJ Industries, Inc.
'64 standard w/2.0L type 4
'62 bug

[Eric&Barb]

[fotoroadie]

Well, still I am unclear.
Split66, the way you have it configured would have the proportioning valve port (rear driver side on the MC) servicing the driver side front brake. If this does not create different pressure rates to the front brakes, then why would they have it there in the first place and if it makes no difference can I leave my setup (fronts to front set of ports) the way it is now.
Again, something here I'm not understanding.
Easy-peasy or not you're not using it as it appears it was designed for.
????

[fotoroadie]

Eric&Barb, again if it makes no difference why would your tutorial have me reconfigure my system with lines & a T when I could simply attach it the way I did with no reconfiguration.

[Eric&Barb]

[olliehank47]

[fotoroadie]

This is starting to make me crazy!

Front/Back Back/Front has no bearing on my basic question.
If the small hole proportioning valve is not used as designed (Split66 has his rigged where it only serves the driver side brake & Eric&Barb has theirs blocked with a sensor ) my logic says that the pressure inside the MC itself would be even & consistent, sooooo, can I run my front lines to the ports closest to the pushrod? Eliminating my need to reconfigure.
I don't know how to ask this question any other way.

yikes!

[Eric&Barb]

Again, there is no proportioning valve in the MC.

Again, VW designed the front circuit for more brake fluid to be pushed to the front cylinders. The rear half of the MC is not designed for dual cylinders in each front drum or stock front disc brakes.
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In Stereo, Where Available!

[cru62]

[BarryL]

[FlatfourFrenchy]

As far as proportioning valves, GM vehicles with proportioning valves it is only a safety device by shutting off fluid to line that has massive leak and turns light on on dash so besides brakes feeling different a light comes on as well. It plays no factor in proportioning or balancing anything on a regular braking situation.

[Eric&Barb]