brakes E21 master cylinder question

[LateApex]

I have the Wilwood big brake kit from Ireland which I ordered with the recommended E21 master cylinder.  This swap involves going from dual to single front brake lines.   I am about to route my lines and have a question.  There are three outlets on the E21 M/C, two on the side (front and rear in the car's orientation) and one on the bottom at the front.

 

I assumed the two at the front were for the front brakes and the one in the back for the rear brakes, but I see that the orifice sizes are different between the outlets. The bottom front outlet has a noticeably larger orifice than the two side ones.  This leads me to believe that the two side outlets are for the front brakes and the bottom front one for the rear.   I've looked online for parts fiche pics, but cannot find one that shows the connection layout of my M/C.  Can anyone confirm the correct connections?

[esty]

clutch slave

[LateApex]

clutch slave

 

No, not the reservoir, the master cylinder.  Below is an image of the M/C showing the three outlets.  Can someone ID the three outlets indicated by the arrows.

 

Edited January 6, 2016 by LateApex

[esty]

i may be wrong but one goes to front, one to rear the other (bottom - larger) to the clutch slave...you feed the hydraulic clutch from the master cylinder

[LateApex]

My clutch slave is gravity fed from the reservoir.  1976 2002

[conkitchen]

You will want a proportioning valve (that larger brass fitting) for the rear port which threads into the master and then the line attaches into that.

 

 

note: rear arrow is NOT the direction of flow.

Edited January 6, 2016 by conkitchen

[esty]

sorry for the bad info...latex is correct, the clutch feed from the reservoir

[AceAndrew]

I've got a .pdf file on this, if you pm me with your email I will shoot it over.

[TobyB]

Erk, I don't think Con is right on this one.  The 2 on the front are one safety circuit, and the 1 on the back is another.

 

If one circuit fails, you probably don't want one front brake grabbing without the other.  At least, I wouldn't.

 

I know that Nissan and others put one front and the diagonal rear on one circuit, and that always scared me too.

 

But then, having only the rear brakes could be interesting, too.  

 

I would put the 2 fronts on the front outlets, and the one rear outlet on the rear.

 

Note that this is just my preference.

 

t

[conkitchen]

Memory held me on the 2002 circuit with the rear port up front.

 

Attached shows the factory blue book directions. LOOKS LIKE YOU MAY WANT TO FOLLOW THE 1502 diagrahm.

 

 

but what do I know.

Edited January 6, 2016 by conkitchen

[TobyB]

Hmm, yeah- and lookee, there's the residual pressure valve on that 1502 diagram, too- doesn't seem to be one on the E21, does there?

 

I dunno- it might come down to personal choice, as having one front brake MIGHT just be better than only having 2 rears.

The 'oh shit' factor would certainly let you know something's wrong!

 

t

[LateApex]

AceAndrew's recommendation is fronts in the front, rear in the rear.  My concern with the different orifice size is mute because the front brake line sizes are equal and are the dominant flow restriction. 

 

BTW, I'm doing a brake booster delete in addition to my brake upgrades (IE Wilwood for 15" and VW rear discs) and will share my configuration soon.  Here's a preview

 

[TobyB]

Moot, you mean.

 

Just to make this more complicated, in your situation, I managed to get a Tilton balance bar

to fit into the booster support, so that balance became both easy and dynamic.

One of the best things I ever did to that car.

 

t

[LateApex]

Moot, you mean.

 

Yes, Duh. 

[TobyB]

Hey- I found some pix for you!

 

This setup worked great- in fact, when I moved it to the floor,

it was fussier, and messed up the clutch.

 

But it made more room for a 'better' airbox...

 

t