Thread: Consequences of removing proportioning valves?

Here´s the situation: i did a 4 pot brake upgrade using subaru calipers and as predicted the pedal is too mushy... bigger master cylinder needed, nothing new... but due to the big calipers up front(that take more oil) the rears brake too much and i almost killed myself the other day... the balance is completly off and the car unpredictable under heavy braking...

It´s been hard to find the proper 1" nabco MC that apparently the P11´s have, and the tokico units don´t accept the nabco proportioning valves...

So my idea is to put a wilwood adjustable proportioning valve(already bought) to the rears and no proportioning valve at all to the fronts... then via trial and error adjust the bias between front and rears...

Any problem with that?

only one way to find out...do it on a closed road please

Well i ended up buying a 1" mc today, not a tokico like in the first post but a bendix... pretty sure the "pv" don´t work... so will be custom braided hose to front and wilwood adjustable proportioning valve to the back...

My biggest fear is if it doesn´t bolt on to the servo...

Anyway i´ll be the guinea pig... and i´ll keep you guys posted...

The PP arived today... let´s see if i find the time to mount it all tomorrow...

Do it up. Keep up the experiment

If your brakes are properly bled and soft right now then you're going to need a smaller master cylinder, not bigger. Pressure output increases as you go down in size with BMC's. If anything you are going to make your pedal softer with a bigger MC

The problem is the travel... way too much pedal travel and not much sensibility... I think the MC doesn´t move enough oil to fill the 4 piston calipers properly in early pedal travel...

I understand what you´re saying but it´s not the case..

Guys can anyone please tell me wich is the front and the rear outlet on the 7/8 ABS NABCO "MC"????

Some are marked as R and F in the tokico units, i presume R for rear and F for front mine is S and P... can´t seem to find a ABS pic of a sentra 7/8MC tokico or nabco...

Any help will be apreciated

believe it stands for "primary" and "secondary" with the primary being front and secondary being rears

Yes it is... thank you very much... i later remembered that i have a nissan b13/n14 service manual. So i investigated further...

P is for primary, and S for secundary, but it seems to me by the drawing on page 551 on the volume 2 manual, that primary is for front right/rear left wheels and secundary is for front left/rear right wheel...

I assume this by looking at the drawing, anywhere on the manual is that explained...

By looking at it i´ll need two adjustable proportioning valves...

Since the MC as 2 outputs, the ABS 2 inputs and outputs and then a 6 way conector with 2 inputs and 4 outputs...

Meaning is not divided by front and rear, but in a cross maner... ft right+rear left and ft left+rear right...

I have to put the Adjustable PV´s right afterwards the conector valve or on the rear wheels before the calipers... DAMN