Disc Brake Swap from 97 LS to 96 EK coupe, few questions.

[ash7]

cool, do I just need to change the proportioning valve, or the master cylinder too? If its just the P-valve, and I have a 96 ex, I have to use one from an si right?

all you would need to do is change out the valve. If your EX came with rear drums, then you need to change it out with one off of a DC, EGsi, EJsi, or DA.

your original master cylinder will perform just fine.

...when do do this, bleed the living daylights out of the brakes after you're done.

-jonathan

[TheProfiteer]

but just to be 100% sure I need the P-valve from an Si right?

[ash7]

or any DC or DA

[TheProfiteer]

DC P-valve is incompatible! Ill post some pictures, but its like the DC has four brake lines running through it while the EK has 6

[ash7]

DC P-valve is incompatible! Ill post some pictures, but its like the DC has four brake lines running through it while the EK has 6

The cars with 4-channel ABS (96-00 Civic, 97 ITR & 98+ integra) do have an external proportioning valve, but it's specifically for the ABS system with only 4-ports (non ABS has 6 ports). You wouldn't have to change it out, and ABS should function like normal provided your rear discs have ABS hubs as well...

The prop valve on there will do the job just fine. I did this conversion about 2 months ago, it is not necessary to do this.

it will function, you're right.

*BUT*

put your car on the track at an HDPE event, you'll change your mind when you want all the extra brakes you can get.

let me put all of this to rest once and for all:
Proportioning valves were designed to help balance braking pressure on cars with front disk/rear drum brakes. Inertia and momentum cause weight to shift to the front of a vehicle when braking, in turn causing the rear axle to lift from the road lowering the traction between tires and road.

Disk brakes require higher hydraulic pressure than drums do because drums use a mechanical servo action to increase force applied to the brakes.

When the brakes are first applied under light/normal braking, the valve does NOTHING. Fluid enters the valve at the smaller piston area and passes straight through. Only when you apply significant braking force, it achieves pressure at the outlet side of the valve exerting greater backpressure than inlet pressure moving the piston back towards the inlet side against spring pressure, thus closing the center valve stem and blocking pressure to the outlet. This pressure is called the split point. As pressure increases from the master cylinder, inlet pressure at the proportioning valve overcomes the pressure at the large end of the piston and reopens the valve. Brake fluid then flows through the center of the valve, pressure rises at the outlet, and it closes again. THIS OCCURS SEVERAL TIMES PER SECOND.

It allows pressure to increase to the rear brakes, but at a lower rate than pressure to the front.

Proportioning valves are rated in a ratio like this: after the split point, pressure to the rear brakes will rise proportionally to the front brakes. If you were to get a valve rated at 100/200 (0.50) for every two PSI of hydraulic pressure at the front you will achieve 1 at the rear.

The ideal braking proportion for the Honda chassis we're talking about is 4040.

-jonathan