Brakes Junction Block

Sep 27, 2017
Sorry If this has been asked before. I'm not finding what I am looking for.
In my 93 l'm going to be using a factory Ford brake junction block from a 99 cobra. I'm using 99 cobra brakes front and rear. I'm installing new lines. I'm using a 93 cobra MC and booster. Do I still need to use a adjustable proportioning valve?


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SN Certified Technician
Mar 10, 2000
Dublin GA
The proportioning valve adjusts the balance between front and rear brakes. It help to keep the rear brakes from locking up when you make a quick or hard stop. It does that by reducing the pressure to the rear brakes. The front brakes do most of the work stopping the car, so they require more pressure to operate properly.


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SN Certified Technician
Feb 18, 2001
99 Cobra is hydroboost and ABS. The fitting style and block is not the same as the fox body Mustang. It's more work to do this vs a simple 3-2 conversion for the 1993 cobra MC you are purchasing.

You need an adjustable prop valve regardless. The valve controls knee point to the rear brakes which is the point that pressure increase to the rear calipers occurs at a slower rate than the front calipers.

Things can vary bias are weight of car, weight distribution, tire sizes, etc, so you'll want a little adjustability. Ultimately what you are trying to avoid is a worst case scenario of panic braking on the highway on loose surface and locking up the rears.

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