View single post by edward_davis
 Posted: 03-28-2007 01:33 pm
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Joined: 07-06-2005
Location: Eugene, Oregon USA
Posts: 162
The stock brake setup doesn't have any sort of proportioning valve.  The  Pressure Differential Warning Actuator (PDWA) in the engine compartment is only an electrical switch to turn on the warning light if there is a loss of pressure in one or another circuit.  I just took mine apart, and the pistons on both sides are the same size, which suggests to me that the pressure in the front and rear lines should be ~equal in the stock system.  It would be easy enough to simply design in the front brake bias by choosing the sizes of pistons properly.  Of course, the system is intended for street use with the stock wheel/tire combiation, so you really need to have an adjustable valve in there if you fiddle with any of those, even if you use the stock brakes.  And if you go for the JHPS big brakes, there's a good chance you'll need to adjust the front/rear bias.  Plus, as I understand it, many racers like to tweak front/rear bias depending on the track and conditions. 

If you did put in an adjustable proportioning valve, I'm pretty sure the stock PDWA wouldn't continue to function properly.  There is a chance of the PDWA leaking, even after you rebuild it (don't ask how I know), so it might be best to simply remove it from the system.  I'm thinking about doing that myself, once I get the gumption to get a hard-line bending kit and experiment.