Reply to "Five modifications NOT to do to your Pantera"

Removing the brake proportioning valve:


If you have stock brakes, they’re balanced with the proportioning valve as part of the equation. And still some choose to rip it out, never stopping to think why the factory spent money and added complexity by adding a proportioning valve. I know from personal experience that a Pantera with stock brakes and the proportioning valve removed is a terrible thing. Some previous owner of my first Pantera had taken out the proportioning valve. On damp roads it would prematurely lock its front wheels and just slide, with almost no brake assistance from the rears. But when I got my second Pantera, which still had original brakes, it was a different world. It stopped well and never locked any wheels, and it still had the proportioning valve installed.

Why do some people with stock brakes take the proportioning valve off? A little theory on brake balancing: The perfect balance is obtained when all four tires brake so hard that the front wheels lock up just prior to the rears. The purpose of the brake effort of the rear wheels is not only to stop the car, but also to make the car tilt forward, so there’s more weight transfer to the front tires, enabling them to brake harder without locking. Both these effects are diminished if the proportioning valve is removed, and the Pantera will then tend to lock its front wheels prematurely and have a longer stopping distance.

So why do people insist that removing the brake proportioning valve is a good thing? Because they don’t measure stopping distance, because locking up wheels tends to be seen as something that only can be achieved by very good brakes, and last but perhaps not least, the pedal feels harder (since the flexing effect of the proportioning valve is gone) and more sensitive in gentle, low-speed driving with light braking, which is all that most people do. It feels like it’s a lot better, but it’s not. Keep the proportioning valve. Working As Designed.

That said, if you go with aftermarket brakes, most require you get rid of the proportioning valve, because the brake balance of aftermarket brakes is designed without a proportioning valve. I now have a Wilwood setup from Dennis Quella, which works perfectly, and the balance is perfect. With all four calipers working together as a balanced system, it generates 0.96G stopping power according to my Racelogic.