Proportioning valve question

[kocho]

The proportioning valves on v6 and i4 '00 Camry are different (at least in color - v6 is green, the i4 is black).

Question is, which one sends relatively more power to the rear brakes?

Also, are the drum brakes generally more efficient than disk brakes, meaning they would require less pressure to stop the same or is it the other way around?

Here’s why I’m asking. I swapped the rear drums in my i4 with disks from v6 and everything seems to work just fine and the car stops better than before - clearly more stopping is being done in the rear with the disks than it used to be the case with the drum. Just wandering if changing my current valve to the v6 will do further improve braking. The v6 is somewhat heavier in the front, but has the same front brakes as mine did from the factory (plus now I got the same rear brakes).

I'm reasoning that, if the rear weighs the same in i4 and v6, but the front weighs more in the v6, then the v6 proportioning valve should actually sends LESS power to the rear than the i4. If this is the case, I probably do not need to change my stock valve… But how do I find out?

Thanks!

[BenG]

I'm not positive about this, but back in high school, my auto mech teacher said that drum brakes are more efficient because how they work make them self actuating and more powerful the harder you brake, but they are not a good choice for performance vehicles because they cannot dissipate the heat they generate, causing fade.

When you engage the drum brakes, the pads get push outwards into the drum's inner surface and because the pads are curved with the drum, the drum basically grabs the pad and "suck" them into itself. That is why you need springs to pull the pad away from the drum when you release the brakes.

Disc brake pads, because they are flat and on the outside of the disc, are constantly trying to be thrown off the disc, so you would need more power to engage and maintain contact between the pad and the disc.

Therefore, less braking power is needed to engage and maintain the brakes on drum brakes than on disc brakes which would explain why the proportioning valve on the V6 with all disc brakes would send more power to the rear brakes, because it takes more power to maintain good stopping power.

[88 LE]

Wilwood (they make bad ass big brake kits) makes a nice adjustable proportioning valve.

[kocho]

Originally posted by 88 LE
Wilwood (they make bad ass big brake kits) makes a nice adjustable proportioning valve.

The thing is I don't know if I need more or less power than I have currently in the rear... I'm willing to try a bit more, so if the v6 sends more to the rear I might install it, since I already got it.

Plus, I think adjustable valves are not street legal, if I'm not mistaken.

[BenG]

Since you used to have drum brakes in the rear, and you converted to discs, I think you should increase the power going back there.