[Porsche]

Originally Posted by OrbitalEllipses

Are we sure there's no integral/internal prop valve?

No we're not. At least I'm not sure. My reading tells me that the EBD has replaced the mechanical proportioning valve on modern cars. I don't know if that's true. I'm thinking, as perhaps you are, that surely they must have some mechanical backup to prevent rear wheel lockup in the event of EBD/ECU malfunction. But, I don't know.

That's why I'm asking people with more experience driving these cars with EBD disabled. I'm reluctant to employ empirical testing on public roads. I don't like the lack of runoff areas, among other things.

I certainly don't wish to learn about this at the expense of a fellow motorist.

The front brakes will have more torque just due to the rotor size and piston area, but you have a point...I'm just not sure how applicable it is.

LOL!

It gets "applicable" right quick when the rears try to pass the fronts heading into a corner.

Try it sometime. Then come talk to me. I'll buy you a beer if you survive the experience.

EBFD is just another safety oriented driver aid; it brakes better and with more precision than an unskilled driver could ever hope to.

"…could ever hope to" implies that it's possible, if improbably. It is not possible.

Perhaps we have a different idea of the function of the EBD system. My understanding is that this system provides a level of control heretofore UNAVAILABLE to a driver. Basically, the EBD/ECU controls the braking force at EACH individual wheel, independently of the other three wheels. I never saw a road car with even two, never mind four brake pedals, the EBD equivalent. People whine about heel-toe being difficult. Imagine giving them FOUR brake pedals. It would be a Candid Camera moment, don't you think?!

Even in modern race cars, I doubt the driver is manipulating the front/rear brake bias LEVER in real time in the midst of heavy braking, down into a corner. She sets it and then accepts the level of front/rear bias for the upcoming corner. There's no skill involved other than the normal threshold braking skills required; the front/rear bias is set, at least until she adjusts the lever again. In any case, none of this is applicable to any road car I've ever driven. The front/rear brake balance is what it is, as set by the manufacturer in my cars. It's not something I can alter through skill in real time on the road. As Mike alluded to, I can alter the balance a bit with different pad compounds, etc. But, again that's a fixed state, once selected, and cannot be altered on the road by any especially skillful use of the brake pedal by anyone or me.

Again, I've read that modern cars do not have brake proportioning valves, which leaves me wondering what happens when we turn off the EBD? Does it bite, now? I don't know. Like you, my first thought is that they cannot be that stupid as to create a monster in the absence of a functioning EBD system.

Well…

Mike assures us that this is not a problem. He's driving the car at the limit, or close enough that his experience reassures me that it would be safe on the public roads. Call me cautious, though.

I should add, too, that where I'm really going is here: I want to turn off the ABS, too. Don't like it. It's dangerous, in my opinion. (But, we're straying way too far from the OP's questions.)

Where will that leave me? In a coffin, maybe?

I wouldn't like that.

I've asked people to disable everything, pull the ABS fuse, and hit the track. Then tell us about it. So far, I have not read of anyone doing this.

Care to be the first? It could be perfectly safe on some tracks at certain corners, I'd think. Just don't do it where you could hit anything if things go awry. Safety first.



If it doesn't work out, return to the pits and plug that ABS fuse right back in.


I long for yesteryear when cars were simpler and the man at the wheel was in control, not a computer.

Ah well, nice chatting with you. :happy0180: