Bigger brakes?

Hopefully, the 355 - and probably the 360 - do have a proportioning valve which reduce the pressure, and so the torque, on the rear braking circuit in order to have a balanced set-up. This delays the operation of the ABS on the rear wheels and make the car still drivable in case of ABS failure. It would be extremely dangerous to drive a car with equal braking torque on the 4 wheels and an evident tendency to lock the rears.

 

Are you sure about the very very early locking? Most cars do lock the rears early, that's for sure, but most cars have the engine (and transmission and diff and axles) up front and a much higher CG and much softer suspension. I don't disagree about the rears locking first, but I wonder how much difference having all that weight in back and down low helps keep them rolling.

(My GT4 actually locks the front wheels first, but my brakes need help. I'll try again in the spring after a little system overhaul and see if that changes!)

 

To clarify one point, we put the prop valve in Chris' setup because the line pressures dropped significantly due to the large piston sizing compared to stock(we bumped the master accordingly to maintain pedal feel). Prop valves read pressure and limit rear circuit output when the preset is reached. If overall circuit pressures are way down, the prop valve never works and the rears are locking all the time.

I feel I've typed all this before but I'll quickly point out some facts.

Number of pistons has no effect at all one way or the other on brake torque, heat, etc. Typically, a multi-piston caliper has larger/longer pads and that can be useful in situations where longevity is required. A pencil eraser with the same friction will stop the car the same as a monster pad size, until the eraser is worn away...

Tires do stop the car, but as it's been pointed out here, modulation and optimized bias front to rear are what create shorter stopping distances.

Lowering the car, in general, improves braking POTENTIAL because you can dial in more rear brake as there will be more weight over the rear wheels in a given stop. Lowering reduces the pitching moment meaning the rear won't lift as much. If you can put a hotter rear pad in or dial your handy adjustable prop valve to the back, you'll realize this.

Things tend to get gray when in comes to modulation and it can be dictated by driver preference. In general, the easier it is to get the front tires to lock, the harder it is to modulate. In the brake business I see two kinds of customers. There are those who feel a great brake system throws you through the front windshield at the slightest touch of the pedal and there are those who actually want a firm pedal that is easy to modulate. Without typing an essay on this, imagine a street car takes 40 lbs of pedal effort(think leg muscle motor skill control) to almost lock the front wheels. Compare that to a race car that take 100-120lbs to almost lock the front wheels. With a wider range of effort required, the legs not so precise inputs are more easily forgiven, if you will, by the brake system. It is easier to modulate, to control more precisely.

Compliance kills modulation. If you have swelling hoses, expanding calipers, compressible pads, slop in clevis joints and mechanism(ever seen a 308 pedal box!!) etc. you have to take all that up with the pedal before the brakes work and then they work erratically. A real race pedal moves very little, the compliance has been taken out of the system. How else can you effectively heel-toe??

A larger diameter rotor is easier to control, ALL other things being equal. Dig out your old vinyl record player and slap on a Doors album. Put your finger on the outer rim of the vinyl and try to hold it at half speed, now put your finger on the outer edge of the paper and try to hold it at half speed. Which was easier to "modulate" and keep the speed closest to half? That being said, a given car on a given track should only have as big a rotor as needed to not overheat, otherwise you are carting around unnecessary rotational and unsprung weight.

Different pad compounds can be used to help keep from locking on initial application of the brakes, if your setup is marginal. They can control initial bite and still maintain high overall friction levels. There is a pad for almost any situation.

Hope this helps some.

Martin