My LeGrand has Lockheed 2-piston outboard calipers in the front, clamping rotors with about a 9" diameter, and a single inboard 4-piston Wilwood caliper in the rear, clamping a 10" rotor. The total piston size is about the same in the front calipers as in the rear, and the brake pad size on the single rear is almost twice the size of the front pads. Considering that the larger rotor in the rear also gives better axial torque "purchase", it seems to me that I am considerably "over-braked" on the rear compared to the front.
In the Porsche (rear-engined) world, which is where I am coming from, the front brakes usually have larger front pistons by a factor of about 1.4-1.6, given the same size rotors and pads, to balance the braking bias F/R, since it is the fronts that do most of the work when the weight shifts forward. I recognize that the mid/rear-engine design of my car is different, but in the little testing I have been able to do at speed in the DSR(a few autocross events and 1 DE), it had way too much rear bias, even after cranking the Tilton balance bar adjuster on the pedal to full forward position. On further inspection, I see that the front circuit has a 3/4" master cylinder while the rear circuit has a 5/8" cylinder. Is this backwards? It seems I would want to have the higher pressure/lower volume 5/8" on the front and the lower pressure/higher volume 3/4" on the rear circuit. Is that wrong? Will swapping them improve the bias towards the front or no? Am I so out of whack with the big rear brake that I will never be able to get the bias right with a balance bar and I need to install a proportioning valve to the rear circuit?
Thanks in advance to any of the DSR engineering gurus who can offer me any advice on this.
TT
In the Porsche (rear-engined) world, which is where I am coming from, the front brakes usually have larger front pistons by a factor of about 1.4-1.6, given the same size rotors and pads, to balance the braking bias F/R, since it is the fronts that do most of the work when the weight shifts forward. I recognize that the mid/rear-engine design of my car is different, but in the little testing I have been able to do at speed in the DSR(a few autocross events and 1 DE), it had way too much rear bias, even after cranking the Tilton balance bar adjuster on the pedal to full forward position. On further inspection, I see that the front circuit has a 3/4" master cylinder while the rear circuit has a 5/8" cylinder. Is this backwards? It seems I would want to have the higher pressure/lower volume 5/8" on the front and the lower pressure/higher volume 3/4" on the rear circuit. Is that wrong? Will swapping them improve the bias towards the front or no? Am I so out of whack with the big rear brake that I will never be able to get the bias right with a balance bar and I need to install a proportioning valve to the rear circuit?
Thanks in advance to any of the DSR engineering gurus who can offer me any advice on this.
TT

















