Really good thread Jim, interesting ideas on a good inspiration car.
The brakes are important as several of us will testify!
A few things are essential to understand.
Brakes work by converting kinetic energy into heat energy and then dissipating that heat faster than the friction of the pad against the disc can produce it, no matter how hard you press the pedal.
Assuming your brakes are hydraulically operated, when you put your foot on the brake you are pressurising the fluid in the master cylinder which in turn pushes the master cylinder piston outwards, moving fluid through the pipework, pushing the brake pads into contact with the brake disc. The harder you press, the higher the pressure and more friction is created which is instantly turned into heat and stored in the disc.
When you lift your foot off the brake, the pressure behind the piston in the brake caliper drops to zero and the brake pads are pulled back, away from the pads by the piston seal (which actually grips the piston slightly in order to do so). The friction drops to zero.
Now the disc can start to dissipate the stored heat and cool down, ready for the next brake application.
Lesson over so back to your point about building a system……..
The volume of the pressurised fluid displaced by the piston in the Master Cylinder must match the volume of fluid required for the Brake Caliper to move it’s piston far enough to push the pads against the disc.
If the master cylinder is too big, the pedal movement will be very small and may be small enough to overcome the return action of the piston seal. This will cause the brake pads to constantly rub on the disc, warming it up. More importantly perhaps, you will have very little in the way of ‘feel’ or ‘feedback’ during braking and the disc will already be warmer.
If the master cylinder is too small, the brake pedal travel will be too long and the brakes will feel very spongy. Possibly, the volume in the master cylinder may be less than the volume required to move the brake pads far enough so the brakes don’t work at all!
Getting the balance right is the trick.
I have always bought a brake 'set' of Master Cylinder and Caliper (from Gemini) to ensure all is well from the start.
Make no mistake, brakes work a lot harder than you might think.
In the past, one of our members built a CycleKart which he fitted with Mountain Bike disc brakes. This seemed a good, cheap option which worked well until one day, it was going fast into a hairpin.
Several corners had already been taken by then and the disc was no doubt very hot.
When the brake was pressed hard the disc instantly heated up to a temperature that it’s low mass could neither store for long enough or dissipate it's heat fast enough. The brake stopped working almost instantly with the result that the Cyclekart crashed heavily into the banking. The driver suffered an injury which he is still suffering from.
The crash was wrongly assumed to be ‘driver error’.
At the next meeting a 'guest' driver had an almost identical crash and was very lucky to get away un-harmed. The driver this time however had had a lot of experience driving race cars and he recognised the problem as 'brake fade'. The small disc and was overwhelmed by the demand placed on it.
The brakes were changed for go-kart brakes and the problem went away.
My advice is to use only Go-Kart brakes, hydraulic or mechanical. (Other suppliers are available) ;>) .
I agree that ordinary flexible pipes are fine. (I use stainless steel braided pipes because I like the look of them).