HOW DOES THE T.H.O.R.P. SYSTEM FUNCTION?
The T.H.O.R.P. System is the most realistic brake system ever made for sim racing. In any given racecar, the brake pedal is always hard. A hard brake pedal is faster (you can brake later) and it is required to proper trail brake and use your muscle memory to do so, as explained later. You can consider a racecar braking system as 2 stages:
The “soft stage”: When you apply pressure on the pedal, it will move 10-20 mm (measured on the pedal plate), while you build up pressure, while the caliper pistons are traveling to and pushing the brake pads against the brake disc, and to compensate for the small amount of play in all the mechanical parts on the pedal system that is required for them not to seize up.
The “hard stage”: When hydraulic pressure is built up, the brake pads are squeezing the discs hard and all mechanical play is compensated. In this stage, your foot is basically “pressing against a wall”, because now your muscles are pressing directly against the hydraulic forces (the brake fluid). Since the fluid cannot be compressed, you will feel the pedal is hard. When a racecar driver complains about a “long” or a “soft” pedal, it is typically because there is air in the system, and since air CAN be compressed, the pedal will feel soft and long. The mechanics then bleed the brakes for air, meaning there is only fluid left in the system, and the pedal is once again hard after passing the “soft stage”.
In our quest to mimic the perfect racecar feel, we also designed a 2-stage system on our Invicta™ pedals with the T.H.O.R.P. brake cylinder:
The “soft stage”: Since we do not have a brake disc, caliper and brake pads in a simulator, we made the slave cylinder to mimic this. The slave cylinder is compressing an elastomer, and like in a real racecar, it will allow a pedal travel of maximum 20-25 mm measured on the pedal plate. When full pedal travel is obtained, the slave cylinder will hit a mechanical stop, just like in a real race as described above. We supply different elastomers to mimic different feelings of the “soft stage” but the different elastomers will not change the pedal travel, only how much force that is needed to fully depress the pedal and engage the “hard stage”.
The “hard stage”: When the slave system is mechanically locked, you have 100% the same feeling as in a racecar, when the brake pads are fully pressed against the brake disc, and your muscles are pressing directly against the hydraulic forces. This is NOT simulated, this IS the same and identical feeling as in a racecar, and you can keep pressing the pedal up to a hydraulic pressure of 100 bar, which corresponds to 185 kg of pressure on the pedal plate – the same as a real F1 car!
Besides from being able to calibrate and measure the pressure in bar, the 2-stage system is exactly the benefit you will get over a mechanical brake system. Most mechanical brakes are relying on the elastomers and a load cell to give you the racecar feeling. It will never be the same, because it is NOT the same! A load cell system IS a simulation and at best, you can implement a mechanical stop to simulate the “hard stage”, but unlike the T.H.O.R.P. system, your pressure readings in the simulator will also stop at that point, because your load cell will stop to physical deflect. And without deflection it will not meassure. In the T.H.O.R.P. system, pressure readings will continue despite the
slave cylinder has reached its mechanical stop (passed the “soft stage”). THAT is the Asetek Invicta T.H.O.R.P. hydraulic difference!
It may surprise you, but as described above, having a hard brake pedal will help you get around the track faster. It all has to do with muscle memory and efficient trail braking. Having a hard brake pedal will allow your muscle memory to be trained to perfection. Muscle memory is the subconscious telling your muscles just the right amount of pressure, leaving your conscious mind to take care of more important things at that moment – like watching traffic or hitting apex. Your muscle memory system is not wired to remember a position. Try to lift your hand with your eyes closed and reach the same spot within 0,5 mm 10 times in a row, and you will get the point. On the flip side, your muscle memory can memorize a pressure extremely accurately, meaning going around a track, your muscle memory can make you brake the same way again and again. This cannot be achieved with a soft pedal – especially when trail braking.
Furthermore, a hard brake pedal will allow you to brake later. Imagine having a brake pedal with 50 mm (common for many sim racers) of travel versus a brake pedal with almost zero travel. You are going 300 km/h down a straight. With the long travel brake, it will physically take you perhaps 1/10 of a second more to reach full braking power. On the stiff brake pedal, you will reach maximum braking power instantly. If you have three hard braking zones on a track, you will lose 3/10 of a second each lap.
The Top 10 in F1 or GT3 is frequently determined in way less than 3/10 of a second. The conclusion is that we at Asetek SimSports have developed the Invicta pedals to replicate a real racecar. Why? Because it is the fastest but may not be what feels the most comfortable. It is your choice whether to be the quickest or have a brake pedal that feels soft and comfortable.
Using the two thumbnuts behind the elastomer, you can adjust the preload of the system closely mimicking the gap you will experience in a real car (between disc and brake pad). We have made this adjustable, so you can have the feeling just the way you like it – and just like your favorite car. Using RaceHub, you can also adjust your dead zone on the brake pedal. This allows you to rest your foot on the pedal without getting inputs to the game.
Should you wish to change the pedal stops, and thereby the angle of the pedals, it can be done entirely toolless. It will require you to recalibrate the pedals and remove the brake cylinder at the pedal arm and adjust the rod length to prevent any preload on the T.H.O.R.P. hydraulic brake cylinder.