Rediscovering the sweet spot.
****NOTE THE FOLLOWING POST IS CAR BABBLE SKIP IF YOU AREN'T DOWN WITH THE SICKNESS****
Since last week’s race I’ve been trying to drive jezebel on a regular basis. The biggest reason is to keep the brake seals nice and wet. Since she was sitting around for a year without any major usage, the seals in at least one of the calipers dried to the point that it would leak the rest of the brake fluid out in a matter of a week. At least by driving her, I’ll be able to monitor the activity in the master cylinder reservoir.
Driving jezebel around on Saturday I rediscovered the braking drift sweetspot. By no means am I accomplishing this on a regular basis since my hiatus, but to feel it again is nothing short of fantastic.
It’s difficult to switch drivetrains. I say that, its mentioned in initial d for fanboys, but really, to go from FR to AWD is difficult. The biggest reason is the envelopes in certain areas are completely different. In general, the basic racing line doesn’t changes. in it’s most simplistic form, you brake, turn, and accelerate. But when these steps and to what degree they occur are completely different between the different drivetrain layouts. When you start switching between cars, it takes a while for one’s body to memorize the different envelopes and cornering procedures. Aftera year hiatus, I think I’m starting to get the hang of it. With a few suspension tweaks, Jezebel can bite into the corner as aggressively as Keiko, pushing her entrance speed higher than before. Keiko is reaping the benefits of a more aggressive RWD line combined with AWD grip. It’s a beautiful thing. The movements feel more fluid and natural. I’m beginning to see the light. Hopefully I can translate that into some real numbers (which, f.y.i. I didn’t do very well on my race, 6th/9 in the class, 101/154 overall). It takes time, and hopefully next time others could join me.
But whatever. Fun is fun. My shoulders are sore from wearing the racing harness, but since the automatic seatbelts broke, i don't have a choice.
two words can sum up why you would want a big brake kit:
brake fade
imagine the sensation that your brakes don’t work. You step on the pedal and it’s like stepping on a sponge all the while your car doesn’t seem to care if you stop or not. That’s brake fade. Effectively, after extended usage of your brakes, the brake fluid powering the vehicle’s calipers begins to boil and releases gas into the system. the compressibility of the gas causes the squish brake feel and the panic to join in the fun. the 240sx, especially the s13, came with a brake setup that is notorious for brake fade. one good round of hot-lapping or even something as short as a few autocross runs, and the idea of stopping is just a pipe dream.
For those of you who care to read such things (see babiarz, djflipbunny, and amishgodfather ), a few weekends ago I installed the front brakes that are attached to the sr20det equipped 180sx. Because of platform sharing, the brake package consists of 94-99ish maxima front brakes and 96ish altima rotors. The calipers themselves are single piston with an increase of about 10% in diameter. The rotors increase roughly 10% in diameter. This amounts to a surface area increase of ~21%, but keeps the rotor width at the stock 22mm as opposed to 32mm of the Z32 and Aaron’s Q45 conversion.
Translation:
Basically the increased caliper piston size does two things, it increases the potential of stronger braking and it increases the surface area of heat transfer from the brake hardware to the brake hydraulic system. I only say potential because of the fact that the larger piston decreases the effective force in the P1A1 = P2A2 proportionality of fluid dynamics persuasions => it’ll take more pedal force to get to the same clamping force. It does, however, also allow the heat absorbed into the brake fluid to radiate into the atmosphere quicker than the smaller stock piston. Cooler brake fluid = less brake fade. On the flipside, without changing the master cylinder (what your brake pedal is attached to) you will have to work harder for the same braking power, and you will also lose sensitivity in the brake pedal. This means instead of being able to modulate with ease, the brake pedal moves towards the on/off switch feel similar to the days of rad racer as opposed to say gran turismo.
The larger rotors have three major effects on the braking system and vehicle dynamic. the most obvious is the larger surface area for the brake pads to contact with. This increase will allow for larger pads, and also for a larger amount of kinetic energy to be transformed into heat. More kinetic energy transformed = slow down faster. With such an increase in heat, it will have to go somewhere; some will be transferred to the rotor, and some to the brake fluid. Fortunately, with the increase in surface area in the rotor, the effective heat transfer area has increased, as noted earlier, by 21% so your braking system can effectively run cooler. The final effect of the larger rotors is in terms of inertia. The increase in mass and larger diameter of the caliper will effectively increase the first moment of inertia, (the rotors will require more torque to get to rotate, and will want to keep moving once they are). In the grand scheme of things, this increase is minimal and absorbed in the relatively gigantic moment produced from the rest of the car.
Since last week’s race I’ve been trying to drive jezebel on a regular basis. The biggest reason is to keep the brake seals nice and wet. Since she was sitting around for a year without any major usage, the seals in at least one of the calipers dried to the point that it would leak the rest of the brake fluid out in a matter of a week. At least by driving her, I’ll be able to monitor the activity in the master cylinder reservoir.
Driving jezebel around on Saturday I rediscovered the braking drift sweetspot. By no means am I accomplishing this on a regular basis since my hiatus, but to feel it again is nothing short of fantastic.
It’s difficult to switch drivetrains. I say that, its mentioned in initial d for fanboys, but really, to go from FR to AWD is difficult. The biggest reason is the envelopes in certain areas are completely different. In general, the basic racing line doesn’t changes. in it’s most simplistic form, you brake, turn, and accelerate. But when these steps and to what degree they occur are completely different between the different drivetrain layouts. When you start switching between cars, it takes a while for one’s body to memorize the different envelopes and cornering procedures. Aftera year hiatus, I think I’m starting to get the hang of it. With a few suspension tweaks, Jezebel can bite into the corner as aggressively as Keiko, pushing her entrance speed higher than before. Keiko is reaping the benefits of a more aggressive RWD line combined with AWD grip. It’s a beautiful thing. The movements feel more fluid and natural. I’m beginning to see the light. Hopefully I can translate that into some real numbers (which, f.y.i. I didn’t do very well on my race, 6th/9 in the class, 101/154 overall). It takes time, and hopefully next time others could join me.
But whatever. Fun is fun. My shoulders are sore from wearing the racing harness, but since the automatic seatbelts broke, i don't have a choice.
two words can sum up why you would want a big brake kit:
brake fade
imagine the sensation that your brakes don’t work. You step on the pedal and it’s like stepping on a sponge all the while your car doesn’t seem to care if you stop or not. That’s brake fade. Effectively, after extended usage of your brakes, the brake fluid powering the vehicle’s calipers begins to boil and releases gas into the system. the compressibility of the gas causes the squish brake feel and the panic to join in the fun. the 240sx, especially the s13, came with a brake setup that is notorious for brake fade. one good round of hot-lapping or even something as short as a few autocross runs, and the idea of stopping is just a pipe dream.
For those of you who care to read such things (see babiarz, djflipbunny, and amishgodfather ), a few weekends ago I installed the front brakes that are attached to the sr20det equipped 180sx. Because of platform sharing, the brake package consists of 94-99ish maxima front brakes and 96ish altima rotors. The calipers themselves are single piston with an increase of about 10% in diameter. The rotors increase roughly 10% in diameter. This amounts to a surface area increase of ~21%, but keeps the rotor width at the stock 22mm as opposed to 32mm of the Z32 and Aaron’s Q45 conversion.
Translation:
Basically the increased caliper piston size does two things, it increases the potential of stronger braking and it increases the surface area of heat transfer from the brake hardware to the brake hydraulic system. I only say potential because of the fact that the larger piston decreases the effective force in the P1A1 = P2A2 proportionality of fluid dynamics persuasions => it’ll take more pedal force to get to the same clamping force. It does, however, also allow the heat absorbed into the brake fluid to radiate into the atmosphere quicker than the smaller stock piston. Cooler brake fluid = less brake fade. On the flipside, without changing the master cylinder (what your brake pedal is attached to) you will have to work harder for the same braking power, and you will also lose sensitivity in the brake pedal. This means instead of being able to modulate with ease, the brake pedal moves towards the on/off switch feel similar to the days of rad racer as opposed to say gran turismo.
The larger rotors have three major effects on the braking system and vehicle dynamic. the most obvious is the larger surface area for the brake pads to contact with. This increase will allow for larger pads, and also for a larger amount of kinetic energy to be transformed into heat. More kinetic energy transformed = slow down faster. With such an increase in heat, it will have to go somewhere; some will be transferred to the rotor, and some to the brake fluid. Fortunately, with the increase in surface area in the rotor, the effective heat transfer area has increased, as noted earlier, by 21% so your braking system can effectively run cooler. The final effect of the larger rotors is in terms of inertia. The increase in mass and larger diameter of the caliper will effectively increase the first moment of inertia, (the rotors will require more torque to get to rotate, and will want to keep moving once they are). In the grand scheme of things, this increase is minimal and absorbed in the relatively gigantic moment produced from the rest of the car.