tastyratz
04-28-2006, 11:03 AM
This is a Page I have typed for the 240sx Performance modificatiosn Wiki.
(http://en.wikibooks.org/wiki/Nissan_240SX_Performance_Modification)
Before it gets tainted and torn apart with inaccurate information from the general public I wanted to post it here to preserve the information in its original form
*PLEASE* do not post useless posts in this thread. Please keep legitimate relavant inquiries in intelligent form if need be so this can retain a professional and informative feel. Anything I deem relavant I can go back up and edit the post to include.
When considering upgrading brakes several factors tie in to the end result. Many of these things you might already know but you might not consider all factors or know about all things mentioned here. Brakes should not be upgraded in front or rear only, the amount of applied braking torque should be increased proportionally front and rear for appropriate feel/bias (I.E. 6 piston front brakes with stainless lines up front and stock pads/lines in the rear)
I cannot emphasize enough how important bias is in a braking setup. Just being able to lockup your front tires easier does NOT mean you are now able to stop quicker!!
All the parts need to be considered in a braking setup to determine if its right for you!
==Master Cylinder==
If you get a larger or smaller master cylinder then for every inch of pedal travel more fluid will be pushed through the lines. Dont just go buying a random larger MC without knowing however, as these have internal valving that determines brake front and rear bias which will severely impact your braking performance.
==Pads==
There are many aftermarket pad companies that produce sport oriented brake pads. There are many different materials a pad may be comprised of, each having its own individual properties. This will impact dust creation & color, rotor & pad wear rate, and A very important thing: EVERY PAD HAS A HEAT RANGE. This means the pad will ONLY function optimally within a given set of temperatures. OEM brake pads are usually designed to function well in very cold temperatures to moderate braking. When you have had several large hard stops they heat up to a certain point and get out of their range causing the pad to not have the same braking torque and "glaze" the surface (A condition where the outermost contact layers properties change and it prettymuch polishes the mating surface causing it not to grab. This is PERMANENT damage to the pads!) There is a wide range of compounds from stock all the way up to full race. Note that a pad designed for full race will NOT grab sufficiently during daily street driving and you will be unable to stop normally! Get a pad that suits your driving style, either that or get 2 sets of pads and swap them out at the track.
==Rotors==
Rotors in a braking system do 2 things. They act as a heatsink so they absorb heat when you brake, and dissipate it normally from air moving over them. The larger the rotor, the more the metal. The more the metal, the more heat can be absorbed during braking and the more fade resistance your car will have. Stock brake rotors are blanks, this means that they are just a flat surface. This is the surface your brake pad will mate to and provides the largest total available clamping area per revolution. There are several different variations of the standard brake rotor that carry a general misconception in their execution. 1 of those is slotting.
Slotting: Doing this to a brake rotor does have benefits, but is more visually appealing than beneficial. Slotting a rotor provides angled slots along the surface that exist to help wipe the pad surface clean on every pass. This ensures a fresh pad surface at all times and it does in fact help protect a pad against fade since it always scrapes off the top layer. It also helps with water and debris evacuation.
There are several problems with slots however that outweight these benefits. One of them is the fact that part of the brake pad is not in contact with the rotor at any given time. This means a lower total square inch area of friction material doing what its there for - applying braking torque. If part of your pad isnt touching, then whats the purpose of it being there? Another issue is with the manufacturing process and physical properties. A slotted rotor is thinner in some areas and although more structurally sound than cross drilling - it still weakens the rotor by providing a thinner section of metal in areas making them more prone to warping there. Another problem depends on if you get a more "economy" production. This means the fresh blank gets churned out in high numbers by a shop that isnt doing it for a quality name but the almighty dollar. In turn, they are cut too hard and too fast by the machine making metals first heat treating an uneven distribution. Its heat treated around and in the cut but the areas nearby dont get hot enough so the isolated spots modified the grain structure of the metal permanently but not all of it. This will also make them more prone to warping. Another problem with slotted rotors is they can tend to create an undesirable pulsating pedal feel by nature. The level is application variant (i.e. more big slots= more pulsing)
Cross drilling:
Cross drilling a rotor is a practice adopted probabbly 50 years ago when the materials for a braking pad were mainly a crude organic base. These pads when heated would produce a gas that would get trapped between the pad and the rotor and making a cusion of air keeping the pad from braking
MOST MODERN RACING PADS ARE DESIGNED WITH DIFFERENT METALLIC MATERIALS THAT ALMOST NEVER PRODUCE MORE THAN A FINITE LEVEL OF GAS
Cross drilling was created to give the gas an area to escape through. This means cross drilling a rotor is no longer needed in 99% of applications. Because of the previous need and the stylish benefits these are still widely sold and people are very misinformed on their need. Cross drilled rotors have a large amount of metal removed and suffer the same problems of slotting. This metal is not in contact with the pad so that is less overall available pad contact surface area for braking torque. This also means less metal available to absorb heat essentially functioning as if you had a smaller rotor. Problems with production on cross drilled rotors is they are drilled too fast causing the initial heat treating to be in isolated spots modifying the grain structure of the metal permanently. Another issue is when drilled it tends to create microscopic cracks in the surrounding area. This can cause severe issues and its been reported and photographed before to cause a rotor to actually CRACK IN HALF! If you feel you must have cross drilled rotors for looks dont get "economy" versions. The real cross drilled rotors have the holes actually CAST into the rotor and have a much lower loss in structural integrity.
Warped rotors:
This is another myth best explained by people who ACTUALLY produce application specific functional big brake kits: http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml
==Brake Lines==
Braided stainless steel lines are a great upgrade for any brake system with rubber lines. OEM brake lines tend to be a very soft rubber that expends slightly when pressure is applied. The expansion rate is not linear however so the impact on pedal feel from having them wont be either. Stainless braided lines have the metal reinforcement to deter expansion and result in a stiffer, more linear feel. When purchasing lines try to purchase ones with a plastic or similar outer sleeve protector. This way rubbing against the shock, etc wont wear through the stainless braiding and stays protected.
==Brake Fluid==
Using quality brake fluid is very important for any performance oriented driver. There are different classifications and rating systems by the department of transportation that determine the minimum dry and wet boiling temperatures. The higher the boiling temperature, the more likely you are able to resist high heat braking without gassing out the lines. Boiling brake fluid introduces air pockets instead of fluid which compress when pressure is applied vs the fluid. This means the pedal might sink to the floor but any line pressure isnt getting to the caliper! That can be very dangerous, and you can tell if your brake fluid is getting to the point where its been boiled by looking at it. fluid appears white if it has ever boiled and should be changed.
Dry / Wet boiling temp
DOT 3 401ºF 284º F POLYGLYCOL ETHER BASED FLUID
DOT 4 446º F 311º F POLYGLYCOL ETHER BASED FLUID
DOT 5 500º F 356º F SILICONE BASED FLUID
DOT 5.1 518º F 375º F POLYGLYCOL ETHER BASED FLUID
Dry boiling temp is the fluid in its virgin state. Wet boiling temp is the fluid + 3% water by volume.
Dot 3,4, and 5.1 are all intermixable without any negatives. Dot 5 fluid is silicone based and cannot be mixed.
Silicone fluid has its ups and down. It is non corrosive to paint unlike normal brake fluid, and it doesnt mix with water so its boiling temps stay the same (actually a negative) Since it doesnt absorb the water the water stays seperate. No brake system is completely sealed and will always absorb water. If the system absorbes water but it stays seperate you will hav 2 fluids, one of them with a very low boiling point (bad) Silicone fluid also has more compressability by nature and will cause a more "spongy" pedal feel.
Fluid sold in metal cans absorb water far less than plastic cans while on the shelves. A good common practice would be to change your brake fluid once every 6 months when your car sees alot of "spirited" braking, And bleed them well every change to be sure there is no air in the system. Bleeding before/after track events is a good idea to be sure your brakes are optimal for the event and you didnt boil your fluid during.
==Calipers==
When upgrading your brake system a larger caliper may be used to provide more braking torque. There are several deciding factors with caliper choice that impact the overall effectiveness. Increasing the overall piston diameter will distribute the braking force over a larger area and generally provide more clamping force whether going to a larger piston than stock in single piston designs, or migrating to a multi piston setup. Bigger and more doesnt always mean better however. Too much braking torque for your setup might mean you can lockup the tires from just tapping the pedal, and making an "on/off" feel impossible to modulate.
Choose a caliper appropriately sized for your tires and application used (just because you can lock all seasons doesnt mean you can stop efficiently on r-compounds)
Caliper mounting brackets determine the pad and caliper clamping location on the rotor. Think of it like a torque wrench... The farther out you brake the more torque you can apply to stop the car and the more overall surface area the pad will contact in 1 full revolution. It may be a sufficient enough upgrade to just get larger rotors and relocate your calipers/pads farther out by extending the bracket.
==Speed Bleeders==
(This one section on speed bleeders goes credit to DJPimpflex and was not my own)
An often overlooked part of the brake system is the installation of speed bleeders. These do nothing for performance, but everything for sanity. They make it so you can bleed the brakes efficiently and by yourself. All you do is crack them a 1/4 turn and pump away. there is a bearing inside the bleeder that every time you let off the pedal is returns in to stop air from coming in as well. Very worth while thing to do, epically if you plan on track racing your car.
=Stock Upgrades=
The stock s13 240sx front brakes are single piston units with 9.8" ventilated rotors. The rear is a 10.2" rotor and a single piston caliper with an integrated e-brake. These brakes are sufficient for most people and with appropriately upgraded pads/flud/lines. Rule of thumb if you can lockup your brakes then a larger brake caliper is not needed for the speeds and tire compounds your using. These brakes are more than adequate for daily driving and some track use, but once your start doing some serious racing you will need to upgrade parts appropriately to handle the heat and to avoid the dreaded brake fade. The stock brakes will be great for spirited driving and light track, But research your options and decide on an upgrade appropriate to you. Several factors need to be considered. Something with larger rotors is needed for more repetetive stops, and something with a larger amount of clamping force is needed if you are not able to push your current tires to the locking point (while using pads with an appropriate heat range).
(http://en.wikibooks.org/wiki/Nissan_240SX_Performance_Modification)
Before it gets tainted and torn apart with inaccurate information from the general public I wanted to post it here to preserve the information in its original form
*PLEASE* do not post useless posts in this thread. Please keep legitimate relavant inquiries in intelligent form if need be so this can retain a professional and informative feel. Anything I deem relavant I can go back up and edit the post to include.
When considering upgrading brakes several factors tie in to the end result. Many of these things you might already know but you might not consider all factors or know about all things mentioned here. Brakes should not be upgraded in front or rear only, the amount of applied braking torque should be increased proportionally front and rear for appropriate feel/bias (I.E. 6 piston front brakes with stainless lines up front and stock pads/lines in the rear)
I cannot emphasize enough how important bias is in a braking setup. Just being able to lockup your front tires easier does NOT mean you are now able to stop quicker!!
All the parts need to be considered in a braking setup to determine if its right for you!
==Master Cylinder==
If you get a larger or smaller master cylinder then for every inch of pedal travel more fluid will be pushed through the lines. Dont just go buying a random larger MC without knowing however, as these have internal valving that determines brake front and rear bias which will severely impact your braking performance.
==Pads==
There are many aftermarket pad companies that produce sport oriented brake pads. There are many different materials a pad may be comprised of, each having its own individual properties. This will impact dust creation & color, rotor & pad wear rate, and A very important thing: EVERY PAD HAS A HEAT RANGE. This means the pad will ONLY function optimally within a given set of temperatures. OEM brake pads are usually designed to function well in very cold temperatures to moderate braking. When you have had several large hard stops they heat up to a certain point and get out of their range causing the pad to not have the same braking torque and "glaze" the surface (A condition where the outermost contact layers properties change and it prettymuch polishes the mating surface causing it not to grab. This is PERMANENT damage to the pads!) There is a wide range of compounds from stock all the way up to full race. Note that a pad designed for full race will NOT grab sufficiently during daily street driving and you will be unable to stop normally! Get a pad that suits your driving style, either that or get 2 sets of pads and swap them out at the track.
==Rotors==
Rotors in a braking system do 2 things. They act as a heatsink so they absorb heat when you brake, and dissipate it normally from air moving over them. The larger the rotor, the more the metal. The more the metal, the more heat can be absorbed during braking and the more fade resistance your car will have. Stock brake rotors are blanks, this means that they are just a flat surface. This is the surface your brake pad will mate to and provides the largest total available clamping area per revolution. There are several different variations of the standard brake rotor that carry a general misconception in their execution. 1 of those is slotting.
Slotting: Doing this to a brake rotor does have benefits, but is more visually appealing than beneficial. Slotting a rotor provides angled slots along the surface that exist to help wipe the pad surface clean on every pass. This ensures a fresh pad surface at all times and it does in fact help protect a pad against fade since it always scrapes off the top layer. It also helps with water and debris evacuation.
There are several problems with slots however that outweight these benefits. One of them is the fact that part of the brake pad is not in contact with the rotor at any given time. This means a lower total square inch area of friction material doing what its there for - applying braking torque. If part of your pad isnt touching, then whats the purpose of it being there? Another issue is with the manufacturing process and physical properties. A slotted rotor is thinner in some areas and although more structurally sound than cross drilling - it still weakens the rotor by providing a thinner section of metal in areas making them more prone to warping there. Another problem depends on if you get a more "economy" production. This means the fresh blank gets churned out in high numbers by a shop that isnt doing it for a quality name but the almighty dollar. In turn, they are cut too hard and too fast by the machine making metals first heat treating an uneven distribution. Its heat treated around and in the cut but the areas nearby dont get hot enough so the isolated spots modified the grain structure of the metal permanently but not all of it. This will also make them more prone to warping. Another problem with slotted rotors is they can tend to create an undesirable pulsating pedal feel by nature. The level is application variant (i.e. more big slots= more pulsing)
Cross drilling:
Cross drilling a rotor is a practice adopted probabbly 50 years ago when the materials for a braking pad were mainly a crude organic base. These pads when heated would produce a gas that would get trapped between the pad and the rotor and making a cusion of air keeping the pad from braking
MOST MODERN RACING PADS ARE DESIGNED WITH DIFFERENT METALLIC MATERIALS THAT ALMOST NEVER PRODUCE MORE THAN A FINITE LEVEL OF GAS
Cross drilling was created to give the gas an area to escape through. This means cross drilling a rotor is no longer needed in 99% of applications. Because of the previous need and the stylish benefits these are still widely sold and people are very misinformed on their need. Cross drilled rotors have a large amount of metal removed and suffer the same problems of slotting. This metal is not in contact with the pad so that is less overall available pad contact surface area for braking torque. This also means less metal available to absorb heat essentially functioning as if you had a smaller rotor. Problems with production on cross drilled rotors is they are drilled too fast causing the initial heat treating to be in isolated spots modifying the grain structure of the metal permanently. Another issue is when drilled it tends to create microscopic cracks in the surrounding area. This can cause severe issues and its been reported and photographed before to cause a rotor to actually CRACK IN HALF! If you feel you must have cross drilled rotors for looks dont get "economy" versions. The real cross drilled rotors have the holes actually CAST into the rotor and have a much lower loss in structural integrity.
Warped rotors:
This is another myth best explained by people who ACTUALLY produce application specific functional big brake kits: http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml
==Brake Lines==
Braided stainless steel lines are a great upgrade for any brake system with rubber lines. OEM brake lines tend to be a very soft rubber that expends slightly when pressure is applied. The expansion rate is not linear however so the impact on pedal feel from having them wont be either. Stainless braided lines have the metal reinforcement to deter expansion and result in a stiffer, more linear feel. When purchasing lines try to purchase ones with a plastic or similar outer sleeve protector. This way rubbing against the shock, etc wont wear through the stainless braiding and stays protected.
==Brake Fluid==
Using quality brake fluid is very important for any performance oriented driver. There are different classifications and rating systems by the department of transportation that determine the minimum dry and wet boiling temperatures. The higher the boiling temperature, the more likely you are able to resist high heat braking without gassing out the lines. Boiling brake fluid introduces air pockets instead of fluid which compress when pressure is applied vs the fluid. This means the pedal might sink to the floor but any line pressure isnt getting to the caliper! That can be very dangerous, and you can tell if your brake fluid is getting to the point where its been boiled by looking at it. fluid appears white if it has ever boiled and should be changed.
Dry / Wet boiling temp
DOT 3 401ºF 284º F POLYGLYCOL ETHER BASED FLUID
DOT 4 446º F 311º F POLYGLYCOL ETHER BASED FLUID
DOT 5 500º F 356º F SILICONE BASED FLUID
DOT 5.1 518º F 375º F POLYGLYCOL ETHER BASED FLUID
Dry boiling temp is the fluid in its virgin state. Wet boiling temp is the fluid + 3% water by volume.
Dot 3,4, and 5.1 are all intermixable without any negatives. Dot 5 fluid is silicone based and cannot be mixed.
Silicone fluid has its ups and down. It is non corrosive to paint unlike normal brake fluid, and it doesnt mix with water so its boiling temps stay the same (actually a negative) Since it doesnt absorb the water the water stays seperate. No brake system is completely sealed and will always absorb water. If the system absorbes water but it stays seperate you will hav 2 fluids, one of them with a very low boiling point (bad) Silicone fluid also has more compressability by nature and will cause a more "spongy" pedal feel.
Fluid sold in metal cans absorb water far less than plastic cans while on the shelves. A good common practice would be to change your brake fluid once every 6 months when your car sees alot of "spirited" braking, And bleed them well every change to be sure there is no air in the system. Bleeding before/after track events is a good idea to be sure your brakes are optimal for the event and you didnt boil your fluid during.
==Calipers==
When upgrading your brake system a larger caliper may be used to provide more braking torque. There are several deciding factors with caliper choice that impact the overall effectiveness. Increasing the overall piston diameter will distribute the braking force over a larger area and generally provide more clamping force whether going to a larger piston than stock in single piston designs, or migrating to a multi piston setup. Bigger and more doesnt always mean better however. Too much braking torque for your setup might mean you can lockup the tires from just tapping the pedal, and making an "on/off" feel impossible to modulate.
Choose a caliper appropriately sized for your tires and application used (just because you can lock all seasons doesnt mean you can stop efficiently on r-compounds)
Caliper mounting brackets determine the pad and caliper clamping location on the rotor. Think of it like a torque wrench... The farther out you brake the more torque you can apply to stop the car and the more overall surface area the pad will contact in 1 full revolution. It may be a sufficient enough upgrade to just get larger rotors and relocate your calipers/pads farther out by extending the bracket.
==Speed Bleeders==
(This one section on speed bleeders goes credit to DJPimpflex and was not my own)
An often overlooked part of the brake system is the installation of speed bleeders. These do nothing for performance, but everything for sanity. They make it so you can bleed the brakes efficiently and by yourself. All you do is crack them a 1/4 turn and pump away. there is a bearing inside the bleeder that every time you let off the pedal is returns in to stop air from coming in as well. Very worth while thing to do, epically if you plan on track racing your car.
=Stock Upgrades=
The stock s13 240sx front brakes are single piston units with 9.8" ventilated rotors. The rear is a 10.2" rotor and a single piston caliper with an integrated e-brake. These brakes are sufficient for most people and with appropriately upgraded pads/flud/lines. Rule of thumb if you can lockup your brakes then a larger brake caliper is not needed for the speeds and tire compounds your using. These brakes are more than adequate for daily driving and some track use, but once your start doing some serious racing you will need to upgrade parts appropriately to handle the heat and to avoid the dreaded brake fade. The stock brakes will be great for spirited driving and light track, But research your options and decide on an upgrade appropriate to you. Several factors need to be considered. Something with larger rotors is needed for more repetetive stops, and something with a larger amount of clamping force is needed if you are not able to push your current tires to the locking point (while using pads with an appropriate heat range).