Them's the brakes... To begin, Im not going to deviate much from standard, safe brake service practices mostly cause I dont want some tool who doesnt understand the concepts of personal responsibility or common sense to sue me. Brakes are important shocker huh? I bet you thought brakes were really handy for things like stopping and stuff but Im here to tell you how important brakes are for going fast. Im saving that part for last no jumping ahead now. This is not going to be too KTM specific, but I will be using my own bike for photos and descriptions. I think anyone can look at a Honda, Kawasaki, Husqvarna or Suzuki and see similarities. KTM brakes are made by Brembo, but that only makes them good quality pieces not unique or appreciably different from anything else. Brake systems on DS bikes are all very similar. Most, if not all, use floating calipers and fixed rotors rather than fixed calipers and floating rotors, so most all will have guide pins, rubber boots and bushings. A floating caliper is simply a caliper that can move laterally so that when the brakes are applied it can self-align, or center itself over the rotor to apply even clamp loads, produce even pad wear and reduce excessive caliper piston exposure. The down sides to floating calipers are that they tend to have a bit of vertical and horizontal play. The vertical play is most noticeable and can be identified by pads that are worn diagonally on the vertical axis. The other downside is that they require service occasionally to clean and lubricate the guide pins, bushings and boots. Ignore this service and it can cause premature wear or failure of the rotor, caliper body bore and piston and of course, the pads, guide pins, bushings and boots. Lets start with a visual inspection, which should be performed every time you go for a ride. OK at least every time you fill the fuel tank. OK fine as often as you can remember. 1. Pre-ride brake inspection A quick pre-ride brake inspection consists of: Looking at your rotors to see if they are discolored or scarred and still have all their mounting bolts. Looking at your pads to determine they have an adequate thickness. Operating your brake lever and pedal to insure you have normal pressure, return and free travel. Thats about it takes maybe a minute to do. If you find something that doesnt fall into normal or acceptable parameters, it will probably take longer than a minute to correct but thats nothing compared to the potentially nasty, painful alternatives if you blow it off and go for a ride anyway. Am I the voice of doom? No, not really, cause lets face it, modern brakes are pretty reliable and for the most part trouble free, so if you do actually find something wrong, chances are there really is something wrong, and really needs your attention... now!. :eek1 2. Pad replacement I suggest that you have an owners manual, shop manual or parts book that shows all the individual parts of the caliper so you know what parts youll be dealing with, where they go and how they relate to one another. For tools you will need needle nose pliers to remove pin security clips and for KTM LC4 rear brakes you will need a drift or punch and a hammer to tap out the pad guide pin from the caliper body. It has a tension collar on it that is a press fit into the caliper. A good flashlight so that you can see inside the caliper and locate the position of the guide plates and how the pad ears engage them is a good idea. Simple pad replacement is usually quick and easy. In most cases it is not necessary to remove the wheel or caliper. In fact, many brake systems could be considered to have quick change pads. Usually when you change pads you will be replacing thin worn pads with new thick pads. To increase the space needed to fit new pads you need to push the caliper piston back into its bore. There are lots of ways to do this, but the safest and least destructive is to simply apply pressure to the outside of the caliper. Your knee, a block of wood, the handle end of a hammer pretty much anything that will apply pressure without scaring up the caliper body. Your head if it suits you. Once youve pushed the piston back into the caliper body, you should have a sufficient amount of space to fit new pads. While the pads are removed DO NOT TOUCH THE BRAKE PEDAL OR LEVER. Rear: To remove the rear pads on a Brembo/KTM rear brake all you need to do is remove a single pin security clip (1), tap out a pad guide pin (2) from the outside and remove the pads. Front: To remove the front pads on a Brembo/KTM front brake you must remove two security clips, pull the pin and pull the pads. If you feel the area is a little too small and crowded for your fingers, go ahead and remove the front wheel assembly to give yourself a bit more room to work. While you have the pads out, inspect them for abnormal wear. The pads should be worn down evenly. If the pads are worn diagonally either on the vertical or horizontal plane, you may have other issues to contend with. More on this later. :huh Inspect the guide pins for grooving, scars and bends. Replace them if they have any flaws that would cause the pads to hang up or stick. Using a flashlight, inspect the guide plates inside the caliper mount for wear, scarring and general condition. Replace them if they are suspect and available as a separate part, not the case with KTM. If you do not have sufficient clearance to insert the new pads, use something that will do no harm to the rotor or caliper piston should you have to lever the piston deeper into it's bore. I have a piece of copper rectangular bar stock, about 3/16" thick that works great. Use a screwdriver and take a chance on doing some damage. To install new pads, insert the ears of the pads into the steel guide plates, rotate them into alignment with the caliper body pin holes and reinsert the pins. Once you have the pins installed and before you seat the pins or reinstall the security clips, visually inspect your work to ensure that the pads are correctly and completely engaged in the caliper guide plates. Having installed the new pads, apply pressure to the brake pedal/lever several times to pump the high pressure portion of the system back up and re-extend the piston out of the caliper body. Make sure you do this before you go for a test ride if you dont you will have absolutely no, as in zero, none, nada brakes. Check your fluid levels to insure they are not under or over filled. That should be it pretty simple stuff. If youve encountered any problems or have questions, read on. 3. Annual caliper D&R inspection As floating calipers move back and forth on metal pins supported by rubber bushings, they will need to be serviced now and again. At least once a year I like to pull the calipers, remove the rubber parts, clean, inspect and lubricate them. Its not a difficult job, maybe a little time consuming and a little funky but not difficult. Some of the tools you will need are a can of brake cleaner spray, a can of silicone spray, a tube of silicone high temperature brake grease and assorted Q-tips, punches and maybe a brass bristle brush. All of the above can be obtained at most auto parts stores. Dow Corning Molykote G-series greases are designed for this application. Addendum: 8-27-06 Something I didn't pay attention to, but was brought to my attention in a round-about way by Braaap!... The KTM rear brake carrier is not available as a separate part! If the component parts on it are worn or damaged, your only recourse for a new part is to buy an entire rear caliper assembly! Rear Brake: For the rear brake, you will need to remove the wheel, slide the caliper and carrier forward and slip the carrier off the swingarm. By pulling, you can separate the caliper from the carrier. Inspect the area around the caliper piston for leaks or dirt/mud build up. An old, soft tooth brush is a good tool to clean the area around a brake piston. There may be a plastic cover over the outside of the brake piston. This is a thin and relatively fragile part the covers the hollow cavity of the piston. Pistons are hollow to reduce weight and aid in keeping the piston true in the bore when it is extended out of the bore. The cover is there to prevent water (and crap in general) collection hot brakes could boil the water and cause the brakes to lock from pressure. Typically, you will have two guide pins and at least one rubber bushing or bushing/boot combinations. If the bushings are of the thru type like the one on the rear of a KTM Brembo rear caliper, make sure you remove it in the same direction it was originally installed. If you try to remove a bushing by pulling on the open end, you may rip it. Clean and lubricate the bushings and/or boots with a generous application of silicone spray and set them aside. Inspect the caliper carrier for wear and tear in particular the guide plates, slider pins and in the case of the KTM LC4 carrier, the upper guide pin bore. As the guide plate and slider pin are not available separately, taking care of these parts on a regular basis will ensure that youre not buying a new carrier assembly every few years. Clean out the bore of the carrier with brake cleaner and a plastic bristle brush or Q-tip. Clean the guide pins and guide plate with brake cleaner and if necessary, a brass bristle brush. Apply a small even amount of silicone grease to the inside of the pin bore and to the outside of the guide pin. Set the carrier aside. The process on the caliper is done in a similar fashion, inspect, clean and lubricate bushings, boots and guide pins. Once everything is clean and lubed, reinstall the rubber bushing with the closed end in the same direction you removed it. A bit of silicone spray on the outside and in the caliper bushing bore makes this an easy job I use a flat nose punch with rounded edges to re-install this bushing. Now you can install the rubber boot into the caliper carrier, slide the two components together and re-install the assembly on the swingarm. Thats it reassemble the wheel into the swingarm, install the brake pads after that, align the wheel and set the chain slack you are done with the rear brake assembly. Front Brake: The front brake on a LC4 uses the exact same bushings and boots and is removed, inspected and cleaned in the exact same fashion as the rear caliper, with one exception the caliper carrier is either fixed to the fork, or in the case of the 640 Adventure uses an extension piece for the 320mm rotor application. Removal is not a requirement unless you chose to do so. Do your pads look like these? These pads are worn diagonally on the horizontal axis, the most likely cause of this type of wear is rear wheel misalignment. Once the rear wheel is correctly aligned, you will want to replace the pads, even if they still have a good amount of material remaining to realign the caliper to the rotor and eliminate any angular loading on the system. These pads are worn diagonally on the vertical axis, indicating the caliper is at an angle. This is not an uncommon wear pattern for a caliper that is supported on rubber bushings. The clearance involved can make wear such as this inevitable. 4. Bleeding The method used for bleeding brakes can vary depending on what tools, if any you own for this job. If you own an air compressor operated pressure bleeder, chances are you dont need to read this and know exactly what youre doing... or you just like to own expensive, dedicated tools that you have no idea how to operate. We will focus on the two most common methods of bleeding using the brakes themselves for bleeding, or using an inexpensive tool like a MityVac manual pump. When we talk about bleeding brakes, we are talking about two possibilities. One, you have air in the system, as indicated by a soft or mushy lever/pedal feel and poor braking performance... or two, you are flushing the system completely to replace old, probably contaminated fluid with new. The symptoms of old fluid are much like those of air in the system a soft or mushy lever/pedal feel and poor braking performance. The third possibility, building and filling a new brake system from scratch is more likely for maybe a SuperMoto guy than a DS guy, and it's not much different from a flush, other than getting fluid into the system to begin with. Preparation To manually bleed brakes you will need a wrench to fit the bleeder valve, a piece of, preferably clear, hose that fits the bleeder valve snugly, a clean collection bottle and a fresh bottle of the appropriate brake fluid DOT 3, 4, 5.1 will be the most common, but there are still a few bikes that use DOT 5 silicone fluid. Check your manual for the correct fluid for your application. If you tend to be a sloppy kind of person, you may want to cover the painted parts of your bike with a tarp or some big trash bags brake fluid can damage paint and seat vinyl. For front or rear brakes, you need to position your bike in such a way that the master cylinder is upright and in a vertical orientation dont want brake fluid spilling all over do we? See covering bike. Install the clear tubing on the bleeder valve and crack the valve loose with the wrench then lightly re-seat the valve back into the caliper. If the bleeder valve is not un-screwing too easily, chances are its corroded in place, or some ham fisted twat has over-tightened it. A bit of penetrating oil should (I hope) loosen it up. Have the bottle of brake fluid sitting near by within easy reach. If you are doing a front brake, it sure is nice to have a bit of help unless you have really long arms. If you are doing a front brake and dont have help, you will need to find a way to apply pressure to the brake lever while you are bleeding the system. OK, lets get this show on the road you can go ahead and remove the master cylinder cap or cover and the rubber gasket/accumulator. The process For front brakes, slowly pull your front brake lever several times to build pressure in the system and hold it. We do this slowly so you dont squirt fluid all over the place via the bleed hole in the bottom of the reservoir. Now crack the bleeder valve and watch the fluid flow from the caliper into the bottle. If you see bubbles this does not mean you had air in the line, it only means there is air in the hose, or the hose isn't that good a fit and drawing air in from the end. Close the bleeder valve while you still have lever pressure if you fail to do this, air may be drawn back into the caliper. Repeat this process a few times, watching the fluid level in the master cylinder. Refill the master cylinder reservoir as needed to maintain a level. If you forget, and drain the reservoir congratulations, now you really have air in the system! :huh Rear Brakes are very much the same as fronts except they usually have a remote reservoir and dont require that you operate the pedal slowly and rear brakes can usually be done alone. Using a manual pump A manual brake bleeding pump such as a MityVac can be purchased for as little as $50. What it does is use vacuum to pull fluid from the system rather than pressure from the master cylinder to push fluid thru it. Some of the more upscale units can also apply pressure thru the caliper to back-bleed the system this is essentially bleeding brakes back-wards and can be useful for getting rid of a uncooperative air bubble that thinks it has found a permanent home. Probably the best things about manual pumps are they make the job cleaner and easier. Pull the pump lever to create a vacuum, crack the bleeder valve just as before, and watch the fluid be pulled from the system... want more fluid? pull the lever a few more times. Top off the reservoir as needed and after a few cycles youre done. 5. Rear brake pedal adjustment. On most rear brakes you have two adjustments. One is for pedal position and the other is for pedal free travel. These adjustments are interdependent and very important. How many times have you heard someone talk about the rear brake locking up, or a rear disc that is scarred and blued usually accompanied by pads where the only thing left is the metal backing? More often than not, this is caused by a lack of pedal free travel. What pedal free travel actually means is an amount of pedal free movement before the pushrod actually comes into contact with the master cylinder piston. Without free travel, a small amount of pressure will be applied to your brakes at all times. Heat will be generated, fluid will boil, more pressure, more heat and so on and so on. Crashing usually ensues. KTM calls for 3-5mm of free play in their LC4 rear brake system. This measurement is taken, according to the manual, at the centerline of the brake pedal pad itself. Too little and the brakes will drag and over heat too much and the pedal travel may be excessive for proper application. To adjust your brake pedal and free travel, begin by loosening both the pedal position eccentric screw and the brake rod jam nut. If the rod, jam nut and heim joint are corroded, you may need to remove that assembly entirely, disassemble and clean it so that it can be turned easily. Using the eccentric, position the pedal so that its easy to contact, but not so high that you rest your foot on it another cause of brake drag by the way. Now adjust the brake rod length by moving the heim joint in or out of it to change the OAL of the rod assembly. Adjust the rod so that you have the requisite 3-5mm of free travel, as measured at the pedal, before the rod comes into firm contact with the master cylinder piston cup. You may want to fine tune this adjustment to suit your riding style and "feel" just make sure you have the minimum of 3mm free travel at the end of the process. Im a bit of an odd duck in that I have slightly more free travel than what KTM calls for at about 6.5mm. What can I say? It works for me. 6. A few Tricks Sorry, only one trick that comes to mind that I havent already mentioned in the guide. If you have symptoms of air in your front brake and are unsuccessful in correcting it by bleeding, you can use gravity and time to remove the air. Air tends to get trapped in the top of the brake line because the line is usually higher than the master cylinder itself. Conventional top to bottom bleeding often times doesn't work... especially when doing it by hand. If you unbolt the master cylinder and hold it above the brake hose, the air can rise up (or fluid flow down) and move into the master cylinder. You may have to leave the master cylinder in this position for several hours... or overnight. Once the air is in the master cylinder bore, all you have to do is position the master cylinder so the reservoir is above the bore and slowly, gently pull and release the lever a few times and the bubble will find its way into the reservoir... never to mush up your brakes again. Thats all I have for now hope it helps and clarifies for them what need help and clarification. If I've overlooked or failed to go into sufficient depth of a particular aspect of brake systems service... Bummer for you huh? ____________________________________________ How can you go faster by using your brakes? Simple... How often have you come into a corner, downshifting, applying your brakes... thinkin' you're all that and a bag 'O chips, and some guy smokes past you like you were chained to a stump? The reason he (or she) could do that... not overshoot the corner and go flying off a cliff is that he uses his brakes better than you do. If you use your brakes to their full effect, you can go into corners faster, get on the brakes later, scrub your speed, set up for the apex, grab a big handful of throttle and punch out of the corner like you wuz shot from a gun. Sometimes the guy that finishes first is the guy not with the most power, but the guy who can use his brakes to best advantage. To print a copy of this guide, go to the top of the page and click on "Thread Tools" then click on "Show Printable Version" C... Addendum: 8-29-06 For them interested in going beyond the scope of this basic guide, there are a few posts that have additional information provided by other members. Post #19 by Stephen regarding brake caliper design and function. Post #40 by Spagthorpe on issues he's encountered with a MityVac bleeder. And post #50 by Neduro on cross-drilling the banjo bolt(s) to eliminate a possible air bubble "hidding spot".