All that glitters isn't enough. Those dull master cylinders and brake calipers need brightening. You've worked hard to make your bike something special. You've changed the wheels, modified the bodywork, even done some motor work. Still, when you look at your handlebar, all you see are the stock master cylinders glaring from under those trick billet reservoir covers. Want to make a change that'll take your ride to the next level? Are you comfortable with striking out into the unknown? Can you handle some risk? Finally...do you feel lucky?
Welcome to the world of the hard-core customizer, a place where you put motorcycle components through processes they were neither designed nor intended for; a level of tinkering where it must be understood that if the process doesn't go exactly right the parts are ruined, requiring replacement. Again, for the sake of clarity (and to satisfy the lawyers amongst us), undertaking this project can yield beautifully chromed hydraulic master cylinders and calipers or useless junk—for no apparent reason other than, say, the phase of the moon. Failure to properly recondition the parts before returning them to service on the road can lead to brake failure, resulting in injury or death—maybe both.
Still reading? Great. Although he's asked to remain nameless for liability reasons, we asked a customizer whose work Motorcycle Cruiser readers are familiar with to take us through the project step by step to show the process and pitfalls of chroming brake and clutch master cylinders. Essentially, this is a three-step procedure. First, the parts are removed from the bike and completely disassembled. (Once again, we've enlisted our long-term Vulcan Classic as organ donor.) Next, the parts go to South Bay Chrome, our favorite chroming shop. Finally, the parts are reassembled and prepped for street use. As with any major work on your bike, a factory repair manual will be invaluable in producing a successful outcome.
1. Right away you'll notice that some of the tools needed for this job are not in everyone's garage. You have two options for removing the pistons from the calipers: The messy way is to leave the hydraulic line attached, take the caliper off the disc, remove the brake pads, and pump the lever until the piston pops out. (Remember: Brake fluid eats paint.) The more elegant way to remove the pistons is to take the caliper off the bike and force the piston out with compressed air. Do not use excessive pressure or you may be the victim of a painful surprise. Do we need to tell you to protect your hand with a rag or heavy cloth, and keep your fingers away from the inside of the caliper opening so the piston can't compress your fragile bones like it does the steel disc? We didn't think so.
2. Since you'll be handling brake fluid and other chemicals, now would be a good time to put on some latex gloves. Carefully remove the dust and fluid seals with a pick or dentist's tool. Remove the bleeder valve and all boots or rubber pieces. Wipe out the inside of the caliper completely. You don't need to clean it with chemicals, but make sure that the grooves the seals were in are clean and free of hydraulic fluid.
3. Pull the boot off the master cylinder piston with a pick by carefully hooking the pick under the boot's bottom O-ring. Rotate the piston's retaining clip toward the open side of the master cylinder. Remove the circlip with circlip pliers. (Push the piston in slightly to access the circlip.) Note (and write down) the order in which the parts come out of the piston bore, when the time comes to reassemble the master cylinder you'll be glad you did. Of course, if you refer to the factory shop manual, you will have any uncertainties clarified.
4. Now we arrive at the step that can turn the master cylinder into a paperweight for no apparent reason. Before the master cylinder can be chromed, the sight glass must be pressed out of the reservoir. Since sight glasses and master cylinders are sold as a unit, the sight glass must be removed without being damaged. According to our customizer, a 20-percent failure rate is to be expected. (i.e. Despite following these directions to the letter, for every 10 sight glasses removed, two will mysteriously fail.) The key to a successful sight glass-ectomy is a bolt that has been turned down on a lathe or belt sander so the head is round and just barely slips inside the sight glass' mounting hole in the reservoir. (In the photo on the right, note how little space there is around the bolt head once the sight glass is pressed out.) The bolt slips inside a socket or an appropriately sized piece of pipe, and by slowly tightening a nut against the pipe the sight glass is pushed out. If the bolt head is too small, it will press against the plastic lens instead of the tiny ring that holds the pieces of the sight glass together. Once the part is successfully pressed out, breathe a sigh of relief. If it came out in pieces, buy a new master cylinder and try again.
5. Spray WD-40 inside the piston cylinder holes, bleeder holes, banjo hole...basically any hole in any of the parts that a pin, or piston, or screw fits in. (This is not necessary, however, for the holes that only rubber boots use for mounting.) Chroming will add metal to the parts and they won't fit back together if chrome is allowed to build up inside them. Don't be stingy, WD-40 is cheap and will act as a release agent when the part comes back from the chromer. Starting with the grooves for the seals, inject a healthy bead of silicone all the way around the piston opening. Completely filling the hole with silicone is not necessary, but the silicone must be thick enough to plug the cylinder without any holes or gaps. Make sure holes don't form as the silicone dries and settles.
6. The master cylinders require special attention. Be sure the little holes in the bottom of the reservoir get filled with silicone or the chrome will ruin the part. Plug the piston hole right at the opening. Also plug all threaded holes for the reservoir cover and mounting bracket. Finally, wipe a silicone bead around the inside of the sight glass hole, or the sight glass will not fit once the parts come back from the chromer. One important note about silicone plugs and chromers: They hate the stuff and may tell you the parts can't be properly prepped or chromed with silicone in them. One chromer even told us the paint thinner(!) he uses to strip the parts would remove the silicone. Chromers, like South Bay Chrome, who deal with high-end customizers on a regular basis are familiar with this technique and use acids to strip the parts. (See "The Shining" in Motorcycle Cruiser, December 1996 for more info on chroming.) However, South Bay Chrome cautions that parts will be ruined if they're improperly prepped. Fair warning.
7. If you plan on having the Classic's adjustable levers chromed, they must be disassembled by straightening the rivet with a punch and hammer. Our customizer recommends Vulcan 1500A levers for a cleaner look and fewer headaches after chroming.
8. Once the parts return from the chromer break the seal of each of the silicone plugs with a scribe or dentist's pick. Next, depending on the size of the plug, carefully remove the plugs with either a pick or a pair of needle-nose pliers. Wear latex gloves and be aware that some of the acid used in etching the parts prior to chroming may have seeped past the seal. Wipe any chemicals from the metal before it has a chance to damage the chrome. Make sure all of the silicone is removed from the part. The crossover pipe between pistons on multipiston calipers is a commonly overlooked area. If you notice that any internal parts (like the piston holes) were etched by the acid, gently clean the metal with extra fine Scotchbrite. Try not to remove any surface material. Double- and triple-check the part to make sure little chunks of silicone aren't left behind.
9. You will need a set of metric taps (A name brand, like Craftsman, is recommended.) to remove the last vestiges of the silicone and "chase" any of the threads that may have been fouled with chrome. Be certain of your tap selection. The wrong size will ruin the part. Double-check each step before moving on. From this point on, a slow and meticulous attitude is required for successful results. Although customizers occasionally overlook prepping a part, requiring the master cylinder to be disassembled, the most common mistake is to not thoroughly clean after chasing the threads. A metal shaving as small as a grain of sand could cause your brakes to fail.
10. Two steps that separate the amateurs from the pros: Using a drill bit that can hold a piece of Scotchbrite or sandpaper, clean up the inside of the master cylinder's piston bore to ensure trouble-free operation. (below) Clean the two small holes in the base of the reservoir. First, insert a single strand of wire to clear the hole. Next, twist a pair of wire strands together and swipe them like a brush in and out of the holes. Do not use a drill bit or attempt to enlarge the holes in any way. Cleaning the holes is essential to proper brake operation. These holes feed brake fluid to the master-cylinder piston when brake pressure is applied, and allow pressure to release when the lever is freed. If either of the holes are blocked, the piston could either cavitate (leading to poor brake power), or cause the pads to drag (resulting in overheated brakes and system failure).
11. Since chroming adds several layers of metal to parts, the lever will not fit inside the master cylinder's pivot. Using a belt sander with 100-grit paper, sand through the chrome and copper until bare aluminum is revealed. You will also need to sand the lever to achieve a nonbinding fit. Stop to check your progress a few times. You don't want to sand away too much metal. The chrome may peel back as you sand through, so always make sure the belt is sanding toward the rear of the lever so any peeled chrome will be hidden by the master-cylinder pivot. The lever's pivot hole also needs to be "hogged out" slightly to allow the stock bolt to pass through. Finally, be certain to file down to the aluminum on the lever stop. If this chrome is not removed, the piston will be slightly compressed past the reservoir's return hole, preventing the caliper piston(s) from releasing.
12. Thoroughly clean all parts with acetone and then let air dry. (Or speed the process with compressed air.) Place the sight glass's O-ring into the reservoir, and place the sight glass into the hole. Place a 17mm socket over the glass and tap gently until the glass seats into position. Wipe the master-cylinder piston and bore with clean brake fluid, then reassemble according to the factory manual's specifications. Lubricate and reassemble the calipers in the same manner.
13. Now you will realize why a 1500A lever is desirable. Go to a hardware store to find a thinner washer to replace the one on the adjustable lever's pivot. Reassemble the pivot with the spring washer underneath the new thin washer. Take the backside of a ball-peen hammer and place it in the rivet you loosened to disassemble the lever. Tap another hammer lightly on the ball-peen hammer to spread the rivet. Finish the operation by tapping the rivet flat with a hammer.
14. Here it is—the fruit of your labor. Now mount the parts and bleed the brake system according to the factory manual. Remember, this project requires patience and thoroughness. If you're rushed or sloppy you may discover a problem the hard way. Include your hydraulics (particularly the sight glasses) as part of your daily safety check, since you have modified parts that are essential to your survival. Still, once you get these shiny bits on your bike, you'll say it was worth the effort.
For more articles on how to maintain and modify your motorcycle, see the Tech section of MotorcycleCruiser.com.