davemosstuning

FRONT BRAKE CALIPER CLEANING

How often should you clean your brakes? On a car we never do it and we transfer that logic and practical experience over to the bike. In truth, we should clean the brake calipers and pistons plus hardware (pins, springs and clips) every month on a commuter bike, every couple of track days on a track bike and daily on race bikes. Shocked?

How much do we depend on or front brakes? How much braking force do the front brakes have over the rear? How often do you use both brakes in your average ride? Take a moment to think that through. Clean and perfectly functioning brakes should be top of the maintenance list.

Before you start this job, you have to determine how far you are willing to go:- a light clean or a full on tear down? A tear down will require you to have a service manual and all the right tools, plus a lot of time and of course, a complete brake fluid change that adds more time. It may also require the installation of oil and dust seals so prepare completely if you are going for the full meal deal!

For this article, lets cover the basics that anyone can do quickly and simply. Task number one? Acquire a toothbrush, preferably not that clapped out one you have in the bathroom. If we are being picky it needs to be a medium bristle (yes we have experimented to save you wasted time). You will also need Simple Green or equivalent, a bottle cut in half to hold sufficient water, dish washing soap, rubber gloves and paper towels.

You DO NOT need brake clean or other equivalent fluid. Huh? Brake clean over time and use dries out all the rubber dust seals and can do the same to the oil seals, eventually causing cracking. It also removes any lubrication between the oil seal and piston causing drag – not a good thing!

If the bike is on a center or rear stand you can start with any caliper, and if you have the side stand only start on the right side and make sure the bike is in first gear. Only remove one caliper at a time or you will have a huge mess to clean up and a big job to do including putting pistons back in that fell out!

Assemble the tools needed, soapy water, toothbrush, towels and get those rubber gloves on.

Examine the caliper to see how the brake pads are retained? Is it a pin with an ‘R’ clip, an allen bolt, spring retainers? Are there any pins? Do the pads anchor in the caliper a different way using a cast pin as part of the caliper? Not sure? Get your service manual out and look. You may need to remove the brake pins/clips before you unbolt the caliper so be thorough to avoid starting over!

Once you have the brake pins ready for complete removal (but keep them loose in place), remove the bolts holding the right brake caliper to the fork. Gently remove the caliper without scratching the wheel and note that you may need to use the rotor to push back the pads to do this. With the caliper in hand, remove the locating pins and pads and place them on the floor in the position they came off. Pads will wear a certain way therefore if you have 4 pads or more it is important to put them back in the same position. At this time look at the pads carefully:
• are they wearing evenly or not?
• is one side thicker than the other?
• is there an angle to the wear front to back?
• are the pads discolored?
• is there any unusual scoring or deformation
• should the pads be replaced?
• Is there a backing plate attached?

If wear is uneven, you may have a sticking piston or the front wheel is not aligned properly and is not centered (yes that is possible), or a fork leg is pinched. Look for the article on aligning a front wheel to correct this problem.

Hang the caliper with a bungee cord or let it dangle and clean the retaining pins, clips or springs completely. If it has been quite some time since the caliper was cleaned liberally soak it in Simple Green.
Feel free to use a scotch brite pad gently on the pins/clips to remove any hard packed brake residue. Also examine the pins for any grooving and if you see evidence of that, you need to replace those pins as it will cause the pad to hang up and you lose effective braking force. Once the pins and clips or springs are completely cleaned, set them aside with the brake pads.

Now it is time to do the worst part of the job. Be prepared if this is the first clean to do this for 10-15 minutes or more. Every clean thereafter will take 2 minutes tops. Don’t short cut this work! The brake calipers should have been soaking in Simple Green or equivalent for 5 minutes or so.

Put on eye protection.

Make sure there is a lot of dish soap in the water container, around 20% by volume. Get a big towel in hand and hold the caliper in it. Brush semi aggressively with the tooth brush around the entire caliper frequently dipping the brush in the water container. If they are really bad, get fresh water and soap and keep going. Eventually you will reach the point where the calipers are pretty free of grime and debris inside and out.

Is your other caliper bolted in place? Continue!

The next step must be done carefully while looking at the caliper in hand. Squeeze the brake lever until one or more pistons start to move. The goal is to get the piston to protrude 2mm further out than its resting position to clean more of it and to see if there is “scum line” or debris line built up at that point. You may find that only one piston moves, so clean that one and then push it back to its original depth and hold it in place. Push the brake lever again a couple of times and see what piston moves next. Clean that one and then hold both pistons in place if you have four or six pistons. The next time you push the lever, the remaining pistons should move out. If not and three pistons need to be held you will need to recruit help to push the brake lever or put the brake pads back in with all pins etc and use a screwdriver on the back of the pads to hold the pads away from the offending piston, then push the brake lever.
Once all the pistons are cleaned completely and move freely, rinse them with clean and very soapy water (the soap acts as a lubricant for the piston). Push the pistons back into the caliper slightly and see if all of the pistons move evenly when you push the lever? If not, clean the offending piston again and repeat as needed.

Next, take a look at your brake reservoir. How much of an air gap do you have? Gently push the pistons back into the caliper and keep an eye on the fluid level. You need to get them back to the initial setting or push them further back in if possible. Refit the brake pads, pins and clips or springs and double check your work completely to ensure the pads are back in the right place correctly positioned along with all hardware.

Refit the caliper in place and set the bolts to finger tight. If you have allen bolts holding the pads in place, torque those now to the correct spec.
You can now move on to the left caliper and repeat the entire process. Once you are done with the left caliper there’s one final step.

Non radial brakes
- use the kick stand and get the front wheel into the air
• have someone spin the front wheel and pump the brakes. Once you have full pressure and the wheel stops immediately, hold the front brake on and put the wheel back on the ground
• visually check that the caliper pistons are evenly spaced
• hold the front brake on and tighten all caliper bolts to spec (this will take 2 people)
• spin the wheel to make sure it spins freely
• if it doesn’t spin freely, check the rotors for warping and look up the front wheel alignment article and follow that process

Radial brakes
- use the kick stand to get the front wheel in the air
• have someone spin the front wheel and pump the brakes. Once you have full pressure and the wheel stops immediately, hold the front brake on and put the wheel back on the ground
• visually check that the caliper pistons are evenly spaced
• tighten all caliper bolts to spec
• spin the wheel to make sure it spins freely
• if it doesn’t spin freely, look up the front wheel alignment article and follow that process


Video Links:
http://www.youtube.com/watch?v=Sbr7Eo4RSvo
http://www.youtube.com/watch?v=LtXlqbbeg74