Performed A Brake Flush lately?

This page will show you how to perform a brake flush on a dirt bike in a way you may not have seen before, and if you haven't done anything like this lately, just know that doing so could give you an advantage getting into the first turn, and reduce recurring brake fade while you're at it.

Although this page is primarily directed toward those who race dirt bikes, the following techniques can be used by non racers alike. The following tips are good for not just routine maintenance alone but as a performance enhancing tip for your brakes, as well as an effective and better method to bleeding the brakes after replacement of a brake line or other component. Bottom line is: Performing a brake flush as described in the steps below will make your brakes so responsive you'll likely be asking yourself why you didn't do this before now.

Just to help make things easy to find on this page, there are 4 main sections that you can go to directly by clicking the appropriate link below:

• Some things you need to know first
• Beginning with the front brakes
• Bringing up the rear
• Some other things for you to know

If you're racing, whether it be Off-Road or on a Motocross track and you're interested in winning (as most of us are), an important thing to remember is this:
The one who is brave enough to hold the gas on the longest with a good start, at the start before shutting off can usually get an edge going into the1st turn, and your probably already aware that this never hurts the outcome of the rest of the race.

Now that you know that, check this out:
After performing a brake flush you will likely have brakes that are stronger and more responsive than you ever thought possible and a good way to get ahead of everyone going into the 1st turn is to stay on the gas a split second longer, then out brake everyone so I'm going to show you how to do a brake flush on a dirt bike here in just a second that will help make this possible.

You may not have ever heard of a method similar to what you're going to see below for bleeding brakes or flushing brake fluid but trust me on this, I suggest you forget all the other methods you've used or heard in the past and use the methods outlined below for performing a brake flush and you will likely have an advantage on everyone else on the starting gate or in the woods and the best part if you race is, No one can protest this.

Some things you need to know first

• The brake fluid used in a brake flush must be exactly what the manufacturer recommends and coming from a new unopened container. You will notice on the original cover of the master cylinder reservoir it states the type of brake fluid to be used which is probably "DOT4". There are a myriad of "High Performance" brake fluids available, but readily available brake fluid you can safely use with excellent results is available at most auto parts stores and is labeled "DOT3 & DOT4 Synthetic Brake Fluid".
• During a brake flush, If you run out of brake fluid do NOT reuse any brake fluid that has already been through the system no matter how clean it appears, You're just going to have to stop and go get some more.
• Brake Fluid is Hygroscopic. Hygro what?? Yea, "Hygroscopic". This means that brake fluid sitting in a container that has been previously opened will absorb airborne moisture effectively ruining the brake fluid, therefore this is why it's been recommended by manufacturers to not use brake fluid from a container that has previously been opened. Brake fluid's hygroscopic characteristics are another reason why a routine brake flush is such a good idea and should be performed more often than you likely do so.

  Check this out:
  If you've ever overhauled or disassembled a brake caliper or master cylinder and seen the white buildup that forms inside these components, you may not know it but that is corrosion of the aluminum parts from moisture accumulation that forms from naturally occurring condensation in the brake system which over time will destroy brake components due to pitting of the components.
  Sorta sounds like another reason to perform a brake flush doesn't it?

• Brake Fluid will damage the paint on anything it is left in contact with, so if you're getting sloppy and there are painted parts or surfaces nearby, be sure to rinse the affected areas well with water when finished performing a brake flush.
• When servicing the front brake master cylinder you should be expectant of the heads of the screws securing the cover to the master cylinder to "Round out" even while using a proper size screwdriver, leaving the screws difficult to be removed, but there is a tip for addressing this problem here that you might want to look at before you begin, Let me just add that if you need replacement screws and don't want to wait for special order screws to arrive, the proper size can usually be found at most hardware stores, just tell them you need some countersunk phillips screws that are 4mmX12mm as these will fit most dirt bikes perfectly.
• A brake flush is best done after washing the dirt bike followed by drying of areas using compressed air as detailed in the article on washing a dirt bike and before removal of either master cylinder cover or loosening of a bleeder at a caliper, it is very important that the areas around the master cylinder reservoirs and bleeders are clean, Very Clean, since even the smallest particle of dirt in the wrong place can lead to brake fluid bypassing seals in the master cylinder or caliper leading to inadequate brakes or total brake loss.

Beginning with the Front Brakes

• Before you begin a brake flush up front it may be necessary to re-orientate the front master cylinder so the reservoir is level before removal of the reservoir cover so as to prevent the fluid from running out of the reservoir upon removal of the cover, as well as during filling with fresh fluid. This can usually be done by simply turning the handlebars if the riders lever position is not at an extreme angle.
• Once the area is clean around the master cylinder, and the reservoir is somewhat level, remove the reservoir cover carefully as to not allow any contaminants that may be trapped between the body of the master cylinder reservoir and the cover to fall into the reservoir's fluid supply upon removal of the cover.

Once the cover is removed...

• Using just your finger (without a rag) wipe the rim area of the master cylinder reservoir in a way that will direct any contaminants (Sand particles etc) away from the fluid supply.
• Next... If possible, use a vacuum source (A common syringe or baster works well for this if a vacuum pump is unavailable) to remove the fluid presently in the reservoir, being careful to not suck it dry uncovering the port(s) where the fluid supply to the master cylinder piston is located. Once the majority of the fluid is removed from the master cylinder reservoir, refill the reservoir again, repeating the process of removing the fluid as a way of flushing the reservoir.
• Now, fill the reservoir again with brake fluid so the fluid level in the reservoir is above the "Max" line and there is plenty of fluid available when starting the brake flush process.

Note: It is very important that during the brake flush process that the brake fluid level in the reservoir does not get so low in the reservoir that the port in the bottom of the reservoir is uncovered, as this could allow air to be introduced into the brake system resulting in you being at this all day and into the night trying to restore adequate performance of the brakes.

If the brake fluid does run out and you end up with no pressure at the lever or pedal and you are not in a rush, allowing the dirt bike to sit overnight with brake fluid in the reservoir and the bleeder(s) closed will usually allow pressure to develop and allow you to continue with a brake flush until optimum pressure is achieved.
• Next, Using the proper size box end wrench (Most likely an 8mm or a 5/16" is equivalent) slip the box end over the brake bleeder on the brake caliper, followed by adding a length of clear vinyl tubing to the bleeder nipple, then routing the tubing into a suitable drain pan or an empty water bottle works good, as these can be positioned in a way that you can monitor the amount of brake fluid that has been flushed through the brake system.
• Once you have the tubing attached to the bleeder, carefully open the bleeder about 1/4-1/2 of a turn watching for brake fluid to begin running out. (If you are having trouble loosening the bleeder see the tip for this here)
  Do NOT squeeze the front brake lever during this procedure. Once the brake fluid is running through the line grab a plastic hammer and gently tap on the caliper starting near the bottom and working your way towards the top, gently striking the caliper and directing the "Hits" in an upward direction. If you do not have a plastic hammer, then use of a wooden hammer handle can be used. Doing this will cause any air or old fluid that may be trapped in the area around the pistons to be dislodged and come to the top where the bleeder port is. I recommend you continue this process until a generous amount of brake fluid has been flushed through the line while continually topping off the reservoir during this process.

Note: If no brake fluid exits from the brake bleeder after a few seconds of the bleeder being "Open", it may be necessary to remove the bleeder from the caliper, and using a stiff piece of wire or a pick, along with brake clean and compressed air, clear the orifice in the bleeder of any obstructions, then reinstall the bleeder in the caliper leaving it about 1/4th to 1/2 of a turn from bottomed so as to allow fluid passage, then continue with the brake flush process.

• Once you have flushed a generous amount of brake fluid through the brake line and the reservoir is full carefully monitor the reservoir level with the bleeder open closing the bleeder when the level falls to between the "Min" and "Max" marks.
• Now, with the bleeder closed tightly, carefully squeeze the front brake lever checking to be sure you have a firm lever, If a firm feel to the lever is not felt, continue to follow the steps outlined above until the lever is firm again.
• With the brake fluid level at the proper height (Between the "Min" and "Max" marks), The bleeder tightly closed and a firm lever ensure that the reservoir cover and gasket / diaphragm are clean by cleaning with brake clean followed by drying with compressed air then reinstall the cover.

Once you're done with the brake flush and everything is back together, it's a good idea to recheck the bleeder to ensure its tight, then rinse the area of the master cylinder and caliper with water, finally using compressed air again to dry everything and clear the cavity in the bleeder of any water or brake fluid, finishing the job by installing a cap over the bleeder preventing any dirt or mud from being packed into the bleeder in the future.

That's all there is to a brake flush that will leave you with a fresh feeling front brake that should be so powerful (provided that the front brake pads are in good shape) that throwing stoppies and out braking the competition should be a piece of cake now.

Bringing up the rear

Alright, You got the front brake working so strong you can't keep the back wheel on the ground and you want to see if you can't make the rear a little better?

Follow along and I'll show you how to do a brake flush to the rear brake in no time.

This is pretty much the same process as for the front brake as detailed above, but I can go over it all again just in case you need a little help, It's not a problem.

As mentioned above when working on the front brake, be sure the areas around the master cylinder reservoir and bleeder at the caliper are clean before proceeding.

A lot of the newer bikes have the rear brake master cylinder reservoir integrated into the master cylinder itself, but a lot of the dirt bikes still out there do have a remote reservoir located above the master cylinder and it is usually connected with a hose.

On the brake systems with a remote reservoir, remember it is possible to remove the reservoir from the feed hose for cleaning of the reservoir if desired before starting the brake flush.

Now, with everything around the immediate area of the reservoir and rear brake caliper clean lets begin.

Once you have the tools in hand and the reservoir cover removed...

• Use your finger (without a rag) to wipe the rim area of the master cylinder reservoir in a way that will direct any contaminants (Sand particles etc) away from the fluid supply before continuing.
• Then... If possible, use a vacuum source (A common syringe or baster works well for this if a vacuum pump is unavailable) to remove the fluid presently in the reservoir.
  Note: If you are working on a dirt bike with an integral reservoir, be careful to not suck it dry uncovering the port(s) where the fluid supply to the master cylinder piston is located. If the system your working on has a remote reservoir, it is alright to remove all the fluid from the reservoir as the hose between the reservoir and master cylinder will still have fluid in it to supply the master cylinder with enough fluid as to not uncover the port(s) supplying the piston, allowing air to be introduced into the brake system.
• Once the majority or all of the fluid is removed from the master cylinder reservoir (Depending on the type of reservoir) refill the reservoir again, repeating the process of removing the fluid as a way of flushing the reservoir before beginning the brake flush.
• Once the reservoir has been flushed, fill the reservoir again with brake fluid, at this point it is best to fill the reservoir above the "Max" line so as to have plenty of fluid available when starting the brake flush process. This is especially true when working with a brake system that has an integral master cylinder reservoir as these have a much smaller capacity and can run dry quickly during the brake flush process easily allowing air to be introduced to the brake system.
Remember it is very important that during the brake flush process you do not allow the fluid level to become so low in the reservoir that the port(s) in the bottom of the reservoir are uncovered on an integral master cylinder reservoir, as this could allow air to be introduced into the brake system resulting in inadequate performance of the brakes and requiring longer bleeding times such as being at this all night.
• Next, Using the proper size box end wrench (Most likely an 8mm or a 5/16" as it's equivalent) slip the box end over the brake bleeder on the rear brake caliper followed by adding a length of clear vinyl tubing to the bleeder nipple then routing the tubing downward into a suitable drain pan or an empty water bottle works good because these can be positioned in a way that you can monitor the amount of fluid that has been flushed through the brake system.
• Once you have the tubing attached to the bleeder carefully open the bleeder about 1/4-1/2 of a turn watching for fluid to begin running out. (If you are having trouble loosening the bleeder see the tip for this here)
  Do NOT depress the rear brake pedal during this procedure.
  Once the fluid is running through the line, grab a plastic hammer and gently tap on the caliper starting near the rear and working your way upwards and towards the front gently striking the caliper, directing the "Hits" in an upward and forward direction. If you do not have a plastic hammer then use of a wooden hammer handle can be used. Doing this will force any air or old fluid that may be trapped in the area around the piston to be dislodged and come to the top where the bleeder port is. I recommend you continue the brake flush process until a generous amount of brake fluid has been flushed through the line while continually topping off the reservoir during this process.

Note: If no fluid exits from the brake bleeder after a few seconds of the bleeder being "Open", it may be necessary to remove the bleeder from the caliper and using a stiff piece of wire or a "pick" along with brake clean and compressed air, clear the orifice in the bleeder of any obstructions, then reinstall the bleeder in the caliper leaving it about 1/4th to 1/2 of a turn from bottomed so as to allow fluid passage then continue with the brake flush process.

• Once you've flushed a generous amount of brake fluid through the brake line and the reservoir is full, carefully monitor the reservoir level with the bleeder open closing the bleeder when the level falls to between the "Min" and "Max" marks.
• Now, with the bleeder closed, depress the rear brake pedal checking to be sure you have a firm feeling pedal, If a firm feel to the pedal is not felt, continue to follow the steps outlined above until the pedal is firm again.
• With the brake fluid level at the proper height (Between the "Min" and "Max" marks) and a firm pedal ensure that the reservoir cover and gasket / diaphragm are clean by cleaning with brake clean followed by drying with compressed air then reinstall the cover.

Once everything is back together, it's a good idea to recheck the bleeder to ensure its tight then rinse the area of the master cylinder reservoir and caliper with water, finally using compressed air again to dry everything and clear the cavity in the bleeder of any water finishing the job by installing a cap over the bleeder preventing any dirt or mud from being packed into the bleeder in the future.

That's all there is to a brake flush that will leave you with a rear brake that should be so powerful provided that the rear brake pads are in good shape, that brake slides will be easy and coupled with the front brake, out braking the competition should become a regular routine especially if you performed a brake flush up front as well.

Provided that the brake pads are in good shape at both ends and you followed the steps above for servicing your front brake, embarrassing the competition by out braking them should come naturally now.

Now go give 'em a demonstration of what strong brakes look like

Some other things for you to know

What to do when the screws securing the master cylinder cover won't loosen

Alright, You tried to loosen the screws securing the master cylinder cover and the screwdriver "slipped" leaving you feeling like you are hopeless, especially considering the way the screws look now but it's not all that bad and I'm going to show you how to handle this.

If the screws that are securing the master cylinder cover started to round out (which is to be expected) and you stopped before mangling them try this:
First, ensure there is no dirt or anything else packed into the bottom of the screw heads, If there is dirt packed into the screw heads, get it out using a small pick, some brake clean and compressed air then grab the screwdriver and a hammer.A hammer? Yea, a hammer.

Ok, with the screwdriver and hammer in hand, stick the screwdriver in the screw head and while putting a slight turning pressure on the handle (but not enough pressure to cause it to slip again), use your hammer and lightly hit the top of the screwdriver while turning and see what happens.

Did that do it? If so, Sweet!! and "You're Welcome" If the screws are still not moving then check out the next tip.

Rounded screws?
If you're at a point where the screwdriver won't grip at all then use a small sharp chisel or a center punch with a good tip and a hammer to carefully turn the screws in a counter clockwise direction. If you do this carefully you should be able to get the screws loose without making the reservoir cover look hammered.

Once you have the old screws out, be sure that you replace these screws and when reinstalling them make sure you apply a very light coating of antiseize to the threads to help prevent any problems in the future

Bleeder frozen and you can't get it loose?
Don't sweat this, It's common. Using a brass hammer strike the bleeder straight on hitting the bleeder at the top while turning. You want to be hitting it downwards like driving a nail while attempting to turn the bleeder but do NOT hit it hard. Just use repeating taps as this will commonly shock the threads allowing you to break the bleeder loose. If you have a heat source you're thinking about firing up DON'T. Using heat should only be a last resort and even then you better start thinking about rebuilding the caliper or finding a new one. Applying heat to the caliper is likely to cause problems such as leaking seals which will leave you with no brakes so firing up the torch isn't recommended.

Saving the best for last...
If you really want a strong front brake when you get to the first turn check this out... Use a zip tie and tie it around your front brake lever to the handle bars leaving moderate pressure on the lever for about 30 minutes before a race then cut the zip tie off and go to the line.
You might be surprised what you'll have when you get to the 1st turn, Just don't cartwheel it...

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