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Tandem Disc Brake Manual

For Formula disc brakes with a remote master cylinder

 

FIRST EDITION

June, 2000

 

Do I Really Need to Read This?

 

For those who prefer not to follow written instructions, the last two pages of this manual contain a tongue-in-cheek test designed to snare even the most experienced bicycle mechanics. By starting there you will realize the purpose of this manual, besides being a dry set of instructions, is to be an entertaining exploration of a fascinating piece of equipment.

 

In other words, after you fail the “Pop Quiz” on page 24…

…sit back, relax and spend some time reading this manual.

 

Table of Contents

 

Diagram of parts

 

Chapter 01     A Different Kind of Brake

 

Chapter 02     The Adjustment Process

 

Chapter 03     How to Check and Adjust Cable Tension

 

Chapter 04    How to Adjust the Pads

 

Chapter 05     How to Replace the Pads

 

Chapter 06     Preparing to Bleed the Brake

 

Chapter 07     Performing a Bleed

 

Chapter 08     How to Replace the Brake Cable

 

Chapter 09     How to Fix a Brake in Vacuum

 

Chapter 10     All About Brake Fluid

 

Chapter 11     Caliper and Rotor Issues

 

Appedix 1     Troubleshooting

 

Appedix 2     Pop Quiz

 

 

 

Chapter 1      A Different Kind of Brake

Some of the features that distinguish the Santana/Formula hydraulic disc brake from disc brakes found on other bicycles are the following:

 

1) Opposing caliper pistons. Formula was the first to employ this design in a bicycle brake instead of less expensive, single-sided systems. This design avoids the rattle and rub inherent to systems with floating discs or calipers.

 

2) Positive pad retraction. Many bicycle disc brake systems are "blessed" with the same pad retraction system used on cars and motorcycles. If you ever get the wheel of a car or motorcycle off the ground, spin it and you'll see what we mean. Positive pad retraction means a properly seated and adjusted Formula disc brake is absolutely quiet and friction free.

 

3) A 203 mm (8-inch) rotor. Santana's tandem-specific version of Formula's best brake uses the largest diameter rotor available to bicycles today. The large disc increases the brake's mechanical advantage, stopping your bicycle quickly while maximizing heat dissipation and minimizing pad and rotor wear.

 

4) An insulated rotor. If you check out the really powerful racing motorcycles you'll find an insulated, or riveted, rotor that will survive temperatures that would permanently warp a one-piece rotor design.

 

5) A remote master cylinder. By mounting the master cylinder and fluid expansion chamber on the down tube, our design fights cable stretch and allows you to use any traditional cable-operated brake lever on the market. Whether you prefer STI or Ergo (or even old Suntour) you can combine this brake with your favorite lever.

 

6) Automatic heat compensation. Every time the lever is released even for a split second-the system automatically adjusts itself to compensate for changes in heat and atmospheric pressure. The Formula brake, unlike many others, won't rub or "pump- up" during a long descent.

 

7) Sealed Reservoir. Because bicycles are commonly stored, serviced or transported on their sides or even upside down, bicycle disc brakes need a tightly sealed fluid reservoir that can resize itself without leaking. The Santana/Formula remote master cylinder includes a variable- capacity, sealed fluid expansion chamber more advanced than any you will find on a car or motorcycle.

 

Why only one disc brake?

 

Some folks have wondered about having a disc brake on the front as well as the rear. A traditional bicycle rim brake is, in fact, a disc brake, one that is incomparably light and elegantly simple in operation. A tandem needs just ONE non-rim brake to dissipate heat that would otherwise cause rim or tire failure. As a heat sink, a disc brake will function equally well at either end of the bike.

 

But shouldn't this brake be in front?

 

There are many reasons this brake has been mounted at the rear of your tandem as opposed to the front. Those reasons include the fact that due to the increased weight two riders exert on the rear wheel, it is virtually impossible to lock up the rear wheel under the most extreme braking- this makes it a wonderful location for such a smooth stopper. (After all, the braking power of an unarticulated V-brake-, one without a parallel-push mechanism-is already strong enough to lock up a tandems front wheel.) Next, a tandem's cable-operated rear brake is far less efficient than its front brake because of cable stretch. Hydraulic actuation, unlike cable actuation, is unaffected by length. For both these reasons it makes better sense to mount a tandem's disc brake at the rear wheel. Additionally, due to Santana's 160mm rear spacing we've got plenty of room for our brake's larger disc and more powerful calipers. The spacing constraints of a road tandem's standard front fork means fitting a front disc will require either a special wider hub and fork (read nonstandard front wheel and fork) or a severely dished front wheel that is prone to collapse during a tandem's low-speed turns. While we're comfortable redesigning any component we think deficient for tandem use, fact is, we think our current front wheels and forks are great products.

 

'It FEELS all wrong!'

 

Our most often encountered criticism from new owners is that the brake feels 'mushy." On a normal rim brake, this would be an understandable concern. A spongy-feeling rim brake is usually caused by energy- robbing flex of the brake arms and pads. Fortunately, that's not the case with a hydraulic disc brake, as we've said before this brake requires a different way of thinking. While we could "fix" the lever feel by trading brake modulation for decreased lever throw, the result would be on-off braking with too-little leverage to allow the power of your hand to control a heavily loaded tandem. Instead, this entire brake system was designed to take advantage of every bit of stroke available with today's drop bar brake levers. This not only improves stopping power, your hands have more strength when you are using clenched as opposed to fully outstretched fingers. In other words, we've optimized power instead of feel, and geared the lever so that its most effective range of modulation occurs where you have the greatest hand strength and are therefore least likely to encounter hand fatigue.

 

The important thing to remember is that as long as the lever feel is a bit soft or spongy, your new brake is probably operating correctly. If the lever instead feels firm, like a traditional rim brake, something is definitely amiss.

 

A second issue among new owners is that this brake doesn't seem to provide enough stopping power. The Formula disc brake, like the disc brake on cars or motorcycles, requires a break-in period. And while a car's power-assist masks the initial inefficiency of a new brake, on bicycles and motorcycles the braking improves dramatically once the pads have been seated and readjusted. Within 200-400 miles (and after you have seated and readjusted the pads) we think you'll agree this brake provides great control, fantastic modulation and incredibly short stopping distances.

 

To tighten this brake, loosen the cable.

 

A hydraulic disc brake with a cable-actuated remote master cylinder is unlike all other bicycle brakes. With this unique brake the characteristics, lever feel and adjustment procedures are all different. For instance, your experience with rim brakes might cause you to think that the cable of a perfectly adjusted disc brake is too loose.

 

When someone discovers the situation, 99% of all enthusiasts and mechanics will find the adjuster and tighten the cable to achieve a firmer lever feel. And while the lever will indeed FEEL better, an over tightened cable will not improve stopping power. Further, over tightening the cable by even the smallest amount will inevitably create problems with the hydraulic system.

 

How does this happen? We'll explain this as we go. In the meantime please be aware that a cable-hydraulic disc brake operates in a counterintuitive fashion, almost exactly the opposite of any rim brake or even disc brakes found on most mountain bikes.

 

Because living with a new disc brake involves relearning old tricks, do not attempt any readjustment until you've read this manual and familiarized yourself with the operation of this brake.

 

Since the operation of this brake is not intuitive, we believe your safety and ultimate satisfaction will depend on your willingness to read this manual and learn how to adjust the pads and cable tension. If you have never bothered to become proficient at making simple gear and brake adjustments on your previous bikes, we encourage you to reevaluate your choice of brakes with your dealer.

 

If the time comes that it is more convenient for you to have this brake serviced by a dealer, please make sure they have a copy of this manual. If not, loan them yours.

 

Surviving the mother of all descents

 

As long as the descent is straight enough, few teams will overheat a rim drum or disc brake. The explanation is simple: As long as you and your partner don’t mind riding fast, wind resistance will hold your speed in check, even on a long or steep hill.

 

Overheating typically occurs on a steep descent where the road is so curvy, rough, or crowded that a speed of less than 45 mph is required. Some roads are so twisted or rough as to require a speed of less than 15 mph. In these cases a tandem can burn out a brake or blow a tire within a half-mile. No brake, not even this Formula Disc, will endure a mile of 18% descent if your speed is constrained to 15 mph. The best brakes for holding a tandem's speed in check, however, like this Formula brake and the Arai drum brake, will progressively fade instead of failing without warning.

 

Given this situation, the following is the best strategy for steep, slow descents:

 

On a treacherous downhill use the Formula Disc Brake to control your overall speed. Use your rim brake only sparingly, such as braking for a particular switchback or to help you maneuver around a chuckhole. As the Formula brake heats up the brake lever will feel firmer as expanding fluid 'pumps up' the system and seems to pry the lever from your fingers. To reset the feel it is only necessary to momentarily release the lever to allow the expanded fluid to reach the master cylinder reservoir. Flicking the lever open once every half-mile is all it takes to maintain a good lever feel. Later, as the pads and rotor get very hot, fading will occur, causing you to have to squeeze the lever progressively tighter to maintain consistent braking. Finally, when the disc brake has faded to the point that you can no longer use it alone to maintain your desired speed, the only safe thing to do is to use the front rim brake to bring the bike to a complete stop. Within five minutes, less on a cool day, the disc and pads will have cooled enough to allow you to safely continue.

 

 

Chapter 2      The Adjustment Process

Before adjusting your brake, take the time to read this chapter thoroughly. This brake is quite unlike other cable or hydraulic disc brakes used on bicycles, and it requires that you follow the adjustment directions step by step. Skipping a step or reversing the order of two steps is likely to result in a poor braking.

 

Perhaps the most difficult feature of this brake to understand is how the cable actuates the piston that pressurizes the fluid to cause the braking. While in most brakes the cable itself pulls on the brake, in the Santana/ Formula brake, the cable is solidly anchored within the remote master cylinder and does not pull anything. Instead, pulling the brake lever forces the brake cable housing down the fixed length of cable, causing it to depress the piston hidden inside the master cylinder. This approach (pushing a piece of housing instead of pulling the cable), while counterintuitive, is supremely efficient. Once you can visualize the relationship, adjustment becomes quite simple.

 

As the pads seat and wear they will need to be advanced closer to the rotor. While a bicycle rim brake may sit a few millimeters away from the rim, the clearance between the pad and the rotor of a disc brake will be a few hundredths of a millimeter. In making such a precise adjustment an essential first step is to be sure that there is no hydraulic pressure pushing against the backside of the pad. The easiest way to be certain of this is to loosen the cable all the way.

 

There are two barrel adjusters that can be used to either tighten or loosen the cable. The first is an inline adjuster mounted 3-4 inches above the frame-mounted master cylinder. The second is at the top of the master cylinder itself. To loosen the inline adjuster, turn it counterclockwise (looking from above) until the chrome, cable-housing ferrule recedes into the barrel adjuster. The second barrel adjuster is at the top of the pump; to expose it, pull back the dome- shaped, black rubber boot to expose the red-anodized dome-shaped adjuster and adjacent, red, knurled lock ring. Twist the two red-anodized pieces apart from each other, and then, while holding the underlying silver-colored plunger with the thumb and forefinger of your right hand (to prevent it from rotating), use your left hand to twist first the knurled, red lock ring to the base of the plunger's threads. Next, tighten the red dome piece up against the lock ring. When the two red pieces are tightened against each other with no threads showing on the silver plunger, the cable will be slack enough to allow you to perform the next step.

 

At this point dislodge the black rubber boot at the top of the master cylinder housing (the boot furthest from the headset), and draw it up to the red lock ring.

 

Now it is possible-without tools-to pinch the plunger mechanism and draw it away from the pump body creating a 2mm gap. Looking into the gap one should be able to see the backside of the piston. Unless there is a problem the upper edge of the piston should be even with the top of the master cylinder housing. If you see something and aren't quite sure it is the backside of the piston, use the plunger to push against it. If the piece can be pushed inward and then pops back into position (there is a spring on the other side), it is, in fact, the piston-the main working part of the entire mechanism.

 

If nothing is visible and the plunger moves into the pump body three or more millimeters before touching anything, a vacuum has formed on the face of the piston which prevents proper operation. A system in this condition is said to be "in vacuum." Because a system in vacuum cannot be adjusted, normal operation of the brake is not possible until the problem is solved (see Chapter 9). Fortunately, 99% of the time you will be able to see the backside of the piston, and can, therefore, proceed to the next chapter - adjusting the cable.

 

Chapter 3      How to Check and Adjust Cable Tension

It only takes sixty-seconds with the aid of a quarter and a BIC pen to verify proper cable tension. While the brake pads and the hydraulic system will not need frequent adjustment, we do recommend checking the cable adjustment before every major ride, or any time the brake does not seem to be performing property. It is NOT that this brake is finicky or comes out of adjustment, but it has been our experience that well meaning enthusiasts fascinated by this cool looking brake will invariably squeeze the lever and decide that the cable is a bit too loose. Half of these people will help you out by tightening the cable's barrel adjuster. They'll walk away satisfied that they've done you a big favor. This seems to happen whenever you park your bike and then turn your back for as little as thirty seconds. It is most likely to happen when your bike is in or near a bike shop. While the cable that operates this brake cannot possibly tighten itself, many enthusiasts have become dismayed at how often the cable needs to be loosened. What follows is the 60-second method for optimizing cable tension and averting 95% of the problems that can occur with a cable-hydraulic disc brake.

 

1) Use a quarter or key to remove the slotted vent screw at the top of the remote master cylinder.

 

2) Press down on the master cylinder float with the blunt end of a BIC pen or pencil.

 

3) If the float doesn't move, the cable is too tight.

 

4) If the float does move, the brake will be applied by pressing the float downward. Verify the braking effect by rolling the bike back and forth.

 

5) Repeatedly let up on the pen, tighten the cable a half turn and then push down on the pen until the over tight cable prevents this method of brake application - the cable is now too tight.

 

6) Loosen the cable just enough (usually a half turn) to restore float movement-the cable is now perfectly adjusted!

 

7) As a final check, depress the float one last time to make sure the passageway between the fluid expansion chamber and the remainder of the hydraulic system is not blocked. Blockage of this passageway is the first step leading to system failure.

 

And now you understand the unique challenge of this system. Bike mechanics and enthusiasts accustomed to adjusting a brake according to lever feel will automatically over tighten the cable of this hydraulic brake every single time.

 

Anything else on a bicycle that gets misadjusted, i.e., rim brakes or indexed shifting, causes an immediate problem. This brake requires a new way of thinking. An improper adjustment might not emerge as a problem for weeks. But if the cable is even a quarter turn too tight, the very first time the brake fluid is heated (which can happen for a variety of reasons including a lightly rubbing rotor, braking on a long or steep descent, sitting in a hot environment or simply by being parked in direct sunshine), the too-tight cable prevents expanding brake fluid from reaching the expansion chamber. Instead, expanding brake fluid will push the pads inward and cause the brake to rub or worse, lock up. More than one customer has returned to a bike sitting in the sunshine and found a locked brake. The culprit is an over-tightened cable or a depressed brake lever, which prevents warm expanded brake fluid from reaching the expansion chamber.

 

While a misadjusted cable will, to most people, make this disc brake feel better (because the lever feels firmer), blocking the passageway between the reservoir and the rest of the system 'chokes" the entire system. Sooner or later the choked system will overheat and fail. Fortunately, the experience is not a loss of braking, but is, in fact, the opposite - a sticking brake that refuses to release. When faced with a brake that rubs or a pad that won't release, or a tandem that won't move, many dozens of frustrated enthusiasts (often with the help of a self-stated expert) have - by loosening a pad, hydraulic line, bleed port or valve - instantaneously destroyed the integrity of their hydraulic system. Ouch!

 

The mysterious onset of brake rub or lock up is a sure sign of only one thing: someone somehow over-tightened the cable, possibly weeks or months earlier.

 

The only way to restore proper operation is to loosen the cable enough to allow hot fluid to reach the expansion chamber. As soon as the cable is loosened (and the piston within the master cylinder is allowed to retract) the fluid that was causing the brake to rub will instantly find its way past the face of the retracted piston that was blocking the path to the reservoir.

 

Chapter 4      How to Adjust the Pads

The performance of a new disc brake is NOT impressive. Within two months, however, you will be amazed by the power and modulation of this disc brake.

 

Car and motorcycle mechanics talk about 'seating' or 'breaking-in' pads on disc brakes. By this, they mean wearing the new pad until the face of the pad is parallel (more correctly, 'coplanar') with the face of the rotor (or disc). Until new pads are seated, only a corner or edge of the noncompliant pad will be able to make contact with the disc. A new or unseated pad has two problems: (1) reduced braking power and correspondingly longer stopping distance, and (2) more caliper flex caused by uneven contact of the brake pads.

 

How long does it take to seat a pair of pads? If you use the disc as your primary brake, seating the pads should require no more than 200-400 miles and two readjustments. As you wear-in the pads and readjust the brake (by tightening the pads and NOT the cable) the power and feel of your new brake will improve dramatically.

 

Typically, the brake's first pad adjustment should be performed after about 100 miles of riding. Some bikes may need the service a little sooner if the captain brakes frequently. Do not proceed until you have adjusted the cable as described in Chapter 3 and understand the overall adjustment and break-in process as described in this chapter.

 

The Necessary Tool

 

The only tool needed to adjust the pads is a 2mm Allen wrench. We suggest you use a straight wrench with a screwdriver handle. While an expensive ball-end Allen wrench may be easier to use, its decreased working surface can split the adjusting screw. Because it is possible even with this small wrench to split the adjusting screw, never force the wrench when adjusting the brakes.

 

The $150 Mistake, and How to Avoid It

 

To adjust the brake's inboard pad, you will have to insert the Allen wrench between the spokes of the rear wheel to make the adjustment. Most split adjustment screws are the result of spinning the wheel or moving the bike without, first, removing the wrench. We advocate keeping one hand in your pocket while adjusting the inboard pad of your tandem’s disc brake. This way, you won't try to spin the wheel with one hand while holding the wrench with the other.

 

The Procedure

 

Each pad is adjusted independently. Please note again that you cannot adjust a pad that has hydraulic pressure forcing it inward. While you can loosen the adjustment screw (turn it counter-clockwise), the pad itself will NOT move away from the rotor, and, if you continue to turn the screw, forcing it past its 'soft stop', you will only succeed in opening the system. The sign that you have done this will be a wet wrench and fluid weeping from the grommet. Bad, very bad. Because it is all-too-easy to do this (inadvertently open the system) while loosening a pad…

 

1). Do not adjust a pad unless the cable is totally loose.

 

2). Do not loosen the adjustment screw beyond its soft stop.

 

The best way to attain proper pad adjustment is to turn the screw clockwise until you feel resistance. The resistance you feel is the pad pressing against the rotor. At this point, turn the wrench counter-clockwise until the pad no longer rubs when the wheel is turning. With a new, unseated pad you may have to back off the adjustment by a half turn. Later, when the pad is seated, or coplanar, one-eighth of a turn is all that will be necessary.

 

Note: Every Hadley Racing tandem hub has four contact seals that can create significant drag when new. It is easy to mistake this drag for brake drag and consequently over-loosen the pads (compromising performance or the integrity of the system), even though the pads aren't rubbing.

 

Congratulations! Now you have properly adjusted the brake pads. Once you get good at it, the entire above process can be accomplished in 90 seconds.

 

Your next step is to properly reset the cable tension. As was explained above (Chapter 3), you should use the blunt end of a BIC pen or pencil to establish the correct cable adjustment.

 

Notice that we performed an entire brake adjustment without squeezing the brake lever once. Never use the brake lever to determine the adjustment without first loosening the cable, checking the position of the piston, adjusting the brake pads and then reestablishing correct cable tension. Don't be surprised if once you've seated the pads and taken the above steps in the proper order, you can still mash the brake lever all the way to the handlebar. The combination of cable stretch, housing compression and brake lever flex make this possible. However, if by using one finger only you can easily squeeze the lever tightly against the handlebar tape, the only remaining cause for excess lever travel must be air inside the system (air is compressible and hydraulic fluid is not). Removing air from the system is covered in Chapters 6 & 7.

 

Chapter 5      How to Replace the Pads

As of this writing, it appears most enthusiasts will obtain 4000-5000 miles of use from a set of brake pads. The best way to check the remaining life of a Formula brake pad is to precede each brake pad adjustment with a loosening of the adjusting screw. With a new pad installed the adjustment screw can only be backed off a bit more than one-half (1/2) turn before you feel increased resistance as the pad bottoms out against a rubber 0-ring. It is important not to turn the wrench beyond this "soft stop" as pinching the 0-ring will instantly open the system (a wet wrench is the sign you've lost the system's integrity). After loosening the adjustment screw to the soft stop (where it contacts the 0-ring), count the turns required to tighten the brake pad against the rotor. If two-and-three-quarter (2-3/4) turns---or more-are required, the pad is worn out and should be replaced. Unlike a car, where a worn out pad will score the rotor, a worn out Formula pad will result in fluid loss that occurs after the adjustment screw is threaded too far inward.

 

While replacing the pads sooner might seem prudent, because new pads can require 200- 400 miles of use before becoming fully seated, it is best to stick with the old pads until there are at least two-and-a-quarter (2- 1/4) full revolutions of adjustment screw travel.

 

Necessary Tools

 

Flat-bladed screwdriver

New set of brake pads

2mm Allen wrench

 

To replace a worn set of pads:

 

1) Loosen the cable completely.

 

2) Loosen each pad to the soft stop. Warning- Loosening past the soft stop will open the system

 

3) Remove the rear wheel.

 

4) To remove an old pad, put a flat-bladed screwdriver under the edge of the pad and pry upward. Formula brake pads snap in and out exactly like the snap on the front of a pair of jeans. ,

 

5) Snap the new pad in place by pressing against it with the flat face of the screwdriver.

 

6) Insert the wheel.

 

7) Tighten each pad using the adjustment screw until it hits the rotor, and then loosen it one-half (1/2) turn.

 

8) If the pad still rubs, it is only touching on one edge or comer and with a few miles of use with aggressive braking, the protruding edge will wear away.

 

9) Carry the 2 mm Allen wrench with you on your next few rides so that you can take up the slack as the pads become seated. Important: always loosen the cable (see Chapter 3) before adjusting the pads.

 

Chapter 6      Preparing to Bleed the Brake

Bleeding the brake, like seating the pads, is a phrase that won't make a lot of sense to non-mechanical types. When someone says they've bled a brake they mean that they have removed all the air from the inside of the hydraulic system. Air in the hydraulic system is very bad because instead of stopping the bike, your hand pressure is being used to make big bubbles small.

 

Unless you open the system (e.g., open a seal that allows fluid to escape and air to enter), the only time you'll need to bleed the system is after you've changed the fluid. Because brake fluid does degrade over time (which lowers its resistance to boiling), most mechanics will advise you to replace the fluid every two to three years.

 

Even if you don't yet need to replace the fluid, the process of bleeding the brake requires you to go out and buy brake fluid. Fortunately, the Formula hydraulic system uses ordinary DOT brake fluid-the stuff found in 99.9% of all cars, trucks and motorcycles. For an exasperatingly long explanation of various DOT fluids and their boiling temperatures, you may refer to the next-to-last chapter.

 

How Tight is Tight?

 

A problem we've seen crop up from time to time is that a rubber part of the hydraulic system has been broken through over-tightening. While car and motorcycle mechanics long ago learned to "go easy" when tightening hydraulic fittings, most of us have not yet learned the distinction between metal-on-metal and metal-on-rubber tightness. Learning this distinction in feel is especially important when adjusting the pads (in either direction), tightening the bleed valve on the caliper assembly or reinstating the 3mm bleed screw on the remote master cylinder. For these fittings, we recommend "light-bulb-snug" as opposed to "lug-nut-tight." If fluid doesn't seep out when squeezing the brake lever, it's plenty tight.

 

Necessary Tools

 

1. DOT brake fluid

2. Formula Bleed Kit which contains:

-a syringe

-a small clear plastic hose

-a large clear plastic hose

-two brass fittings

-a 6mm white nylon spacer

3. Four Allen wrenches---2, 3, 4, & 5mm

4. An 8 mm box or open-end wrench

5. A flat-blade screwdriver

6. Shop glasses or safety goggles

 

Which Fluid?

 

If you need to bleed your bike's brake before tomorrow's ride, it's okay to use D0T 4 brake fluid - which can be found anywhere motor oil is sold. Otherwise, if replacing all the fluid, we recommend searching out DOT 5.1 (Motul is a brand stocked by better motorcycle shops). If you have trouble finding DOT 5.1, contact Santana and we can ship some to you. DO NOT USE "bicycle" brake fluid, mineral oil, or DOT 5 (blue) brake fluid (Chapter 10 explains the salient differences in brake fluids).

 

Find a Good Spot

 

Bleeding your brake is best performed in your driveway or a workshop. Because brake fluid is incompatible with good flooring and splattered droplets will soften paint if not cleaned off within a few minutes, this is not a kitchen table operation.

 

Chapter 7      Performing a Bleed

NOTICE!

Brake fluid containers feature a warning label. Read it. Be especially careful when compressing the syringe. If the clear plastic bleed hose blows off the bottom of the syringe, getting fluid in your eyes is very painful to say the very least.

 

1) Loosen the cable (see Chapter 2).

 

2) Determine pad wear (see Chapter 5). Combining pad replacement with fluid replacement can be a good thing.

 

3) Adjust the brake pads (to attain optimal performance, the pads should be properly adjusted BEFORE bleeding the system-see Chapter 4).

 

4) Attach the slotted brass fitting with the knurled nut onto the Formula syringe.

 

5) Draw in 10ml of brake fluid from the brake fluid container. DOT 5.1 is recommended (see Chapter 10).

 

6) Disconnect the hydraulic line where it enters the caliper. The red part should stay with the caliper but the silver part should remain with the hydraulic line. Note: Because the master cylinder and the caliper are both self-sealing (there are spring loaded check-valves within the red anodized connectors), these pieces won't leak when you disconnect the hydraulic line. The hydraulic line itself, however, can weep a bit when you disconnect one end, and will drain completely if both ends are disconnected. Therefore the bleed process is typically a bit neater if you always leave one end of the line connected. One warning: if after you disconnect the line at the caliper (per the above instruction) someone squeezes the brake lever, your disconnected brake system becomes a toxic squirt gun. When working in an area where someone might squeeze the brake lever, the recommended process is to disconnect both ends and catch the fluid seepage in a rag or hand full of napkins.

 

7) Thread the brass fitting onto the red fitting of the caliper body.

 

8) Use your 5 mm Allen wrench to remove the caliper from the mounting bracket. Note: If you use your 5 mm Allen wrench to remove the horizontal mounting bolts instead of the 4 mm Allen wrench to remove the vertical mounting bolts you won't have to readjust the angle of the caliper when you reinstall it. Further, watch for any washers, as you'll need to replace them in the same position.

 

9) The caliper should now be free of the bike and dangling from the half-filled syringe. With the red fitting of the caliper pointed upward and the syringe held above it, use a downward stroke to compress the pads until they touch each other. Continue pumping up and down with the syringe to extract fluid with bubbles and pump in fluid without bubbles. Tapping the caliper with the backside of your screwdriver will loosen bubbles that would otherwise stick in the comer of an internal cavity. With enough pumping, tapping and other gyrations, you should finally get to a point where no more bubbles appear on the upstroke. Congratulations! You have successfully bled the caliper. With experience, you can do this in 60 seconds.

 

10) Reinstall the caliper onto the frame.

 

11) Remove the syringe from the caliper and reattach the lower end of the hydraulic line.

 

12) Remove the slotted brass assembly off of the syringe's clear plastic bleed hose and replace it with the threaded one.

 

13) Use a 4 mm Allen wrench to remove the bolt securing the master cylinder to the down tube.

 

14) Use a 3 mm Allen wrench to carefully remove the master cylinder's bleed screw. Warning: the bleed screw tightens against a small rubber 0-ring which occasionally becomes stuck to the bleed screw's pointed end. Watch for it. Don't lose it. If, when you remove the bleed screw, you don't see this 0-ring, that's good news - it stayed seated at the bottom of the bleed port.

 

15) Fill the syringe with 20ml of DOT fluid and thread it into the port where you (moments earlier) removed the 3 mm bleed screw.

 

16) Use a screwdriver to remove the slotted vent screw at the top of the expansion chamber. Insert the 6mm white, nylon bushing (or a 1/4" ball bearing) in the chamber. And replace the slotted vent screw.

 

17) Using the same pumping, tapping and gyrating method you successfully learned earlier, remove all vestiges of air from the master cylinder. In this case upstrokes and down strokes will push the float up and down in the expansion chamber, creating movement of the fluid past the bleed port separating the pump's two chambers (the expansion chamber and the wet side of the piston). While it takes longer to successfully bleed the master cylinder than the caliper, a pro can do this in 120 seconds.

 

18) Attach the large, clear plastic bleed hose to the bleed valve on the caliper unit. The other end of this hose will be placed in a container to catch excess fluid.

 

19) Depress the plunger of the syringe lightly while reattaching the hydraulic line to the master cylinder.

 

20) Continue to maintain light pressure on the syringe while opening the bleed valve one-quarter turn.

 

21) Slowly pump 10ml of brake fluid into length 7-8 ml of brake the hydraulic line will be expelled through the caliper. Note: While it might seem stupid to pump air through a caliper you bled a few minutes ago, it is easier for the air to exit by way of the bleed valve than it will be for it to fight its way into one of the fluid- filled cavities behind the pads. If you want to worry about air from the hydraulic line reaching these areas, raise the front end of the bike so that the bleed valve and red fitting are above the pads.

 

22) SNUG the bleed valve.

 

23) Holding the master cylinder so that the bleed port is pointing upward, remove the syringe from the master cylinder.

 

24) Use three or four drops of brake fluid to overfill the port where you just removed the syringe-

 

25) Through these excess drops reinstall the pointed bleed screw into the master cylinder - do not over-tighten-and wipe away the excess fluid.

 

26) Reattach the master cylinder to the frame.

 

27) The final step is to remove the white, nylon bushing from the expansion chamber and replace the slotted vent screw.

 

Chapter 8      How to Replace the Brake Cable

In the course of performing periodic maintenance on your bike you should inspect the brake cable for signs of wear. Frayed or rusty cable should be replaced.

 

In order for the brake to work optimally the new cable must be cut precisely to a length of 35 mm beyond the end of the second piece of housing.

 

Necessary Tools

Cable cutters

Metric ruler

2 mm Allen wrench

 

1) Remove rear wheel.

 

2) After releasing all tension on the on the cable at the inline adjuster, loosen the red, knurled lock nut.

 

3) Depress the plunger and unthread the red, domed cap off the end of the plunger. When the red domed cap is no longer threaded to the silver plunger, it is possible to swing domed cap sideways to remove it from the cable.

 

4) Once the domed cap is out of the way, slide the plunger up over the cable housing to reveal the two (2) 2 mm Allen bolts on the master cylinder's cable anchor.

 

5) Loosen both Allen bolts to remove the old cable from the master cylinder.

 

6) Pull the released cable out through the brake lever.

 

7) Feed a new cable through the brake lever and pass it through the longer section of housing, the inline barrel adjuster, and finally the short section of cable housing. Make sure that the housing is properly seated in the brake lever and in the inline adjuster.

 

8) From the end of the housing, measure 35 mm of cable and cut off the excess.

 

9) After threading the end of the cable through the silver plunger (and knurled red locknut), insert the cable into the cable anchor until it bottoms-out before cinching the two (2) 2 mm Allen bolts.

 

10) Push plunger into the master cylinder and then reinsert the red, domed cap.

 

11) Properly re-tension the cable assembly, following the instructions on page 9.

 

12) Replace rear wheel.

 

Chapter 9      How to Fix a Brake in Vacuum

As we noted earlier, a too-tight cable prevents complete retraction of the piston, which blocks the passageway connecting the master cylinder's two reservoirs: the working reservoir on the wet side of the piston and the expansion chamber. Typically, a too-tight cable is a problem when the fluid heats up, expands and causes the brake to rub, or even lock up.

 

The opposite, however, can also happen. A too-tight cable can also keep the working part of the hydraulic system from being replenished while the system is cooling and the brake fluid is contracting. In this case contracting fluid creates a vacuum, sucking the piston into the lower half of the remote master cylinder. The primary indicator for an in-vacuum system is an extremely limp brake lever, and braking only at the very end of the pull. Attempting to readjust the cable or pads with the piston sucked downward will be totally ineffective.

 

Under what circumstances will the in- vacuum problem occur? Most often, this occurs just after you've descended a hill. While the fluid is still hot, you might either over-tighten the cable or, more likely, park the bike in such a way as to depress the brake lever (against a fence or another bike). Another possibility is when a rider uses some sort of strap to lash down the brake lever, thinking the disc will make an excellent parking brake. In any of the above cases, as the brake cools and the fluid contracts (a couple of minutes is all it will take) the piston within the master cylinder is sucked into vacuum. The least common (though still possible) way we've seen for a brake to go into vacuum is if the cable is over-tightened on a warm afternoon and then you try to use the bike the following morning when the temperature is still cool.

 

Prevention Strategies

 

1) Never over-tighten the cable.

 

2) Never lash down the brake lever. The disc is not a parking brake.

 

3) Do not attach the disc brake cable to a shift lever - the disc is not a drag brake.

 

Two Step Cure

 

Because an in-vacuum system can't restore itself until the piston is retracted, and the piston can't be retracted while the vacuum exists, the system must be opened to release the vacuum. Because you don't want air to enter the system, you'll need to: 1) Loosen the cable. 2) Fill the larger clear plastic bleed hose with 2 to 3 inches of DOT fluid. 3) Attach the bleed hose on top of the caliper's bleed valve (the steel nipple with the rubber cap). 4) Use an 8 mm open-end wrench to open and then immediately close the valve with one-quarter counterclockwise and clockwise turns. The system will inhale about an inch of brake fluid, which allows the spring at the face of the piston to push the piston back into its normal, retracted position.

 

At this point, the brake will work fine, but there is a little bit too much fluid in the expansion chamber, which means the next time the brake heats up, there won't be enough room in the expansion chamber to accommodate the expanding brake fluid. To cure this second problem, which will cause a hot brake to drag, you'll need to remove the slotted vent screw at the top of the master cylinder, drop the bleed kit's plastic spacer (or a common one-quarter-inch ball bearing) into the recess, and then tighten the slotted vent screw back down which will pressurize the system. If you then open and close the bleed valve the excess fluid will dribble out. Don't forget to remove the spacer or ball bearing and wipe away all excess fluid.

 

A Typical In-Vacuum Scenario:

 

At the bottom of Five-Mile Hill Luke and his friends stopped to have a Coke at a convenience store. While parking his tandem, Luke inadvertently depressed the brake lever by leaning it up against another bike. Three minutes later he returned to discover a limp brake lever. To confirm his fears, Luke loosened the cable, pulled back the master cylinder's boot and plunger to find that the "dry" side of the piston, normally visible, had disappeared. As the brake had cooled, contracting brake fluid had sucked the piston down into the lower end of the master cylinder.

 

Calmly, Luke walked back inside the store, retrieved a plastic soda straw, and stood in the parking lot until someone drove in. At this point, he asked to "borrow" a couple of inches of brake fluid. Because Luke realized 99.9% of all cars, trucks, and motorcycles use DOT 3 or 4; he could get all the fluid he needed from an under-hood brake fluid reservoir. He dipped the straw two inches into the reservoir and placed his thumb over the top of the straw to extract the fluid. Holding the straw away from his body, he walked back over to his bicycle, jammed the straw onto the caliper bleed valve, released his thumb from the top of the straw and used his multi-tool to open and close the valve. As the valve was opened, the master cylinder spring pushed the piston back into its normal retracted position. As quick as the valve could be opened and closed, most of the fluid was sucked out of the bottom of the straw. The system had been restored.

 

Days later, on the eve of the next ride, Luke figured out how to remove the excess fluid.

 

To optimize the fluid level Luke removed the master cylinder's slotted vent screw, inserted the 6mm white plastic spacer from his Formula bleed kit (he could have instead used a one-quarter inch ball bearing) into the chamber, and tightened the vent screw back into place. In doing this, the spacer was forced down against the reservoir's float, which in turn pressurized the hydraulic system and applied the brake. Luke then opened and closed the caliper bleed valve, which allowed the excess fluid to dribble into the rag he was holding. Because he remembered to remove the spacer from the reservoir, Luke's system again had the proper 6mm of space for fluid expansion.

 

Chapter 10      All About Brake Fluid

Brake systems for cars, trucks, motorcycles and airplanes all use "DOT" fluid. Even in the smallest third-world outpost DOT is the term used by car and truck mechanics. DOT is shorthand for the U.S. Department of Transportation, which long ago determined a specification for the performance of brake fluid. The original DOT specification was replaced by DOT 2 which, when disc brakes became common, was replaced by DOT 3. Today's high performance cars with antilock brakes need a better fluid still, DOT 4. When certain racing motorcycles needed a fluid that could withstand temperatures hot enough to make discs glow red, the U.S. Department of Transportation developed a standard for DOT 5.

 

The problem is that while DOTs 2, 3, and 4 are all compatible with each other, none are compatible with DOT 5. If you add DOT 5 to a system that already contains 2, 3 or 4, the resulting mixture will dissolve the rubber 0-rings common to all hydraulic systems. Within a couple of hours the brake system will leak like a sieve, and the fix requires a complete system overhaul with all new rubber parts. Not cheap, or easy. The moral of this story so far: Don't ever mix DOT 5 (known to most as "the blue stuff") with any other DOT fluids (which are all the color of motor oil).

 

We wish that were the end of the story. But progress marches on and eventually a higher-temperature-rated version of DOT 4 was developed. While we think someone should have named it DOT 4.1 or DOT 6, it is instead labeled DOT 5.1. It is this super- fluid, DOT 5.1, which was installed in your Formula brake at the factory. Unfortunately 5.1 is extremely hard to find. When you ask for it, people will typically try to sell you DOT 5. If you are simply topping off or bleeding fluid we recommend DOT 4, which is totally compatible with DOT 5.1. If you are refilling the entire system, call us and we will sell you DOT 5.1.

 

Wet vs. Dry Boiling Temperatures

 

DOT brake fluid is "hydrophilic". This means the fluid will absorb water from the air. Rumor has it that you can fill a shot glass with DOT fluid and after an hour or so the glass will overflow. The DOT brake fluid absorbing moisture from the surrounding air causes the volume increase. This is why every container of DOT fluid requests that you keep it closed when not in use. As the fluid absorbs water its vaporization temperature (or boiling point) is reduced. DOT 4 becomes no better than DOT 3 and eventually degrades in performance to the level of DOT 2. Amazingly enough, a small amount of moisture will be absorbed right through rubber seals and nylon hydraulic lines (virtually any material except metal or glass). This is why car manufacturers recommend brake fluid replacement every two to three years.

 

Because fluid that exists in a hydraulic system will have a lower boiling point than when new, the Department of Transportation specifies two minimum boiling points for each brake fluid, known as “dry” and “wet.” The distinction “dry” is given to fluid uncontaminated by water, while “wet” is the expected boiling point for a fluid with approximately four percent water content, the average amount the DOT found when randomly testing truck brakes.

 

“Racing” brake fluid found in a high-performance auto parts store will boast a high dry boiling point. Less expensive fluid might have a higher wet boiling point. Which is best? For racers who replace their brake fluid following every event, dry boiling point is all important. Unless you wish to replace your brake fluid after every ride, ignore the dry temperature and choose a fluid based on its wet boiling point. The minimum wet boiling point that qualifies a fluid for DOT 4 status is 311 degrees Fahrenheit. The synthetic version of Valvoline's DOT 4 has a wet boiling point of 333 degrees, making it the best fluid you are likely to find in your hometown.

 

What's so good about 5.1?

 

DOT 5.1 has a wet boiling point of 365 degrees. Better yet, DOT 5.1 is half as viscous as DOT 4. This means a system filled with DOT 5.1 provides quicker lever response, better modulation and faster pad retraction When servicing, the lower viscosity facilitates bleeding and pad adjustment. DOT 5.1 also experiences less volume change as a result of temperature shift than DOT 4, allowing more consistent braking through a range of temperature. It may require a little more effort to purchase DOT 5.1, but we feel it is well worth it. In every case make sure any fluid used is labeled “DOT 3”, “DOT 4”, “DOT 5.1” or “Compatible with DOT 4”. You can obtain Motul 5.1 from Santana or through your Santana dealer.

 

Warning: Other bicycle disc brake systems use common mineral oil or a proprietary “miracle” fluid (snake oil?). A well-meaning bike shop mechanic might not realize the can of "Super Fluid" he has on his shelf is totally inappropriate for your automotive-quality brake. While bicycle disc makers often use a less caustic (and cheaper) fluid, these fluids will have higher compressibility, greater expansion and contraction, and a lower boiling point. In short, when performance matters, there is ample reason to use DOT fluids (except DOT 5) in spite of the additional care required.

 

Chapter 11      Caliper and Rotor Issues

This is the one chapter you should never need to read, but don't stop now, this is the last chapter.

 

In two years we haven't found a lot of problems with calipers or rotors. As long as you pay attention to the placement of any washers when you remove and reinstall the caliper in order to bleed it, the original factory alignment should stay intact. If, for some reason, you lose this adjustment, the mounting bracket has slots on the chainstay side that allow you to change the angle of the caliper relative to the rotor and ovalized holes on the caliper side that allow you to move the caliper closer to or further from the axle.

 

If the caliper itself rubs the rotor, loosen the 5 mm horizontal mounting bolts and move the caliper forward until it misses by the thickness of a fingernail.

 

If the caliper gets cocked sideways, simply loosen the 4 mm vertical mounting bolts, apply the brake (which will align the caliper) and then, without releasing the lever, tighten the bolts. You’ll need a friend to help you with this.

 

If the rotor itself is not running true, re-torque the 4-6 rotor attachment bolts. If this doesn’t solve the problem, gently massage the rotor by hand. Often, during expansion and contraction the rotor will get hung up on the rivets and will “click" back into position when you massage it with light pressure. If, through an accident, the rotor becomes bent, heavy-duty hand massage may save you from having to buy a replacement. In our experience, a nearly straight rotor becomes straighter with use.

 

Broken rivets, thankfully rare, can be replaced at the factory.

 

Appendix 1 -- Troubleshooting

Brake lever feels spongy.

 

 

 

 

1)  This brake has been designed to allow full lever stroke, i.e., you should be able to mash the lever all the way to the tape.

 

2)  A new disc brake becomes firmer in feel with extended use. This is because the pads seat within the first 200-400 miles (see Chapter 4). Optimal brake feel cannot be obtained until the pad is readjusted after proper seating.

 

3)  The brake needs to be adjusted; see chapters 2-4. In the meantime do not tighten the cable. While tightening the cable will make the brake feel firmer (more like a cable-actuated brake), it will disrupt the self-regulating hydraulic system's ability to compensate for temperature and atmospheric pressure. An over-tight cable will ultimately cause the system to fail.

 

My brake rubs or locks up with use.

 

 

 

 

1)  The cable is too tight; this prevents the heated brake fluid from expanding into the expansion chamber. The heated brake fluid will expand despite the lack of an appropriate reservoir, and will force the pads against the rotor, even though you haven't squeezed the lever.

 

2)  If the pads continue to rub even when the cable is completely slack, either the pads are too tight, the rotor is warped (Chapter 11) or the caliper is out of alignment (also Chapter 11). Since the pads cannot tighten themselves, unless you've just tightened them, you should refer to Chapter 11.

 

My brake doesn't develop enough stopping power.

 

 

 

 

1)  Lever feel does NOT equal stopping power. Many mechanics, however, will tighten the cable to improve feel while neglecting pad adjustment. The result - good lever feel and abysmal braking. Read and follow the instructions in Chapters 2-4 to solve this too-common problem.

 

2)  A brake with new pads will have diminished stopping power until the pads have been adequately seated through as much as 200-400 miles of use. Full power is obtained when the pad is readjusted after proper seating (see Chapter 4).

 

3)  The disc or pads may be contaminated; always be careful when using spray lubricants - they are the enemy of stopping power. If you suspect your brake is contaminated, you'll need to clean the disc with rubbing alcohol and remove and clean the pads using emery cloth.

 

I have carefully readjusted the brake and cleaned it as noted above, and the brake still performs poorly.

 

 

 

1) Find a comfortable chair and reread Chapters 2-4. 95% of the time we receive a phone call from an understandably frustrated customer or dealer we learned that they have skimmed the material and attempted to adjust the brake before fully understanding how simple this system really is. Without this understanding, it is far too easy to skip a necessary step. While there are a half-dozen ways to adjust a rim brake or derailleur, and two or three ways to adjust any other disc brake, there is just one way to property adjust this brake. While the brake system is neither fussy, nor difficult to adjust, the necessary steps must be performed in the proper order.

 

2)  There is air in the system. Because air is compressible (and hydraulic fluid is not), even a tiny amount of air in the system will prevent the hydraulic fluid from fully actuating the caliper. If you have already rechecked the adjustment of the system and the condition of the pads, you will need to "bleed" the system in order to remove the air. Follow the instructions found in Chapters 6 & 7.

 

When to cry for help

 

Technical support is available from Santana 8-4:30 weekdays: (909) 596-7570. Should you feel that the brake is not responding to your best efforts, you may want to put your tools down, take this manual into the next room and reread this section. If you have no epiphanies as a result of this experience, don't hesitate to pick up a phone to call us. We've always been able to walk our customers through the adjustment process to get their bike ready for the next day's ride.

 

Appendix 2 -- Pop Quiz

Only partly in jest, this part of the manual is a test on the procedures involved in servicing this brake. You'd be surprised how many experts will fail this test - especially when they haven't yet bothered to read this manual.

 

Question 1 --- 95% of all problems with the Formula cable-hydraulic disc brake are caused by:

A)   Fluid leaking out of the system.

B)   Air leaking into the system.

C)   Worn pads.

D)   Cable tension.

 

Question 2 --- What fluid must be used in this system?

A)   Certified bicycle brake fluid.

B)   DOT 5.0 brake fluid.

C)   Mineral oil.

D)   Any DOT fluid that isn't blue.

 

Question 3 --- The type of store where you WON'T find suitable brake fluid:

A)   Wal Mart. B)

B)   A corner gas station.

C)   A country store.

D)   A good bike shop.

 

Question 4 --- To check the cable adjustment of this brake you'll need:

A)   Good eye-hand coordination.

B)   Allen wrenches and a screwdriver.

C)   Small pliers and a third hand.

D)   A large coin and a BIC pen.

 

Question 5 --- The first step in pad adjustment is to:

A)   Tighten the cable.

B)   Remove the rear wheel.

C)   Disconnect the hydraulic line.

D)   Loosen the cable.

 

Question 6 --- Pad adjustment requires:

A) Feeler gauges and Allen wrenches.

B) A flashlight and Allen wrenches.

C) Removal of the timing chain.

D) An Allen wrench.

 

Question 7 --- The best way to avoid making a mistake when adjusting the pads is to:

A)   Use a ball-end Allen wrench.

B)   Spin the wheel to check alignment.

C)   Pray.

D)   Keep one hand in your pocket.

 

Question 8 --- Do which of the following to seat the pads:

A)   Tighten them.

B)   Loosen them.

C)   Score them with a file.

D)   Ride your bike.

 

Question 9 --- After a long descent the brake rubs; what should you do?

A)   Loosen the pads.

B)   Bleed off excess fluid.

C)   Squirt water on the disc.

D)   Loosen the cable.

 

Question 10 --- Your bike has been sitting in a hot parking lot and the brake has locked up. You should:

A)   Loosen the pads.

B)   Bleed off excess fluid.

C)   Apply sunscreen.

D)   Loosen the cable.

 

Question 11 --- New pads:

A)   Improve stopping power.

B)   Improve lever feel.

C)   Will squeal.

D)   Require 200-400 miles of break-in.

 

Question 12 --- The person best qualified to service this brake:

A)   Has worked on motorcycles.

B)   Has been factory-certified to fix mountain bike disc brakes.

C)   Has tattoos and body piercings.

D)   Is holding this manual.

 

In case you haven’t yet figured it out, the final choice is always the correct answer. This should only come as a surprise to those who haven’t yet read this manual.

Santana Customer Service: 909-596-7570

 

 

 

 

 

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