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Arai Drum Brakes

GENERAL INFO

 

THESE ARE NO LONGER AND WE ARE OUT OF STOCK.  WE DO HAVE Q.R. KITS AND THE REMOVAL TOOL AVAILABLE, NO OTHER PARTS THOUGH.

 

The Arai brake is a cable operated drum type brake which threads onto the left side of a "tandem hub" designed for the application. Threaded tandem hubs are "standard equipment" on virtually all quality tandems with the exception of a couple of racing models.

The unit is rather simplistic in design and consists of a drum and backing plate to which the shoes, return springs and actuation arm are mounted. The design is strikingly similar to drum brakes used in automotive applications only mechanically operated rather than hydraulic.

Arai Drum Brake Assembled

Arai Drum Brake Disassembled

     

    

This time tested reliable brake continues to be an affordable and effective way to control speed on long descents seen in mountainous terrain.

The main function of a drag brake is for speed control, something necessary to avoid over-heating the rims which can lead to melted tubes, melted rim strips and tire blow-off problems. One certainly does not want this to happen during a high speed descent!

Generally one sets the brake to control speed whereby the rim brakes can be briefly actuated for changing road conditions. A secondary benefit to having a drag brake is its function as a "parking brake" but it is hardly worth lugging two pounds around just for that purpose.

The brake is generally not used as a primary brake to stop a tandem but it is often very useful as an assist brake when extra weight is involved such as on triplets, quads, heavy teams, or loaded touring.

 

INSTALLATION TIPS

1) Coat the threads with grease or better yet, anti-seize compound (available at any auto store). This is VERY important otherwise removal may be virtually impossible at a later date.

2) The left end of the axle will have a 2mm or so thick spacer which must be removed along with an outer locknut or axle end depending upon the hub design. It is usually best to remove this spacer before installing the drum onto the hub. Shimano tandem hubs use a locknut, White Industries an axle end secured by small Allen set screws and DT Hugi an axle end which simply slides into the axle. Hadley and Phil Wood both have field serviceable designs where the axle ends are removed via two 5mm Allen wrenches.

3) Carefully thread the drum onto the left side of the hub. It has a "normal" right hand thread so turn the drum clockwise to install/tighten. Don't confuse the right from the left on older freewheel style hubs since they are threaded on both sides.

4) After tightening the drum snugly with your hands, use a rag and remove any extra grease from the inside and outside of the drum. The heat generated from braking will likely cause the grease to turn to oil thus contaminating the brake shoes if you skip this step.

5) Slide the backing plate and brake shoe assembly over the axle so that the backing plate replaces the spacer you removed earlier. If the hole in the backing plate is too small for the axle, carefully drill or file it out to the proper size. It is certainly best to retain the centering effect of the hole. One can draw a larger circle around the hole to ensure uniform enlargement.

6) Thread or slide on the outer spacers, locknuts or axle ends but do not tighten at this point. Next move and hold the actuation arm in the "brake on" position while tightening the outer locknut or axle end. This step will help the shoes center up by the tolerances available between the backing plate and the axle. Please note that Hugi and White Industries use an axle end which does not tighten against the backing plate so it is best to do this step as you secure the wheel in the frame with the quick release.

7) The reaction arm must be connected to the frame upon wheel installation. There is usually a Pac Man type bracket or mount on the frame to accommodate this need. The newer Santanas have a Hayes disc brake mount to which one must attach the arm via an adapter available from your Santana dealer. If your frame does not have provisions for a drum brake mount, you can secure the reaction arm with a strap around the frame similar to that used on old coaster brake bikes.

Typical Pac Man Mount

Hayes Type Disc Brake Mount

Santana Hayes Mount Adapter
                 

Most tandem frames manufactured in recent history are designed with clearance to accommodate a drum brake. If your frame is equipped with the features pictured above it is safe to assume that one will fit. That said, some frames are not designed with the Arai drum brake in mind. Below is a drawing furnished by a T@H regular which will simplify the process for you in determining whether you have enough room for the brake.

WILL THE ARAI DRUM BRAKE FIT MY TANDEM?

Arai Drawing

(Click to Enlarge)

 It is certainly worthwhile to purchase a quick release kit which allows you to disconnect the cable and reaction arm from the frame in the event of a flat tire without the use of tools. A 5mm x 25mm or 6mm X 25mm bolt secured to the reaction arm which nestles in the Pac Man hook prevents rotation during brake application. Please note that a 6mm bolt requires a very slight hole enlargement or in the alternative you may wish to run a tap through the hole.  Sometimes the hook slot may  not permit use of the shouldered bolt that comes with the q.r. kit thus double-nutting a 5mm or 6mm bolt may be required.

As pictured below, a 5mm bolt is secured to the arm by two nuts which when tightened together actually sandwich the arm.

Bolt Mounted to Reaction Arm

Reaction Arm Bolt In The Hook

Cable Quick Release Assembly

We send a 6mm bolt with our kit along with a nylok nut.  Force the 6mm bolt to thread through the hole in the reaction arm using a 3-way Allen wrench and then secure with the nylok nut behind the reaction arm.  The reaction arm bolt pictured is a 5mm bolt requiring a nut on both the inside and outside of the arm.


ACTUATION METHODS

There are primarily three types of controls and positions commonly used to actuate the Arai drum brake. First one must decide who should be in control, i.e., the stoker or the captain.

When the stoker is in control of the hub brake, the team often has difficulty communicating whether the brake is on too much, not enough or whether it should be on at all. This is compounded by the wind noise associated with rapid mountain descents. Under this scenario, the team could inadvertently lock up the rear wheel resultant of too much braking with the captain and stoker being unaware of how much braking effort the other is doing combined with the possibility of adverse road conditions.

After hearing first hand of these problems and for safety's sake, I now recommend the captain be in control of ALL of the brakes.

The captain can control the Arai drum brake by:

1) Using a Bar End shifter if STI or Ergo levers are in use.

2) Using an inexpensive Thumb Shifter when either Bar End shifters, STI or Ergo are in use.

3) Designating one brake lever for the hub brake and operating both rim brakes via one lever. This can be accomplished with the Dia Compe 287 lever designed for two brakes or via a cable wishbone or wishbone type adapter. I don't really favor this scenario as I strongly prefer to have the rim brakes operate independently of each other, especially should an emergency situation arise.  Use of the Bar End or Thumb Shifter options permit being able to control the rim brakes individually. 

     Deciding which control method is a personal preference issue.  It is easy to recommend using a thumb control mounted on top of the bar if you spend most of your time riding with your hands in that proximity. Those that ride in the drops a great deal would likely appreciate the bar end shifter.

 

DRUM REMOVAL

Sometimes removal of the drum can be done successfully by rolling the bike backwards while applying extreme braking pressure while someone sits on the stoker saddle. Most commonly the unit is loosened via a large spanner wrench designed for the purpose after removing the backing plate and turning the drum counter clockwise.

You will notice in the disassembled picture above that a very large nut is designed on the interior surface. A very large socket, 41mm or 1 9/16" is required. One can use a tool of this magnitude and certainly get the job done or one can purchase a spanner type wrench which is the easiest option.  It is also possible to make a tool.

 

CABLE ROUTING

The various tandem manufacturers have different philosophies about how to route cables and who should control the drag brake. Santana and Meridian have a cable stop on the down tube used for captain control. Co-Motion uses a cable stop affixed to the lateral tube in the stoker compartment, primarily for stoker control. Newer Co-Motions come with stops for either captain or stoker control. If you have an older Co-Motion with a stoker cable housing stop only and desire to have the brake be controlled by the captain, simply run a long housing down the lateral tube and use zip ties to affix the housing to the frame tube.

 

MAINTENANCE

Arai brakes require very little maintenance and they last a LONG time. If by chance you wear out a pair of brake shoes, they are available as an assembled backing plate assembly with shoes, springs and the backing plate. It is really best to replace the entire backing plate module if a problem such surfaces such as the brake failing to release. Wear takes place at the cam, the brake shoe lining and the brake shoe cam surface, all of which add up to a sticking problem after usually years of use.

If braking power is less than normal, i.e., I view normal as being able to lock up the rear wheel with drum brake application alone when no stoker is on the bike, you can sometimes improve the friction relationship by sanding the brake shoes and drum surface. Please realize you are dealing with an inhalant hazard and I have no idea if asbestos is used in the lining compound but it would be best to treat it as if that is the case.

To view these items in our Catalog, Click on "Parts" below, then "Brakes" after the Catalog loads, and scroll down to "Drum Brake".

The drum removal tool is found in the "Tool" section of our "Accessory" Catalog accessible via the link below.

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