Brake fluid is one of the most neglected fluid in vehicles today, yet is vitally important for safe towing. Consequently, trailer owners should check the fluid in both the tow vehicle and the trailer on a regular basis. The brake fluid should be changed if it is contaminated. The issue is that old brake fluid may not be safe if moisture contamination is above a certain level.

Many experts have long recommended changing the brake fluid every year or two for preventative maintenance. Their rationale is based on the fact that glycol-based brake fluid (DOT 3 & 4) starts to absorb moisture from the moment it is put in the system. The fluid attracts moisture through microscopic pores in seals and exposure to the air. The problem is obviously worse in wet climates where humidity is high and with marine trailers constantly subjected to dunking in lakes, rivers or oceans.

DOT 5 cannot be used in trailer brake systems unless specifically stated by the actuator and brake manufacturer. DOT 5 does not absorb water, however the silicone in the DOT 5 makes the seals swell and can bind up caliper pistons.

Silicone has several other properties that make it less then desirable for trailer use. When forced thru small orifices under high pressure, like the solenoid valves in a disc brake system, it tends to foam, generating bubbles. Bubbles in brake fluid make for spongy brakes. Silicone also tends to become slightly compressible at temperatures near its boiling point, which makes it generally inappropriate for trailers used in mountain conditions. Tie Down Engineering brakes are designed for DOT3 or DOT 4 fluid ONLY.  NEVER USE DOT 5.

Water can actually cause air to accumulate in your brake lines. Brake fluid is hygroscopic. It absorbs and retains water. The problem arises when the fluid has absorbed as much water as it possibly can and becomes saturated. Brake fluid is designed to have an extremely high boiling point; however, if you subject your tow vehicle and trailer to excessive braking, such as a trip through the mountains, you can easily cause the brake fluid to heat up to this temperature or beyond. When the brake fluid boils, especially when there is excessive water in the system, steam is a by-product. The braking system ultimately compresses this steam and turns it into water. The air separates from the water creating large pockets of air in your brake lines.

After only a year of service, the brake fluid in the average marine trailer may contain as much as two percent water. After 18 months, the level of contamination can be as high as three percent. And after several years of service, it is not unusual to find brake fluid that contains as much as seven to eight percent water.

As the concentration of moisture increases, it causes a sharp drop in the fluid’s boiling temperature. Brand new DOT 3 brake fluid must have a dry (no moisture) boiling point of at least 401 degrees F, and a wet (moisture-saturated) boiling point of no less than 284 degrees. Most new DOT 3 fluids exceed these requirements and have a dry boiling point that ranges from 460 degrees up to over 500 degrees.

Only one percent water in the fluid can lower the boiling point of a typical DOT 3 fluid to 369 degrees. Two percent water can push the boiling point down to around 320 degrees, and three percent will take it all the way down to 293 degrees, which is getting dangerously close to the minimum DOT and OEM requirements.

So consider this: After three years of service, the average boiling point of the brake fluid has dropped to a potentially dangerous level because of moisture contamination and may not meet minimum federal requirements for brake fluid.

Water Contamination increases the danger of brake failure because vapor pockets can form if the fluid gets too hot. Vapor displaces fluid and is compressible, so when the brakes are applied the actuator may completely compress without applying the brakes!

In addition to the safety issue, water-laden brake fluid promotes corrosion and pitting in caliper pistons and bores, wheel cylinders, master cylinders, steel brake lines and reverse solenoids.

From time to time we hear about reports of “unexplained” brake failures. When the vehicle’s brakes are inspected, no apparent mechanical fault can be found. The fluid level is normal, the linings are within specifications, the hydraulics appear to be working normally. Yet the brakes failed. Why? Because something made the brakes hot, which in turn overheated the fluid causing it to boil. The underlying cause often turns out to be dragging brakes caused by the E-stop cable being tripped, or the use of DOT 5 Fluid, but that is another story.

Nev-R-Adjust Trailer brakes

So says Dexter Axle as they have developed a solution to this problem in their new line-up of trademarked Nev-R-Adjust electric drum brake assemblies. They have used technology already available in heavy-duty truck and trailer brakes and adapted it to the smaller 10 inch and 12 inch electric brakes found on most RVs, utility, horse trailers etc.

Dexter accomplished this self-adjusting feature by adding a 9 piece “Adjuster Kit” to the standard brake assembly backing plate. This allows the brake assembly to constantly adjust the lining position as the brake drum turns during trailer operation. In speaking to Dexter’s Engineering team, the adjustment feature works as the trailer moves in both forward and reverse directions but the increments of adjustment are much higher in reverse. Since there are specific brake assemblies designed for the driver-side and curbside of the trailer, problems will occur if the brake assemblies were installed on the wrong side of the trailer. Brake assemblies mounted on the wrong side will act like they are traveling in reverse. This would cause “over-adjustment” and can cause the brakes to overheat and lock. Therefore, for self-adjusting brakes, it is imperative that the proper brake assemblies are installed on their specified side of the trailer.

Dexter introduced their 12 inch self-adjusting brake assemblies in May of 2008 and their 10 inch unit in May 2009. They performed extensive reliability testing using a dynamometer and also real life testing on their own trailer fleet before they marketed the product. They offer a 2 year limited warranty on these products.

It seems that recreational trailer owners have been the first to embrace this new product offering with more commercial trailer owners loyal to the standard product. The new self-adjusting brake assemblies cost about 20% more than standard brakes.

Trailer Parts Superstore offeres both sizes online at: ELECTRIC TRAILER BRAKES

Kodiak Trailer Disc brakes

Check out out complete offering of Kodiak Trailer Disc Brakes online here: KODIAK BRAKES

Disc Brake for RV & Utility Trailers

Here are some compromises associated with electric trailer brakes
1) Drum brakes need to be adjusted periodically to compensate for shoe lining wear – this adjustment is done mostly by “feel” and it is unlikely that the average person can get all four wheels calibrated properly
2) Drum Brake magnets tend to gradually lose their magnetic strength, causing more calibration problems and loss of braking power
3) Drum brakes are relatively complicated with many moving parts that can cause a failure and need some experience to rebuild the brake assembly
4) Drum brakes tend to accumulate corrosion faster than discs, especially in marine and snowmobile applications

Disc brakes do not have these issues to deal with and are relatively simple with fewer moving parts. Unfortunately, they are not available in an electrically actuated system like the aforementioned electric brakes. They are only available hydraulically actuated. In order to take advantage of disc technology, a new device has been developed to allow for electrically actuated disc brakes. It is called the Electric over Hydraulic Actuator. This device is nothing more than an electrically driven hydraulic pump and relief valve that is controlled by the standard cab mounted Electric Brake Controller, typically used for standard electric drum brakes.

The E/H actuator will be added to the trailer and connected electrically to the brake controller through the 7- blade RV socket on the tow vehicle bumper. Also connected in line will be a Breakaway kit with a 9 amp-hour battery that provides enough power to actuate the pump should the trailer accidentally separate from the tow vehicle while on the road. The output will be connected to the trailer hydraulic system through a standard trailer hydraulic brake line. The E/H system can handle trailers with up to 4 axles by providing 1600 psi maximum. The E/H actuator device does add some expense to the installation.

Of course, the electric brake assemblies and drums on the trailer will have to be replaced with hydraulic disc brake assemblies and brake lines.

The Electric/Hydraulic actuation system also has advantages over trailers that already have hydraulic disc brakes with a Surge Actuator.

1) The E/H actuator keeps the trailer brakes active while in reverse – with the surge actuation, the brake lines must be locked out so that the trailer can be backed up. There is no need for a brake line lock out device.
2) In hilly or mountainous areas, the surge system can incidentally engage the brakes while going down a grade; this will not happen with the E/H system
3) The tongue mounted Surge brake actuator can still be used as the trailer’s ball coupler with a small modification

The Electric/Hydraulic actuation system blends the advantages of disc brakes with the benefits of the cab mounted brake control for the safest experience in trailer towing.

The Trailer Parts Superstore carries a complete lineup of TITAN Brake-Rite E/H actuators as well as the DEXTER 1000-1600. We also carry a complete assortment of KODIAK Disc Brake assemblies for to fit most any trailer application. You can check out our complete trailer brake selection online at: http://www.easternmarine.com/em_store/trailerbrakes/

Disc brake for Boat Trailers & Utility Trailers

There are two basic types of hydraulic trailer brakes typically seen on trailers: Drum brakes and Disc brakes. Drum brakes are an older style and use a hydraulically actuated wheel cylinder to force a pair of spring loaded brake “shoes” against the internal braking surface of brake drum, which also acts as the hub.
Disc brakes use a hydraulic actuation of a piston in the caliper to force the pads to close (pinch) both sides of the rotor. This is a newer design found on most modern automobiles.

Disc brakes have a few advantages over drum.
1) Better stopping power
2) No adjustment necessary to compensate for shoe wear
3) Easy pad replacement
4) Less complicated – no springs
5) For boat trailers, reduced incidence of corrosion

Disc brakes come in two basic designs: Vented and Non-vented. Vented rotors are preferred because they tend to dissipate heat better than non-vented rotors, minimizing a main cause for failure.

For boat trailers, corrosion caused by immersion in fresh or salt water is always a main concern. The salt water can also cause problems when salt crystallizes in the moving parts of the caliper and on the caliper pins. The disc brakes available today, come in either powder coated for standard use, silver cadmium plated for standard salt-water use or stainless steel for extended saltwater use.

To begin the conversion from drum to disc brakes, it is best to start at the front of the trailer. The Hydraulic actuator, (surge or electric/ hydraulic) will need to be either modified or changed out to one that is designed for disc brakes. The disc brake actuator will have an outlet brass fitting with a larger aperture (5/32”) and the check valve found in the drum brake actuator will be absent. Disc brakes require more flow of brake fluid than drum brakes.

Since disc brakes are not designed with the (free-backing) feature, a method to lock out the brake lines will be required. This can be accomplished by installing either an electric lockout solenoid or a mechanical manual ball valve placed in the brake line.

The disc brake calipers require a flexible brake line leading into the piston to work properly. Inspect your brake line and install if necessary.

Safely jack up and block your trailer. Remove the tire / rim assembly. Remove the old brake drum and the brake assembly. The brake assembly is fastened to the axle brake flange with 4 or 5 bolts.

The new disc brake assembly will have a bracket, caliper, rotor and mounting hardware included. General steps to make the conversion are as follows.
Step 1: mount the bracket to the axle flange.
Step 2: prepare and slide the rotor on to the axle spindle and lock in place. Follow standard practice to set the bearings.
Step 3: The caliper will then sit on the rotor and be fastened to the bracket with “slider pins”. Read your assembly instructions before beginning the installation.

Trailer Parts Superstore carries Disc Brakes by Reliable, Kodiak and Tie-Down Engineering. You can find everything you need to make a drum to disc brake conversion at TrailerPartsSuperstore.com

Electric Trailer Brake Assy.

Electric brakes are a very common and reliable means to control your trailer while towing. They are used most often used on utility and smaller equipment trailers. When the time comes to repair or replace them there are many choices available. It can be confusing to decide what brakes or parts you need for your trailer.

Parts most often replaced are the shoes and magnets. They wear from use and should be inspected periodically and replaced when needed. Depending on how often you use the trailer will determine how often to inspect them. The shoes are easier to check then magnets. You can just measure the thickness of the shoe to find of they need to be replaced. Magnets are harder to troubleshoot sometimes they quit working or will just get weak over time. To replace the shoes or magnets look at your existing brakes. For the shoes measure the diameter of the drum and the width of the shoe. This should help you to determine the correct shoes. Sometimes different weight capacity brakes will have the same size shoes. When this happens you will use the magnet to determine the correct replacement. Use the wires that come directly out of the magnet the color will determine what exact brake you have.

Replacing the entire brake backing plate is sometimes a more cost effective and easier to install. The new magnet and shoes are already mounted on the backing plate. You just unbolt your existing plate bolt on the new plate hook up your magnet wires and adjust for tension. This eliminates having to take apart and rebuild the old brakes, which can be a difficult job. To determine the correct brake assembly use the methods discussed above for the drum diameter, shoe width, and magnet wire color. Also you are going to count the number of bolts that attach the backing plate to the axle. With this information you should be able to easily determine the correct brake for your axle.

A question often asked is if the brake magnets are polarity specific. The magnets do not have polarity they work like a common resistor. One wire is attached to the power and one is attached to the ground wire. It is recommended to run a common ground wire from the plug to the magnets. The brakes should be wired in parallel, not in series.

Installing brakes on a new trailer or one that doesn’t have brakes is very common. You will need to determine if the axles you have are designed to have brakes. There will be a steel plate welded to the axle behind the spindle. This will most often have four or five holes drilled in them. They are critical to install brakes on a trailer. If your axle doesn’t have the flanges installed it is recommended to replace the axle assembly with one that does.

Electric brakes are an economical and reliable way to control your trailer. Eastern Marine stocks a full line of electric brakes and related products for towing. Give us a call or visit us online at TrailerPartsSuperstore.com for all your electric brake needs.