Frequently Asked Questions
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Brakes
Braking systems use friction to slow the vehicle and the energy used to slow the trailer is converted to heat. Dexter brakes are designed to operate up to extremely high temperatures during hard braking application. This heat is noticeable on the hub and drums and is to be normally expected on a properly functioning brake. If a brake is malfunctioning and running excessively hot, this can be noticed by smoking brakes or the paint burning off of the brake drum.
Brakes must be adjusted to compensate for the lining and drum wear that occurs during the use of the braking system. Some brakes require manual adjustment to move the linings closer to the drum.
Refer to the brake adjustment section of the OPERATION MAINTENANCE SERVICE MANUAL for your style of brakes. Other brakes may have an automatic brake adjuster such as the automatic slack adjusters for air brakes.
Refer to the brake adjustment section of the OPERATION MAINTENANCE SERVICE MANUAL for your style of brakes. Other brakes may have an automatic brake adjuster such as the automatic slack adjusters for air brakes.
On an unloaded trailer, you may be able to lock up your brakes if your electric brake controller is supplying full amperage to the brakes. When loaded to capacity, you may not be able to lock your brakes as electric brakes are designed to slow the trailer at a controlled rate, and not designed to lock up the wheels on a fully loaded trailer. Our brakes are designed to meet all applicable safety standards. All of our brakes will perform better after numerous burnish stops to seat the brake linings to the drums.
Most electric brake malfunctions that cannot be corrected by either brake adjustment or synchronization adjustments of your brake controller can generally be traced to electrical system failure. Mechanical causes are ordinarily obvious (i.e. bent/broken parts, worn out linings or magnets, seized lever arms or shoes, scored drums, etc.). A voltmeter and ammeter will be essential tools for proper troubleshooting of electric brakes.
NOTE: After replacing your brake shoes and magnets you will experience a decrease in braking performance until the components have worn into the drum and finished the burnishing process. This process requires many stops to bring the new shoe's performance back to normal. This may take more than 100 stops to finish this break-in period with stops of 20 mph decreases in speed.
Please refer to the Dexter Service Manual for detailed troubleshooting instructions to further determine the cause of poor brake performance.
NOTE: After replacing your brake shoes and magnets you will experience a decrease in braking performance until the components have worn into the drum and finished the burnishing process. This process requires many stops to bring the new shoe's performance back to normal. This may take more than 100 stops to finish this break-in period with stops of 20 mph decreases in speed.
Please refer to the Dexter Service Manual for detailed troubleshooting instructions to further determine the cause of poor brake performance.
The actuation lever should curve around the front side of the spindle. The wires should always exit the brake to the backside of the assembly when installed on the trailer.
The Dexter magnet is not a polarized component. Use one wire to connect to power from the brake controller and use the other to attach to the ground. It is Dexter's recommendation that a common ground be run from the trailer plug to the magnets. Do not ground each brake individually to the trailer frame or structure. Also note that the brakes should be wired in parallel, not in series. The wire color is used to identify the component since so many Dexter magnets physically look the same on the outside; however they are different strengths for the different capacity brakes.
Usually, light cracking of the surface of a brake lining can be expected under normal use. This is not cause for replacement. However, if the lining is deeply cracked to the shoe surface or is missing chunks, your brake linings will require replacement.
Dexter offers marine application free-backing hydraulic brakes in both 10"x2-1/4" and 12" x 2" sizes. The brake components are all either E-Coated, stainless steel, or zinc plated to resist corrosion.
Dexter recommends that manual adjust brakes be adjusted:
1 ) After the first 200 miles of operation when the brake shoes & drums have "seated"
2 ) At 3,000 mile intervals
3 ) Or as use or performance requires
System voltage is measured at the magnets by connecting a voltmeter to the two magnet lead wires at any brake. This may be accomplished by using a pin probe inserted through the insulation of the wires dropping down from the chassis or by cutting the wires. The engine of the towing vehicle should be running when checking the voltage so that a low battery will not affect the readings.
Voltage in the system should begin at 0 volts and as the controller bar is slowly actuated, should gradually increase to about 12 volts. This is referred to as modulation. No modulation means that when the controller begins to apply voltage to the brakes it applies an immediate high voltage, which causes the brakes to apply instantaneous maximum power.
The threshold voltage of a controller is the voltage applied to the brakes when the controller first turns on. The lower the threshold voltage the smoother the brakes will operate. Too high of a threshold voltage (in excess of 2 volts as quite often found in heavy duty controllers) can cause grabby, harsh brakes.
Voltage in the system should begin at 0 volts and as the controller bar is slowly actuated, should gradually increase to about 12 volts. This is referred to as modulation. No modulation means that when the controller begins to apply voltage to the brakes it applies an immediate high voltage, which causes the brakes to apply instantaneous maximum power.
The threshold voltage of a controller is the voltage applied to the brakes when the controller first turns on. The lower the threshold voltage the smoother the brakes will operate. Too high of a threshold voltage (in excess of 2 volts as quite often found in heavy duty controllers) can cause grabby, harsh brakes.
Dexter 7" brakes draw about 2.5 amps per brake and all other brake magnets draw about 3 amps per brake. The total system amperage is calculated by multiplying this number by the number of brakes/magnets connected to the brake system.
To measure the brake current, the engine of the towing vehicle should be running. Disconnect the wire at the point that you wish to measure the current draw and put the ammeter in series with this line. Make sure your ammeter has sufficient capacity and note polarity to prevent damaging your ammeter.
NOTE: If a resistor is used in the brake system, it must be set to zero or bypassed completely to obtain the maximum amperage reading.
The amount of current draw will depend on what point you are measuring. If the ammeter is at the plug, you will get the total current draw from all magnets. If the ammeter is connected at one of the magnets, you will measure the current draw through that magnet only.
To measure the brake current, the engine of the towing vehicle should be running. Disconnect the wire at the point that you wish to measure the current draw and put the ammeter in series with this line. Make sure your ammeter has sufficient capacity and note polarity to prevent damaging your ammeter.
NOTE: If a resistor is used in the brake system, it must be set to zero or bypassed completely to obtain the maximum amperage reading.
The amount of current draw will depend on what point you are measuring. If the ammeter is at the plug, you will get the total current draw from all magnets. If the ammeter is connected at one of the magnets, you will measure the current draw through that magnet only.
It is not possible to put a larger magnet in the 12" x 2" electric brake. However, we do offer a more aggressive lining. The lining kit number is K71-127-00. You will need one for each brake. Keeping your brakes adjusted up can now be done using a forward self adjust brake. The part numbers for this brake are K23-464 LH and K23-465-00 RH.
The wires on a Dexter magnet do not have polarity. It works like a common resistor. One wire will connect to power and the other to a ground. It is Dexter's recommendation that a common ground be run from the trailer plug to the brake magnets. Do not ground each brake individually to the trailer frame or structure. Also note that the brakes should be wired in parallel, not in series.
Adding brakes to an idler axle is relatively easy if the idler axle is equipped with brake mounting flanges (the plate to which the brake is bolted). About half of the trailer manufacturers decide not to put the flanges on their idler axles in order to reduce their cost. If the axle does have flanges, you need both a right hand and a left hand brake assembly as well as two hub and drums to replace the plain hubs currently on the axle. If the axle is not equipped with flanges, you will need to purchase a new axle beam with brake flanges attached by Dexter Axle.
Dexter Axle does not recommend the use of brakes on small touring trailers designed to be pulled by motorcycles.
Proper control of the brakes on these vehicles can be very difficult. Even the slightest imbalance of the trailer brakes might cause the rider to lose control. A secondary issue is the spontaneous and unexpected actuation of the brakes.
This can occur when a Torflex axle is not fully loaded. Under this condition, the torsion arm is not rotated to its normal position, which puts the brake assembly out of level. If the axle is fitted with electric brakes, this non-level condition can result in unexpected brake actuation when the trailer encounters large bumps. This can occur because the magnet inside the brake has sufficient mass to move the actuating lever during extreme jounce situations. The farther the brake assembly is rotated out of level, the greater the chance that this spontaneous action can take place.
Proper control of the brakes on these vehicles can be very difficult. Even the slightest imbalance of the trailer brakes might cause the rider to lose control. A secondary issue is the spontaneous and unexpected actuation of the brakes.
This can occur when a Torflex axle is not fully loaded. Under this condition, the torsion arm is not rotated to its normal position, which puts the brake assembly out of level. If the axle is fitted with electric brakes, this non-level condition can result in unexpected brake actuation when the trailer encounters large bumps. This can occur because the magnet inside the brake has sufficient mass to move the actuating lever during extreme jounce situations. The farther the brake assembly is rotated out of level, the greater the chance that this spontaneous action can take place.
No, the different brake sizes offered by Dexter are not interchangeable on existing axles. There are only a few cases where you may be able to upgrade with stronger magnets and more aggressive linings. Typically, the problem that causes weak brakes is under-adjustment in the smaller brakes that require frequent manual adjusting (see: How often should I adjust my brakes?) or insufficient brake voltage in the electric brakes (see: Why aren't my electric brakes working properly).
This can be done on most axle models. We recommend contacting the trailer manufacturer prior to changing your braking system to identify any potential problems.
Leaf springs that feature a curved surface on both ends of the spring.