This boat trailer surge actuator from UFP by Dexter is their model DX8.5L designed for use with larger 2 5/16 inch trailer tow balls. This brake system is a direct OEM compatible replacement component on many boat trailers with single axle and tandem axle disc brake systems. This Dexter manufactured Disc Brake Actuator replaces the former UFP (Unique Functional Products) actuator model A-84. This low profile surge actuator unit is sized to fit onto 3 inch wide trailer tongues for an easy top-mount bolt-on installation. The actuator is rated for 8,500 lb towing capacity , so you will typically see this surge actuator outfitting either a single axle or tandem axle trailer with one or two 3,500lb capacity trailer axles. This makes this model ideal for trailers utilizing 3500lb Capacity UFP or Dexter Disc Brake Kits, as the capacity of the kits exceeds the actuator's weight rating.
A Surge Disc Brake Actuator works by using the force of the towing vehicle stopping to engage the master cylinder, applying pressure on the brake fluid to flow through the brake lines.
This particular actuator features a pre-installed reverse lockout bypass solenoid. The job of the reverse lockout is to allow you to go in reverse with your trailer without locking the brakes out. Two wires run from it, one as a ground, and the other connects to your wiring harnesses 5th wire (for 5 Flat connectors). This wire is commonly blue. Under normal operation while driving forward and braking the Reverse Solenoid Valve does nothing, however, once you need to reverse or back onto a boat ramp, the Solenoid Valve becomes crucial. When you put your truck in reverse, a signal is sent to the reverse lockout solenoid (through the 5th wire, which on the truck side connects to your vehicles reverse light) and the device blocks the flow of hydraulic fluid, this allows you to reverse without the surging of the trailer brakes stopping you as you go backwards down the ramp. Keep in mind this means as you reverse, your truck is your only source of braking.
Typically you will be using (3) 1/2 inch Diameter by 4 1/2 inch Long Stainless Steel Bolts to mount to your trailers 3 inch wide tongue. You must have a straight, 3 inch wide tongue to mount this DX8.5L (formerly A-84) actuator. It is not uncommon to need to drill new holes, as different manufacturers use different bolt spaces when the tongue actuators are produced.
When installing a new disc brake system on single or tandem axle disc brakes it is not uncommon to spend extra time priming the lines, and using a good amount of brake fluid. It is important to begin at the furthest away caliper when trying to get the fluid through the lines and out the caliper bleeder. This style of UFP / Dexter A-84 / DX8.5L actuator is one of the most common surge couplers used on saltwater or freshwater boat trailers from many manufacturers, such as Ranger, EZ Loader, Trail Master, Karavan, Triton, and many more. If you have a boat trailer, utility trailer, enclosed trailer, or any other type of trailer in need of a surge actuator that fits 2 5/16 inch ball hitch mounts, then this 8,500 lb Dexter / UFP hydraulic surge coupler might be exactly what you need!
Specifications:
- The A-84 / DX8.5L inner housing is interchangeable with any UFP actuator 8,500 lbs and below.
- Fits 2 5/16 inch size Trailer Ball
- Top Mount (slides over your 3" wide tongue)
- Housing: 14.5" Long, Zinc Finish. 4 mounting holes - 3/4" down, 3" centers/ top mount for 3" & 4" tongues
- Mounting hole configuration interchangeable with Atwood 6k, Titan Model 60 & Tie Down Model 66
- Former UFP Model #A-84 (#40220), now DX8.5L with 2 5/16 coupler by Dexter
- 850 lb max tongue weight
- Uses DOT 3 Brake Fluid
