This UFP by Dexter DX8.5L boat trailer surge actuator is a popular OEM trailer replacement, compatible with single axle and tandem axle disc brake systems from a variety of trailer manufacturers. This Dexter manufactured Disc Brake Actuator replaces the former UFP (Unique Functional Products) actuator model XR-84. This low profile surge actuator unit fits a 2 inch trailer tow ball, and 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 XR-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 8,500 lb actuator unit is one of the most common units used on saltwater or freshwater boat trailers from many manufacturers, such as Triton, Ranger, EZ Loader, Marine Master, Karavan, and many more. Get your boat trailer's brake setup back in tip-top shape with this corrosion resistant zinc-plated surge actuator from UFP by Dexter!
Specifications:
- The XR-84 / DX8.5L inner housing is interchangeable with any UFP actuator 8,500 lbs and below.
- 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 XR-84 Model # (#40220), now DX8.5L by Dexter
- 850 lb max tongue weight
- Uses DOT 3 Brake Fluid
