INSTALLATION MANUAL
LIGHT DUTY ACTUATORS

6,600 - 8,500 LBS. CAPACITY
www.dexteraxle.com/surgeactuators

TABLE OF CONTENTS
SECTION 1 - PRODUCT IDENTIFICATION
1.1 - STANDARD PROFILE........................................................................................................................ 3
1.2 - LOW PROFILE................................................................................................................................. 3

SECTION 2 - IMPORTANT INFORMATION
2.1 - BRAKE REQUIREMENTS.................................................................................................................. 4
2.2 - TOWING/HITCHING REQUIREMENTS............................................................................................... 4

SECTION 3 - INSTALLATION
3.1 - BOLT-ON (STANDARD AND LOW PROFILE)........................................................................................ 5
3.2 - WELD-ON (LOW PROFILE).............................................................................................................. 5
3.3 - CONNECTING THE REVERSE SOLENOID.......................................................................................... 6

SECTION 4 - BRAKE BLEEDING
4.1 - STANDARD PROFILE....................................................................................................................... 6
4.2 - LOW PROFILE.................................................................................................................................7

SECTION 5 - TRAILER HITCHING
5.1 - DROP-N-GO™ COUPLER...................................................................................................................7
5.2 - MANUAL AND LEVER LOCK COUPLER..............................................................................................7

SECTION 6 - BEFORE TOWING
6.1 - EMERGENCY BREAKAWAY CABLES.................................................................................................. 8
6.2 - ROAD TESTING.............................................................................................................................. 8
6.3 - TOWING CONSIDERATIONS............................................................................................................. 8

SECTION 1 - PRODUCT IDENTIFICATION
There are two types of actuators referenced in this document. While mostly similar, there are places where they have separate
instructions. These actuators are designed to fit 3” wide tongues in heights of 3”, 4”, and 5”.
Throughout the manual, actuators will be referred to their groupings listed below.

1.1 - STANDARD PROFILE
DX6.6
DROP-N-GO™

DX7.5
DROP-N-GO™

DX8.5
DROP-N-GO™

G.V.W.R.: 6,600 LBS.

G.V.W.R.: 7,500 LBS.

G.V.W.R.: 8,500 LBS.

TONGUE WEIGHT: 330 - 660 LBS.

TONGUE WEIGHT: 375 - 750 LBS.

TONGUE WEIGHT: 425 - 850 LBS.

BALL SIZE: 2” AND 50MM

BALL SIZE: 2” AND 50MM

BALL SIZE: 2”

1.2 - LOW PROFILE
DX7.5L
MANUAL COUPLER

DX7.5L
LEVER LOCK COUPLER

DX8.5L
DROP-N-GO™

DX8.5L - 2-5/16”
DROP-N-GO™

G.V.W.R.: 7,500 LBS.

G.V.W.R.: 7,500 LBS.

G.V.W.R.: 8,500 LBS.

G.V.W.R.: 8,500 LBS.

TONGUE WEIGHT:
375 - 750 LBS.

TONGUE WEIGHT:
375 - 750 LBS.

TONGUE WEIGHT:
425 - 850 LBS.

TONGUE WEIGHT:
425 - 850 LBS.

BALL SIZE: 2”

BALL SIZE: 2”

BALL SIZE: 2”

BALL SIZE: 2-5/16”

DO NOT EXCEED THE MAXIMUM TONGUE WEIGHT RATING OF YOUR TOW VEHICLE OR ITS HITCH SYSTEM.
EXCESSIVE TRAILER TONGUE WEIGHT CAN NEGATIVELY AFFECT TOW VEHICLE BRAKING AND HANDLING.

LIGHT DUTY SURGE ACTUATOR
INSTALLATION MANUAL

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SECTION 2 - IMPORTANT INFORMATION

2.2 - TOWING/HITCHING REQUIREMENTS

READ AND UNDERSTAND THE ENTIRE PROCEDURE BEFORE
INSTALLATION OF THIS PRODUCT. THIS MANUAL APPLIES
TO AFTERMARKET SURGE ACTUATOR INSTALLATION AND IS
NOT MEANT TO ASSIST IN NEW TRAILER DESIGNS.

Using the correct hitch ball size is critical to the safe operation
of your trailer. Use the chart in the actuator identification
section to ensure the correct fit. DO NOT use a multi-piece ball,
an incorrectly sized ball, or a worn/damaged ball.

CAUTION
FAILURE TO PROPERLY MAINTAIN THE ACTUATOR ACCORDING TO
THE SERVICE MANUAL COULD LEAD TO DAMAGE, INJURY OR DEATH.

Surge actuators work by the “surge” or “push” of the trailer
toward the tow vehicle. This automatically synchronizes the
trailer brakes with the tow vehicle brakes. When the trailer
pushes against the tow vehicle, the actuator telescopes together
and applies the force to the master cylinder, supplying hydraulic
pressure to the trailer brakes.
Review and understand the manufacturers’ manuals for your tow
vehicle and trailer before installation. The user is responsible for
the consequences of inadequate maintenance, deliberate misuse,
alteration, or damage to the actuator.
If corrosion is present on the actuator, replace the metal brake
lines and/or hoses due to metal corrosion or rubber breakdown.

CAUTION
DO NOT LIFT OR SUPPORT THE TRAILER ON ANY PART OF THE
AXLE OR SUSPENSION SYSTEM. NEVER GO UNDER ANY TRAILER
UNLESS IT IS PROPERLY SUPPORTED ON JACK STANDS WHICH
HAVE BEEN RATED FOR THE LOAD. IMPROPERLY SUPPORTED
VEHICLES CAN FALL UNEXPECTEDLY AND CAUSE SERIOUS INJURY
OR DEATH.

2.1 - BRAKE REQUIREMENTS
This actuator is part of a complete trailer hydraulic brake
system. When replacing an actuator, ensure you replace it with
the correct system to match the brakes. Drum brake actuators
cannot be used on disc brake trailers and vice versa. Disc brake
actuators also require an electric solenoid. Drum brake actuators
must be used with free-backing drum brakes.
State brake laws are minimum standards. Dexter recommends
having brakes on all axles.

CAUTION
DO NOT USE AN ACTUATOR AS A PARKING BRAKE.

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Before each trip, inspect the hitch ball, coupler latch, and
safety chains for wear, corrosion, or damage. Repair or replace
components per manufacturer’s instructions as necessary.

CAUTION
INCORRECT OR DAMAGED TOW BALL USAGE COULD LEAD TO A
TRAILER SEPARATION FROM THE TOW VEHICLE, RESULTING IN
DAMAGE, INJURY, OR DEATH.

Any control devices that restrict the operation of the actuator
cannot be used including certain sway control devices. The actuator
must be free to telescope in response to braking signals.
Equalizing or weight-distributing hitches that are designed to be
use with surge brake actuators may be utilized and must allow
6-8” free chain length.

CAUTION
ALWAYS INSERT THE COUPLER LATCH SAFETY PIN INTO THE
CORRECT HOLE BEFORE TOWING. DO NOT TOW THE TRAILER IF THE
COUPLER IS DAMAGED.

Review the trailer and tow vehicle manufacturers’ manuals
for information on towing capacity, trailer brake requirements,
weight-distributing hitches, and other towing recommendations.
The user is responsible for ensuring the tow vehicle and towing
components are rated to match the trailer G.V.W.R.
The actuator may not function properly if the trailer is not level.
To ensure the trailer is level, the trailer tongue should be parallel
to the ground.

There are no adjustments on the actuator. Do not attempt to
adjust or modify the coupler latch in any way to compensate for
wear, damage or to fit a tow ball. The Model DX7.5L A-75 actuator
has a locknut underneath its coupler latch that is factory set. Do
not attempt to adjust the nut setting.

LIGHT DUTY SURGE ACTUATOR
INSTALLATION MANUAL

SECTION 3 - INSTALLATION

3.2 - WELD-ON (LOW PROFILE)

3.1 - BOLT-ON (STANDARD AND LOW PROFILE)

1.

OUTER MEMBER

2. Remove inner member subassembly, then weld outer
member to trailer tongue using the following diagrams.

MEMBER BASE
LOCK NUT, BOLT,
AND WASHER

REINFORCEMENT SPACER

Weld according to AWS specifications. Welder must wear
appropriate personal protective equipment and meet AWS
qualifications. Ensure that the welding location allows
access to wiring and brake lines for service.

TRAILER TONGUE

3. Reinstall inner member.
4. Route and install brake lines following brake manufacturer’s
instructions. Flexible lines may be necessary in certain cases.
5. For trailers with a reverse solenoid, move to section 3.3. For
all other trailers, move to section 5.
Top Mount Welding

1.

These actuators are completely assembled and ready to bolt
on using 1/2” x 4” grade 5 bolts, not included.

In-line Welding

2. Torque the bolts and locking nuts to 80 ft.-lbs.
3. Spacer tubes for reinforcement are required on tongues less
than 3/16” thick. Attachment hardware needs to be rated at
least 150% of G.V.W.R. of trailer.
4. Route and install brake lines following brake manufacturer’s
instructions. Flexible lines may be necessary in certain cases.
5. For trailers with a reverse solenoid, move to section 3.3. For
all other trailers, move to section 5.

LIGHT DUTY SURGE ACTUATOR
INSTALLATION MANUAL

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In-line welding needs to allow the inner slide, master cylinder,
and solenoid to slide rearward during operation.
A-Frame, Short Tongue

SECTION 4 - BRAKE BLEEDING
For ease of bleeding the system, keep the actuator lower than
the disc brake calipers if possible.
Ensure brake lines do not slope up before slopping down,
trapping air. Ensure bleeder screws on the brake calipers are on
the top side of the caliper before beginning.

CAUTION
DO NOT REUSE BRAKE FLUID. ALWAYS USE FRESH DOT 3 FLUID
FROM A FRESH CONTAINER. FAILURE TO MAINTAIN PROPER
LEVELS OF FLUID IN THE RESERVOIR WILL CAUSE BRAKE FAILURE.

Start the bleeding process at the brake located at the farthest
point along the brake line routing from the surge actuator.

A-Frame, Tall Tongue

If using a pressure bleeder, follow the manufacturer’s
instructions. The pressure in the power bleeder should not
exceed 18 psi. Exceeding this pressure will damage the
diaphragm in the master cylinder reservoir, causing it to leak.
Set up the area with a clear container filled with clean brake
fluid. Ensure that the end of the bleeder hose can be completely
submerged to prevent air from traveling back into the system.
NEVER REUSE THIS FLUID.

A-Frame trailers may require additional structure to withstand
the torsional twist during actuator use. The cross member should
be installed as close to the actuator as possible.

Constantly check brake fluid levels when bleeding as the
reservoir can quickly run out and put air in the lines. If this
occurs, the process will need to start over.

3.3 - CONNECTING THE REVERSE SOLENOID
Disc brake actuators come standard with a reverse solenoid. By
using the reverse lights of your tow vehicle, it eases the process
of backing up the trailer.
You can add an aftermarket reverse solenoid to a drum brake
actuator as well. Follow manufacturer’s instructions.
1.