Posted by on 12/9/2021 to
The surge brake system works by the inertia of the boat trailer moving forward when you apply the brakes on your tow vehicle. When coming to a stop the trailer weight pushed against the ball housing putting force on the piston inside the master cylinder assembly. When taking off from a stop it yanks it back out. Hydraulic surge actuators have a tensioned spring and dampener built into them that along with a properly bled system softens the stop and go forces. Usually when the system has a leak or is not properly bled is when you would commonly experience this issue. Surge brake systems should be inspected at least once a year.
Typical causes that develop leaks are lack of inspection and cleaning of the caliper slide pins, when a caliper hangs up on its slide pins it can lock at an angle against the rotor allowing the rear boot to extend to far and blowing past the rear boot as well as causing the pads to wear improperly. Other causes are due to corrosion depending on the brake system. Drums systems are susceptible to salt or rust buildup on the wheel cylinder piston which works itself past the dust boot and destroys the inner seal. Disk systems are susceptible to salt and rust buildup on the caliper pistons and inner cup as most marine disk brakes utilize a steel cup and brass insert or steel cup and stainless insert.
A yearly bearing pack / inspection allows to catch these issues before they develop into an expensive repair.