Trailer jerking

[Davpmars]

As I've mentioned in some other posts, I just bought my first boat. 2013 LSV. I soon realized the trailer was jerking each time I hit the gas from a stop. This is what I found and I can't see a fix for it. I'm wondering if this is by design for some odd reason.

The silver part that connects the ball to the black trailer is fastened with a circular pin. However each time I move the vehicle this pin slides back and forth in that grove. The pin doesn't appear to be damaged and also doesn't appear to be designed to be tightened. Am I wrong? What am I missing?






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[dusty2221]

It is designed as such. The trailer has surge brakes on it, inside that actuator is a master cylinder. Each time you stop, the actuator allows the trailer to surge forward, forcing break fluid into the system..which then applies the breaks.

On the topside of what you took a picture of you should see a removable cap. You can check the fluid here. Add fluid if needed, it seems if it is a little low on fluid it gets very "clunky." You will always have some degree of "clunk" sound, it's just the actuator moving back to it's position.

[Davpmars]

It is designed as such. The trailer has surge brakes on it, inside that actuator is a master cylinder. Each time you stop, the actuator allows the trailer to surge forward, forcing break fluid into the system..which then applies the breaks.

On the topside of what you took a picture of you should see a removable cap. You can check the fluid here. Add fluid if needed, it seems if it is a little low on fluid it gets very "clunky." You will always have some degree of "clunk" sound, it's just the actuator moving back to it's position.

This is great info! Thanks.

Does this mean that the trailer brakes are working independently from the trailer brake controller in my vehicle? When I plug the trailer into my tow vehicle the trailer brake controller doesn't register a trailer and thus I figured my trailer brakes were not working.


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[dusty2221]

The trailer brake controller in your vehicle is for electronic trailer brakes (like what most travel trailers have). This controller has no impact on the hydraulic brakes on your boat trailer. The harder/faster you stop your tow vehicle, the more the breaks are applied to the trailer as the actuator pushes more fluid.

[JesseC]

A good habit to start while towing your boat is after you come to a complete stop, pull forward about 5 inches to take the slack back out of the surge breaks. After you come to a complete stop, don't just gas it and go, take the slack out first and then give it gas. This will stop the heavy clunking and you will just feel the boat/trailer reengage with the tow vehicle softly.

[clark]

Jesse is exactly correct. The first Moomba I had was just like that. If takes a little getting used to. Like he said,,, slowly start and it will slowly slide back into place. I understand how that can scare you. Good luck.. and yes,, do check the fluid.

[gregski]

One other thing to keep in mind, especially given your electrical issue in your other thread: The same force that is sliding that mechanism forward when braking will also move when you are backing the trailer (when you have to "push" it backwards - not usually an issue going down the launch ramp). The fifth pin of the wiring harness is the reverse "lights" but what it does on the trailer is bypasses/disable the surge brake. If that signal is not coming through, the brakes will apply and lock up when backing up. You can get a cheap lock-out key that you put in that slide area to do the same thing mechanically. It's a good idea to have one in the truck just in case you have an electrical problem.

[trayson]

One other thing to keep in mind, especially given your electrical issue in your other thread: The same force that is sliding that mechanism forward when braking will also move when you are backing the trailer (when you have to "push" it backwards - not usually an issue going down the launch ramp). The fifth pin of the wiring harness is the reverse "lights" but what it does on the trailer is bypasses/disable the surge brake. If that signal is not coming through, the brakes will apply and lock up when backing up. You can get a cheap lock-out key that you put in that slide area to do the same thing mechanically. It's a good idea to have one in the truck just in case you have an electrical problem.

I guess it is good for people to keep in mind that while backing downhill (or uphill for that matter) that the trailer won't have any braking power. it's all the tow vehicle at that point. It's not a huge deal typically (especially when compared to old drum brakes that had little braking power in reverse anyway), but just remember that your trailer isn't helping you stop as you back down the ramp. Because we'd hate to see someone slide too far into the water. (there have been situations where someone has backed too far into the water, and their boat able to lift the nose of the trailer and in turn it lifted the rear wheels of the tow vehicle so it lost traction and rolled into the water.

They do make an "electric over hydraulic" brake system for boat trailers now. It's not as common, but i've seen it on more expensive boat trailers. They have a battery backup and a separate actuator for the brakes (that IS controlled by your tow vehicle brake controller). No clunking on those. But it's been way too expensive of an upgrade for me to justify. (the actuators are $800+ IIRC.)

[lee]

You could also have a worn out shock absorber in the actuator.

[mmandley]

Of you feel you have excessive clunking when pulling away after a stop, your brakes might be worn out or you might be low on fluid.

On my 13 last summer I got a lot of clunking and had the breaks checked. Dealer bleed them.

Problem still there, since I was moving to GA from OR I replaced the brake pads and no more clunking.

This is because the tongue doesn't compress as much and you get less play when stopping starting