MFI Trailer- Is this normal?

[flyin_dutchman]

I'm not sure if it has always done this, but recently I started getting a thump from a stop while towing? Had someone pull truck&boat forward while I was outside watching, and I see the trailer tongue between the silver & black part move/slide fwd/aft when starting/stopping? Is this supposed to move like that?

 

[Scottintexas]

that is your surge break unit moving, when you stop the momentum pushes the unit forward towards the hitch to activate the breaks, when you accelerate it pulls the unit back apart until it reaches it's max and then the trailer starts following.

If you feel the thump from a start or acceleration that's ok, if you feel it while breaking it may mean you breaks are not engaging and it's traveling the full length and hitting the stop instead of gradually getting there.

If you put your break lock out hub into the space above the white sticker where the bolt is sticking out it will prevent the unit from travelling forward and activating your breaks.

 

[Boat Crazy]

That is your surge brake. Yes, it is suppose to move. When you pull out it should pull completely forward to where the pin in the side is completely forward. When you apply brakes the trailer will surge forward and that pin you see will slide rearward. The harder the brakes are applied the further back it will slide. (when traveling the pin on the side should be fully forward).

 

[Craig]

No experience with the MFI trailer, but the tongue on my shorelander moves some as well. If I understand it correctly it's the mechanism that operates the surge brakes on your trailer. Not being sarcastic but did you check that you had the right size ball? If you're like me and pull multiple trailers, I have to double check myself that I have the right ball and hitch in.

 

[Craig]

I must type slowly...lol. I swear there were no responses when I started typing.

 

[Boat Crazy]

I noticed the rubber/plastic cap is missing over your brake fluid reservoir. I highly recommend you get one. It does help in keeping moisture and water out.

 

[Boat Crazy]

I must type slowly...lol. I swear there were no responses when I started typing.

X2 .Scotts reply was not there when I started typing. (LOL). It is a good thing we all replied YES.

 

[Boat Crazy]

Also noticed on picture That the silver cable is not hooked up (that is your emergency brake in the event your trailer becomes unhitched)
The black cables hooked to your hitch should be crossed. The intent behind this is that in the event the trailer comes unhitched the cables will create a cradle and allow the trailer to ride on them without digging into the ground.
Pin is missing from trailer hitch lock.

 

[Julian]

The clunk may just be the hitch reciever moving around. I wrapped a little electical tape around mine to make it fit snugger and to reduce the hitch klunk

 

[Ronnie]

Looks like everyone covered what you are hearing. I don't think the noise can be completely eliminated but they sell wedges to tighten things up (I'd use a piece of hydro turf of something similar. I'd also check that the coupler that goes around the bottom of the ball is not loose and the nut holding it in place it tight.

I didn't recall reading if that is how you tow your boat or not but if it is, in addition to making sure the emergency cable is hooked up to the tow vehicle, I suggest you put a pin or lock through the couplers handle while towing. I used to think that the emergency cable was overkill than last year I had an experience which tested all of that gear, thankfully it did what it was supposed to do, it was the first time I needed it to in over 25 years.

http://yamahajetboaters.com/forum/viewtopic.php?f=1&t=59119&hilit=+disaster

Here are links to two different outer covers for the surge brake reservoir. The stock one and one that mechanically blocks the surge brake from activating. Either one is fine and neither is really necessary. My stock cover has been missing since I bought the boat used a year and a half ago (who knows how long it was missing before that) and I have had no issues to date. However, I did just order to stock covers and a locking cover today since I'm refurbishing my boat's trailer this year.

http://www.pacifictrailers.com/UFP-Outer-Member-Cap-for-brake-actuator-A-60-A-75-32547/

http://www.pacifictrailers.com/UFP-A-60-Top-Lockout-Upgrade-34359-A-60-Brake-Lockout-Cap-/

Lastly, here is a link to the home page for the company's surge brake assemblies and parts. At the top is a good and short animation of how surge brakes work. At the bottom you can find just about any surge brake part you need or want.

http://www.pacifictrailers.com/UFP-A-60-Brake-Actuator-Replacement-Parts-for-Disc-Drum-brakes/

 

[Lspeedss]

@flyin_dutchman .if you are getting that much compression when braking where it clunks. You need to check your fluid level while fully extended. I may be low. Also you may need to bleed your trailer brakes or replace pads...

 

[smack]

Agree with everything said so far, basically with a surge braked trailer, a thunk when starting is ok (that's the tongue extending to it's maximum extension from the compressed brake setting) - to much thunk on starting means there isn't enough fluid in there. Thunks on stopping is bad - surge brakes actuate no different than your car brakes in that the harder your car stops the more pressure is applied (compressing the trailer tongue into the surge sleeve) , and thus more braking pressure results (like stamping on your car brakes) - Getting a thunk is like being able to push your brake pedal to the floor with ease.

 

[Glassman]

@flyin_dutchman .if you are getting that much compression when braking where it clunks. You need to check your fluid level while fully extended. I may be low. Also you may need to bleed your trailer brakes or replace pads...

x2

 

[flyin_dutchman]

Also noticed on picture That the silver cable is not hooked up (that is your emergency brake in the event your trailer becomes unhitched)
The black cables hooked to your hitch should be crossed. The intent behind this is that in the event the trailer comes unhitched the cables will create a cradle and allow the trailer to ride on them without digging into the ground.
Pin is missing from trailer hitch lock.

I just hooked it up to pull boat forward a bit to keep tires from flat spotting. I do normally cross the cables and pin the hitch lock too. My silver cable is unable to attach as the end is just frey'd off. I did just order a upgrade resivoir cover from Pacific trailer thanks to helpful advice/links you all gave me. A big thanks and cheers to all!

 

[Speedling]

OMG! Don't let it move, just weld it shut! How else will your electric brakes be effective!!!???
Oh, nevermind....

 

[flyin_dutchman]

OMG! Don't let it move, just weld it shut! How else will your electric brakes be effective!!!???
Oh, nevermind....

Weld what shut? Electric? You kiddn me?

 

[Speedling]

Not at all, I am running electric brakes, welded it solid, and lovin it.
No, it doesn't shock the fishies, it's low voltage and doesn't do that kinda thing. No, it doesn't corrode really quick and junk. Any other questions?