2006 MFI 210 Trailer Refurbishing

[CaptRedbeard]

Hey all. New to me 2006 AR210 and I’m refurbishing the trailer. I’m new to surge brake systems. Actuator is a UPF A-70 which is an older model A-75 from what I understand.

When I bought the boat, the trailer had a snapped brake line and a frozen actuator shock. Got those fixed and everything reinstalled now I'm attempting to bleed the brakes using the “tube and water bottle filled partially with brake fluid” method. No air or fluid coming of the (open) bleeder screw. Bleeder screw is clean and not rusted or clogged.

I disconnect and take the actuator back out of the tongue and attempt to get some brake fluid pumping out of the master cylinder but nothing. I disconnect the reverse solenoid to see if it’s clogged, but still nothing pumping out of the master cylinder. Air passes through the solenoid freely so I think that’s good.

I assume a functioning master cylinder would squirt brake fluid when pumped even if disconnected from brake lines, correct? At this point, next step is to replace the master cylinder, right?

Thanks for the help!

 

[AZMark]

Try running a little tube from the outlet back up into the master cylinder’s reservoir full of fluid and then pump on it.

 

[AZMark]

Like this, but just put the tube through your fill hole. You may be sucking air right back in every time you pump it if you ran it all the way dry.
Look up bench bleeding.

 

[CaptRedbeard]

Like this, but just put the tube through your fill hole. You may be sucking air right back in every time you pump it if you ran it all the way dry.
Look up bench bleeding.

View attachment 170901

Gotcha, so if I’m able to prime the master cylinder that way, then I should be able to install and bleed the system like normal?

 

[AZMark]

Gotcha, so if I’m able to prime the master cylinder that way, then I should be able to install and bleed the system like normal?

I think that’s what should happen if your issue is air in the master.

 

[Seadeals]

This thread may have some useful info.

https://jetboaters.net/threads/mfi-trailer-brake-hydraulic-hose-ruptured.33514/#post-541889

 

[CaptRedbeard]

Progress! Thanks @AZMark for the tip - I was able to re-prime the master cylinder by “threading” a 1/4” ID vinyl tube into the reverse solenoid and sticking the other end into the reservoir. About 8-10 pumps and air was out of the master cylinder.

Now I have the system installed and bled. It appears I have one partially stuck caliper and one completely stuck caliper. I was able to dismount the worse of the two calipers and clamp it to open the pads. Reinstalled and the rotor spun freely. I went to pump and release the actuator and it locked right up again.

Correct me if I’m wrong but I should just replace both brake calipers and re-bleed the system. Anyone have a part # for this?

 

[AZMark]

If you’re going to have to buy new ones anyway you could pull the pistons out of yours and see how bad of shape everything is in. You might be able to just clean them up & get them working with or without new seals. There’s really not much to a brake caliper.

Sorry can’t help you on part numbers.

Also if you’re just turning it by hand it might have quite a bit of drag. Disc brakes don’t have springs to retract so they will remain in light contact with the rotor. Your rotors look pretty rough. It could be that if you tried to drive it a little they wouldn’t actually be totally frozen. Better to fix everything the right way now though while you’re at it.

 

[CaptRedbeard]

I had some time this weekend to work on this. On the worse of the two calipers I pulled the piston out and it was a bit rusted. I knocked the rust off as best I could with a series of sandpaper and got it pretty smooth. The seal and dust boot both had a bit of rust build up but I was able to pull them and clean them up. Reinstalled that piston and checked the other one but it was in pristine condition. Added photos of the worse of the two pistons. I’ll keep an eye on it and might need to replace this caliper down the road. For now I’ve invested a total of about $50 for the new shock and brake fluid.

By the way, sliding a piston back in a caliper smoothly is satisfying as hell ?

Got everything installed and bled and went for a test drive. Everything working smoothly! Thanks for the advice everybody and especially @AZMark

 

[AZMark]

That’s awesome! Glad you got it all working

 

[CaptRedbeard]

Note: here’s the one man brake bleeding setup I used. 1/4” vinyl tubing fits on the bleeder screw and extend it down into the fluid into the bottle. Allows you to crack the bleeder screw, leave it open and pump the actuator without sucking air back in through the bleeder.

 

[CaptRedbeard]

More work on the trailer this weekend. The electrical was pretty sketchy when I purchased the boat. he 7 blade plug was cracked and damaged and the wires at the tongue had lost their wire loom and had some visible damage to some of the insulation. I had no drivers side running lights or brake lights.

I decided to rewire it entirely. Bought this 6’ RV cable and spliced in this trailer wire kit. I added 16awg tinned copper wire for a dedicated ground down each side of the trailer. I used a combination of waterproof heat shrink butt connectors and in-line splice connectors.

The trailer already has LED taillights but all running lights are still the original incandescent lights. Maybe I’ll swap those at some point down the road.

It’s a great feeling having a safe trailer setup after a few trips without one of my brake lights and no brakes ?