Boatmate surge brake problems

[SomeYeahoo]

I've got a 2015 T23 on a 2015 Boatmate trailer with surge brakes. The trailer brakes have felt weak to non-existent, worsening lately, so I took it to the dealer. They've since replaced the main cylinder and one of the calipers and flushed all the lines. It's apparently rigged up to go to the port front tire first, then port rear, then starboard rear, and finally starboard front. There is apparently adequate pressure at the port front tire, but by the time it gets to the starboard front, pretty much none. They're not sure what to do and are trying to contact the "engineering department" at Boatmate. Anyone else run into this problem? Any suggestions? Honestly, I'm not positive the brakes have ever worked completely right since I bought it.

[oldjeep]

Only reason for tgat would be a clogged t fitting or a ballooning soft line. 

[wdr]

I had a boot go bad on one of the caliper cylinders and it rusted and the cylinder locked up that brake. Could be the other cylinder(s) are some how locked and not engaging as designed. There is only one continuous brake line and if they bled the brakes from the rear most caliper like they are supposed to than the lines should be clear. That really only leaves the calipers or bad pads.

[Falko]

Trailer brakes are pretty much the same design of car brakes, 50 years ago. They have one master cylinder feeding one hydraulic circuit. The amount of fluid displaced in the master cylinder is quite small and the hydraulic circuit is quite small. Any expansion or air pocket in any of the lines will reduce pressure throughout, not just in one leg. You either have a large restriction somewhere (as OJ stated) or you have failed down stream wheel cylinders (as wdr stated). Given my experience with trailer brakes, I'd say you have bad cylinders. OR, the testing method they are using is not good and you have no pressure anywhere. Again, based on my experience only, the master cylinders on these things fail because they get water in them, especially so when you only have that silly plastic cap on the fill port and not the older threaded style.  I'd pull each line from the wheel cylinders and pump a bunch of fluid through to clear them and measure again. also inspect the master and make sure there the piston is moving freely BOTH WAYS. Just because the plunger up front is going both ways doesn't mean you are moving the cylinder fully. A partially moving cylinder may actuate only one wheel cylinder if the others are sketchy.

Good luck, these trailer brakes are an extreme weak point in our wonderful rigs.