2006 Ranger trailer

Just bought a new to me ranger 188vs. The trailer has surge disc brakes. While driving it home, there was a jerking every time the brakes disengaged no matter how hard or soft the stop.

I took the brakes apart today and while filthy, the calipers, discs, and pads looked ok. I cleaned them up good.

There was full fluid in the reservoir.

The problem I noticed was when bleeding the system at the end. Using the screwdriver in the top hole of the hitch with the cap off, it pumped a couple times but was very slow to return and as a result I wasn't getting any good pressure in the lines.

Could this be a bad master cylinder??

I would start by getting some PB Blaster and spray down that entire sliding mechanism. Could be just coroded up causing it to be slow to return. That is where you are getting your jerking. Not releasing smoothly. If you have to replace master cylinder, do your research, you can replace entire coupler assy about a cheap as master cylinder.

Thanks I'll spray it down and see, but I think you're right about just replacing the whole coupler. Doesn't look like the previous owner paid much attention to the trailer.

Well good news is took it out for a test drive today and it was much better. No more jerking when the couple releases. Just gonna keep my eye on it. Eventually I think I'm going to convert to the vortex hubs.