Clunky surge brakes

[mf01]

The surge brakes on my trailer seem to be clunkier than last year. I flushed them last summer and checked the fluid. I cleaned the shock and other areas with WD40, then put some spray grease on them. Now it actually seems worse. The trailer is 16 years old. Could it be the shock or master cylinder?

[DanielC]

When was the last time you adjusted the trailer brakes?

[Rick]

Clunking usually means air in the lines

I think that if you bleed your brakes the clunking should improve. It is usually caused by the air in the cylinder compressing quickly before the hydraulic fluid is compressed.

[mf01]

When was the last time you adjusted the trailer brakes?

I checked them last summer and they seemed fine. They had a slight drag.

[mf01]

I think that if you bleed your brakes the clunking should improve. It is usually caused by the air in the cylinder compressing quickly before the hydraulic fluid is compressed.

How often do they need to be bleed? I bleed them about a year ago. The clunk is on the release from a stop. I realize there will be a small amount of clunk with surge brakes, but it's getting really bad.

[steve-o]

The shock is probably worn out. It dampens the clunk both stopping and moving.

[jmo]

Check the brake fluid level in the actuator and make sure it's holding steady. If the level is dropping on you it could be that the brake line inside the box frame of the trailer has rusted through rendering the brakes useless, this happened to me. Some actuators are designed to cause clunking when the brake fluid level is low as a way of alerting you to this condition.

JMO

[mf01]

I thought I checked the fluid a couple months ago, but it appeared to be low last night. The tank was maybe 1/2 to 2/3 full. I filled it up to below the bottom of the cap. I'll see if that helps out this weekend.

[mf01]

I added fluid and I'm still getting some clunking. I took out the shock and it seems alright by hand, so I looked at the fluid in the master cylinder after taking the boat out. The fluid looked rusty on my finger. I'm thinking I need to get a master cylinder rebuild kit.

[steve-o]

Depending on the actuator, the master cylinders are very simple. You can piece together a "rebuild kit" by going to the hardware store. There aren't many parts at all. I rebuilt one that I thought was hopeless. It was full of rust. Works fine now. I converted it over to a disc brakes. Here are some pics.

[bkhallpass]

I think it would be more likely that you have a whell cylinder sticking than a master cylinder.

It doesn't take much rist or dirt in the wheel cylinder to make the hydraulically actuated pin stick. Usually they stick with the breaks on. If they are catching and then releasing, you may feel a clunk.

Are you able to tell if the clunk is in the wheels/brakes, or if it is in the trailer tongue?

Have you actuated the brakes by hand? If put your hitch into the tongue, and actuate the brakes by hand, it should be very stiff. If not, bleed the brakes again, and make sure the reservoir is full.

My $.02.

BKH

[mf01]

Depending on the actuator, the master cylinders are very simple. You can piece together a "rebuild kit" by going to the hardware store. There aren't many parts at all. I rebuilt one that I thought was hopeless. It was full of rust. Works fine now. I converted it over to a disc brakes. Here are some pics.

Good idea, I can save $120. What all did you need from the hardware store?

[steve-o]

Suprisingly not much. Just a couple of o-rings and e-clips. Everything else was in great shape.

[mf01]

Suprisingly not much. Just a couple of o-rings and e-clips. Everything else was in great shape.

What did you use for the gasket? My reservoir seems pretty bad. The actual cylinder seems alright. I have been cleaning it with PB blaster, brake parts cleaner, and now rust resolver. How did you end up getting all the rust off?

[steve-o]

Are you talking about the main gasket for the reservoir cap? I used RTV for gaskets.