Do it Yourself Trailer Surge Brakes

It’s been quiet on this blog in November and December with the holidays and winter preparations taking up much of my free time but there’s also been a lot of working going on with Summer Dance. This post reveals the first of several large projects that I’ve been working on.

The original trailer had hydraulic surge brakes when new but those were eaten away by salt water. The replacement trailer had no brakes at all. Our tow vehicle is a 1998 Toyota Tacoma Extra Cab 4×4. With the fiberglass canopy, it weighs in at an even 4,000 pounds. The Calkins trailer and boat, not including the outboard motor, fuel, water, and other gear weighs around 3,200 pounds. The Washington State Patrol Inspection and Trailer Requirements specify that all trailers exceeding 3,000 pounds or 40% of the tow vehicle weight must have brakes, so ours qualifies on both points. Our load is 80% of the tow vehicle weight, double the allowance. Plus, it’s common sense to not expect to be able to slow or stop a load that size without some help. If we were to be involved in any kind of traffic accident, not the least of which rear-ending a vehicle in front of us, we would most certainly be held liable.

What happens when you don't wash salt water out of your brakes.
What happens when you don’t wash salt water out of your brakes.

Design considerations

Surge brake systems are relatively simple and effective. That’s good news. The design choices are few, drum type or caliper type. Drum type systems are slightly lower cost and sufficient for this load, so that’s what I chose. This is the $tingy Sailor blog, after all. But the tongue extension of our trailer posed a couple of uncommon build challenges. First, the tongue extension is 2-1/2″ square tube but surge brake actuators are only available in 3″ or larger sizes. Second, the hydraulic line between the actuator and the brake cylinders would need to be able to be easily disconnected to extend the tongue for launching and then reconnected for towing.

Bargain shopping

Parts for these systems have standard sizes and have been around for a long time, which means suppliers are many and prices are competitive. More good news. I compared prices from local and online suppliers. I try to buy local when the cost difference is negligible or service after the sale is important. Local discount suppliers had reasonable prices, especially when shipping costs (nearly $100) are added to online prices. But if you can find a free shipping promotion like I did, the savings makes a big difference. I settled on All the major parts: Demco actuator with breakaway lock, Dexter drums, Demco galvanized free-backing assemblies, hydraulic line kit, bearings, and seals came in under $400 delivered. Delivery was fast and the packing was excellent. Bob Gisi at was prompt when I requested a review of my order before shipment and he was very helpful when replying to installation questions by email. I can recommend them without hesitation.


Except for the challenges mentioned above, the installation was pretty straightforward. The trailer axle already had mounting flanges that the brake assemblies bolted right on to. The drums and bearings were direct replacements for the old brake-less hubs. Other than a dog fight drilling a hole in the axle to mount the hydraulic line tee, the steel lines were easily routed through existing holes in the frame to the tongue.

Steel hydraulic exiting the frame on its way to the axle tee. The hose allows axle movement.
Steel hydraulic line exiting the frame on its way to the axle tee. The hose allows axle movement.

I secured the lines to the outside of the axle with stainless steels ties hoping they will last longer than plastic, but they don’t tighten as well as I had hoped.

Right wheel. Extra tubing is rolled into a coil.
Right wheel. Extra tubing is rolled into a coil.

Biting my tongue over the tongue

It’s at the tongue where I got to (had to) be creative. As I said before, the actuator didn’t fit the tongue extension and the hydraulic line needed to be disconnectable.

I solved the first challenge by installing two 1/4″ thick spring shackles as shims between the actuator’s 3″ wide mounting flanges and the 2-1/2″ wide tongue. The shackle holes were almost perfectly spaced out of the package but required slight resizing. I made a couple of 2-1/4″ long spacers out of 1/2″ steel pipe to reinforce the inside of the tongue tube so that I could torque down the actuator mounting bolts through all four pieces.

The hydraulic line problem was solved by installing a quick disconnect fitting between the actuator and the steel hydraulic line. This required 1/8″ to 1/4″ adapters on both sides of the fitting. I inserted a short brake hose between the quick disconnect fitting and the steel line and attached the end of the steel line to the frame with a handmade bracket. The result is that the brake line can be easily disconnected along with the lights before launching and reconnected before hitting the road. I’m curious to see if this will introduce air into the system and affect braking.

Quick disconnect hydraulic line to the new Demco actuator.

After all the hardware was installed, all that remained was filling and bleeding the fluid, adjusting the brake shoes, and road testing.

The new setup is much easier to stop now. Besides being safer, it should also make trailering a more relaxing experience. It’s still winter as I write this, so I’ll update this post after some real use. Except for minor cosmetic issues, I think I’m done with the trailer now. I like the way it’s set up and I don’t plan to do any more projects on it.

The Bottom Line

Suggested price: n/a
$tingy Sailor cost: $429
Savings: n/a

What do you like most or least about your trailer brake setup? If you have electric brakes, how have they held up to wet launches?


2 Comments Add yours

  1. S/V G'Day says:

    Have you had any problems with the quick disconnect part of the system since you installed this?

    1. I will probably replace the O ring seal inside the female coupler soon but other than that, none.

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