Best Auxiliary Braking Systems That Follow Flat Towing Laws

When Do You Have To Have An Auxiliary Braking System For A Towed Car?

Compared to a large RV a car doesn’t seem like it would be a big deal for the braking system but most states have some strict laws for flat towing a vehicle. In fact, many states require your towed vehicle to have an auxiliary braking system, as well as a break-away. It might seem like a hassle to get a braking system for your own flat towed vehicle but if you are a traveler and a frequent camper the safest and most legal thing to do is to get the braking system.

See Also: Towing Cars Behind RVs – The Flat Towing Guide

The good news is there are all kinds of auxiliary braking systems for flat towing and they range from removable boxes that press on the brake pedal to hardwired brakes that are usually more difficult to install but don’t ever need to be removed in order to drive.

In this article, I’ll go over each kind and list some of the most popular and best auxiliary braking systems for flat towing behind an RV. Hopefully, it will help you decide which kind is right for you so you can be safe out there on the road and complying with towing laws no matter what state you decide to adventure in.

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Best Portable System
Blue Ox BRK2019 Patriot 3 Brake System
Roadmaster 9400 Even Brake System
Hopkins Brake Buddy Select 3 Towed Vehicle Brake System
Hopkins 39530 BrakeBuddy Stealth
Roadmaster 8700 Invisibrake Hidden Power Braking System
Best Permanent System
Demco 9599007 Air Force One Braking System
Kind
Portable Braking Unit
Portable Braking Unit
Portable Braking Unit
Hidden Brake Pull System
Hidden Brake Pull System
Hidden Brake System
Install Type
Removable
Removable
Removable
Permanent
Permanent
Permanent
Hybrid Vehicle Compatible
Breakaway Included
In Coach Controller
Will Charge Battery
n/a

Best Portable System

Blue Ox BRK2019 Patriot 3 Brake System
Kind
Portable Braking Unit
Install Type
Removable
Hybrid Vehicle Compatible
Breakaway Included
In Coach Controller
Will Charge Battery
Roadmaster 9400 Even Brake System
Kind
Portable Braking Unit
Install Type
Removable
Hybrid Vehicle Compatible
Breakaway Included
In Coach Controller
Will Charge Battery
Hopkins Brake Buddy Select 3 Towed Vehicle Brake System
Kind
Portable Braking Unit
Install Type
Removable
Hybrid Vehicle Compatible
Breakaway Included
In Coach Controller
Will Charge Battery
Hopkins 39530 BrakeBuddy Stealth
Kind
Hidden Brake Pull System
Install Type
Permanent
Hybrid Vehicle Compatible
Breakaway Included
In Coach Controller
Will Charge Battery
Roadmaster 8700 Invisibrake Hidden Power Braking System
Kind
Hidden Brake Pull System
Install Type
Permanent
Hybrid Vehicle Compatible
Breakaway Included
In Coach Controller
Will Charge Battery

Best Permanent System

Demco 9599007 Air Force One Braking System
Kind
Hidden Brake System
Install Type
Permanent
Hybrid Vehicle Compatible
Breakaway Included
In Coach Controller
Will Charge Battery
n/a

Note: Scroll left/right on small screens to view all products in the table.

Portable Braking Systems

One popular auxiliary brake style for flat towing is a little machine you place on the floor in front of the driver’s seat of the vehicle you want to tow. There’s a mechanical arm you hook to the brake pedal and a 12V plug you use to power it.

Most of these systems are proportional. That means the brakes will follow the RV and apply the same amount of pressure. This is done by the wireless monitor with an inertia sensor that usually sits in the RV coach. There is an inertia based sensor in the monitor that sends signals to the brake in the vehicle and tells it how much pressure to apply.

These systems work very well and are popular in the RVing world. The many pros include being easy to install, can be transferred to other vehicles, can be sold once you are done with it, and more.

One of the main cons is the inertia sensor can be inaccurate at times and you may experience “false braking.” This is when the towed vehicle brakes even though the RV isn’t. This is rare but it can happen.

Below are some of the best portable auxiliary braking systems for flat towing behind an RV.


Blue Ox Patriot 3 Brake System

Blue Ox BRK2019 Patriot 3 Brake System

Check Price at Amazon

The Blue Ox Patriot 3 is a common auxiliary brake system you will see RVers who flat tow using. It’s reliable, easy to set up and use, it comes with a break-away, and there’s an in coach controller with an LCD screen you can use to adjust the brake and monitor the brake pressure in real-time inside your RV while towing. The monitor is powered using a 12V plug.

The braking unit is 21 inches long, 13 inches wide, and 10 inches tall. It weighs only 14 lbs and is compatible with almost all vehicles including hybrids. The only vehicle it won’t fit in due to the configuration of the driver’s seat is the Honda Fit.

One of the benefits of this style of brake system is there is virtually no initial installation. The only thing you will have to do is run a line through the vehicle for the break-away system but after that the brake only needs to be set on the floor, connected to the pedal and plugged in.

When you plug it in and turn it on, it will pump the brakes three times to test the brake pressure. If something is off the unit will alert you that something is wrong. The Blue Ox Patriot 3 will monitor the brake pressure the entire time you are towing which means you will know if the brakes are working or not. It’s a great safety feature and provides peace of mind.

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The Patriot 3 is an inertia driven proportional braking system which means it will match the brake pressure from the RV when it senses that the speed has decreased. It means smoother, safer braking that is going to be easier on both the RV and the towed vehicles braking systems.

Traditional portable braking systems use compressed air to move the pedal but the Blue Ox is all electric which means you don’t ever have to worry about an air compressor catching up if you are braking a lot in a short amount of time. Brake response time is also faster.

It does require power from the vehicle’s battery. That means there is a small possibility that your vehicle’s battery will run down if you tow for an extended amount of time.

The Blue Ox Patriot 3 Brake System is reliable, easy to use, requires very little installation, and is super easy to move to multiple vehicles. I recommend this for people who are only planning on RV traveling for a few years or for people who have multiple vehicles they want to tow. It’s also doesn’t require any kind of professional installation which is important if you don’t want to go to a mechanic.

PROS

  • Requires Very Little Installation
  • Can Easily Be Moved To Another Vehicle
  • Has A Break-Away
  • In-Coach Controller To Adjust Breaks While Towing
  • Follows Tow Laws In Most States
  • Powerd With 12V Plug (No Hardwiring Necessary)
  • Not Permanent (Can Be Sold When No Longer Needed)
  • Works Will All Kinds Of Vehicles
  • Proportional Braking System
  • All Electric (No Air Compressor)
  • LCD Screen Monitor

CONS

  • Drains Vehicle Battery While Towing
  • Has To Be Set-Up & Removed Every Time
  • Risk For “False Braking”

Roadmaster Even Brake System

Roadmaster 9400 Even Brake System

Check Price at Amazon

The Roadmaster Even Brake System is another fantastic portable proportional braking system for flat towing a vehicle behind an RV. It automatically tests your brakes, tells you what they are doing even when you are towing, has an included break-away, and complies with most flat tow laws in the US.

The unit is 19.3 inches long, 12.7 inches wide, and 12.5 inches tall. It weighs 22.3 lbs. There are 4 independent legs under the box that can be adjusted so it will sit stable and flat in any vehicle. The brake pedal clamp is also fully adjustable to fit any size of brake pedal.

The braking arm is moved with compressed air that is generated by a small air compressor inside the unit. The compressor has a quick recovery time that allows you to brake confidently.

There is a 12V powered in-coach monitor with an LCD screen you can use to adjust the brake pressure while towing as well as see what the brakes are doing and how much pressure they have. There is even an alarm that will sound if the break-away is used and there is an emergency.

You can also press a button on the monitor that will tell the braking system to apply the brakes. This is handy in a situation where your towed vehicle is starting to lose control and you need it to stop immediately.

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A cool feature that Roadmaster has added is automatic brake protection. If the brakes in the towed vehicle have been applied continuously for a longer than normal amount of time the Even Brake will release the brake to avoid ruining the brakes on the vehicle. It will also alert you via the remote monitor.

Another great addition is the low power sensor. Like the Blue Ox the Roadmaster the Roadmaster runs off the vehicle’s battery which means it could drain it all the way. The Roadmaster has a sensor that will alert you if the battery is getting low.

If this happens you can stop for a break and run your towed vehicle’s engine for a few minutes to recharge the battery.

The Roadmaster Even Brake System is another fantastic portable flat tow braking system you can use in pretty much any vehicle including hybrids. It requires very little set up. Just run the break-away cable through the vehicle and you are good to go.

PROS

  • Requires Very Little Installation
  • Can Easily Be Moved To Another Vehicle
  • Has A Break-Away
  • In-Coach Controller To Adjust Breaks While Towing
  • Follows Tow Laws In Most States
  • Powerd With 12V Plug (No Hardwiring Necessary)
  • Not Permanent (Can Be Sold When No Longer Needed)
  • Works Will All Kinds Of Vehicles
  • Proportional Braking System
  • Low Battery Sensor
  • Auto Brake Release
  • LCD Screen Monitor

CONS

  • Drains Vehicle Battery While Towing
  • Has To Be Set-Up & Removed Every Time
  • Bulky
  • Uses Air Compressor
  • Risk For “False Braking”

Hopkins Brake Buddy Select 3 Brake System

Hopkins Brake Buddy Select 3 Towed Vehicle Brake System

Check Price at Amazon

The Hopkins Brake Buddy Select 3 is another portable braking system that uses an air compressor to move the arm and apply the brakes in the towed vehicle.

Some special features you get with Brake Buddy are 4 independent feet that move to fit the floor of any vehicle, a carry handle that folds down when not in use, and a 15 amp battery charger that will charge your vehicle’s battery while towing.

The battery charger is probably the coolest thing about the Brake Buddy. None of the other portable braking systems on this list come with a battery charger.

Aside from the battery charger, the Brake Buddy works much like the others. It has an adjustable clamp on the arm that’s made to fit the brake pedal of almost any vehicle, it’s powered using a 12V plug, and it covers towing laws in every state.

The in-coach monitor is a battery powered device that looks a little bit like a toy phone. It has a part that flips up to show you various buttons and LED lights. The monitor will indicate if there is an issue with the Brake Buddy, what the brake power is, or if the break-away has been activated.

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You can also adjust the brake sensitivity or change the braking from proportional to full.

There is an included break-away system included, all you have to do is get the cord from the back of the RV to the braking system inside of the towed vehicle.

After set up, the Select 3 will perform an “AutoStart” diagnostic of the brake pedal by pressing down on the pedal a few times to test the system.

The unit is 19 inches long, 11.75 inches wide, and 8.25 inches tall. It weighs only 12 lbs.

The Hopkins Brake Buddy Select 3 Brake System is a great little braking system that is simple but still does the job. If you often tow for extended amounts of time this may be the better system for you because of the battery charger. The only downside is the in-coach remote is battery powered and doesn’t give you as much information as the kind with an LCD screen.

PROS

  • Requires Very Little Installation
  • Can Easily Be Moved To Another Vehicle
  • Has A Break-Away
  • In-Coach Controller To Adjust Breaks While Towing
  • Follows Tow Laws In Most States
  • Powerd With 12V Plug (No Hardwiring Necessary)
  • Not Permanent (Can Be Sold When No Longer Needed)
  • Works Will All Kinds Of Vehicles
  • Proportional Braking System
  • Battery Charger Built-In

CONS

  • Has To Be Set-Up & Removed Every Time
  • Uses Air Compressor
  • Monitor Doesn’t Use LDC Screen
  • Battery Powered Monitor
  • Risk For “False Braking”

Stealth/Hide-Away Braking Systems

If you flat tow a lot behind your RV and find that removing and setting up a portable braking system is a hassle there are other options. One such option is to use a stealth braking system.

Stealth systems take a lot more work to install but you don’t have to remove anything to drive away. Just unhook from your RV and go.

These kinds of braking systems usually have a box hidden away somewhere in the towed vehicle and a vacuum pump under the hood. A cable is then run from the motor to underneath the brake pedal where there is a little pulley and cable attached to the pedal.

It still pushes the brake pedal to stop but the system is permanently installed and out of sight.


Hopkins Brake Buddy Stealth

Hopkins 39530 BrakeBuddy Stealth

Check Price at Amazon

The Hopkins Brake Buddy Stealth is one of the smallest and easiest to hide inside a vehicle. Once installed it won’t require more than just disconnecting a few cables to preserve battery power to get driving.

For installation, it’s recommended to have a professional do it. It requires you to get under the hood of the towed vehicle to secure a vacuum pump, electrical wiring, and even cutting into the vehicle’s vacuum hose to install a tee.

If you don’t want to deal with a difficult installation, then I recommend a portable braking system instead.

The main motor part of the Brake Buddy Stealth is a rectangular box that you will hide either behind a seat or in the trunk of your tow vehicle. You then run cables to the brake pedal where a small pulley is screwed to the floor under the brake pedal The electrical and vacuum pump are all installed under the hood of the car.

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Because it connects to the battery and the RV the Stealth will be powered by the RV which means no more drained battery on your towed vehicle.

There is also a plug that goes on the front of the tow vehicle you use to connect the wired brake controller to the brake system. That same cable also acts as a break-away. If the connection is lost, the Brake Buddy Stealth will automatically apply the brakes and stop the tow vehicle.

The in-coach controller looks a look like the kind of brake controller you see in a truck for trailer brakes. It’s not wireless which means you will have to run cables from the front of the RV to the back.

The controller can apply the brakes manually, adjust the sensitivity, and switch from car to trailer. That’s right, the brake controller will also work for trailers.

If you can get past the difficult installation using the Hopkins Brake Buddy Stealth is super easy. Just plug in a cable from the front bumper to the RV and you’re all set.

It’s safe, responsive, can be adjusted in-coach via the controller, there’s a break-away, and you never have to move anything in order to start driving your vehicle. It also works with most vehicles, including hybrids.

PROS

  • Has A Break-Away
  • In-Coach Controller To Adjust Breaks While Towing
  • Follows Tow Laws In Most States
  • Works Will All Kinds Of Vehicles
  • Proportional Braking System
  • Powered By RV (Will Not Drain Battery)
  • No Moving Things (Just Plug In & Go)

CONS

  • Difficult Install (Includes Electrical Wiring & Vacuum Install)
  • RV Controller Must Be Wired Through RV
  • Can’t Easily Transfer To Another Vehicle

Roadmaster Invisibrake Hidden Power Braking System

Roadmaster 8700 Invisibrake Hidden Power Braking System

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The Roadmaster Invisibrake is a lot like the Brake Buddy Stealth but there are some major differences. The biggest one being that you cannot control the brake from inside your RV.

Instead, there is a light that will be installed on the dash. When the light is on the towed vehicle is braking. If you want to adjust the brake power you do it via the Invisibrake box which can be mounted anywhere inside the towed vehicle.

Otherwise, most features are basically the same. The brake pedal inside the vehicle will be moved via a pulley system that needs to be installed. The electrical will connect directly to the vehicle’s battery and not only be powered by the RV but it will also trickle charge the towed vehicle.

There is a break-away kit included with purchase.

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Once again this brake system requires a complicated installation. Roadmaster recommends you hire a professional to do the installation for you. It’s also permanent and you won’t be able to transfer it to another vehicle.

One great feature other than the fact that you never have to take anything in or out of the towed vehicle is you also get Roadmasters auto shutoff that will turn off the brakes in the vehicle if you have been braking for over 18 seconds (normally happens at a stoplight). This helps to not overwork the braking system in the towed car.

The Roadmaster Invisibrake Hidden Power Braking System is small and will work in almost any vehicle with flat tow capabilities, including hybrids. It’s a safe, reliable, and lawful supplementary braking system but it’s not easy to install and cannot be transferred to another vehicle.

There is also no way to adjust the brake pressure inside the RV which isn’t optimal.

PROS

  • Auto Shutoff After 18 Seconds
  • Has A Break-Away
  • Follows Tow Laws In Most States
  • Works Will All Kinds Of Vehicles
  • Proportional Braking System
  • Powered By RV (Will Not Drain Battery)
  • No Moving Things (Just Plug In & Go)

CONS

  • Difficult Install (Includes Electrical Wiring & Vacuum Install)
  • No Inside RV Controller (Just An Indicator Light)
  • Can’t Easily Transfer To Another Vehicle

Demco Air Force One Braking System

Demco 9599007 Air Force One Braking System

Check Price at Amazon

The Demco Air Force One or AFO braking system is another hidden braking system that is going to be permanently installed into your towed vehicle and RV. This is one of the most popular supplemental braking systems for Class A RV owners because of its responsiveness and overall performance.

This system uses the air brakes inside the RV which means if your RV is small and doesn’t have air brakes, this system will not work for you.

If you do have air brakes this is a fantastic choice.

The way it works is a small air tank and relay valve assembly is going to be installed under your RV and connected to the RV air brake system. When you apply your air brakes air from the exhaust will push into the air tank and valve. This will not only supply air to the AFO brake but also tell it when you are braking and how much pressure is being applied.

Using a quick connect coupler on the back of the RV there will be an airline hose stretch to another quick connect on your towed vehicle. The air then goes into the Air Force One operating unit that will be installed somewhere under the hood.

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It’s a square black box that is low profile and will fit in any vehicle. The box reads the air pressure and sends the correct amount to an air cylinder that is installed above the brake pedal. The cylinder will use the air to apply the exact right amount of pressure to match the amount of braking pressure being applied to the RV brakes.

The Air Force One is also connected to the towed vehicles vacuum line to not only boost the brakes but to ensure that they always have power for a quick stop. If your car doesn’t have vacuum breaks the AFO comes with a kit that can bypass that feature.

A break-away is also included.

There is an indicator light that will be installed on the back of the rearview mirror of the towed vehicle that illuminates when the brakes are being applied. You will need to have a backup camera in order to see this.

The Demco Air Force One Braking System is the premium choice when it comes to auxiliary braking systems for flat towed vehicles. It brakes better, safer, and more accurately than any other braking system on the market today.

It does require professional help to install it and you have to have an RV with an air braking system but if you flat tow a lot or long distances this is one of the best options you will find.

PROS

  • No Need To Adjust Brake Intensity
  • Has A Break-Away
  • Follows Tow Laws In All States
  • Works Will All Kinds Of Vehicles
  • Proportional Braking System
  • Powered By RV (Will Not Drain Battery)
  • No Moving Things (Just Plug In & Go)

CONS

  • Difficult Install (Includes Electrical Wiring & Vacuum Install)
  • No Inside RV Indicator Light (Only On Towed Vehicles Rearview Mirror)
  • Can’t Easily Transfer To Another Vehicle
  • Only For RV’s With Air Brakes

Auxiliary braking systems when flat towing behind your RV are required by law in most states.

Which Supplemental Flat Tow Braking System Is The Best For Me?

When it comes to flat towing behind an RV or even another vehicle there are vastly different options. Finding the right one really depends on a few things. The first and most important is how long are you going to use the vehicle you want to tow. If you like to change vehicles every few years then a permanent option isn’t going to be the best for you. Something removable like the Blue Ox Patriot 3 Brake System is going to be better because no matter what vehicle you get next you will be able to transfer it over easily.

If you tow all the time and plan on owning the vehicle you will tow for years to come then a permanent option like the Demco Air Force One Braking System is going to be fantastic. That is if you have an air brake system in your RV. Otherwise, one of the other permanent options will do.

No matter which one you decide on it’s safer and more legal to use one than to not use one at all. It’s very unlikely that your state doesn’t require a supplemental/auxiliary braking system and if you plan on seeing other places you are going to want to have one.

Have any questions about supplemental/auxiliary braking systems for flat towing? Leave a comment below.

Jenni grew up in a small town in Idaho. With a family that loves camping, she has been towing trailers since a very young age.

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