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Old 03-13-2013, 08:01 PM   #1
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Tow Dolly Brakes

Tow Dollys can come with Elec or Surge brakes. The elec ones require a brake controller and wiring in the RV. Can someone explain the differance between the two types and if Surge brakes require and mods to the RV to work? Also is one better than the other?
Thanks, Chuck

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Old 03-13-2013, 08:14 PM   #2
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Surge brakes work by the compression of a master cylinder between the dolly and the tow vehicle. No additions or modifications needed to the towing vehicle. I've had surge brakes on both our dollies. What I like is that I can tow almost any front wheel drive vehicle on the dolly without adding brakes, towbar, brackets, wiring etc. Even loaned my old dolly out to my son to recover one of his cars.
Electric brakes do one thing that might be an advantage and that is it allows you to activate the brakes from the cab, but I've never felt the need to have that.
The surge brakes also have a built in mechanical breakaway system, no battery required.

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Old 03-14-2013, 07:49 AM   #3
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Personally I prefer electric brakes to the hydraulic surge style. The electrics require a controller in the towed vehicle, but most motorhomes today come prewired for the installation. It took a few minutes to find the plug under the dash of our 2001 Adventurer, but less than 10 minutes to install the controller. I bought a 2010 Ford truck a couple years ago and it took less than 5 minutes to install the controller.

I prefer electric brakes for several reasons:

1. No scheduled maintenance like changing brake fluid or adjusting brake shoes. Some will tell you the've never changed the fluid in XX years, but considering most motorhome chassis builders recommend changing it every 2 years they probably should consider it.

2. True proportional braking even at low speeds. If the controller detects the tow vehicle is dlowing down and the brake lights are activated it engages the brakes at the same rate as the vehicle brakes.

3. The controller can be programmed to engage and hold the dolly/trailer brakes when stopped on an incline.

4. Electric brakes can be programmed to apply appropriate braking pressure for the load being carried. Even with light loads the brakes can be activated.

5. The brakes aren't engaging and releasing when traveling over rough terrain. This may not apply to most dolly owners. I had a couple equipment trailers over the years with surge brakes. When traversing over rough terrain the brakes would activate when pressure was applied to the hitch. This made for some seriously rough rides unless the brakes were locked out.

Over the years I've gotten rid of all the trailers with surge brakes and replaced them with trailers (and a Dolly) with electric brakes. In my opinion they are much easier to maintain and more user friendly. As I mentioned earlier they do require a controller which adds about another $125.00 to the cost. We use a Tekonsha Prodigy (now replaced by the Prodigy P2). It's over 12 years old and has been transferred to 3 trucks. When we use it in the motorhome it takes about 5 minutes or less to remove it from the truck and install it in the motorhome.
2013 Adventurer 32H
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Old 03-14-2013, 07:59 AM   #4
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Originally Posted by packerfan704 View Post
Tow Dollys can come with Elec or Surge brakes. The elec ones require a brake controller and wiring in the RV. Can someone explain the differance between the two types and if Surge brakes require and mods to the RV to work?
Electric brakes work by an electric signal from the cab that causes magnets to press the brake shoes against the inside of the brake drums. Different types include an integrated trailer brake controller (ITBC) that works on newer vehicles that have the ITBC as an option. Those work great. Not quite as good is the aftermarket proportional brake controllers, that try to control the amount of trailer braking based on how hard you press on the brake pedal in the tow vehicle, similar to the way the brakes in the tow vehicle work. The simplest kind are simple time delay and will apply brake pressure based on the setting dialed into the controller. Most electric brake controllers work based on the brake light signal. If the brakes lights are on, the driver must be mashing the brake pedal, so the controller sends the signal to activate the magnets in the trailer brakes.

Surge brakes are hydraulic brakes like the ones in the tow vehicle, but instead of a master cylinder controlled by the brake pedal, there is a master cylinder controlled by the surge mechanism in the trailer hitch coupler. When the tow vehicle is braking, perpetual motion causes the trailer to keep on going, so it tries to roll into the back of the tow vehicle, causing the surge mechanism in the coupler to apply the trailer brakes. The faster the tow vehicle decelerates, the harder the trailer tries to run over the tow vehicle, so the more pressure on the coupler and therefore the more trailer braking is applied.

Surge brakes don't require any mods to the tow vehicle other than a bumper or receiver with a ball mount rated for more than the gross weight of the dolly and it's load. Electric brakes require an electric brake controller and wiring in the trailer plug that will include the brake wire. Today that means a 7-pin "RV" plug or a 6-pin livestock trailer plug on the back of the tow vehicle, instead of the more common flat 4-pin "U-Haul" plug.

Also is one better than the other?
The general consensus is that electric trailer brakes are preferred over surge brakes, provided you have a good electric brake controller.

The main reason is that surge brakes are dumb and cannot tell whether the coupler is applying the brakes because the tow vehicle is braking, or because the driver wants to back the trailer. For the better surge brake designs, there is a disconnect that you can manually switch to disable the surge brakes so you can back the trailer. But it's a manual switch, so you have to stop, get out of the tow vehicle, set the switch to disconnect the trailer brakes, then back up. Then don't forget to enable the surge brakes when you are through backing the trailer.

Another reason is that any "bumper pull" trailer that grosses over a few thousand pounds requires a weight-distributing hitch. But very few weight distributing hitch designs will work with surge brakes. Ordinary weight carrying ball hitches should be okay for a tow dolly towing a 3,000 pound car, but not for a 7,000 pound diesel 4x4 pickup.

But hydraulic brakes are thought to be better than electric brakes, especially if the brakes might get wet, such as on boat trailers. Electricity and water don't mix well. So there is a hybred design called "electric over hydraulic" brakes. An electric brake controller controls the master cylinder instead of magnets in the brakes. So the best of both worlds. But not cheap.

And two other hybred designs are called air over hydraulic and vacuum over hydraulic. Instead of an electric connection to control the trailer's master cylinder, they use air pressure or vacuum pressure. "Air brakes" as in big trucks, or vacuum actuated brakes as in most cars. Those require completely different types of brake controllers, and are not as popular as electric over hydraulic.
Grumpy ole man with over 50 years towing experience. Now my heaviest trailer is a 7,000-pound enclosed cargo trailer, RV is a 5,600 pound Skyline Nomad Joey 196S, and my tow vehicle is a 2012 F-150 3.5L EcoBoost SuperCrew.
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Old 03-14-2013, 11:16 PM   #5
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Thanks to all that replied to me. Now I have another question, has anyone ever used a Brake Buddy in the car that is on a tow dolly that does not have brakes? I would assume the rear brakes on the car would brake just like a dolly brake would.
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Old 03-15-2013, 05:42 AM   #6
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I don't think I would do it the rear brakes would pull on the straps I added brakes to my dolly they are electric from northern tool they were dexter about $225
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Old 04-16-2013, 03:43 PM   #7
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Some surge brake connections have a system that disconnects the surge brake if the backup light is on, which lets one back the trailer up. Most good boat trailers with surge brakes have this so you can back them down into the water. I would think same could apply to tow dollys.
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Old 06-24-2014, 09:07 AM   #8
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I don't know if I an hijacking this question or not but I have a Master Tow tow Dolly with electric brakes. I am planning to pull behind class c motorbike. Does anyone have recommended prodigy p2 settings for this setup?
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Old 06-25-2014, 05:17 AM   #9
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The most common question I am asked is, “ how do Car Tow Dolly hydraulic brakes work?” . So today we will explain Car Tow Dolly brakes. First, understand that to be 50 state and Canada legal you must have brakes of some kind on your Car Tow Dolly. In addition to that if you ever want to sell your tow dolly the first question a potential buyer will ask is if it has brakes or not. 8 out of 10 tow dollies sold have brakes.

An Idler tow dolly simply means it has no brakes at all. Idler dollies are most commonly used around town for short shuttling trips of lighter weight cars.

Electric brakes require a brake control device inside your RV or truck. These units have internal sensors that are dependent on the settings from 2 exterior adjusting knobs. If you do not precisely adjust these knobs then you will probably not even have brakes at all. Also, if a malfunction occurs one must trouble shoot the brake controller, the wiring from the controller to the dolly and then the dolly. A new quality digital controller will cost between $450.00 and $600.00 installed into a typical RV.

The most superior and trouble free braking system is a Hydraulic Surge Disc Brake System. Not to be confused with a surge Drum brake system. Surge Disc brakes never need adjusting, cool off much faster and resists brake fade. A disc brake design is 4 times more efficient than a drum design. The pads are in clear sight and can be easily changed by a novice. Car Dollies do not have self adjusting brakes. The brakes have to be manually adjusted on a regular basis. If not you will not even have brakes and simply will not know it. In addition on most dollies the spindle plate blocks the adjusting port, making it impossible to adjust the brakes without removing the wheel. Yes, even Electric brakes have to be adjusted.

So, how does a Surge Disc Brake system work? A surge disc brake system is self contained and self actuating. If you imagine that the coupler housing that goes over your hitch ball is actually a piston that extends back into the actuator on the dolly tongue. When you apply your brakes the weight of what you are towing surges forward slightly and pressurizes the brake line. The harder you brake the harder the tow dolly will brake. The Surge Disc Brake design is very sensitive and precise from slight to hard braking. It never chucks or hits hard. It is very smooth and precise braking. Because tow dollies are so light weight the brake system will not activate on an unloaded dolly, thus saving the tires from locking and dragging while unloaded. A surge brake system should be towed as close to level as possible. The more level the more precise and efficient the brakes will be. The Disc Brake design incorporates a clever but simple emergency brake away system. Should the dolly separate from the ball for any reason the brakes on the dolly instantly go to full lock up helping to bring everything to quick and certain stop.

So, in closing, understand that electric brake and surge drum brake systems are functional but old technology. The most current generation braking system is the Hydraulic Surge Disc Brake design.
Now many people will disagree, it is a matter of personal preference, it is something you have decide for yourself. Richard Brown.
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Old 06-25-2014, 03:05 PM   #10
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"Car Dollies do not have self adjusting brakes. The brakes have to be manually adjusted on a regular basis. If not you will not even have brakes and simply will not know it. "

This is false!
My 2011 Demco Kar Kaddy 460 SS tow dolly is equipped with surge hydraulic self adjusting drum brakes.
New Demco KK460SS all have surge self adjusting disc brakes, and EZE Tow dollys are NOT the ONLY dollys with disc brakes.
Who said that disc brakes are four times more effective over drum type?
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Old 06-26-2014, 11:10 AM   #11
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I don't want to argue, but I have to state the facts. The 2011 Demco 460SS does not have self adjusting brakes, according to the the manufacturer, Demco. Self adjusters work while in reverse and you cannot easily back a loaded tow dolly. Of course Disc brakes never need adjusting. It is true that Demco now offers Disc brakes on some of their dollies, however, Acme was the first and only manufacturer to offer disc brakes as standard equipment from 2006 till Demco started in 2013. So we are making the effort to change our marketing to read, The "Original" Disc Brake Tow Dolly. It is our opinion that Demco builds an outstanding product with a serious dedication to design and engineering. In fact it is the only other dolly we ever recommend to people that ask.
It is common knowledge that Disc brakes are significantly more efficient then drum brakes. They are lighter, much more braking force, never need adjusting and cool off 6 times faster then drum systems. It is pretty much accepted knowledge but I cannot give you a name.

Good Day, Happy and Safe Motoring.....

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brakes, dolly

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