Supplemental Brake... Necessity or Preference

[JohnnyT]

We seem to have a good number of discussions on the issue of the need for supplemental brakes... Unfortunately many of the discussions are not very productive in terms of giving those who have an open mind and who are genuinely trying to gather information useful information. Nor is there much value in trying to get those that have their minds made up to change or even consider another point of view...

As is often the case when the subject of supplemental brakes comes up some opinions offered are based on their own choices... Which may or many not fit your situation. In some instances these opinions offered are not constructive but lapse into you are wrong and I am right...

Area's to do your own assessment as to need or desirability;

State Law's
Weight of towed vehicle in relation to motorhome
Amount of rear overhang
Rated capacity of motorhome service Brakes
Chassis/Motorhome Manufacturers recommendations
Reduction of braking force required of motorhome service brakes..
Ability to have Break Away braking
Motorhome brake wear
Operational Reliability of the Supplemental Brake

State Law
The reality is that almost all states do have laws requiring supplemental brakes for trailers and most states do not have any stated requirements for supplemental brakes for motor vehicles in tow... However many states do have laws specific to motor vehicles being towed, in some instances those laws require the ability to stop within a specified distance at a specific speed. There are also a number of states that have a weight limitation on the weight that can be towed without a supplemental brake. There are a good number of states that require a supplemental brake system. The link previously posted appears to give an accurate summary of the specific requirements by state.
Towing Laws By State I would review the information in the link provided and reach your own judgment as to the legal requirement...

Rather than any legal requirement or wear issue to the service brakes on the motorhome, the issue I would be considering first is safety margin. I would want to be in compliance with the legal requirements where ever I towed, but my issue is safety margin. I would start with understanding the;

Rated capacity of motorhome service Brakes
Some chassis manufacturers will specify that the use of a supplemental brake is required after some minimal weight usually around 1500 pounds. Other Manufacturers will state that the service brakes are only rated for GVWR not GCWR... So I would consult your owners manual or call the chassis manufacturer.

A supplemental brake ought to lessen the braking force required by the motorhome service brakes. This would be of particular note on long down hill descents since the added braking force will lessen the amount of braking force needed by the motorhome service brakes. Which should lessen the potential for brake fade due to overheating of the brakes. I personally do not put much faith in advertising claims in terms of stopping distances but I have done a bit of non scientific testing to the point that I am certain that when using the same amount of pedal pressure I am able to stop in a shorter distance with the dinghy in tow with the supplemental brake activated than without...

The other issue is that the weight of the towed vehicle will be pushing its full weight on the back of the motorhome which would exacerbate any handling issues during hard braking if the towed vehicle and the motorhome are not in alignment. If the motorhome happened to have a long overhang and the weight of the towed vehicle is any significant percentage of the motorhome the more likely that the weight of the towed vehicle pushing on the back of the motorhome will be a factor relative to handling in a hard braking situation.

One last area...If you decide you want a supplemental brake system... Then pick the one that best maps to your requirements... For those brake systems that have user adjustments invest the time to calibrate your brake so that it will provide the braking force intended. Here is an excellent description of the various Supplemental Brake Systems.

For those that are only interested in having a supplemental system that only provides braking in the event of a break away here is one such system Break Away only option

As you work through the decision process of whether or not making the investment for a supplemental brake system is warranted...There are a myriad of variant opinions... With justifications for supplemental brake system or rationales against... Unfortunately many of the discussions are predicated based on extremes some of which are uncommonly unlikely or have the potential to be avoided; Brake fade, a dinghy that breaks away, an accident where braking ability was a factor or becomes a factor in litigation. Any of which are either rare or unlikely. The odds of any can be reduced by adjusting ones driving strategy or going the route of investing in a suitable supplemental braking system or both... In my case both. In addition our coach is also equipped with a 2 stage engine brake.

The reality is that beyond any legal requirement which is not commonly going to be an issue in terms of enforcement or liability. The issue of brake fade can be avoided by altering driving style to reduce the factors that cause brake fade... Stopping distance can be taken into account by increasing the distance between the vehicle in front and driving a lower speeds. The potential for a break away can be lessoned with preventive care of towing apparatus and the proper use of safety chains/cables. The added braking force of a supplemental brake system can be an added safety margin for those un predictable situations... Its up to each individual to reach their own conclusions.

The one area that is the most difficult take preventative measure for is the weight of the dinghy pushing against the back of the motorhome in a emergency braking situation where the dinghy is not in direct alignment with the motorhome... In those instances where the motorhome has a long overhang will exacerbate the potential problem which will be amplified as the weight of the dinghy increases as a percentage of the motorhome weight.

While I have invested in a supplemental brake system, that is my personal choice... I fully subscribe that the likelihood that the absolute need beyond conformance with legal requirements would fall into the very low percentile... Which is comforting..unless you are in the small percentile group.

JohnnyT Moderator