Located 7 miles North of Athens, TX
on Hwy 19
Installing an M&G Tow
I've used a Brake Buddy
and US Gear's Unified Tow Brake in the past but after trying
the M&G tow brake I'm spoiled. The M&G Tow Brake is a great setup. It utilizes the existing air brake system
of any coach with air brakes to proportionately actuate the
toad's brakes. For RVs without air brakes they do offer an
air compressor setup, but this does add to the cost. The
beauty of this system is that there are no electrical
connections and no decelerometers. When descending a grade
the jake brake will not prematurely engage the toad's
brakes. The only time the toad's brakes work are when the
coach's brakes are applied. Being totally proportional the
amount of braking depends upon how hard you step on the
brake pedal so the toad and coach are always in sync.
So, after having this system
on my Allegro Bus and Grand Cherokee for some time I felt it
was time to add it to the Wrangler for when we tow it.
Following details some of those steps.
adaptor fits between the master cylinder and the vacuum
booster. It consists of a housing with an internal split
shaft. Where the shaft is split the piston on the frontmost
half is acted upon by the air pressure input. Whenever you
are not towing, this system acts as a large pushrod allowing
the brakes to function normally. This is a fail-safe design
so even if the M&G module was to fail you would still have
manual braking. However, when towing, there is nothing
pushing on the pedal. Instead, the air pressure from the
coach is applied to the M&G module which works the front
half of the split shaft to apply the brakes evenly and in
direct proportion to the coach. I did have to relocate the
cruise control diaphragm unit which was in the way of the
master cylinder but that was easy enough. I just relocated
it to a wide open space underneath the master cylinder (it's
barely visible in the lower-right corner of the above
ordered the optional breakaway kit. This kit consists of a
small air reservoir tank that will supply air to the M&G
module should the toad come loose from the RV.
This air tank is charged up after 3 good pushes on the brake pedal and holds enough air pressure to lock up the brakes on the towed vehicle should it come unhooked from the RV. It is connected to a 3 way solenoid valve.
This valve allows the tank to charge up while driving and directs normal braking air pressure to the M&G module. Upon breakaway, the valve dumps the contents into the M&G module and locks it up to keep the toad from going ballistic. This does require wiring in a breakaway switch. One wire goes to ground an one goes to a battery "hot" source. I mounted both the breakaway switch and the air inlet fitting on the front bumper of the Wrangler. The breakaway cable, as well as the air line, fits neatly inside the coiled trailer light umbilical cord to protect it from dragging or snagging. Both the hose and cable were cut to the exact lengths to eliminate any excessive "stuff" hanging out.
recommends that you just leave the hose loosely coiled up
under the hood of the towed vehicle, then hang it out the
hood when towing. I wanted something more stationary so I
mounted everything in the bumper. Besides, it's a Wrangler,
not a Ferrari.
The only drawback to this is that you can get dirt
into the fitting. M&G states that the end of this hose should not be
capped off or else air pressure could increase within this hose as things
warm up under the hood and you might find your brakes dragging while
driving. To rectify I took a right angle spark plug boot and inserted a
short whip of the nylon brake tubing into it. This gave me a vented dust
cap which keeps dirt out, yet allows venting of the
The M&G Car Braking System
by Carol S. Maxwell & Edwin S. Gurdjian, RVTechStop,
Family Motor Coach Association Magazine, February 1996