Dexter's Hydraulic Disc Brakes
You remember the old joke—How do you stop a charging Rhino?...You take away its charge card. But how do you stop a 15,000 pound Toyhauler? You call the Dexter Axle Company!
SAFETY. It’s something that we are always concerned with as toyhauler owners. Our sport involves our taking risks every day; however, our journey to and fro should be anything but risky. The very essence of what we own surpasses the definition of what a towable recreational vehicle was just ten years ago when the average trailer length was 25 feet and had a GVWR (gross vehicle weight rating) of less than 6,000 pounds. Today, the average 5th wheel toyhauler is 35.5 feet long and can have a GVWR exceeding 18,000 pounds. Stopping this much vehicle is something that has always been a concern and was key in my decision to research upgrading my stock electric drum brakes to a highly efficient, reliable and low maintenance disc brake system for my toyhauler. When I began to consider my choices for disc brakes, my first thought was to consult my axle manufacturer for a recommendation. That proved to be an excellent decision.
I called Dexter’s corporate office in Elkhart, Indiana, and they put me in touch with Mark Pray, their senior sales engineer for California. Mark had just recently upgraded to disc brakes on his Weekend Warrior, so I knew I was in good hands. When we met to discuss my options, Mark noticed that the tires I upgraded to a few years ago were a little oversized for what Rage’n had designed the wheel wells to accommodate and the conversion to disc brakes would create an issue with the offset (the relationship of the center line of the tire to the hub face of the axle) of the Dexter disc brake hub. In order to correct this, I chose the 8K, eight-lug disc brakes. Not that I needed that much brake, but the geometry of an eight-lug hub offset would keep the wheels within factory design tolerance.
The next suggestion was to upgrade my existing standard equalizer to Dexter’s E-Z Flex® equalizer. The equalizer is the device that is bolted to the center hanger between the axles and in turn connects to the leaf springs via shackle bolts, and mine were showing considerable wear. Dexter’s EZ Flex has a rubber core between the equalizer arms which provides damping to the trailer during shock loads. While traveling, the E-Z Flex® compresses and absorbs road shock that can damage the trailer’s frame, interior and contents. Standard equalizers are a solid device without any means to absorb the shock. The E-Z Flex® system also has a greaseable pivot point at the hanger and a brass bushing. In addition, the E-Z Flex® kit includes heavy-duty shackles and bolts with grease zerks and brass bushings. This sounded like a great idea as I am constantly traveling on secondary and county roads that are usually very rough and full of potholes not to mention the miles of unpaved access roads to my favorite riding areas.
For whatever reason, Rage’n chose axles without zerks to grease the wheel bearings. This required me to remove the wheel and bearings for my annual inspection. I asked Mark if we could add grease zerks or upgrade somehow. He said that it was not possible to retrofit my axles; instead, Mark recommended that we swap out the axles and include Dexter’s Nev-R-Lube® bearings. We could change the axles, brakes and equalizers all at one time. I came to refer to this as a “Drop-N-Swap.” This consisted of a set of hydraulic disc brakes mounted to new axles with Nev-R-Lube® maintenance-free sealed bearings and an electro/hydraulic actuator. This kit along with a set of the E-Z Flex® equalizers would give me the braking power I wanted along with a much smoother ride. Mark said that with a few basic tools, including a floor jack, multiple jack stands and a torque wrench, just about anyone can do this. To prove this point, Mark offered to help with the installation if I would be willing to bring my trailer down to the Dexter plant in Southern California, or I could take my toyhauler to a local RV shop to do the work. I was sold, and accepted his offer.
On my drive down to Southern California, I had a shackle failure. If you have ever had this happen, you know this is quite unnerving and there is not a thing you can do about it except to limp your way home or to the nearest repair shop. Fortunately, I was just south of Lancaster on my way to the Dexter plant in San Bernardino when it happened. I asked Mark what could have caused this kind of failure on a trailer that was just over three years old. He said that it was probably a combination of the rough roads I travel on and the amount I use my toyhauler coupled with the extremely stiff G-rated Goodyear tires I use.
Since this is a two-person job and I was not covered under the plant’s insurance, Mark enlisted Danny Gomez, quality control manager of the Dexter plant, to help. Once we put the trailer up on jacks and removed the wheels, Danny noticed that the shackles on the other side were quite worn and one of my electric brakes had never been properly connected to the electrical system. Essentially, I had been towing with only three brakes since I purchased my Rage’n in 2005. If I had been a little more diligent in my regular safety inspections, I would have discovered the shackle wear before the failure as well as noticed that one set of brake shoes was virtually unused.
I was truly amazed at how fast everything progressed from here on. Just a few bolts from the suspension brought down my old axles, brakes and all. Raising my new Nev-R-Lube® axles populated with the new disc brakes was a cinch by using a floor jack to raise them into position. A few bolts into the frame and they were in place and ready for the new equalizers. But before we go there, let me introduce you to my new brakes!
Dexter Axle Company designs and manufactures their disc brake system. These are not your usual floating caliper disc brakes you find on your family minivan or even your tow vehicle. These are massive four- piston fixed caliper brakes akin to high performance race cars with unparalleled stopping power. Dexter’s fixed caliper design uses two pistons on each side of a large vented rotor. During actuation, hydraulic pressure pushes against the pistons to apply the inboard and outboard pads equally to decelerate the rotor. In comparison, the floating caliper brake uses only one piston on one side of the brake rotor. Hydraulic pressure pushes the inboard pad against the rotor; the caliper moves laterally towards the vehicle frame and in turn applies pressure to the outside of the rotor.
These powerful brakes are driven by Dexter’s E/H 1600 electro/hydraulic actuator which is in turn controlled by the Dexter Predator DX2® electronic brake controllers. Dexter’s E/H 1600 will generate 1600 psi for maximum performance from the disc brakes. The sealed, weather-tight housing contains the electronics necessary to control the high pressure piston pump and proportioning valve for smooth, efficient braking. This actuator was connected to my breakaway switch and brake controller then installed in the storage compartment for easy access to check fluid levels during my usual “pre-flight” inspection.
The next task was to remove what was left of my old equalizer and shackles, drive out the old plastic sleeves and replace them with new brass bushings. Once that was complete, Mark and Danny bolted in the new E-Z Flex® equalizer with grade 8 bolts, greased the zerks and torqued to specs.
Now that everything was in place, it was time for the brake lines. This was the most time-consuming part of the project; running 1/8” stainless steel high pressure brake lines from the actuator to the axles, then in turn to each brake caliper with a flexible high pressure line. Next they added brake fluid to the reservoir, primed the actuator and bled the brake lines. After testing the actuator with the breakaway switch, we connected the trailer’s umbilical cable to my truck and checked for proper operation with my truck and the brake controller.
Everything checked out great and we were ready for the road test…well, almost. There was the small detail of my 6-lug wheels that needed to be upgraded to 8 lugs. The good folks at Dexter introduced me to Tim Ball from Tredit Tire Company. Tredit is the exclusive OEM Goodyear Marathon tire distributor for the RV and trailer industry. My needs were simple: a set of eight-lug wheels that were rated to handle 110 psi for my G-rated tires. Tim showed me aluminum wheels for about $150 each in a style that gave me the ability to inspect my brake components without removing the wheel, not to mention they were good looking too! After changing the wheels out, we were ready for our first test run.
The anticipation was killing me as we pulled out into the parking lot. I didn’t feel anything different on my first application of the brakes. Mark had set the controller at a low setting and instructed me to increase the gain in small increments to find the best response. The third adjustment rendered the desired results. Not the usual jerky “clunk” of magnets and brake pads, but a very smooth pull from the trailer that increased with the application of foot pressure. Very nice! Once satisfied with low-speed braking, we increased speed to 45 MPH and applied the brakes normally and then again in an emergency stop. We were firmly pulled to a stop with a cloud of burning rubber from the tires. After a few more adjustments to the controller, we took a ride out to Interstate 10 for a little highway off ramp action. The braking response was smooth and consistent as we exited the freeway at posted speeds and with a heavy foot I was able to stop in very short order without locking up the wheels. On my way back to Sacramento, I was able to use the manual lever on the brake controller to slow my descent down the Grapevine from 75 to 45 MPH in just a few hundred feet with absolutely no brake fade. Very impressive!
On a scale of 1-10, I would give this upgrade an 11 and well worth anyone’s investment for much less than you’d think! The Dexter components, consisting of two new 6K axles and disc brakes and Nev-R-Lube® bearings along with their E/H 1600 actuator and plumbing kit, can be purchased from a Dexter distributor for $2450. The E-Z Flex® Equalizer system with heavy duty shackle links and brass bushings is less than $285. These are suggested prices and prices may vary depending upon your local authorized Dexter Axle dealer. For more information and to locate an authorized Dexter distributor near you, visit www.dexteraxle.com.
I’d like to thank Dave Gealow, Phil Duckworth and everyone at the Dexter Axle plant in San Bernardino for giving us the space for this installation. I’d also like to thank Tredit Tire Company and Tim Ball for his sage advice and extensive insight into RV’s tire and wheel applications that I plan to share in a future issue. Finally, special thanks to Mark Pray and Danny Gomez for all of their hard work. You guys did a fantastic job!
Look for a more complete road test report in an upcoming issue as well as information on Dexter’s Torq-N-Go™ lug nuts that eliminate the need to re-torque your lugs, a report on electric brake maintenance and Dexter’s Nev-R-Adjust™ (self-adjusting) electric brake replacement kits.
-Scott Butera
