RV Tech Q&A: Downhill Braking

I read February’s “Tundra Brake Problems?” letter from David Chapman and your reply about truck and trailer brakes. Neither your reply nor Chapman talked about downshifting the transmission, which is an important part of driving down long or steep hills, particularly with a trailer. Some newer truck automatic transmissions downshift themselves on a downhill grade.

My opinion is that the engine and transmission should provide most of the retarding, and that the brakes should be used only to help hold the speed down. If Chapman’s truck wasn’t downshifted to help retard the unit, then that might be the cause of the overheated brakes. The owner’s manual should provide information about towing and descending grades.

Rick Stuchell | Centennial, Colorado

You’re right, Rick. Using downshifting and engine compression to help control speed down a grade should always be part of the discussion. Some of the people who report consistent brake problems when others have great towing success with the same vehicles are likely among those who don’t downshift to help maintain speed and experience brake fade, adverse wear and/or warped rotors due to heat. That wouldn’t apply to all of those with brake problems, but certainly the majority.


Disc-Brake Selection


My wife and I are planning a cross-country trip in about two years. After reading various articles about disc brakes, I am considering changing my fifth-wheel drum brakes over to disc brakes. We own a 2013 Keystone Montana 3582RL. I believe the axles have a 7,000-pound gross axle weight rating (gawr), and dry weight is 12,600 pounds. Can you recommend a brand of disc brakes that has performed better than the others?

Art Frament, Clifton Park | New York

The use of disc brakes will make a big difference in stopping ability. Titan is a well-known brand, and there’s also Kodiak, and both offer parts and kits to fit today’s trailers.
You might want to make sure that you’ll own the trailer you want to convert for a while, as the kits aren’t cheap, and you’re unlikely to recover the full investment cost at resale.

Even at a price, it’s one of the best safety-related accessories you can add to your trailer.


Hitch Extension

I have a 2014 Toyota Tundra with which I towed a 26-foot Aljo trailer. Aljo had trailer models many years ago, but its Skyline brand was built until fairly recently. We traded it in on a 2018 26-foot Keystone Cougar. I am using the same hitch with the new trailer, but I can no longer lower the tailgate while hooked up. It contacts the electric jack, which makes it difficult to get our dog into and out of the bed shell.

I searched for hitch extensions but found that they generally are not recommended for towing trailers. I did find that the Roadmaster Anti-Rattle Hitch Extender for Tow Bars (item number RM-071-1075) can be used for trailer towing, if the tongue weight is less than half the extender rating.

Do you have any suggestions?

David Tyler | Las Vegas, New Mexico

The use of a hitch extender can go overboard when people use one that’s too long. This places an undue amount of leverage on the receiver, and that’s where the problem arises.
The extension you identified (which is listed at 7½ inches) is fairly modest. Roadmaster posted a 10,000-pound trailer weight and 400-pound hitch weight for that extension, and as long as you observe the hitch-weight limitations, you should be OK.

The use of a weight-distribution hitch also helps because it redistributes some of that dead-weight torque on the receiver, so that’s also in your favor.


RV-Cover Sunburn


My next-door neighbor recently purchased an ADCO RV cover for his travel trailer that he parks beside his house, which is about 30 feet away from our two-story home. A few weeks ago, I noticed what appeared to be a long “burn” in a 12-foot arc on his cover on the side that faces our house. After taking a closer look and experiencing a couple sunny days here in the Pacific Northwest, we determined that the burned and melted arc was caused by sunlight reflecting off our upstairs window onto the cover.

My neighbor called ADCO, whose customer service told him they had never heard of such a thing and that it was not covered under the warranty. They suggested that he park his RV in a different location and somehow block the reflected light or purchase another cover made from a different fabric.

Of course, the fabric that might be immune to reflected light was well over $1,000.

Larry Lucas | Portland, Oregon

The chance that an RV cover could be burned by a sun reflection seems unlikely, especially in Oregon’s not-always-sunny Willamette Valley, where I live as well. There would need to be something reflecting the light that focused and concentrated it enough to make the burn, and that wouldn’t happen with straight, flat windows.

The reflection image you sent shows an irregular section of reflected sunlight, and the center where it’s brightest could be some type of focused spot. You’d need to track that back to one of the windows on the house by alternately covering each window until you find which one is creating the reflection. If there’s something inside your house that’s reflecting, it may need to be moved. If the window glass has some type of flaw that causes the focused reflection, you may need to replace the glass or add something like a couple layers of window screen to diffuse the light enough to avoid future problems.

Drop another note and let us know what you discover.


Trailer Level and Tire Wear


Last year I purchased a 2017 Ram 2500 4×4 truck to pull my 31-foot 2016 Dutchmen Denali 262RLX fifth-wheel. The mounting-surface plate of the fifth-wheel hitch on the new truck is 7 inches higher than it was on my old 1995 Ram. The nose of the fifth-wheel is up, and the trailer does not travel parallel to the road surface by less than 2 degrees, measured from the kingpin to the center of the tandem axle.

On our last trip, there were two blowouts on the rear axle. The trailer has an Equa-Flex leaf-spring suspension and had the original ST225/75 R15 load range D tires. I kept the air pressure up to 65 psi max and was well within the gross vehicle weight rating (gvwr) and gawr.

Is it possible that when the trailer travels nose up there is more weight on the rear axle? I replaced all four tires with Goodyear Endurance ST225/75 R15 load range E and hope that I don’t have to go through that nightmare again.

Klaus Krolik | Fallbrook, California

Although the equalizing suspension part of a dual-axle trailer is supposed to provide more or less equal weight on the axles, that’s not 100 percent the case. If the trailer body is angled back somewhat, there’s going to be a weight transfer toward the rear axle, but how much weight is transferred depends on a lot of trailer-body design factors and the suspension configuration. It also depends on how much weight is carried on the axles and tire carrying capacity. The weight transfer would need to be pretty significant to have an effect like overloading and blowing out two tires.

You can use a commercial scale to determine the trailer’s axle weights. Park the trailer so both axles are on the scale and note that figure. This is also a good time to compare the trailer’s posted gawr to those scale results, as this will tell you where the RV stands on being overloaded or not.

Now, with the help of a spotter, roll ahead until one axle is off and one is still on the scale. Note that figure and deduct it from the total for both axles to determine how much weight is being carried at each axle. If there is a significant difference in weight, that could aggravate the blowout situation. It would also affect the tires during a sharp turn, which will scrub sideways, placing a lot of stress on the sidewalls.

It’s best to figure out a way to get the trailer riding level. This can be done by lowering the fifth-wheel hitch saddle, if there’s still enough bed-rail clearance for trailer movement, or raising the suspension somewhat using the techniques we discuss in this column on a regular basis. A level ride will help with the axle-loading situation.

Have a Question?

Email or write to RV Clinic, 2750 Park View Court, Suite 240, Oxnard, California 93036. Include your full name and hometown. Selected letters will be answered in the magazine, but time does not permit individual replies. No phone calls, please.


 

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