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RV Tech Q&A: December 2018

Originally Published in Trailer Life Magazine

Trailer-Tire Balance

Red letter Q

I took two new tires to a tire-service store to have the old ones dismounted and the new ones mounted, as well as having them balanced. This was not my first time having this done on wheels and tires, and no one had ever tried to explain what they did until now. Here is what went on, and I find it a bit confusing.

The wheels are aluminum, so I can understand them not wanting to put wheel weights on the outside and damage the finish, but here is the confusing part of the explanation. As the spin balancing was being done, the store manager told me the rims come static balanced to the trailer manufacturer, and even though the spin balancer was calling for weights to be added to both inside and outside beads, the only way he would balance the tires was to “static balance” them.

He changed the machine to a new setting, which told him where to place a weight, and if the reading on the machine was under 20, it was considered balanced. One wheel-and-tire assembly came in at 11, and the other was 7, as I remember.

What does the customer do? I have never, on any form of vehicle or trailer, been told the rims come static balanced from the manufacturer. Do I believe this guy, or should the wheels and tires be pulled off and rebalanced? I am not against using stick-on weights, as a properly balanced tire saves both the tire and the trailer. I would appreciate your feedback on this.

Bill George | Bloomfield, New York

Green letter A“Static balanced” likely refers to the use of an old-style bubble balance device once used as the standard wheel-balancing system. It’s possible your trailer tires and wheels were checked at the factory, but unless you saw some type of weights on the wheels at the beginning of this process, it’s possible your tire dealer led you astray. If the dealer meant it was just the rims that came “static balanced” from the factory, that doesn’t take into account any imbalance by the tires, so they should still be rebalanced. You may want to check with a different tire dealer for follow-up service.
There’s no reason the tire dealership can’t do a spin balance on the wheels and tires, just as they’d do for a passenger vehicle. It isn’t necessary to have the stick-on weights on the outside of the wheel. The balance can be achieved with the weights added on the inside, or back side, only.

More on Axle Greasing

Red letter Q

I read your response to Robert Lauzon’s “Axle Greasing” comment in the May issue with interest. I have a 2014 Keystone Montana Big Sky fifth-wheel. We pulled it to Soldotna, Alaska, this past May with our Ram 3500 dually diesel. When I stopped to refuel in Tok, Alaska, I noticed accelerated wear on the outside bead of the right-forward tire on the trailer. I put the spare on and continued our trip.

I didn’t notice any suspension/shackle problems, so I contacted Kenai Diesel & Marine with suspicions of a bent spindle or axle. John inspected the tires and suspension, and found a broken spring bolt on the left side of the fifth-wheel. This allowed the left axle to creep forward. The end of the bolt that remained showed a lot of wear. I suspect the bushing is missing or badly damaged. The inside bead of both left tires showed serious wear.

These bolts have Zerk fittings for a reason, and I had the wheel bearings repacked before we left Arizona. On inspection, the fittings on these suspension bolts showed no indication that they had been greased. This is a reminder to me that I need to be more specific when getting my “home” prepared for the road.

I’m having all of the bolts and bushings replaced and greased on both sides before we begin our return trip. I’m also considering replacing the shackle assemblies with the Roadmaster Comfort Ride system.

Doug Gold | Sioux Falls, South Dakota

Green letter AWheel-bearing and spring-bolt maintenance are two different jobs, Doug. If the dealer doing the wheel-bearing repack wasn’t told to also grease all available fittings, that would explain why they appear dry, although the original installer should have greased them as part of that project. Greasable spring and shackle bolts are terrific safety and durability additions to a trailer suspension, and they’re always worth installing. It’s a good reminder for all towable RV owners to include those fittings in a regularly scheduled maintenance program.

Brake-Control Failure

Red letter Q

August’s “Breakaway-Switch Brake Failure” reminded me of the same problem I had with my 2011 Chevy Silverado 2500HD with the Duramax engine while towing my Alpenlite Augusta 34-foot fifth-wheel. I was using the GM-supplied brake control that was installed in the truck. I noticed that even at full braking that control would not stop the trailer or lock the trailer brakes. This control is made for smaller trailers. I replaced the controller with a new one from Camping World and, boy, what a difference it made with the braking — the brakes will now lock the wheel with room to spare in the controller.

John Abel | Prescott, Arizona

Green letter AA couple of items stand out, John. The integrated brake control in your Chevrolet is fully rated and designed to handle the braking needs of any trailer the truck can haul, according to its tow rating. The brake control, like the truck’s other hardware, such as suspension, braking, cooling and so on, is part of the full system, with all the parts rated to handle, for example, the truck’s 17,400-pound maximum potential tow rating. That brake control was either defective and in need of repair, or it was way out of adjustment with the gain and/or the braking rate set too low.

Ideally, a trailer-brake control should be adjusted so that the truck and trailer feel like a single unit when stopping. The trailer should not seem to be dragging on the truck, with the brake control adjusted for too much gain, and it shouldn’t be pushing the truck when the gain is too low.

The trailer-brake control should never be adjusted so it can lock up the trailer brakes. That can lead to loss of control and jackknifing during an emergency stop when the tow-vehicle
brakes have activated the antilock braking system (ABS) while the trailer is fully locked and skidding. The truck is in directional control due to its ABS, while the trailer is sliding anywhere it wants. To avoid this, the brake-control gain should be adjusted so that, even fully applied, the trailer brakes are just short of seizing up and locking the wheels. Once that gain adjustment is set, you set the rate, or how the brake control applies the trailer brakes relative to the truck’s brakes, to suit your preference. If in doubt, a qualified RV-service center can help you with the fine-tuning.

Tacoma Brake-Control Connection

Red letter Q

I just bought a 2018 Toyota Tacoma truck with the tow package. Do
I need a wiring harness to connect the brake control? It is supposed to have
a service connector for the towing brake controller, but I cannot find it. Do I need a harness?

Donald Burkart | Vancleave, Mississippi

Green letter AYour truck has a brake-control plug receptacle under the dash, Donald, and there should be an included pigtail that you wire to the brake control on one end and plug into the receptacle with the other. Your Toyota dealer tech guys can locate the plug for you; it’s under the far-left side of the dash behind a plastic molding.

See Related Story:
RV Clinic FAQ:
Top 20 Tech Questions

Once you locate the receptacle, the rest is pretty easy. There are generally four wires to connect the brake control, and between the brake-control instructions and the Toyota pigtail-wiring diagram, you should have it figured out in no time. In the event your truck didn’t include a pigtail adapter, you can purchase an aftermarket wiring harness that plugs into the brake control and the Toyota receptacle so you don’t need to do any wiring except attaching a ground-screw connection.

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.


Jeff JohnstonRV ClinicRV DIYRV Tech

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