RV Tech Q&A: October 2018

diesel-fuel-gas-pump

Diesel for Small Trailer?

As a new RV owner, I’m looking for some professional advice regarding towing. My travel trailer is 1,670 pounds, and my vehicle’s tow capacity is 2,700 pounds. Once loaded with people and gear, it’s up to around 2,500 pounds. This becomes a problem when towing up and down the hills. That got us to thinking of purchasing a truck specifically for towing. I’ve reviewed Trailer Life’s towing guides.

Is there an advantage to going with a diesel instead of a gasoline truck, if we choose a used vehicle with a towing capacity of, say, 6,000 to 7,000 pounds? I know the diesel will pull the load easier, but is this benefit worth the added price we’d pay for a diesel? Or would a V-8 gas-powered truck do the same job with no noticeable difference?

Mark Ladetto, via email

Mark, you can refer to Chris Hemer’s article “Diesel Versus Gas” in the September issue for an in-depth presentation. In short, you’d be wasting your money buying a diesel-powered tow vehicle for such a compact trailer. Today’s gasoline-powered vehicles are rated to tow many times the weight of your trailer. A diesel would do the job, of course, but the extra cost of fuel and maintenance may not be worth it. Select a gas-powered rig, such as a 1500-series pickup or full-size SUV with a towing package, and you’ll find it is more than adequate.

You can also check the Trailer Life website, www.trailerlife.com, or do a web search on “match a tow vehicle and trailer,” and you’ll find all kinds of extensive and detailed advice about the nuts-and-bolts figures regarding making such a matchup.


Slideout-Mount Failure

I have a Keystone Outback 210RS with a rear slide. After only three years, the slide tracks broke free from the ceiling, and the tracks cracked. My dealer says he has seen this before. The factory doesn’t use enough screws, and even more importantly, doesn’t use washers under the screws to hold the track up. The extra stress will cause the screws to pull through the track, causing the unsupported slide to crack the track.

If I had just added a few screws with washers, I would have saved an $800 repair. So others avoid this, I wanted to suggest that everyone take a look at how many screws hold up the track(s) on their slide(s) and check for washers. The screws should be no more than about 6 to 8 inches apart, depending on the size of the slide.

Rick Wilking, Golden, Colorado

It’s too often that RV manufacturers rely on structural hardware being screwed into a wood-frame element, Rick, and when it’s a load-carrying component like a slideout support, it has to be done just right, or it can fail prematurely. In your model, the roof structure elements run crossways to the trailer, while the slideout rails run lengthwise, so the only places the manufacturers can join the two is where the pieces cross each other. If you’d added screws between the roof beams, all the screws would be grabbing is the 1/8-inch decorative interior wallboard on the ceiling.

You could do that if you installed something like metal molly bolts that are designed to provide a secure grip in a thin material. Then you’d need to hope that the ceiling is securely mounted because the thin wallboard isn’t load-bearing. The best bet would be for the manufacturer to add structural backers where the slideout rails would be installed, something like 2-by-4s or even 1-by-4s, to give the screws something to securely hold.


 

Fifth-Wheel Sag and Lift

I have a 2014 38-foot dual-axle fifth-wheel. When towing it, I look through my truck’s rearview mirror, and the fifth-wheel doesn’t look level; one side seems to sag. And one of the landing-gear jacks was extended 12 holes, and the other one was at 13 holes when they just touch the ground.

I had a toy-hauler fifth-wheel, and I lifted it by reversing the axles from top to the bottom on the springs. I later had trouble with the frame cracking at the crossbeam welds. After much arguing, the manufacturer paid to fix it but told me reversing the axles had caused the problem. The technician said it caused too much flexing in the main beams. The repairs didn’t hold up, and the manufacturer refused to repair it again. I sold it and bought a new fifth-wheel.

I have a Ford F-350 dually, stock suspension with airbags. I run about 70 psi to level the truck. The kingpin box and fifth-wheel are as low as I can adjust them to allow about 6 inches between the bed rails and trailer front end. The tail of the trailer drags; the back is about 3 inches lower than the front. Is there another way, like adding leaves to the springs or helper springs, or even replacing the springs to raise it up a bit, other than reversing the axles?

Bob Weiler, Gilroy, California

Swapping the axles from above to below the leaf springs is not that much of a change, Bob, and I doubt the frame cracking is related to that swap. We’ve heard from many readers who’ve made this axle swap with great ongoing success. Most likely, the manufacturer and dealer were looking for something to pin the failure on, and your swap was a convenient scapegoat.

You could add airbags to the trailer using a Trailer Flex or Kelderman air-
suspension system, and those might help with the trailer-height situation, but those systems are mainly used to help smooth the ride rather than widely varying the trailer height. Check the manufacturer’s specifications, though, as they may offer ride-height adjustment as part of the installation process.

You could also have a custom spring shop fabricate leaf springs with more arch, which would effectively raise the trailer. Adding leaves to the springs would stiffen the suspension, and that could accelerate wear and tear on the trailer. Practically speaking, I’d stick with swapping the axles below the springs and have a frame shop add a few extra steel-tube crosspieces, side to side, near the spring perch mounts to reinforce the assembly for extra strength.

Editor’s note: MORryde (www.morryde.com) in Elkhart, Indiana, specializes in trailer suspensions, including the SRE4000, which we installed in the March 2017 issue. The company would also be able to assist with raising the trailer to suit your needs.


EZ Lube Hub

In May’s “Axle Greasing” letter, I believe you gave Robert Lauzon bad information. Lauzon asked about “greasable axles.” Your response described a boat-trailer greasable axle spindle. However, I think Lauzon has a Dexter axle with EZ Lube hubs, which are not similar to greasable boat-trailer spindle hubs.

The Dexter EZ Lube spindle has a hole through the center that goes to the rear bearing, not to the middle of the spindle, as you described. Allowing the grease to go to the rear bearing allows old grease to be pushed out of that bearing and then pushed through the hub through the outside bearing, which replaces the rear-bearing grease and the outside-bearing grease. This is unlike a boat-trailer axle with a center-drilled grease fitting that deposits fresh grease only to the middle (sometimes only to the outer bearing) of the spindle but does not actually replace the grease that’s in either bearing.

Dexter recommends 12,000 miles to inspect the wheel bearings, even with the EZ Lube axle. I greased the EZ Lube spindle at 6,000 miles and then pulled the hub at 12,000, as recommended by Dexter. Your response was to pull the hubs annually, which is not the manufacturer’s recommendation.

Pulling the hubs annually is some­- thing I do with my boat trailer because the grease is not getting replaced like it does with the EZ Lube Dexter axle.

Dean Smith, Henderson, Michigan

I understood from your answer to the “Axle Greasing” letter that you should not, or could not, grease the bearings from the Zerk fitting on the axle.

I have a 2014 Keystone Outback travel trailer with Dexter EZ Lube axles. They have a hole drilled through the axle to the back of the inner bearing with a double grease seal on the inside. As you add grease through the Zerk fitting and spin the wheel, the grease is pushed through the inner bearing to the outside bearing where it exits through the hole in the wheel hub. You continue with the grease until the old grease is followed by the new grease out the hole. You then clean off the grease that has exited and put the rubber cap back on.
When I brought my trailer from a private party, I greased the axles on all four wheels until the new grease was exiting the axle cap. I did not know about the Dexter axles when I bought the trailer but have been very pleased with the thought of not having to pull off the wheels and hubs to repack the bearings, as I have done for the past 44 years.

The Dexter EZ Lube website has a video of how to complete the repacking without removing the wheel or hub.

Charles Morris, Thatcher, Arizona

The bottom line with any of the alternate-lubrication hub systems is to follow the manufacturer’s recommended service procedures and schedules. These systems create a lot of problems for people who don’t follow the directions or are just too lazy to read them — as the tendency is to overlubricate. The hub has a Zerk fitting, so, therefore, some owners feel they absolutely must add grease now and then, and that’s not right. It’s fairly easy to overdo it and contaminate the brakes with excess grease. Some users, as a knee-jerk reaction of sorts, routinely add a pump or two of grease every few thousand miles, and that’s totally unnecessary and can be damaging.

It’s also not necessary, unless the trailer wheel is immersed in water on a regular basis, to add “fresh grease” now and then. As long as the bearings and grease are maintained on a regular schedule, and that includes disassembly to inspect the bearings (which you can’t do if you just pump in grease as a service procedure), the grease inside the hub is just fine.
Bearing grease does not degrade quickly like engine oil because it’s not subjected to the heat and combustion contaminants. If the trailer is dramatically overloaded or the bearings are poorly adjusted, and those factors cause overheating then, yes, the grease can degrade faster than normal. That also can happen if using the wrong type of grease. On a properly set up and used trailer, the grease is fine on a year-to-year service schedule. It’s best to follow the manufacturer’s service schedule.

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

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.


 

1 COMMENT

  1. Regarding diesel vs gas. The better mpg of diesel should offset the cost of the fuel. My gasser got a strong 8 and didn’t really have the power in Arizona’s mountains. Got a diesel and doubled my mpg to 16/17. It’s not the cost of fuel, but when something goes wrong with diesel, it’s going to cost a lot more then.

LEAVE A REPLY

Please enter your comment!
Please enter your name here