4wd Hardware
4WD versus 2WDJohnston, Jeff
straight talk from the TL Tech team
We have owned five motorhomes and are thinking of getting into a fifth-wheel. A couple of reasons are steering us in that direction, including a smaller overall package with comparable living space and the more obvious cost factor.
Is there any advantage/disadvantage to choosing a four-wheel drive (4WD) versus a two-wheel drive (2WD) when towing a medium-size fifth-wheel? Comfort, handling, ease of entry/exit, MPG and noise are all considerations. We would be looking at ¾- or one-ton dualie with automatic transmission and a diesel engine, and an extended-cab long box. Another general question: Is there a guideline about how much towing capacity you should have over and above the trailer's gross vehicle weight rating (GVWR) as a safety and performance cushion?
JIM MAGI
INVER GROVE HEIGHTS, MINNESOTA
Those are good questions, Jim. You have to partly answer one of them by considering your towing and camping style. If you put your trailer and tow rig away for the winter, or if you head south at the first sign of a snowflake, you probably don't need 4WD. If you stay in well-developed campgrounds with paved or gravel roads, 2WD will do fine. As for general towing performance, handling, safety and so on, there's no need to buy a 4WD. Regarding comfort, noise, ease of entry and so on, you can best judge those by visiting your local dealer and taking some test drives because my opinion on such things will surely differ from yours.
If bad-weather camping strikes your fancy, or you stay home in the winter and need to drive your tow rig solo in some of the North Star State's finest weather, or you regularly plan to take on camping areas with truly bad road conditions, then a 4WD would likely be your best choice. However, note that some 4WDs have high bed sides that may require a lift for your trailer to maintain adequate bed/trailer clearance.
You can tow a trailer that doesn't exceed the truck's tow rating (but comes dose to the rating) and you'll be just fine. The truck manufacturers establish the tow rating with a certain set of performance, durability and safety parameters in mind. The rating is the point at which those parameters are all met to the manufacturer's satisfaction and, hopefully, the buyer will be satisfied, too. If you exceed that point, your performance will degrade. If you stay back from the tow rating, your performance will improve because you're giving the truck some breathing room. There's no set figure on how far to hold back from the tow rating. It's up to you to decide how much towing capacity you want to give up in exchange for that extra "breathing room." -J.J.
Where's the Power?
Back in the May 2003 issue you have a letter from Charles Carter, owner of a 2001 Dodge Ram 2500 with a V-10 engine. I read this column several months ago but was traveling and did not respond. He was complaining of a lack of power to pull his 13,000-plus-pound fifth-wheel. I also own a 2001 Dodge Ram 2500 with V-10 engine and pull a Holiday Rambler Presidential trailer that, when loaded, weighs close to the rated capacity of my truck. I have experienced the same problems of no power after a pull and when taking off from a stop, especially on an incline. Flooring the accelerator works to no avail, but the solution is very simple. Before starting off from a stop, simply downshift the automatic transmission to the next gear down. The truck will pull ahead fine and the driver can shift up to DRIVE once rolling. Alternately, the driver can simply click off the OVERDRIVE switch, leave the automatic transmission selector in DRIVE and the truck will pull just fine. Then, re-engage the OVERDRIVE when rolling. There is no problem with the transmission, and he will have all the power needed to pull his trailer. I enjoy your informative column each month.
LARRY B. STREELMAN
SAN MARCOS, CALIFORNIA
Thanks for taking the time to write, Larry. We'll pass that along in case some of our readers haven't tried that technique. - K.F.
"Extra" Tow Rating?
I've noticed that you publish a towing guide in the December issue of each year. I know you have articles on towing with trucks, but you have never mentioned what percentage over the maximum weight a truck can go before it becomes a problem with the vehicle.
I own a 2003 Dodge Ram 4WD with the 5.7-liter Hemi, automatic, regular cab and a maximum towing rating of 11,000 pounds. I recently purchased a 2003 Carriage Cameo LXI with a rating of 10,110 pounds. With gas bottles, a 10-gallon water heater full and our personal items I think I am near that limit of 11,000 pounds and maybe a little over. I have a feeling that all manufacturers of trucks have a percentage that can be over their quoted scale, but for warranty purposes they hold back a little. If I would go over the maximum by, say, 400 or 500 pounds, would I be harming my transmission or engine?
HAROLD OVERDORF
TROUT RUN, PENNSYLVANIA
* That's a good question, Harold, but first I need to make it clear that we always recommend you stick to the manufacturer's tow ratings. The vehicle manufacturers establish tow ratings based on many criteria, including cooling ability, engine power, suspension, hill-climbing ability, braking capacity and so on. By sticking to the published tow ratingyou'll help avoid overload-induced mechanical problems.
The manufacturers do not allow any percentage of overload when they establish a tow rating, nor do they downgrade a tow rating to automatically provide a "holdback" for overloading.
At the same time, a component rated for, say, 1,000 pounds doesn't fail because you add ten pounds to its load. If you add 100 pounds, that's a different story. You can go over the truck's tow rating with your trailer weight but, first, you'll risk warranty claims if the overloading causes a component failure. Second, that overload will cause your brakes to be a bit less effective and wear out a bit faster, your acceleration will be slower as will your hill-climbing ability, your mileage will likely be somewhat lower, your tires and bearings will likely wear out a bit faster, and so on. You make a choice in what you tow, and take your chances.
You'd be best off to take the trailer to a public scale to determine exactly what it weighs. The manufacturer's weight guesstimate is likely to be low, especially once you add the weight of your cargo, passengers in the tow vehicle and so on. It's a complicated picture, but you need to look at every angle if you're going to make an effective tow rig and trailer match up. -J.J.
Transmission Cool-Down
We have a 1996 Ford F-350 pickup with the 7.3-liter Power Stroke and E4OD transmission. It pulls a 37-foot fifth-wheel trailer that brings us up near the GCWR limit. The owner's manual says to let the engine idle to cool down the turbocharger after a hard pull, but what about the transmission? We often jump off the Interstate for a quick pit stop and let the engine idle. Would it do any good to set the brake and select NEUTRAL to let the transmission spin?
Also, on cold mornings I've noticed it takes a few miles for the torque converter to lock when first starting out. On the occasions I have allowed the engine to warm up and selected NEUTRAL on the transmission, it seems to function better. Is this true?
RICH BRYAN
LINWOOD, KANSAS
* Functionally, the only significant difference between PARK and NEUTRAL is that the parking pawl is engaged when it's in PARK. Other than that everything is pretty much the same as in NEUTRAL. Actually, whenyou've been driving and stop to park, you should get in the habit of applying the parking brake first, before shifting the transmission into PARK. This takes most of the impact load (as the truck and trailer roll slightly and are then forced to stop by PARK) off the parking pawl in the transmission.
The reason that the torque converter doesn't lock up when it's cold is because the powertrain control software is programmed to keep it disengaged, because the slippage warms up the fluid faster and brings everything to operating temperature quicker.
When the turbocharger is hot, chances are the transmission fluid is hot too. Taking the load off the transmission by selecting either PARK or NEUTRAL will have the same effect and idling will circulate the fluid through the cooler (heat exchanger). Since you're towing a heavy load, I recommend that you install a transmission fluid temperature gauge and an exhaust gas temperature gauge. That way, you can make informed decisions on when it needs to cool down and how long to let it idle. - K.F.
Trailer Disc Brakes
A reader recently inquired about disc brakes for trailers and how to equip his trailer with disc brakes. He indicated that he contacted one of the component suppliers and was told they only provided a portion of what is necessary. His letter inquired as to who might supply all the components necessary to install the disc brakes. In your response you gave him information on the axle and brake suppliers. I think I can provide some information that might be helpful.
At MOR/ryde we have been installing disc brakes on trailers for the last 15 months and we are seeing a very significant increase in interest for disc brakes. As a result, we have compiled a listing of the parts and information necessary to complete an installation. Here's a listing of the different parts needed for an installation as well as some installation details:
1. Disc brakes: current suppliers are Dexter Axle and Kodiak Brake; capacities are from 3,500 pounds up to 10,000 pounds per axle.
2. Booster pump: suppliers include Titan, Masterbrake, and Carlisle (Note: this is an electric/hydraulic brake actuator).
3. Plumbing: these items include lines, tees, unions and hardware and can be purchased from a brake supplier or assembled through miscellaneous parts available at many auto-parts stores.
4. Electrical components: wiring, circuit breakers, etc. These parts can be supplied by an electrical supply store.
In addition to purchasing the previously mentioned parts, there are other factors that determine what is necessary. For example: knowing the size of the current brakes is necessary (such as 12 × 2, 12 ½ × 2 ½ or 12 ½ × 3 3/8). The current suspension system, be it leaf springs, Al-Ko Kober, MOR/ryde, Torflex or air suspension, is also relevant. The type of brake controller currently used is also important, and may need to be changed per the disc brake manufacturers' recommendation.
In addition, we have received inquiries from retail consumers and dealers as to what is necessary to perform an installation. As a result, we have started to "package" all the components and information necessary for installations. We can and have been providing this package to dealers and retail customers for their installation. We provide detailed instructions that will assist in performing the installation or customers can come to the factory for installation. I hope this information is helpful and would be of use to your readership.
JACK ENFIELD
MOR/RYDE INTERNATIONAL
* Thanks for offering this information Jack. A lot of people have been asking us about disc brake installations. MOR/ryde can be contacted at (574) 293-1581, or onlineatmorryde.com.-JJ. TL
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