Maintenance Q&A
Quirky kingpins and biodiesel basics

By Paul Abelson, senior technical editor

Q. I have a problem that may be an ongoing one throughout the industry. I pull a flatbed, and more than 90 percent of my miles are on paved roads or freeways. The rest are on oil field roads, where the speed limit is 25 mph or less.

We have a problem getting kingpins to last. For example, when I drove a company truck, they lasted only about six months. Since having my own truck, I’ve had to put in a new kingpin. At the same time I put on new steer tires, had them balanced, and had a front end aligned. Less than a year later I needed another new kingpin and new tires.

There’s got to be an answer. I mean I kept them greased, every week for the first three weeks as directed, and I keep the front end greased during oil and filter changes.

A. You will need more frequent alignment when driving in the oil fields. Twelve months on a set of steer tires in rugged conditions may or may not be normal, depending on the type of wear you experienced. But needing new kingpins after only six months is definitely a cause for concern.

Because I have limited experience with oil field operations, I checked with my “Brain Trust,” retired Technology and Maintenance Council Silver Spark Plug award recipients Carl Tapp and Tom Tahaney. Both are experienced with off-road operations. We have some questions.

Who determined that the kingpins needed to be replaced and what was the basis for that determination? Why did the shop do a steer axle alignment and not a total vehicle alignment? Was that your direction or their decision? Third, where did the replacement kingpins come from? Could they have been counterfeit? Last, were shocks, bushings and steering linkage checked for wear? They can have a major influence on tire wear and they protect the kingpins from damage.

If an outside vendor does your front end work, question any parts replacement. While the vast majority of shops are ethical, too many will sell unneeded parts to pad their bills. “In more than 40 years of maintenance work,” one of my advisors said, “I have seen only one kingpin that needed replacing and that was due to poor maintenance.”

A kingpin is a massive steel rod, but if the metal is not properly formulated or is not properly heat-treated (hardened and tempered), it can wear. Bushings will usually wear first, but they do not carry the kingpin’s price tag.

TMC suggests in Recommended Practice RP642, Total Vehicle Alignment, that all wheels (axles) of a tractor, truck or combination vehicle be aligned with each other to maximize tire and component life. If only the steer axle is aligned (camber, caster and toe-in), the steer tires may still be subject to side forces from drive axles. That can cause uneven wear. You can check your particular wear pattern using TMC’s RP216C, Radial Tire Conditions Analysis Guide. It will indicate probable wear causes.

If the kingpins truly need frequent replacement, either the kingpins are defective or they are not properly maintained. If your shop stocks cheap parts rather than durable ones, you could be getting off-shore counterfeits. They are cheap because the material may be substandard, machining is off, or shortcuts were made in the finishing process. If not properly hardened, they will wear excessively, although usually not enough to warrant replacement. Bushings take the brunt of the wear. If the shop takes shortcuts with parts, they may also do so with maintenance.

You mentioned having the kingpin greased “every week for the first three weeks” and at every regular oil change after that. For off-road use, the chassis including kingpins should be greased at least once a week. When greasing the front end, the tires should be unloaded. If the truck is greased sitting on the ground, the kingpins will not get sufficient grease. Kingpins should be greased from the top until clean grease flows all around past the bottom seal.

Any reputable manufacturer’s kingpins should last the life of the truck, provided they are properly maintained. Check bushings and use grease generously. And you should also consider using a different front end shop.

Q. I was just wondering what biodiesel fuel really consists of? How truly harmful is it to my motor and the environment? I have a Cat C7 motor, and the HUEI fuel system does not like biodiesel fuel very much. In fact, I have had to replace most of that system about every 200,000 miles. Is there anything I can do to help improve the situation?

A. Like petroleum diesel, biodiesel is a hydrocarbon fuel. It is made from vegetable or sometimes animal sources. It’s renewable and therefore better for the environment. It has no sulfur, aromatic molecules that burn less completely, particulates or carcinogens. Its emissions are cleaner.

Most is processed from soybeans, although any fat or oil can be used. It must be processed to remove glycerin by cooking it with alcohol and a catalyst.

Biodiesel should not be used full strength. A 5-percent concentration will not harm components, but in older engines, fuel system gumming may occur. Biodiesel adds lubricity to ultra-low-sulfur diesel, but it gels more quickly in cold weather.

Fuel sold today can range from 5 percent to as much as 20 percent biodiesel. Fuel additives and conditioners formulated for biodiesel blends are sold at truck stops and parts dealers. Read directions on the container. Used in proper proportions, they can help extend your engine’s service life. LL


DO YOU HAVE A maintenance question?
Send your question to Paul Abelson, senior technical editor, in care of Land Line Magazine, PO Box 1000, Grain Valley, MO 64029; email them to or fax questions to 630-983-7678. Please mark your message Attention: Maintenance Q&A.

Although we won’t be able to publish an answer to all questions in Land Line, we will answer as many as possible.