technically SPEAKING

Like any manufacturer of a quality product, wheelmakers want us to know how to get the best service, the best performance and the longest wear out of what they make.

 

Recently, we talked with Bill Noll of Accuride Corporation, which makes both steel and aluminum wheels, and Mark Holtz of Alcoa, which makes aluminum wheels.

Rather than focus on comparisons between steel and aluminum, we decided to concentrate on “care and feeding” issues common to both.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

For every dual assembly, you need twice as many nuts with a stud-piloted wheel system. And, you need both right- and left-handed nuts as well.

 

Has everyone switched to hub-piloted wheels?
Bill Noll, vice president of product development & technology, Accuride Corporation: “Hub-piloted wheels represent about three quarters of the wheels in use, and practically all the wheels supplied on new trucks. Nevertheless, there still are a fair number of stud-piloted wheels out there.”

What’s the crucial difference?
Mark Holtz, technical manager, Alcoa Inc. Wheel Products International: “There are huge differences. Stud-piloted wheels use the studs and ball-seat cap nuts to position the wheel properly on axle ends.
“With hub-piloted systems, metal projections, called ‘tangs,’ provide the proper alignment.”
Bill Noll: “There’s also a big difference in hardware. Stud-piloted dual wheels require both inner and outer nuts – total of 20 per dual assembly. With tandem axles on both tractor and trailer, that means:

 

 

 

 

 

 

With hub-piloted systems, the wheels are positioned by metal projections, or “tangs” on the hubs, rather than by the mounting nuts.
“And, you need 10 nuts for each steer tire, so that’s a total of 180 in all.”

 

 

And with hub-piloted wheels?
Mark Holtz: “There are no inner nuts in hub-piloted wheel systems, so in our earlier example, that eliminates 80 nuts. If you consider duals only, you cut your fastener inventory in half.
“And with stud-piloted wheels, you need both right-hand and left-hand threads, for the right and left sides of the vehicle. So, you need more nuts, do more labor installing and removing them, and need four different types of nuts in inventory.”

 

 

 

 

 

If we’re changing to hub-piloted, will some of our old hardware work?
Bill Noll: “Unfortunately not. Ball-seat nuts, for stud-piloted systems, and the new, two-piece flange nuts for hub-piloted systems, work totally differently.
“ In some cases, the hardware won’t interchange, because sizes and threads are different. But even if you could get nuts to fit, interchanging them would be a very bad idea.”

 

What’s the risk?
Mark Holtz: “Because the nut designs are so different, mixing them will result in incorrect contact with the wheels. That makes achieving proper torque difficult or impossible, can result in damage to the wheels and studs, and can cause wheels to loosen – obviously a very bad thing.”
Bill Noll: “For the same reasons, you never want to interchange wheels either.” Using flange nuts on stud-piloted wheels or ball-seated nuts on hub-piloted wheels can damage wheels or cause them to loosen.

 

 

 

 

Are there differences in the way you install stud- and hub-piloted wheels?
Bill Noll: “In both cases, you want to make sure the studs and nuts are clean of corrosion and dirt. That’s essential to getting the right clamping force to hold the wheels.” [Editor’s Note: For more details on torquing lug nuts, see Real Answers, Volume 3, Issue 3, p. 34-37. If you don’t have a copy, visit our website, www.trucktires.com.]
Mark Holtz: “It’s also a good idea to lubricate the studs in both systems. We recommend a few drops of SAE 30W oil on the end of the studs before you install the nuts.
“Be sure you put the oil ONLY on the studs. You don’t want any oil – with either type of nut – on the surface that makes contact with the wheel. This can cause excessive torque, stretched or broken studs, damaged or loose wheels.”

With hub-piloted systems, you also lubricate the nuts, don’t you?
Bill Noll: “Yes. Nuts for hub-piloted systems have two pieces, and you should put SAE 30W oil between the nut and the flange washer. If the nut is in good condition and you’ve lubricated it properly, it should turn freely against the washer. “When you torque two-piece flange nuts, the nut should turn against the washer, but the washer should not turn against the wheel. Lubrication helps make that happen.”

Using flange nuts on stud-piloted wheels or ball-seated nuts on hub-piloted wheels can damage wheels or cause them to loosen.

 

 

 

 

 

 

 

 

 

 

 

 

Are there other differences?
Mark Holtz: “With hub-piloted systems, it’s a good idea to put lubricant on the locating tangs. You can use tire-mounting lubricant, so long as it’s not water-based. This helps prevent wheels from seizing to the hubs. You don’t want trouble getting the wheels off later on.”

What torque should we use?
Mark Holtz: “It’s best to check the data supplied to you by the wheel manufacturer, because different wheels and nuts do vary. On stud-piloted wheel nuts ONLY, you can decrease torque per manufacture’s recommendations
– IF you lubricate the studs.”
Bill Noll: “And, even though it’s not a popular thing to say, you should check and re-torque all lug nuts, including both inner and outer nuts on stud-piloted systems, about 50 to 100 miles after installing the wheels, and at frequent intervals thereafter.”

That’s difficult to do.
Mark Holtz: “We recognize that. Still, it’s the best way to maximize component life and to make sure wheels are properly secured. If you can’t do it within 50-100 miles, please be sure to do it as soon as possible, and check torque frequently between wheel removals.”

 

 

 

 

 

 

 

 

Editor’s Note: Our thanks to Accuride and Alcoa for assistance in preparing this article.