Maintenance Q&A – December 2020/January 2021
Steering through winter driving problems
Q: The snow and ice hit early on the roads near Des Moines, Iowa, and the winter weather has been giving me steering problems. My 2017 Peterbilt just doesn’t want to grab on snow and ice. I still have between 6 and 7/32nds on my steers. That’s well above the 4/32nds that’s required. I had the power steering checked, and the tech told me it was good and the fluid was right up to the top. The belts were good, too. Do you have any ideas why this is happening?
A: You didn’t mention the power steering belt tensioner. They often lose the ability to continuously tension the drive belt with a constant force when they are starting to wear out. That could result in on-and-off power steering, which could give you erratic steering. After we spoke, you had it checked, and it was OK.
It sounds as if your straight rib steer tires are not biting aggressively in the winter conditions. I suggest going to a new set of all-position tires with full tread depth for the steer axle instead of steer tires. All-position tires have a somewhat deeper and more aggressive tread, but there is a tradeoff. Some all-position tires may not have the lateral stability and wear resistance that steer tires do, although many are based on steer tire carcass construction. Steering is a high-stress position that requires a great deal of braking, often while overcoming a lateral force from the direction change. You can expect shorter life for the all-position tires on a per-32nd basis. However, with the deeper tread you may get equal life before removal. Check with your tire dealer.
Another alternative is to take your current steers to an authorized retread shop and have them retreaded with an all-position tread belt.
There is a myth that you’re not allowed to run retreaded steer tires on commercial vehicles. That pertains only to passenger buses. According to Federal Motor Carrier Safety Regulations, retreads are allowed on trucks. All military and government trucks run them. What’s more, with today’s inspection and manufacturing techniques, they are as safe as new tires. If you look at the “road gators” along the highway, you’ll see the vast majority have steel wire showing at the ends. That means a carcass has let go, probably from under inflation that resulted in excessive flexing and heat buildup. That is what destroys the rubber bond and breaks the steel cords. There is no steel in a tread cap. Properly maintained retreads are perfectly safe and legal on big trucks.
The retreads will be more economical in the long run, but if you decide on new all-position tires, keep your current steers for use when the snow and ice have melted.
Q: I have a 2017 Mack Pinnacle pulling a 2014 Heil tanker. My steering has gotten really bad lately. When I try turning, the truck seems to have jerky motions. It almost bounces around corners. It’s even worse when the road is wet or icy. I had the alignment checked on both my tractor and trailer, separately and as a unit. I had the shop check all the steering connections, the tie-rods, the power steering, the pump and drive belt. Everything checked out. Have you ever seen this before, and if so what can I do about it?
A: Your shop was thorough, covering the common ailments. I think the problem may be that your tractor and trailer are “married.” Many drivers who operate tractor-trailer combinations don’t separate the units often enough in order to re-grease the fifth wheel. Some don’t remove the old grease completely. It may carry grit and road debris that could damage the fifth wheel assembly over time. There are several possibilities.
Less likely is that he changed the type of grease you use on the fifth wheel. Not all greases are compatible with one another, and some will react and reduce or destroy their friction-reducing properties of the grease left on the upper plate. Another possibility is that moisture, road salts and/or road debris has gotten in and damaged the fifth wheel top plate or the trailer’s upper coupler plate. All those will result in the jerky turning performance you described.
Another item to check is the trailer king pin. It can get damaged during coupling operations.
Burrs, bends and dents can disrupt smooth turning operation. Gauges are available at dealers and from manufacturers that will show any king pin damage.
If the fifth wheel is damaged beyond repair by resurfacing, consider replacing it with a new fifth wheel with a high-density polyethylene insert. HDPE is quite durable and very slippery. The surface does not need greasing, which is a great time saver.
A less expensive alternative to a new fifth wheel is to resurface the damaged portions of your fifth wheel and buy a HDPE disc to place between the fifth wheel and upper coupler plate. This will change the net effective kingpin length, so a new kingpin may be required for the trailer. Many manufacturers and accessory companies carry fifth wheel discs and longer kingpins.
Perhaps the ultimate in HDPE fifth wheels is The Revolver. It’s a complete upper coupler and kingpin assembly with protection against intrusion by debris and road salts. The Revolver’s literature claims many advantages, but the price is quite high compared to the other devices I mentioned.
I believe that, after all the checking your shop did, the problem is with your fifth-wheel/upper coupler plate assembly. You have to decide whether to repair, augment or replace. That depends on the soundness of the components, your budget and how long you plan to keep your equipment. Get advice from dealers, but remember that each one is trying to sell his or her component. LL
Read more Maintenance Q&A here.