You pull off for fuel on Route 5 between Versailles and Camdenton, the trailer loaded with water, gear and half a pantry, having just come down a long Ozarks grade with your foot on the brake more than off it. Everything feels fine, so you top off and get back on the road. That is the moment a failing wheel bearing hands you a warning, and the one most campers drive right past.
The failures that end lake trips around here rarely start with the rubber, and there is already good advice out there on what to know about your tires. They start at the wheel end: the bearings, the hub they ride in, and the brakes packed in behind the drum. Lake of the Ozarks State Park alone drew 1,473,192 visitors in 2023, and this corner of Missouri sees a lot of loaded trailer traffic working the same hills every weekend.
This post works from the wheel end inward: bearings, then the hub, then the brakes and the actuator that applies them.
What a Loaded Camper Asks of the Wheel End
A trailer bearing does not care that you only tow a few weekends a year. It cares about load and heat, and a loaded travel trailer brings both at once. The same logic that makes regular oil changes a calendar item on your tow vehicle applies at the trailer’s wheel end.
On flat highway, a wheel bearing has an easy life. On the long pulls and drops that come with towing here (the Highway 54 run into Camdenton, the ridges above Versailles, the US 65 descents toward Hollister and Branson), two things change together: the trailer’s weight pushes forward against the tow vehicle, and the trailer brakes do sustained work rather than short stops. That work puts heat into the drum, the drum is bolted to the same hub the bearings sit in, and heat travels. It is why a wheel end can look perfect in your driveway in April and be in trouble at the bottom of a grade in July. Grease that is fine at rest thins as it heats, a dragging brake shoe never gets a chance to cool, and etrailer’s technical staff put the usual causes of a hot hub as inadequate lubrication, a castle nut adjusted too tight, loading past the hub’s rating, the wrong grease, or brake drag.
The Fuel-Stop Hub Check That Takes Two Minutes
You do not need a temperature gauge, and there is no number to memorize. The check that catches most wheel-end trouble is a simple comparison.
- Touch each hub, briefly. Back of the hand, quick contact on the cap or hub face. Is one wheel end noticeably different from the other three?
- Look at the wheel face and inside the rim. Slung grease or a wet-looking streak means a seal has given up and the bearing is losing its lubricant.
- Use your nose. A hot metallic smell at one wheel, or any smoke, is not something to drive away from.
- Listen on the road. A growl or hum that changes with road speed rather than engine speed is a classic bearing complaint.
- Check for play. With the wheel safely off the ground, rock it top and bottom. Movement, or a gritty feel as it turns, is bad news.
If one hub is the odd one out, the trip stops there. A bearing that has gone from warm to hot has already lost its grease film, and the distance from hot to a seized bearing or a wheel off the spindle can be short.
Grease Hubs, Oil Baths, and When a Trailer Bearing Repack Is Due
Trailer bearings run on a calendar as much as an odometer.
Dexter, one of the country’s largest trailer axle makers, states in its repack instructions that bearings should be lubricated every 12 months or 12,000 miles. Whichever comes first is what matters. A camper that sits all winter and gets towed twice a year has barely moved the mileage number, but it has blown through the 12-month half more than once. Grease does not stay put forever in a hub that sits, and moisture works its way past a resting seal.
A proper trailer bearing repack involves more than squirting new grease in. The hub comes off, old grease is cleaned out, bearings and races are inspected for pitting, flaking or heat discoloration, the seal is replaced, fresh grease is worked in by hand, and the spindle nut is set so the hub turns with a little drag rather than spinning free. That last step matters: too loose and the bearing hammers itself, too tight and it cooks.
Wheel ends differ:
- Conventional grease-packed hubs are the most common on travel trailers: hand-packed, sealed, and on the interval above.
- Zerk-fitting hubs take pumped grease through the spindle. Convenient, but over-pumping pushes grease past the inner seal and onto the brake linings, which is how an over-greased hub takes out the brake behind it.
- Oil-bath hubs are common on boat trailers and heavier axles, the bearings running in an oil reservoir behind a clear cap. What changes is how the wheel end is checked, not whether it needs attention.
Grease type matters too. Timken’s automotive wheel bearing grease is an NLGI No. 2 lithium complex product carrying NLGI GC-LB certification, with an operating range of -40 F to +300 F once in the application. That is what a wheel-end grease is built to survive; general-purpose grease is not.
How a Surge Brake Actuator Should Behave
Plenty of trailers around the lake use surge brakes, where the trailer supplies its own braking force hydraulically instead of taking a signal from the truck. Knowing what normal feels like is most of the diagnosis.
UFP, a major actuator manufacturer, describes it plainly. At constant speed the master cylinder piston sits in its free, extended position and the trailer brakes are off. When the tow vehicle slows, the trailer pushes forward, the actuator slides over the coupler, and force goes into the piston in direct proportion to how fast the tow vehicle is slowing and how much the trailer weighs. A built-in shock absorber keeps the application smooth rather than grabby. Two things follow: a slight clunk pulling away from a stop or right after braking is normal for surge brakes, by UFP’s own account, and the coupler has to slide freely for any of it to work.
Worth checking before you tow:
- Fluid level in the master cylinder, which UFP says to check every time before towing, plus any weeping around the actuator. DOT 3 and DOT 4 must never be mixed.
- The hitch ball. UFP specifies 1.970 to 2.000 inches for its A-60 and A-75 actuators and 2.282 to 2.312 inches for the A-84, measured in every direction. A worn or egg-shaped ball is unsafe and can cause improper braking.
A clunk that has grown loud, one side grabbing, a soft braking feel, or brakes that stay on after release are all reasons to book brake service near Lake of the Ozarks before the next weekend, rather than guessing at trailer brake repair on the shoulder of Route 5.
The Breakaway Cable Is Not a Parking Brake
UFP is clear that every actuator must have a way to apply the trailer brakes if the trailer comes completely detached, and it calls the breakaway cable the third line of defense. The order matters: the coupler has to come off the ball, then the safety chains have to fail, and only then does the cable get pulled. It is not designed to lock the brakes either, only to apply enough force to keep the trailer from free-wheeling, and it must be reset by hand afterward.
- Secure the cable to the bumper or frame of the tow vehicle, close to center, and never to the safety chains.
- It must hang clear of the tongue and be long enough to allow sharp turns without pulling.
- It is never a parking brake. UFP puts that in capital letters, and so do we.
UFP calls inadvertently setting the trailer brakes by pulling the breakaway cable the single most common mistake owners make. Picture a cable left too short, snagging on a tight turn out of a campground, then the brakes dragging for the next twenty miles of hills. That is a cooked set of drums, and quite possibly the hot hub we opened with.
Signs a Bearing or Brake Magnet Is Going, and When to Book Trailer Brake Repair
Bearings are on their way out when you find heat at one wheel end the others do not share, a growl that tracks road speed, roughness through the tongue, grease slung onto the wheel, play at the wheel with it off the ground, or blue and brown discoloration, pitting or flaking on the rollers and races once the hub is apart.
Electric trailer brakes wear at the magnet, and Dexter is specific about it. Check the magnet face with a straightedge; replace it if wear is uneven, and replace it regardless if any part of the coil has become visible through the friction facing. Magnets go in pairs, both sides of an axle, because the good one has been doing extra work, and Dexter recommends refacing the drum’s armature surface at the same time.
Adjustment intervals come from the makers and they differ. Dexter says adjust electric brakes after the first 200 miles once shoes and drums have seated, then every 3,000 miles or as performance requires. UFP says inspect its surge actuators annually or every 2,000 miles, whichever comes first, and adjust the trailer brakes after the first 300 miles and at least every 2,000 miles after that.
Missouri Law, Your Axle Rating, and the Line Other States Draw
The RV Industry Association’s 50-state summary of trailer brake requirements lists Missouri, citing V.A.M.S. 307.170, as having no requirements. RSMo 307.170 requires all motor vehicles except motorcycles to have two sets of adequate brakes in good working order, and requires commercial vehicles and trailers to have adequate and proper brakes, but it does not draw a pounds-based line for trailer brakes the way most states do. The same RVIA table shows Montana and Nebraska requiring trailer brakes above 3,000 pounds.
Do not read that as trailer brakes being optional here. Since the state does not set the number for you, your trailer’s own axle rating and its manufacturer’s manual are the standard to work to, and the moment you tow out of state somebody else’s threshold applies.
Before the Next Trip Down to the Lake
Check the calendar rather than the odometer against your axle maker’s lubrication interval, touch every hub cold in your driveway, check the actuator’s fluid level, inspect the hitch ball and coupler, and have the wheel ends pulled if nobody remembers the last time anyone did.
Clark Warehouse Tire & Auto has been giving honest recommendations in Mid-Missouri since 1949, and our store locations in Camdenton, Versailles, Hollister, Jefferson City, California, Clinton and Sedalia sit on the roads your camper travels. Need a trailer bearing repack in Camdenton MO, trailer brake repair before a Lake of the Ozarks weekend, or camper trailer service in Mid-Missouri? We will look at what you have and tell you what it needs.
Trailer Bearing and Brake FAQ for Lake-Area Towing
How often should I repack my trailer bearings?
Dexter’s guidance is every 12 months or 12,000 miles, whichever comes first. For most lake-area campers the 12-month half arrives long before the mileage does.
Can I keep towing if one hub is running warm?
Warm is normal; noticeably hotter than the other three is not. If one wheel end stands out, or you find slung grease, smoke or a hot smell, stop and have it looked at.
Do I actually need trailer brakes in Missouri?
RVIA’s state summary lists Missouri as setting no trailer brake requirement, and RSMo 307.170 sets no weight threshold for trailers. Your axle rating and manufacturer’s manual do, and other states you tow through set their own lines. If your trailer came with brakes, keep them working.
What will a repack or a trailer brake job come to?
That depends on your axle rating, your brake type and what we find once the hub is off, and a figure in a blog post would be guessing. Tell us what you tow and we will give you a current quote.
Get a Quote Before the Next Ozarks Grade
The wheel end is the easiest part of your camper to look after and the worst one to ignore on a downgrade. If it has been more than a season since anyone pulled your hubs, let’s get eyes on it first.
Request a quote from Clark Warehouse Tire & Auto, or stop by the store nearest you. Tell us your trailer’s axle rating and brake type, and we will take it from there.
