Truck Wheel Ends & Hub Assemblies: PreSet, Service & Replacement
The wheel end is where a roadside wheel-off starts, so it’s worth understanding what’s actually in there: a hub, two tapered bearings, a seal, the spindle nut system, studs, and the oil or grease that keeps it all turning. Get any of that wrong on assembly and you’ll know about it down the road.
Pre-adjusted vs. the old way
The old wheel end made the tech set bearing preload and end play by hand — a real source of comebacks. Pre-adjusted hubs (the “PreSet” style that’s been around since the mid-’90s) use a machined spacer that fixes the bearing spacing at the factory. You torque the spindle nut to spec and you’re done — no guesswork, less downtime, and usually cheaper once you count the labor.
Catching one before it lets go
Pull the hubcap and look at the oil: dark, milky, watery, or full of metal flake means contamination or a failing bearing — that hub comes off. A wheel end running hotter than its neighbors, a growl that changes with speed, a leaking seal staining the brake, or play at the wheel are all on the same list.
Oil bath or grease
Some wheel ends run an oil bath with a sight-glass cap, others semi-fluid grease. Follow the spec for your hub — overfilling or mixing lubes kills seals and bearings.
GBK hubs and wheel-end parts cross-reference ConMet, Stemco, Webb, and Accuride. Browse hub assemblies and hub cover kits, and give us the axle and old number if you want it matched.
Semi-Trailer Landing Gear: Maintenance, Symptoms & Replacement
Nobody thinks about landing gear until it won’t crank with a loaded trailer on it. Those two legs hold the front of the trailer when it’s off the tractor, and the two-speed gearbox lets you wind it up fast with no load and then drop into low gear to take the weight.
The warning signs
A handle that’s getting hard to turn, slips between gears, or grinds is the gearbox telling you it’s wearing out. Add bent or buckled legs from a hard drop, grease weeping from the box, or feet worn through, and you’ve got a set on borrowed time. Catch it before it seizes with a trailer on it and you’ll save yourself a roadside mess.
Keeping a good set alive
Grease it on schedule through the zerks, always crank fully into high or low (never leave it parked between gears), and keep both legs synced so the load stays even. A quick look at the feet and mounting bolts during PM catches most trouble early.
Replacing it
When a set’s done, replace both legs — they work together, and a new leg paired with a tired one twists the cross-member. Match the speed type (almost everything on the road is two-speed), the mounting, and which side the crank’s on.
GBK landing gear cross-references the common brands — JOST (the A400 series turns up everywhere), Holland, and SAF-Holland. Browse landing gear and confirm the cross-reference on the product page, or send your current model over.
Brake Shoes & Drums: When to Replace and How to Match
Shoes and drums are the parts you’ll replace more than any other on the foundation brake, and they wear as a pair — so it pays to know when they’re done and how to get the right ones back on.
When the shoes are finished
Lining down to a quarter inch is the line in the sand — replace before you get there, not after. Glazed, oil-soaked, or cracked linings are out too, and so is a set that’s wearing unevenly side to side. Always do shoes in axle pairs; a fresh set on one side and worn on the other makes the truck pull under braking.
When the drum is done
Every drum has a maximum diameter stamped on it. Past that, or with cracks, deep heat checking, or blue hard spots, it’s scrap — and a cracked drum is never something you machine and reuse. Out-of-round drums show up as pulsing or vibration when you brake.
The FMSI number is your friend
Brake shoes carry an FMSI number — 4515, 4707, and so on — that nails down the shoe’s geometry and lining. Match the FMSI and you’ve matched the shoe across every brand, which is exactly why cross-referencing shoes is so clean. Drums match on size, bolt circle, and weight class.
GBK shoes and drums cross-reference the usual names — Gunite, Webb, Meritor, Bendix. Start in brake shoes or brake drums and check the cross-reference table on the product page, or hand us the FMSI or OE number and we’ll confirm it.
Signs Your Air Dryer Is Failing
Drain your tanks and get a cup of water out? That’s the air dryer telling you it’s done. It sits between the compressor and the wet tank and pulls moisture and oil out of the air before they reach your valves — and when it quits, the symptoms turn up all over the truck.
What a dying dryer looks like
The tell-tale sign is water where there shouldn’t be any — draining out of the tanks, or worse, frozen lines on a cold morning. You might also notice the dryer purging constantly (or never), a hiss around the purge valve, oil in the discharge line, or the compressor cycling more than it used to. None of these fix themselves.
Why you don’t let it ride
Moisture in the air system rusts valves from the inside, washes the lube out of moving parts, and in winter it can freeze a line solid — and a frozen line means no service brakes. A bad dryer also drags every downstream valve toward an early grave, so replacing it on time is cheap insurance.
Rebuild or replace
Plenty of the time you don’t need a whole new unit. Most dryers take a desiccant cartridge, and the common service items — cartridge, purge valve, heater, check valve — bolt on without replacing the housing. If the housing’s cracked or the heater circuit is dead, then it’s time for a new dryer. (More on that call in the rebuild-vs-replace writeup.)
GBK air dryers and cartridges cross-reference the big names — match your number on the Bendix or Haldex page, or browse air dryers and repair kits. While you’re at it, get in the habit of draining the tanks daily — it buys the dryer time between services.