Servicing wheel bearings and brakes
A wheel bearing and brakes service is one of the more straightforward, but most essential, maintenance requirements for any caravan. The wheel bearings should be checked and regreased every 12 months or 10,000km, whichever occurs first.
This is also a good time to check the brakes – in particular the brake shoes, electric brake magnets and the inner drum surface.
You’ll need to be prepared to replace some key components, even if your bearings and brakes are in good condition. You’ll need a new split-pin and a new bearing seal for each axle, and be prepared to replace the inner and outer bearings if they are pitted or worn. Caravans often use Holden or Ford bearings and are easy to find at any good spare parts shop.
GET TO WORK
You’ll also need a clean environment to work in, with somewhere to place the cleaned or new parts ready for refitting. You’ll need a tub – an old, clean ice cream container will do – and a brush and some kerosene to clean the old grease off the parts you plan to reuse.
Park the van on a level surface and, if possible, keep it hitched to the vehicle as an additional safety measure. Chock one of the van wheels that are not being removed and loosen the wheel nuts half a turn on the wheel you’re taking off – they will be much harder to loosen once the wheel is off the ground and free-wheeling.
Jack up the van and also support the chassis with an axle stand. Undo the wheel nuts and remove the wheel, then prise off the bearing dust cover with a pair of multigrips or, if it is stubborn, by gently tapping a hammer on a screwdriver. Most wheel bearing covers are thin metal so, while they can be difficult to remove, don’t go too hard with the hammer as you’ll do a fair bit of damage. Tapping it gently, close to the drum, should eventually get it moving.
With the dust cover off, you’ll see a large castellated nut secured with a split pin. Remove the split pin by straightening the pin out at the single ends, then pull out the pin at the pin head with a pair of pliers. Then you can proceed to loosen the castellated spindle nut and remove it.
Remove the outer washer and then the outer bearing from the axle spindle; they should come out easily, but grab hold of the brake drum and give it a shake, if needed, to loosen them.
With a clean cloth placed underneath the brake drum, carefully remove the brake drum from the spindle. The inner bearing and bearing seal will hopefully remain attached to the drum, but if they do drop out, your strategically-placed cloth should catch them.
Now is the time to inspect the brakes. Look for worn, cracked brake shoes (as pictured) and for a worn brake magnet (as pictured). A good magnet will still have the water marker indents on its outer surface. Also check for any breaks in wire insulation to the magnet.
Now, back to the bearings. With the brake drum placed on a clean work surface, carefully pry out the inner bearing and seal.
Degrease the bearings, inner seal and outer washer. Dry the parts, using compressed air if you have access to it to remove the remaining moisture from within the bearing. If you don’t, then use a clean cloth to wipe off as much of the kero as you can, rolling the bearing rollers to try to get out all the moisture. Leave the bearings for a while to allow the remaining kero to seep out, and come back to them later for a final wipe over.
Then inspect the bearings for damage. What you’re looking for is pitting or scoring of the rollers, and any resistance to movement in the rollers. Any blue haze on the bearing surfaces is not a good sign, as it suggests excessive heat. If in any doubt, swap it out. New, good quality wheel bearings are cheap insurance.
Regrease bearings (using a high-temperature bearing grease) by pushing the grease in through the rollers by hand or by using a bearing packing tool, easily available at good spare parts shops.
Clean the brake drum’s inner surface thoroughly with a solvent, such as wax and grease remover, and examine it for any scoring (as pictured). The drum can be machined but you’re better off replacing it with a new one – they are fairly cheap.
Clean the brake drum centre of all grease and apply clean, high-temperature bearing grease. Refit the inner bearing and new bearing seal to the brake drum, tapping in the seal with a wood block drift if necessary so the seal sits flush. Fit the outer bearing and washer, and mount the drum on the spindle (wipe the spindle with solvent before fitting the drum and make sure there are no score marks on the spindle, which would mean the spindle needs replacing).
Tighten the castellated spindle nut, easing off and retightening a few times to let the grease work its way into the bearings properly. Then tighten so the drum can still spin smoothly, and then ease off so that you can fit a new split pin through. At this point, you may wish to refit the wheel as it will be easier to spin than just the brake drum and will give you a better feel of when the bearing is too tight.
Once you’re happy with the tension on the bearings (you should back off the nut just enough for the wheel to spin freely, but with no lateral movement to the wheel), fit the split pin. Lock it in place by ensuring the head of the pin is seated and bend one half of the ‘split’ section towards you, along the face of the spindle. Cut this section of pin where it protrudes past the spindle with pliers, and cut the other section where it protrudes from the spindle. Gently tap the dust cap back on.
Fit the wheel and tighten the wheel nuts enough so the wheel is secure on the hub, then spin the wheel to ensure it is still moving freely, and then grab the wheel top and bottom and see if there is any lateral movement. If the wheel is binding, you may have over-tightened the bearings and need to loosen off to the next pin hole. If it is not tight enough, the wheel will have some lateral play in it and you’ll have to tighten the castellated nut.
Now it’s time to check the brake shoe adjustment. There’s a small opening in the lower side of the drum backing plate to allow access to the serrated shoe adjuster. Use a screwdriver (or, better still, a dedicated brake shoe adjuster tool available at auto spare parts shops) to adjust the shoes until the wheel cannot spin. Now back it off until the wheel spins freely. If your vehicle is still hooked up, you can get a helper to apply the brakes. You should not be able to turn the wheel by hand.
Now you can return the wheel to the ground, remove the jack/axle stand and tension the wheel nuts to around 125Nm of torque.
Then check the handbrake adjustment. Caravan handbrakes are notoriously poor, so don’t be tempted to adjust the nut at the threaded adjuster rod at the A-frame too much. Adjusting the handbrake so the lever sits about halfway along the handbrake indents is enough. As the suspension compresses, the cable tightens so your brakes will intermittently go on as you drive along. Remember to check the wheel nut tension again after 100km.
The full feature appeared in Caravan World #543 November 2015. Subscribe today for the latest caravan reviews and news every month!