Changing Trailer Wheel Bearings & Disc Brake Pads
I had to do this job today, I was a little bored so I decided to document it for anyone who might like to try this themselves but doesn't have any experience with this kind of thing.
I want to say from the outset that I'm no expert, feel free to correct me if you know better or add anything you feel is helpful.
SAFETY
There are several issues you need to take care with when performing these tasks. I am going to assume that if you're reading this then you're probably not used to mechanical work all that much (Maybe you are & just want some basic starting pointers I dunno)
Jacking the trailer.
Make sure the ground is level, firm & can support the jack & the weight of the trailer. A perfect place is concrete but if that's not an option ensure the ground is firm firm firm. If there is any doubt a large block of timber with a surface area at least twice what the jack base is under the jack is advised. As a general rule the base of any jack will not be large enough to prevent the weight of the boat & trailer from pushing the jack into the ground in non firm conditions or worse, kicking it sideways & falling off altogether.
ALWAYS chock the wheels on the opposite side your working on. I'm fortunate enough to have proper wheel chocks for my work, but timbers or even sand bags will be better than nothing. Serious injuries can happen to if jacks fall or fail. Don't risk it.
TIP – once the wheel is off, a good additional safety back up is to place the wheel under the trailer so if it does fall of the jack the axle & trailer frame won't hit the ground. (Somewhere it can support the trailer if anything goes amiss without the springs hitting the ground) Single axle trailers are the most dangerous, dual axles are a little less hazardous because the second wheel will hold things up a bit if the jack fails.
Working with hammers (on bearings especially)
Brake discs and some of the components that make up the axle / tyre group are usually cast steel or iron. That means they will break if struck with a hammer hard enough, they won't bend like ordinary steel they will break. Take care if you need to "Encourage" something to move, dislodge or come apart with a hammer. Glasses are a must. You can't cast for fish if your blind![/size]
Bearings & the tapered bearing races in particular which you will need to strike with a hammer to remove, are extremely brittle. Think of & treat them like tough glass, they shatter, splinter & in most cases explode spectacularly when the are hit hard enough. Finesse is the key when using a hammer on bearings. Gloves are also a very good idea but I can't stress enough the importance of a good pair of clear safety glasses. Oh, bystanders should be well away from the strike zone also, I've witnesses a serious accident when someone was hit with small piece of an exploding industrial sized (2.8 metre diameter) bearing. Not pretty. This is the main reason I strongly urge you to spend a few quid & buy a good quality soft faced hammer if you intend to do this kind of thing even semi-regularly.
So, you own a boat & want to do some maintenance yourself. Maybe to save a buck or just because you want to add a feather to your cap. There are several items you will need to complete these tasks,
The Prefered Toolkit.
You might as well go back to the ironing if you don't have the essentials.
NOTE: There is no substitute to quality
Don't be fooled, inferior quality tools WILL cause you grief.
TOOLS
NB – Spanner sizes may vary depending on your trailer.
10" Shifter
12" Shifter
5/8" open end spanner (A combo 5/8" spanner is handy too!)
Pliers
Circlip Pliers
Small Flat Screwdriver
5/8" Socket & ratchet with extention bar
Scraper
Wire Brush
Small Ball Pene Hammer
Soft Face Hammer (Not essential but if you're going to do this kinda thing they are an excellent item, although they are expensive)
10mm Pin Punch
Grease Gun (Don't have one, sell your boat now before the whole thing falls to bits on you!)[/size]
SAFETY GLASSES!!!!! Bearings are VERY brittle, if you hit one with a hammer & shatter it the pieces will move at around the speed of light, generally right into the nearest soft tissue)
Duct or Electrical Tape
Wheel brace
SPARES (Bearing replacement)
Bearings – Spherical Tapered Roller Bearings (Two part bearing, a tapered cone part & the roller part)
Seals – Depending on your trailer make you may have anywhere from 1 to 3 seals. Some seals, like the grease cap seals can be several components to make one sealing assembly.
Seal ring (Some trailers have a steel ring at the back (Inside) that retains the seal & gives it strength) Some seals are fully integrated into one unit.
Return Springs (Goes on the arms, you will notice I didn't replace my broken one as I'm still waiting for it to arrive at the shop)
Split pins
Circlip (May not be required if yours are in good condition)
Grease Cap Spring (As per the circlip)
Grease Nipple
NOTE: Some of the above items may be available in a kit. I prefer to buy individual items as its usually cheaper if you don't need all items in a kit.
Trailers that are in really bad condition & haven't been maintained well may require additional items like bolts / studs etc. You'll just have to see as you go.
Bearing Number (Depending on your trailer what size) the numbers identifying it should be on the inside edge of the thickest part of the internal section of the bearing, any decent bearing supplier will see you right, or an auto spares shop)
SPARES (Brake Pad replacement)
Brake Pads
Return Spring
NOTE: Some brake pads come with retaining springs. Yours may or may not be required depending on the calliper configuration. Mine were not so I didn't re-fit or replace them as the pad & calliper design retains the pads without the aid of a ridiculous pair of tiny springs.
Ok, so you've got everything you need to do the job. There's one more thing you should do before you get stuck into tearing things off your pride and joys ride.
Organise yourself an area to lay all the bits out as they come off. Do it BEFORE you start that way you will not risk loosing anything.
I like to be a bit anal when it comes to this stuff, lay out the new parts, tools & things you need. Get a pile of rags or paper towel & a small container with some degreaser & lay some large cardboard under the work area. Grease is a bugger to get all over the place & you will get it everywhere, its best to minimise the grease to floor contact so you don't have to spend the next 3 weekends cleaning the garage/driveway floor.
Right, NOW we're ready to get stuck in. Take you right hand, firmly grasp your manly testies & grunt the following workshop oath....
"When I'm done and all is good, I'll tell me mates I knew I could.
But if this contraption I should break, No one will learn my dumb mistake"
Now, back off the brakes on the adjuster at the front of the trailer.
First undo the lock nuts, holding the pully with one shifter or pliers undo them so you can turn the threaded bolt.
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Unscrew the bolt so that there is plenty of slack in the cable to the brakes.
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Remove Wheel & Wheel Hub (The big round thing) Grab your wheel brace & "Loosen" the wheel nuts. Just crack them a little so the wheel doesn't spin when it off the ground & your reefing like mad to undo tight nuts.
Position the jack so that its square & the base is flat on the ground.
I like to place the jack on the axle, there is less chance it will slip here than if you place it under the spring bracket.
Your jack hopefully has ridges on either side of the top to prevent slipping. Ensure the axle is inside these on both sides.
Jack the trailer so the tyre is off the ground about an inch.
Remove the wheel & place it under the trailer for a safety stop.
Back the brake arm adjuster bolt off by first loosening the lock nut, then back the bolt off till its nice and loose (Should be able to move it freely back & forth.
Ok, now if you're planning to replace brake pads you need to remove the brake calliper. And as an added bonus to those who want to be lazy & just do the bearings, you can remove the brake callipers also. That's right, doesn't matter what you do the callipers need to come off, so you might as well at least check the pads.
Here's a breakdown of the components.
A Brake Disc
B Outside Brake Pad
C Inside Brake Pad
D Inside Brake Pad Push
E Top Caliper Bolt
F Bottom Caliper Bolt
G Adjuster Arm & Adjuster Bolt (Pushes on Push Plate)
This is about the hardest bit of the job. It involves a little dexterity & some groaning to get under & undo the calliper top & bottom bolts.
NOTE: Now would be a very good time to double check your jack & make sure everything is sturdy. You may need to reef on the bolts & if things are not stable under there you could end up with your head becoming a new winged keel attachment to your hull. Be safe for goodness sakes.
Depending on your trailer design, you may find that the bolts (One or both) will unscrew but you can't pull them all the way out because the springs, frame, guard etc is in the way. As long as you can screw the bolts all the way out all is good. If you can't unscrew them all the way then you might be in a spot of bother old chum! I have known standard box trailers to be so badly designed that the axle has to come out (Springs & all) to get the brakes of. Lets pray you don't have a trailer designed by Gandalf the Magician.
The bottom bolt of my calliper set does not pull out because of the spring, but it can be undone all the way & that means everything is sweet for 'Ol Boof.
Top bolt & sleeve removed.
A word on the sleeves.
The calliper bolt sleeves or spacers are designed to allow the calliper to move in & out along the axis of the bolts. The bolt actually tightens on the sleeve, not the calliper. So when you've got the callipers out, take the time to free up the sleeves if they are frozen inside the calliper & ensure you apply some lubricant when reinstalling them. Remember, they are meant to be a free moving part inside the calliper & if they are not then chances are your brakes will not work effectively or even not at all. Sideways movement allows for pad wear & self alignment when brakes are applied.
With both bolts removed the calliper assembly can now be removed by rolling it forward. Grasp the top of the calliper & pull it forward. If the pads are in reasonable condition they may hold the calliper to the disc a bit. Firm grip & a good force should get it off. If its frozen to the disc or axle mount plate a gentle knock with your hammer should budge it.
As you can see my return spring is buggered so I didn't have to remove it first. If yours is intact it may help calliper removal to get the spring off first.
Next, remove the grease cap. Mine has a plastic cap held on with tape. Once thats removed you can tap it gently out.
Mine is a knock in type that needs to be gently tapped from side to side, it will work its way out as you alternately tap at 180 degree. Don't knock it too far sidways or you may damage the hub &/or cap.
Cleaning the grease away will reveal the hub nut. It is a castellated lock nut held on with a split pin (Same as your prop nut) Remove the split pin & then undo the nut.
After the nut there should be a flat washer.
The outside bearing is now accessible. If its free it might fall out, remove it if you can but don't worry if it stays in the hub.
Now you can remove the entire hub assembly from the shaft. In cases where things have been maintained well the hub will pull straight off with very little effort. If it won't budge this is where you learn the lessons of hard knocks & realise all that gobbledegook about "Maintenance" might actually have some credit to it.
Get your soft face hammer if you've got one and very carefully give the disc a tap from behind to knock the hub free. If you don't have a soft face hammer you've got two choices, go back to the missus & admit you ain't as well equipped as you bragged to her about.......or, wrap a rag around the head of your ball pene hammer & do the same careful tap from behind. A small block of wood is even better.
Try to strike your blows flat against the disc (Not like in the picture) As close to the centre as you can get. It also pays to have a hand on the front of the hub to stop it flying off. If it hits the ground you'll probably damage the wheel stud threads.
Once the hub is removed the rear or inside seal should either be left on the axle shaft or it may still be inside the hub. Mine was on the axle shaft.
Remove it.
Ok, so far so good. The calliper is off, the hub is off & you're ready to remove the old wheel bearings & brake pads.
Let's start with the bearings.
At the back of the hub the seal backing ring or retaining ring needs to be pried out with a small flat screwdriver. If your new parts don't include a new ring then with a little care, provided its in good condition to start with, the ring can be reused.
Now you can see the inside bearing. It should pull out easily.
This pic shows the new bearing & tapered sleeve with the old sleeve still in the hub. This part is tricky for the uninitiated & the reality of it is, that if you intend to maintain your equipment well then it should be replaced, its poor engineering practice to replace the bearing and not the sleeve.
However........... If a good thorough inspection including running your fingers around the inside of the tapered sleeve reveals no nicks, burrs or indentations (Ripple count as indentations & should be considered worn) Then you could leave the sleeve in. But its really not that big a deal to replace it if you have the right tools.
IE, a nice clean edged (That is square corners not rounded ones) pin punch will knock that little feller out in no time.
On larger industrial bearings we would sometimes run a weld around the inside of the sleeve. The weld causes the sleeve to shrink & it comes out easily. (You need to be setup & ready to go as any stuffing around sees the heat transfer to the wrong areas & everything locks up iuntil it cools down naturally again)
We're not gonna play with welders here, this size bearing will pop out with a little tap or two.
See Part 2 to continue......
