I service hubs & brakes every year …. Always one of the tasks that means season is about to start.
Did a bit more this time … thought I document it.
I have an Indespension Super Roller Coaster Trailer – which uses AlKo hubs & brakes
First off you need to realise that trailer brakes in the UK are really a 50 year old technology ……. They have not moved with the times.
They are mechanical overrun …….if you don’t know, I’ll explain … the trailer hitch is connected to the tow ball on your car … it has a mechanical spring loaded piston, when the car brakes, under momentum the trailer tries to carry on going … forcing this compresses the spring, and operates a lever … it turn this pushes on a brake rod, ultimately the brake cables then pull on a lever which forces one end of the brake shoes against the brake drum … when momentum stops … i.e car pulls away the linkage releases and spring pressure pulls brakes back to rest position.
The problem is these bakes have a number of springs and levers and they corrode rapidly in salt water:
Alko brakes come as a backplate assembly, this has a fixed tub axle, the outer drum has a front taper roller bearing … you remove a split pin, undo castellated nut, thrust washer and the drum pulls off.
Discard the split pin – always fit a new one
I remove the front bearing fully clean in petrol ..inspect and they are usually fine.
The rear bearings are the problem one … there is an outer grease seal, then an inner taper roller bearing again with its own grease seal. This grease seal has to spin on the stub axle shaft, while keeping the grease in and the water out … They don’t do this perfectly and as a result grease will leak out of this seal, which messes up the inside of the brake backplate.
The problem is if grease comes out water can get in and very rapidly corrode up the rear bearing.
On last years service I noticed bearings were starting to pit ………. So decided to change them this time round.
…found a supplier on line …
wittydealer@gmail.com they sell on eBay as Wittydealer
Their prices are very good with free 1st class delivery.
£9.40 for a pair or Taper rollers & matching cups … way cheaper that local trailer centre
Using a large screwdriver levered out the old seals as replaced them the same time …
Again found an ebay dealer at only £3 a piece from Simply Bearings.
I use a parallel punch to drive out the rear bearing cups … and had a mate press new ones in place, as he has access to a 10 Ton press … you can tap them in with a drift and a hefty hammer if you are careful.
You absolutely MUST replace cup & cones at same time as they are matched pairs.
I spend a fair amount of time working grease into the rollers before they are fitted as now is the best time to get it in there.
After dropping in the rear Taper roller complete with its own grease seal, I then press in the outer grease seals.
The ones I found on line are better than standard as they have a helical spring and a double lip seal ..
They have to be pressed in so that they are flush with rear hub casting ……….. I found an easy way was to place the hub on my pillar drill a small piece of wood across seal, and bring press drill chuck down pressing on a large socket to give a nice even pressure.
Now the back plates …
I remove the brakes … which is simple enough .. press on the shoe springs pull out the rear retaining clip and the brake shoes and mechanism come out easily.
Them its wire brush time clean off the crud … then I used brake cleaner spray … this time I also treated with a salt removing solution, rinsed and after drying painted the plate in a 2-part epoxy paint. Epoxymastic 121
The RNLI paint their life boat trailers in it – highly rated. This stuff is harder than steel .. and unaffected by saltwater
So backplates painted
Reasembled they look a whole lot better than when I started:
I remove the adjuster mechanism and fully clean that – the screw is often seized and needs freeing up.
Making sure the spindle is well greased before sliding back in place.
The actuator is hooked onto brake cable, the shoe & retuen spring are in place at this time … seems like a 3 handed job … fiddly.
You simply clip top of shoes into the slots, push tyrough springs and refit the clips.
Reassembly of the hub is achieved by lighlty greasing the stub axle – particularly where seal will run, and pack grease between seal & rear bearing … I part fill the hub with grease at this point, and slide hub on gently so as not to damage rear seal.
The front bearingis pushed into place, the thrust washer is put in place and the castellated nut is spun up and a pre-load is applied of 20Lbft.
I slowly revolve the drum as I slowly take it up to required torque … then back it off and do it again, spin it round a few times and then do the same thing again , sets everything where it should be.
The the absolutely key point – skip this and bye-bye bearings. Taper roller bearings must have end float – they need an amount of play.
This is achieved by turning the nut back ¼ of a turn, then fit the slit pin.
Also took the opportunity to paint the outside of the hubs ….
On this trailer … I have bearing savers … these are tapped in with a leather mallet
I then fill the hubs from the grease nipple of the front of the savers.
These work by keeping a reservoir of grease under spring pressure – so as any is lost past grease seals it is topped up from the reservoir – avoid water getting at rear bearings.
The problem with boat trailers is that hubs get hot driving to launch site, grease becomes almost liquid … the hub then gets dumped in cold water the metal shrinks back and this movement allow grease leakage … the bearing savers prevent the water ingress by replacing lost grease with more grease.
Finally you need to adjust the brakes… for the Alko ones you insert a screwdriver into a hole in rear of plate and turn the star wheel until the brake shoes are touching the hub, then back-off as little as possible until shoes are clear.
Having adjusted all 4 brakes, you also check to see with handbrake off that there is no play at end of the actuating rod – if there is you simply tighten up the fixing not.
Job done.
