Beginners guide to servicing your drum brakes

[stinkwheel]

There is always a steady trickle of threads from people having trouble with their drum brakes. Usually the rear one sticking on.

I've just been sorting out the ones on my H100 so I took lots of pictures. The idea is that a total novice ought to be able to follow what's happening. The rear drum brake on an H100 is almost identical to that on a CG125 and indeed, those on most learner legal bikes.

A brief word on safety
Oils, greases and lubricants can cause dermatitis. Use barrier cream or gloves.
Brake dust shouldn't contain asbestos any more unless it is an older bike. It is still unpleasant to inhale though so avoid this.
If using a drift, beware of metal splinters and sparks that could damage an eye.
It's very easy to blacken a fingernail with the springs holding the brakes together, take care.
If you aren't confident you've done the job correctly, get someone to check. On the road is NOT the time to find out you made a mistake!

What tools will I need?
I kept the ones I used to one side. Obviously the tools required will vary from bike to bike:
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image038.jpg
10,12,13,14,17 & 19mm combination spanners; Small adjustable spanner; drift; hammer; pliers; 17mm deep socket.
I also used copper grease, molybdenum disulphide grease; WD40; wire wool and kitchen towel.

First remove the wheel.
Take a good look at everything first. Maybe take a couple of pictures so you know how it's supposed to look. Check the movement of the brake pedal and look at what it does. Oil the pivot of the lever using genreral purpose oil if it's stiff.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image000.jpg

Place the bike on the centrestand, if you don't have one, either use a paddock stand or find some way of propping the rear wheel off the ground in a stable fashion.

First undo the nut on the end of the brake control rod (the bit that joins the pedal to the brake itself). This is sometimes a cable rather than a rod. Take it all the way off and put it somewhere safe, it's a special type that would have to be replaced from a dealers if you loose it.
Notice use of the closed end of the spanner. Only use the open end if the closed end won't fit.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image003.jpg

Now remove the nut that holds the torque arm to the brake drum. The torque arm is the piece of metal tube or bar that stops the brake drum from rotating with the wheel. Some bikes have a peg or slider that engages with a notch or peg on the swingarm instead of a torque arm.

Most torque arm bolts have a split pin through the end to stop them coming undone (I forgot one once and nearly lost a toe when I put the brakes on!). So, straighten and remove the split pin using a pair of pliers then undo the nut.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image004.jpg

You should now be able to pull the torque arm free of the brake drum.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image005.jpg

Now undo the big rear wheel nut. This will be done up pretty tightly. You may need to use a second spanner on the other end of the wheel spindle to stop the whole thing rotating.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image006.jpg

You should now be able to pull the wheel spindle out. Before doing so, make sure the bike is going to be stable on its stand with the wheel removed.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image007.jpg

Take careful note of where any wheel spacers, washers and adjusters that were threaded on the wheel spindle are located and put them to one side. An H100 has one spacer between the brake drum and the swingarm, this is the time to remove it.

By rolling the wheel forwards slightly, you ought to be able to unhook the chain from the sprocket.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image008.jpg

Rotating the brake drum itself will allow you to slide the brake control rod free.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image009.jpg

With a little wiggling, you now ought to be able to pull the wheel back and free from the bike.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image010.jpg
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

Removing the brake shoes.
The whole brake calliper should lift out of the wheel. You sometimes need to wiggle the brake arm a bit if the pads are gripping the inside.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image011.jpg

Now is also a good time to inspect the brake lining inside the wheel hub. It should be shiny, free from corrosion and without any deep scores. Light corrosion can be removed by rubbing with emery paper. More serious corrosion or scoring is a job for an engineer.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image015.jpg

It's not tricky to remove the old brake shoes, simply lift one of the shoes (being careful not to trap a finger in there):
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image012.jpg

Fold it over on top of the other one:
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image013.jpg

And lift them off:
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image014.jpg

Before throwing them away, check your new shoes come with springs. Some do, some don't so you might have to save those.

Now is also a good time to remove the trunnion from the brake arm (see picture) and put is somewhere safe.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image016.jpg

Servicing the brake cam shaft.
This is often the bit that is sticking on these type of brakes. Either that or the pads are so badly worn they are getting stuck out.

First undo the brake arm pinch bolt.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image017.jpg

Lift the brake arm off its shaft. You may need to gently prise the ends apart with an old screwdriver in order to remove it.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image018.jpg

Now find a piece of tube that fits over the inside part of that shaft and butts against the alloy casting. In my case, a 17mm deep socket fits the bill nicely.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image019.jpg
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image020.jpg

The tube is to allow the shaft to be driven out of the alloy casting from outside to in. In an ideal world, it would pull out by hand, but if it did that, you wouldn't need to be stripping it.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image021.jpg

Don't use excessive force to drive the shaft out or you'll crack the alloy. If it's well stuck, apply some penetrating oil and leave it to sit for a while. I'm using a drift here, an old bolt or a socket extension bar would work as well. Take care not to damage the end of the shaft by battering away at it or the brake arm won't fit back on.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image022.jpg
A couple of sharp taps ought to have it out, otherwise back to the penetrating oil. Failing that, heating the area up with a blowlamp works wonders.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image023.jpg

Now give the whole lot a clean up. WD40 and kitchen roll does a good job. Aerosol brake cleaner also works nicely. Clean any corrosion off the shaft and the hole it sits in using wire wool.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image024.jpg
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

Re-assembling the brake.

So, it's all clean and ready to go back together but it'll need some lubrication first. Smear the shaft with molybdenum disulphide grease (black grease), this is designed for high-load, low movement applications like this. I usually put a tiny smear of grease on the pin and cam that the brake shoes attach to.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image025.jpg

Then it's simply a case of pushing the cam back into its hole. It ought to go in with no real resistance and turn freely once it's in there. Wipe away any excess grease from the inside of the brake, you don't want it contaminating the pads.

Now you're ready for the new brake shoes which have been left in their box up to now to stop them getting greasy/oily.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image026.jpg

You'll see the brake shoes have a flat on one side and a circle on the other for going over the pin and cam respectively. You'll probably need to hook the springs that join them together yourself.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image027.jpg

As with taking them off, stack the joined brake shoes on top of one another, position one of them.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image028.jpg
Then fold the other one into position.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image029.jpg

Now to reattach the brake arm. On small hondas, the splines (the ridges on the shaft the arm engages with) have a 'plain' area. This corresponds to the "gap" on the brake arm and prevents you putting it back on in the wrong position. If it's 180 degrees out, don't worry, you can turn the whole thing round while the brake is out of the wheel.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image030.jpg

Not all bikes have the splines "keyed" in position. In fact, it's common for people to move the brake arm round a notch to get more life out of the brake pads. Not recommended because they can jam on once they are worn past a certain point. If they aren't keyed, have a guess about the position, it's easy to move it round a notch later if you're wrong.

So, apply copper grease to the splines to prevent the brake arm seizing in place and press the brake arm back in place.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image031.jpg

Tighten the pinch bolt.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image032.jpg

Put the brake back into the wheel and you're ready to re-fit it.

Putting the wheel back into the bike
Essentially the reverse of dismantling it. Roll the wheel into position.

Put the trunnion back in place. Slide the control rod through the trunnion and screw the nut on the end (don't put it on all the way yet, just enough to stop it coming off).

Roll the wheel forwards, hook the chain back on and roll it back again.

At this point I usually give the wheel spindle a light coating of copper grease and slide it most of the way through the frame and hub (don't forget any washers or adjusters). This supports the wheel in position well enough to put the spacer back in. This sometimes needs a gentle tap in with a hammer because it's a tight fit.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image033.jpg

You can then push the spindle all the way through and do the nut up finger tight.

Re-attach the torque arm, again do the nut up finger-tight.

Now adjust the chain tension using the adjusters nuts on either side. Assuming the wheel was in square before, adjust both sides by the same number of turns. Many bikes also have "ruler" markings on the swingarm to assist with keeping the wheel straight.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image034.jpg

Now tighten the torque arm, don't forget that split pin!

Tighten the wheel nut. If you have a torque wrench, you might want to use it on this. Otherwise do it up pretty much as tight as you can manage with both hands on a spanner. Some bikes also have a split pin through the wheel spindle.

Now tighten the nut on the brake control rod while turning the back wheel by hand. Tighten it until you can feel the brakes binding then back it off just enough for the wheel to turn freely. You'll need to adjust this a few times over the next few miles as the new shoes "bed in".

Finally, check the brake light is coming on but not staying on.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image036.jpg

If it isn't working properly, you may need to adjust the distance the brake light switch is from the lever.
https://i48.photobucket.com/albums/f216/stinkwheel/drumbrake/Image037.jpg
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Howling TerrorOutOfOffice]

[stirlinggaz]

Hi,
why didnt you post this last weekend? lol
thats when i done the brake on my little gamma.(first time i've worked on drum brakes)
looks like i've done it ok though.(apart from the obvious)
i just used ordinary lm grease on the shaft, presuming that'll be ok?.
& didnt think to put some copper grease on the splines.
but i havnt actually finished it, as i've lost the nut that goes on the control rod. lol
why wont any old nut do?
or a wing nut?
pretty sure i've lost the spring that goes on the rod as well,lol
(there probably on the shed floor somewhere-when i say shed, i mean bedroom, since thats where i done it)
as i havnt tightened up the nut & bolt that go on the arm, i can pull it back off & put a dab of copper grease on.
the gamma doesnt seem to have any particular way the arm goes onto the splines, just got to make sure its seated properly.
i wasnt sure how to set it up, so thanks for the tip about tightening it up until it starts to drag, then backing off a bit.
would have just guessed at it, went for a wee run & tried it out.
then adjusted it.
rarely use my back brake now anyway.
not since i accidently stamped on the back brake last year,whilst trying to do a plug chop. ended up fishtailing all over the place until i finally lost it & slid 500yards on my arse.right outside my house.
coming to a stop on the other side of the road, right in front of a packed number 52 bus.
i know it was a 52, cos i saw it coming towards me, as i was sliding along the wet road.
i'll never forget the look on the bus drivers face.
& of couse it was rush hour, loads of people milling around & all the neighbours were watching out the window cos they heard the scream of my little 2 stroke tearing along the road at 10000rpm in 4th, followed by a second of silence then the unmistakable sound of fairings scraping along the road.
cheers,
GAZ

[stinkwheel]

[Odie]

You made that look so easy.............
Try telling the twin leading shoe Jawa front wheel i had to sort the other week on a mate of mine VW based trike, "BASTARD" wasnt the word for it.
(these things are sent to try us now and then)
____________________
You are so ugly when you were born the doctor said "I?m gonna drop it, if it falls is a rat, if it flies is a bat."

[stinkwheel]

[rottie007]

great guide there mate..

just 1 little thing I would change (from personal experience) I normally take the brake rod off first and put allthe bits back onto it , trunion spring etc

spent a weekend looking for that trunion once after pulling the shoe assembly out without realising it was a loose fit in the arm !

[MaybeGuy]

way to complicate things. i did it on an RXS at the side of the road using a pair of pliars and an adjustable (see ''sabotage'' thread for more details)
____________________
Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[alone]

Any clue what would cause pulsing in the rear drum brake?
____________________
Bikes; '06 Triumph Sprint ST 1050 (for sale) - '95 BMW R1100GS

[stinkwheel]

[map]

FWIW I understand one last gasp measure to get little more life out of a set of pads is to swap them round. The way drum brakes work one will always wear faster than the other. This trip sort of evens out the wear.

Of course replacing the pads is always the better option.


____________________
...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
Gibbs, what did Duckie look like when he was younger?

[stinkwheel]

[stirlinggaz]

Hi,
i must have been having one of my sensible days when i replaced the shoes on the gamma...(i dont have many of those nowadays)
i thought i had lost the weird shaped nut & the spring that goes on the control rod.
went out today to remove clutch lever (to fit on another bike) & found that the spring & nut were on the rod!
its not like me, i usually just take things apart in a random order, chucking stuff into large plastic ice cream tubs or if im in the shed-the corner of the floor.
THEN i look in the manual to see how i should have done it.

on a more serious note,
the wheels on this bike have been been powdercoated since it was last on the road.
i bought it off someone who had bought it from someone else in its current state-75% complete.
i have went over everything anyway, not knowing who done the work in the first place.
im presuming that whoever done it, removed tyres, rear brake etc but left the bearings in, then went & got them powdercoated.
i have replaced the bearings & theres new tyres on.
but the inside of the rear wheel, where the pads come into contact with the wheel, the coating looks like its coming away.
im presuming this is a result of the previous owner moving the bike about with the rear brake seized on?
as the part thats worn is exactly the size & shape of a brake shoe.
the brake is now working,with new pads.(well the wheel stops turning if i move the arm, i havnt actually road tested it yet, thats for next weekend when im hoping to put it all back together with a view to getting it mot'd)
but im now worried.
should the inside bit of the wheel (where the pads touch) even have been powdercoated?
should i do anything to this? like sand it down?
as surely the coating will come off, contaminating the pads?
or does that just sound stupid, lol
cheers,
GAZ

[Odie]

[stinkwheel]

[stirlinggaz]

hi,
ypu, looks like the powdercoated everything.
even the bearings had a layer of coating. (which is why i changed them)
i was thinking about sanding it all off, but how to get it even all the way round?
might try nitromors & then sand it lightly.
thing is, brake actually works, lol
though i'm thinking they will deterioate as the pads will slip off the shiney part & only grip on the rough bit& the coating will wear off, contaminating the pads.
wheels look nice though.
cheers,
GAZ.

[spetom]

Really good description, thanks stink.

[Pete.]

Great write-up Stinky.

Can I just add, that if you are just servicing the brake rather than replacing the shoes, when you re-assemble the brake you might want to flip the shoes over so that the cam is pressing on a new part of the wear-plate, because in time you can wear a groove in the plate and eventually lock the rear brake on.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[spetom]

Stink what gloves are using? Nitrile, vinyl, latex?

What are standard mechanic disposable gloves?

[stinkwheel]

[pepperami]

Mr Stinky,......... that is a First Class write up
____________________
I am the sum total of my own existence, what went before makes me who I am now!

[spetom]

[stinkwheel]