My rear drum brake needed a clean, but last week started make a whine at the slightest touch of the pedal. So the other day I took the wheel off and gave everything a clean using just brake cleaner, a brass brush, and a shop towel.
It all looked fine to me, so a bit of copper grease on the pivot bits and put it all back together. With it on the centre stand I put it in first to test the brake, and the wheel stopped without any noise.
Was going to go for a ride this morning, and checked the brakes as usual by engaging the brakes and pushing and pulling on the bike before setting off. But it moved with the back brake engaged. It only seemed to hold the bike when the pedal was fully depressed, as though it was an all or nothing switch.
Adjusting it made no difference other than to the free play in the pedal. I rode to the end of the street and back but it was like having no brake, so I came straight back.
I took a photo of the shoe for no apparent reason at the time, but it seemed fine to me. Will take everything apart again later, but any ideas for what I should be looking for?
I did. The first time I cleaned the brake I did not fully tighten the bolt fully and felt it moving slightly when braking, so will not forget that agin.
Externally everything looks fine, the drum does not move and the pedal freely moves the camshaft lever.
If you’ve removed the shoes then it may be a misplaced or dislodged retaining/return spring in the drum . Best to remove drum and start again … if you’re unsure take a photo on removal to compare/ future reference and can aid diagnosis
I have taken it apart and then just put it back together with little difference. The photo below of the brake is how it came out, the shoe properly positioned on the pivot and cam, with the springs outward and correctly attached. Other than giving everything a wipe just to make sure it was clean and dry I did not know what else to do.
I had the pedal adjusted so the wear indicator was in the middle, but tightening it only reduced the free play in the pedal, not how it operated.
So I can only guess the problem is either the brake surface or the inside of the drum not causing enough friction. I did rough the brake a little and it is still thick enough to think it okay. In the drum photo there is a reddishness around the inside, could this be the problem? The brake did work before cleaning, though, and the drum was only sprayed with cleaner and wiped down.
Looking at the drum it seems to have a sheen of copper to it but it could be the light .but give it a good clean to make sure If you roughed the surface up they could require bedding in
The reddishness is definitely there, so how should I clean the drum? The manual said to avoid causing any scoring to it beyond wear or it would become irreparably damaged, hence only giving it a rub to clear out the dirt.
That is basically what I did though, the reddishness in the photo is not loose grease but baked into the surface, so will need something rougher if it is to be removed. The only grease I applied was on the pivot and cam, and the light in the photo makes it look like there is more on the cam than actually applied.
The shoe is definitely the correct way around, with the springs facing outwards. That is how it was originally and in the Haynes manual. I am not sure how you would fit it on the otherwise anyway, as it would not fold to place on the pivot and the springs too tight to attach with it already in position.
sounds to me as if you’ve reassembled it with the drum rotated a bit more clockwise so the brake arm boss is a bit more to the rear, that would lead the lever to need more pressure
I thought the torque arm would keep the drum in the same position? Although even if not, the adjusting nut on the brake rod is relative to the drum so surely it would not make any difference anyway.
But I have taken it all apart yet again and cleaned the drum with wire wool, having searched and found enough people say to use that, but it made no difference to the reddish patches. Running my finger around the surface it does not feel uneven so I am not sure if it is a problem.
My waddle test felt a bit better yet not enough that I am still worried it will not work safely. Not able to properly try a test ride now so will do one tomorrow. Maybe I just need to fill it back up with dirt.
Meanwhile in all the times I have had the wheel on and off I am now also a bit worried about how quickly the middle os the rear tyre is wearing down. It was new in March, 6.5k miles since. I believe wear in the middle is due to overinflation, but I only have them a couple PSI over the up-to-199lbs minimum to account for the top box. Although I am slow enough on corners that I only really use the middle, so maybe it is just not being balanced out as it should.
Test ride today offered no noticeable effect over engine braking. Next I tried repeatedly jabbing at the brake with the same result, then riding with it fully engaged but that only slowed me down 1mph.
It is seems to be physically engaging just with not enough friction. It has to be the shoe or drum so I have ordered a new shoe. Worst case scenario it does not help and I have to take it to a mechanic, but will already have a spare shoe ready for when it next needs changing.
Just a shame that there is no way of testing the brake without putting everything back together first. I still have the original Yamaha shoe (current one is EBC), which was still working but replaced after an MOT advisory, so would have tested with that. Mind, it would need cleaning first, and that is what started this mess.
Test ride today offered no noticeable effect over engine braking. Next I tried repeatedly jabbing at the brake with the same result, then riding with it fully engaged but that only slowed me down 1mph. It is seems to be physically engaging just with not enough friction. It has to be the shoe or drum so I have ordered a new shoe. Worst case scenario it does not help and I have to take it to a mechanic, but will already have a spare shoe ready for when it next needs changing. Just a shame that there is no way of testing the brake without putting everything back together first. I still have the original Yamaha shoe (current one is EBC), which was still working but replaced after an MOT advisory, so would have tested with that. Mind, it would need cleaning first, and that is what started this mess.
Michael
Have you tried putting it on the centre stand; giving it a spin and pressing the pedal?
Yes, as per the first post! Testing on the stand slows and stops the wheel as more brake is applied. The first time I was only checking it did not squeak, but it left me with no reason to doubt it before trying to ride yesterday.
That is why I am certain it is engaging normally. The rod is pulling the camshaft lever correctly, before inserting the plate I can see the cam is correctly separating the shoe halves when it turns, and with no other force on the wheel the brake is stopping it.
Though I never directly sprayed the shoe’s braking surface, I now just hope that the brake cleaner (the white can one from Halfords) somehow damaged it. Otherwise the only other thing that makes sense is that the drum surface is damaged, but it was working before and brake cleaner should not do that.
It is all very frustrating as it is such a simple mechanism even I should be able to understand it.
Ic; I think the rear should come to an abrupt halt when on the stand. Given the moment of just the wheel is nothing in comparison to the whole bike. Can you adjust it so it doesn’t spin, i.e its locked, then release it so it just spins freely?
Your photo did look like the leading edge was worn somewhat - but since it worked before hand; i guess its ok.
I could have explained better, but when I was testing on the stand in first gear it was with the clutch out, that way I could slow push the pedal to see its effect. That has never just stopped the wheel dead.
The wear limit is apparently 2mm at the ends, but I never measured as there was visibly more than that. Although maybe the Haynes manual only applies to OEM shoes and the YBR compatible EBC ones could be slightly smaller?
Also whilst I never adjusted the brake to the point it would not spin, I did reach a point where there was not enough free play in the pedal for normal operation, yet manually I could still spin the wheel. So it did not seem worth going any further.
But will wait for the new shoe to arrive now and try again later in the week. Thanks anyway.
Why did you change the shoes? Normally an MOT advisory will be in relation to the wear indicator, which is just that an indicator and it does not necessarily follow the shoes are worn below their tolerance limit. In real life its all about the thickness of the friction material on the shoe which should be >1.5 mm, replace at 2 mm.
Looks and sounds to me as if the friction material on the replacement shoes are contaminated in some way, did it work properly with the old shoes in there?
Cleaning of the drum should be done with soap and water applied by a green scotch pad, dry with a clean dry cloth and follow up with a goodly spray of brake/clutch cleaner. No need to wipe the brake/clutch cleaner off as it will evaporate fairly rapidly.
Because I did not know that, so assumed when being told it would need replacing soon by a mechanic that it would need replacing soon!
No idea what the expected life span of a shoe should be, but I am a bit too heavy and reliant on the back brake and had done 8.2k miles, so it did not seem unreasonable. Although soon ended up being a further 3.2k miles later. The replacement shoe is only 6.5k miles old.
I did not bother with the old shoe back as by the time I remembered I still had it, I had had the wheel on and off so many times I just did not want to go through it again. Off is fine, but getting it on is fiddly on my own, then the chain and wheel alignment. Urgh. It would have been a waste of effort, if it worked I would only have to go through it again with the new shoe, and if not I would just assume it was an old worn shoe so would need to try with the new one. Easier just to wait for that, then.
For cleaning the drum I just sprayed with brake cleaner and wiped out the remaining mess. The cleaning effort was scrubbing the plate and metal parts of the shoes.
