"Oval" rear wheel (drum brake) - what is it?

[ThunderGuts]

Morning all

So I'm going to take a look at my ER5's rear wheel this weekend as my rear brake "pulses" when applied (and has just started making a slight squeal just before I come to a stop). Now from what I can gather, a good clean up and lube of joints/pivots etc. can solve a lot of rear drum issues, but I've also heard of the infamous "oval wheel" syndrome.

Is this literally what it sounds like, i.e. the drum itself is no longer round? Or is it something else? What sort of roundness (!) can I (or should I) expect if I measure the inside of the drum? Within half a mm or something?

Cheers all.
____________________
TG.

[Meatybeaty]

Maybe just an adjustment on the rear brake shoes

[redeem ouzzer]

Yep, the drum lining either has a big rusty deposit in one spot, or has warped and gone oval. There might be an ovality tolerance in the manual but any at all will be felt through the pedal.
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Be a REAL MAN!

[Riejufixing]

[ThunderGuts]

Thanks all. The feel is more of a gentle pulsing (clearly linked to speed though)

If there is a rusty deposit inside the drum, can it just be gently sanded down to remove it?
____________________
TG.

[Pete.]

More likely cracked than oval. Does the wear indicator show that you need new shoes?
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a.k.a 'Geri'

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

[R1stu]

My 350 has this, never worried about it, last 3 MOTs just been an advisory for 'Slight fluctuation of the rear brake'

Drum was clean from the powder coaters so must have been uneven wear causing it.

If it gets to point it fails, I have a spare rear wheel and more than likely cheaper than repairing.
____________________
Carbon closet tart! https://www.bikepics.com/members/r6stuk/02r6/
Stolen bike. 2000 R1: https://www.bikepics.com/members/r6stuk/00r1/
Current bike 1991 Honda ST1100 Pan European, 1986 Honda cb350sg (Finished)

[ThunderGuts]

[Riejufixing]

[ThunderGuts]

By the way, not sure if relevant, but when I first got the bike (600 miles ago) it had been stood for a long time and when the rear wheel was turned over by hand it encountered a lot of resistance once every revolution - now that resistance has virtually gone and it pretty much turns freely.
____________________
TG.

[Riejufixing]

[Pete.]

[ThunderGuts]

[MCN]

If in doubt whip it out.
15-20mins will remove the wheel and open the drum.
YU still posting?
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[kgm]

Whip the wheel off and have a look, it's an easy job. Give the drum and shoes a light sand of there's rust patches, clean and lightly grease the cam then chuck it back together

[ThunderGuts]

Cheers all. It's a job for the weekend really! I've got some marine grease - presume this should be OK for this job as I don't think I've got any bog standard grease?
____________________
TG.

[Pete.]

That will be fine just don't over-do it. You don't want the grease to end up plastered over the shoes.
____________________
a.k.a 'Geri'

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

[ThunderGuts]

Grease on the shoes might stop the squeaking . . . joke
____________________
TG.

[MCN]

[ThunderGuts]

Ok I think I’ve found the issue. Looks like the lining as lifted slightly from the wheel in one spot creating a high point. It’s clear this is where the shoes are wearing the drum the most. There is a small crack in the centre of this high point approx 8mm long.

The engineer in me tells me this is bad
____________________
TG.

[redeem ouzzer]

Time for a decent 2nd hand wheel....
____________________
Be a REAL MAN!

[ThunderGuts]

Now I’ve cleaned it up I don’t think the lining has lifted at all - think that was an illusion caused by a shadow between the lining and the wheel itself. The crack seems pretty hairline....can’t feel it with a fingernail
____________________
TG.

[Pete.]

No matter which way you look at it that drum liner is warped. Could be that the ally hub has oxidised under that crack and the oxidisation has pushed the liner in.

If it was a very rare wheel I'd look at finding someone with a lathe and skim that drum, but otherwise a replacement would be sought. If the juddering was bad and I absolutely had to have the bike for use I'd maybe linish off the high spots with a flap wheel whilst I spent time looking for a replacement.
____________________
a.k.a 'Geri'

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

[ThunderGuts]

It’s more of a gentle pulsing than juddering - I don’t really notice it that much unless I focus on it. Only really apparent at very slow speeds. I agree, it’s clearly not round though. Will it “wear in” over time?
____________________
TG.

[MCN]

If it's only on the rear brake then it's not a biggy. It's a drum brake, It's on the rear so it's effects become kind of redundant as weight shifts onto the front wheel when braking.

I forget to use the rear brake unless stopped on a hill and I want to sit upright.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.