Cracked drum liner

[sgd37]

Hey everyone!

I have been trying to get the back wheel on but if it isn't one thing it was another. I discovered a minor crack in the drum liner. I don't have experience in these things so could someone tell me if it's something to worry about? Is there anything I can do to prevent it from getting larger? JB Weld maybe?

Cheers

[hairygit]

NO!  It's a case of find another hub that aint cracked, or get that one re lined. Don't put it back together and ride it like that, you've announced it on a public forum, and should the worst happen your insurers will want nothing to do with it, and you can end up in court for using a dangerously defective vehicle, and if anybody gets hurt......

[SteveD CB500K0]

It's also an mot failure as the rear brake pulses.


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[matthewmosse]

Paul Jackson - Huddersfield. Or if you have a lathe it can be done at home, I've done my own before but needed the hub bare to get it on my lathe. I've seen the next stage after the crack appearing, bits of liner can come out which potentially could lock your rear wheel when riding, not fun, had it happen when some brake shoes dropped their linings - avoid very cheap ebay brake shoes!

[Colonial-Clive (yindi)]

Yep mine just failed mot for that the bloke in Huddersfield does it £50 I think he said was the charge.
I opted for a different rear hub. That and the cost of wheel building not cheap. So you could look for a whole rear wheel from a dealer.

[sgd37]

Hmm that's unfortunate news. By the way Hairy I think you've given me nightmares

I have access to a lathe so will try that if I have enough liner, also don't mind rebuilding the wheel myself. If that doesn't work out however where could I find a hub or wheel (which dealers were you referring to Clive)? Does anyone know if I could I put a Disc brake on from another bike?

Thanks again for your help

[Johnwebley]

try DK spares,

 

[sgd37]

Thanks they do have one but it's looks in worse shape than mine.

matthew could you give a brief explanation or point me to one of what you did with your liner

Cheers

[matthewmosse]

Machine out the old liner. Make up new liner and put it in freezer, put hub in oven or heat with blowtorch in the lathe then press the 2 together, as the heat equalises they'll be very firmly fixed together. I went for a fit too tight to get them together but close, I think about 1/4 mm larger liner than the hub - I was using old style calipers not verniers as my verniers were too small. The new liner was found in a breakers yard on a dead hulk of a car back when scrappies still let you wander around measuring things and removing bits yourself. The resultant fit was tight enough to turn the remaining portion of liner off flush once fitted and worked in service. Both mating serfaces were left a bit rough to reduce slippage. Its a bit of a one shot deal getting the new liner in place first time, if it doesn't sit right first shot the tempreature difference means they will not ever move again, it would be back to machining out the new liner and re do from start if it goes wrong, but boy is it satisfying if it goes right. That said the cost of farming it out to a pro means its not a great way to spend your time, plus I belive  paul Jackson can fit the whole wheel on his lathe too, saves a rebuild. I managed to re use my spokes and rim, wasn't that easy though. I have since bought a large enough lathe to fit the whole wheel, tyre still mounted on but am not willing to compete with the guy in humberside, he's too cheap to compete with, I earn more cutting grass than I would doing brake drum re linings at his rate, maybe I'm slow on the lathe....

[sgd37]

Crickey that sounds like a lot of work for an inexperienced hand might have to give the man a call.

Is it difficult to save the spokes?

Never ends with this bike

[matthewmosse]

It was one of the first things I did on my lathe, and I am self taught. Took an age and was right at my lathes limmits though I was able to not disturb the bearings. I did this before I discovered this forum and before the late Rod Gibson published the details of Mr Jackson in classic motorcycle mechanics. I think his services are a bargin.
saving the spokes is a 50/ 50 thing - a good set will with care and pre soaking in duck oil or wd40 a possibility but if badly rusted its both near inpossible and potentially dangerous. Ditto paintec spokes - I had one wheel where the paint was hiding some bad pitting, only found out when they snapped, I thought I had a flat and pulled over only to find i was down to about 10 spokes holding a rather wobbly wheel together, I'd only bought the wheel a few months before. Beware of painted spokes, they might be hiding some nasty pitting, mine were looking very good but were down to 50% metal in a few places and the rest was filler and sanded smooth. I think the huddersfield guy will mean the wheel can be left in 1 bit as he's skimmed my dads bmw rear wheels brake drum and that has a cast alloy wheel and same size tyres as cb550. 

[AshimotoK0]

Given that the alloy is cast onto the metal liner on those drums you have to question pressing or shrinking an insert into the the drum to repair it . I wonder how you would stand with an insurance company or inspection after an RTA ? Personally I would  would try to get an original from the likes of DK or GovnorsBridge . Or am I just being a 'wuss'  and it's known acceptable practice?  Is the cast onto surface on the original steel part profiled or knurled in any way to give better grip between the alloy and the steel ?

[Bryanj]

It may be Ash but it has long been acceptable engineering practice to shrink fit a liner as long as the correct interference for the materials in question are use. In the 500 case I know that Rod Paulheats the alloy to expand it and cools the liner to shrink it which gives an increased "nip"

[sgd37]

Given that wheels in good condition are pretty rare (only one rusted thing on DK) I will have to go with relining.

Clive, did you go with Paul Jackson in the end? If so how did you get the wheel to him

Cheers

[matthewmosse]

Given they use a very similar process to fit metal tyres to train wheels I think heat expansion and a rough finish are going to keep that drum well and truly stuck in place, especially vs the actual drum and brake lining which are desighned to slip and dissipate kinetic energy as heat, something that I've found this repair has managed ok on my bike and that was carrying a sidecar that got well filled with shopping quite often and has stood up to prolonged and heavy braking - I live in a very hilly part of the world, must have done 80k miles with that repair in place, all weathers. I have a repaired drum by someone else that has 3 grub screws evenly spaced each half in the liner, half in the hub, drilled and tapped down the join, I think a keyway might be more elegant and easier to stop the drill wandering into the soft alloy instead of the liner - not that I think its needed. I've been doing a fair bit of keyway cutting recently and the last few have been very satisfying with the home made key steels and keyways needing a light tap with a 4oz hammer to get them seated in the shaft and a similar fit into the female part. Very satisfying to get that result with simple and cheap hand tools.