Cycling UK Forum

I have just started trying to renovate my son in laws Dawes Kalahari - its an aluminium framed hybrid with suspension forks which has a hard life - left out in all weathers and is used as a commute to station bike. The sealed bottom bracket is shot but i am unable to remove it as it appears to be seized in the frame. Almost everything else was seized but i have managed to release them. I have tried using the proper removal tool - holding it in place with a chainset bolt and washer to prevent slippage but it refuses to budge on either side and yes i am going the correct way anticlockwise on the non drive side and clockwise on the drive side. Ive currently left it soaking with freeway release oil but feel anymore effort and the frame is likely to collapse.
Anyone have any other ideas?

you don't say what kind of BB it is or what tool you are using; I'm guessing it is a shimano splined tool.

But to give you an idea of how bad they can be, the last one I took out of a similarly neglected aluminium frame (a couple of days ago), I too bolted my shimano BB tool to the BB unit and then used a 3/4" drive 32mm socket on the end of a 5' long extension bar.

I stood the bare frame on the ground (packed with timber) and braced against the frame with my foot so that it became a ~4' long lever. I then swung on it like a chimp. Fortunately it cracked off OK. But had it not done so I would have added some length to the frame to increase the leverage and then I would have heated the BB shell.

You can usually heat the BB shell using a kettle full of boiling water; this doesn't always work but it does usually avoid damaging the paint finish.

IME in this situation penetrating oils (cold) don't help all that much; the gap between the BB unit and the frame threads is already packed tight with (expanding) oxide debris. By contrast heat helps first because of the differential CTE of Al and steel and second because the oxide debris is always hydrated; heating to about 170C helps to dry the oxide out and this loosens it's grip somewhat.

If you do get the blowtorch out go carefully; over ~200C and the temper of the aluminium alloy may well be changed for ever.

cheers

Thanks Brucey,
I only tried a 18" lever and you are correct it is the Shimano splined remover. I assume it is probably a cheap generic bottom bracket - no visible markings to identify it. Looks like the blowtorch next then. 5 foot lever - will keep an eye out for a scaffold tube.

if you start putting a long lever onto a 1/2" drive socket I would suggest that you look carefully at the quality of the kit that you are using; I've broken a lot of cheap sockets and bent a lot of cheaper breaker bars too (even in 3/4" drive, but not on bike stuff, admittedly).

BTW some folk have broken their shimano BB tools. My theory is that some of these tools were made brittle. Mine's been OK for years but others have had the same tool and it broke quickly. In any event don't feel tempted to lay into it with a hammer, and do be sure that the tool is secure and then what you drive the tool with isn't trying to cam the tool out.

cheers

I keep an old motor cycle fork stanchion for this purpose, put the socket ratchet drive handle in it

We got one out for a neighbour by putting the removal tool in a strong bench vice and then two off us turned the frame, it was really tight and let go with a crack. We thought something had broken but it was just it letting go. We'd tried heat , oil etc first but it didn't budge but might have helped.

mercalia wrote:I keep an old motor cycle fork stanchion for this purpose, put the socket ratchet drive handle in it

I'd advise great caution if adding a 'helper bar' to a ratchet drive; most ratchet drives are not rated to anything like the torque that you can exert. As a rule you will be unlucky to break one by hand but there are few that you can't break fairly easily once you have a lever added.

Oddly enough I broke a 1/2" drive ratchet when I removed the BB from the frame I mentioned earlier. Once the thing started to move it still needed about 200ft-lbs to turn it, and as soon as I thought the torque was low enough I started to use a 1/2" drive ratchet with a (fairly small) 'helper bar' on it. I got it wrong, and broke the ratchet. The ratchet cost more than the bike frame was worth.... ho hum....

I felt especially stupid to have done that because as well as various 3/4" drive ratchets I even have a 1" square drive ratchet with a 3/4" drive adaptor on it, and IIRC that ratchet is rated to over 1000ftlbs or something mad like that. I just couldn't be bothered to dig them out....

BTW if you use a bench vice and don't want to break it, think about welding up a 3/4" square drive tool that is the full width of the vice jaws to hold a socket and then use the socket to hold the tool. This can lower the reaction forces on the bench vice by about 80% vs (say) trying to hold the flats on a 32mm hexagon directly. Bench vices are either cast steel or cast iron and it isn't obvious which you have until you break it....

cheers

Brucey wrote:

mercalia wrote:I keep an old motor cycle fork stanchion for this purpose, put the socket ratchet drive handle in it

I'd advise great caution if adding a 'helper bar' to a ratchet drive; most ratchet drives are not rated to anything like the torque that you can exert. As a rule you will be unlucky to break one by hand but there are few that you can't break fairly easily once you have a lever added.

Oddly enough I broke a 1/2" drive ratchet when I removed the BB from the frame I mentioned earlier. Once the thing started to move it still needed about 200ft-lbs to turn it, and as soon as I thought the torque was low enough I started to use a 1/2" drive ratchet with a (fairly small) 'helper bar' on it. I got it wrong, and broke the ratchet. The ratchet cost more than the bike frame was worth.... ho hum....

I felt especially stupid to have done that because as well as various 3/4" drive ratchets I even have a 1" square drive ratchet with a 3/4" drive adaptor on it, and IIRC that ratchet is rated to over 1000ftlbs or something mad like that. I just couldn't be bothered to dig them out....

BTW if you use a bench vice and don't want to break it, think about welding up a 3/4" square drive tool that is the full width of the vice jaws to hold a socket and then use the socket to hold the tool. This can lower the reaction forces on the bench vice by about 80% vs (say) trying to hold the flats on a 32mm hexagon directly. Bench vices are either cast steel or cast iron and it isn't obvious which you have until you break it....

cheers

well mine is a big very sturdy one had it for years and not broken it so far - but then my extension not 5 feet and just use it to remove the gear box oil sump plug which tends to seize in a bit

Brucey wrote:
BTW if you use a bench vice and don't want to break it, think about welding up a 3/4" square drive tool that is the full width of the vice jaws to hold a socket and then use the socket to hold the tool. This can lower the reaction forces on the bench vice by about 80% vs (say) trying to hold the flats on a 32mm hexagon directly. Bench vices are either cast steel or cast iron and it isn't obvious which you have until you break it....

cheers

Learnt this the hard way - broke the 3"jaw on my bench vice when removing the freewheel from my tandem. Remover in jaws and turning wheel like a capstan- the reaction when it came free snapped the cast iron vice in 2

Back to the bottom bracket, the penetrating release oil is ineffective, put enough welly on the tommy bar with an additional 2 foot extension. Gave up at the point when I could see a distinct curve on the tommy bar. My tools are worth more than this frame.

Might try some gentle heating next - watch this space

Ok tried heating with a blowtorch then used the extension but nothing moving. Even the hammer pretreatment was ineffective. I think this ones going for scrap.
Unless anyone can offer another solution!

when you say 'hammer pretreatment' are you thinking of the usual brutal method? By which I mean radial blows onto the BB shell using a solid (flat-ended) drift? This does work but obviously risks frame damage.

BTW if you have not taken the paint off, it is arguably not hot enough.

Also, apologies if this is B obvious, but as positioned in your picture it looks like you might be trying to take off the NDS cup by turning it CW; this is of course the wrong direction.....?

cheers

Brucey wrote:when you say 'hammer pretreatment' are you thinking of the usual brutal method? By which I mean radial blows onto the BB shell using a solid (flat-ended) drift? This does work but obviously risks frame damage.

BTW if you have not taken the paint off, it is arguably not hot enough.

Also, apologies if this is B obvious, but as positioned in your picture it looks like you might be trying to take off the NDS cup by turning it CW; this is of course the wrong direction.....?

cheers

I gave the bottom bracket the hammer treatment by both radial blows on the drive side on the exposed cup and also on the axle ends both radially and at 90 degrees on the basis that it should transfer some shock loading to the cup bottom bracket interface.
I was standing on the frame to keep it stable and pulling up so anticlockwise. I wondered about had I got it hot enough - it spat back at me when i did the spit test might have another go now that I have nothing to lose.

Could you drill it out as a last resort? Grind axle ends off and bore through several times then fold remaining tube in.

Id hate to beat by something like that

I drilled a seized bottom bracket out, about nine years ago. A handheld Black and Decker drill, slowly removing bits of metal (About 4 hours over a few days). Then prised bits of the remaining metal out of the threads and to my surprise, it worked (I've still got the bike). It may have been the case that I obtained more leverage once a substantial hole existed where the bottom bracket had been, but it's too long ago to remember the precise details.

That said, Saturday just gone, I dropped another bike off at a bicycle/marine engineering workshop. While I'm careful to remove the BB at least every few months to prevent it seizing, this had been stored inside for two months. It was absolutely solid. Apparently it's been soaking in a bath of some sort, heat will be applied and the stuck BB will be removed! I'd be happy to pay £30.00, as there was no way I could shift it

if you are into 'last resort' methods then with steel BB cups you can always weld something onto them. This puts the heat exactly where it will break the bonds of corrosion most effectively, and gives you something else to hit/swing on.

cheers