Cycling UK Forum

So I need to change this bottom bracket of mine because it is no good and the pedal arms are loose. And then after switch to a new one.
Only issue is it is stuck there. Sits hard as a mountain.

I have tried squirt fire on it, rust loosener and bigger leverage to really crank on it. But it does not want to come off.
Any idea how to get it off? Perhaps drill it out with a big metal drill bit or something?

Is in link here:

https://www.veed.io/view/3ad37a41-4d22- ... anel=share

if you use two hammers to 'massage' the BB shell (ie. use the head of one hammer as a bolster against the BB shell, whilst using the other one diametrically opposite) you should find your rusty BB gives up without too much of a struggle, once the 'massage' has been done on all sides. You will probably have to use a longer spanner though.

Ensuring care is taken to avoid damage to BB threads, I'd look at partially cutting through the stuck BB cups, perhaps trying to apply some leverage to the stuck cups by some means, to loosen and ensure they can be taken out

Just a thought - one end of the BB has a LH thread, the other a RH thread. I always look at a new one to check which is which. Easy to get it wrong and be tightening it!

AndyB1 wrote: ↑4 Oct 2024, 6:37pm Just a thought - one end of the BB has a LH thread, the other a RH thread. I always look at a new one to check which is which. Easy to get it wrong and be tightening it!

Aha so they are basically quite similar to pedals? One left threaded and the other one right threaded or something like that?

Brucey wrote: ↑4 Oct 2024, 6:12pm if you use two hammers to 'massage' the BB shell (ie. use the head of one hammer as a bolster against the BB shell, whilst using the other one diametrically opposite) you should find your rusty BB gives up without too much of a struggle, once the 'massage' has been done on all sides. You will probably have to use a longer spanner though.

Aa interesting. Kind of hammer in the middle but not at the exact spot where the threaded outer screws are? Is that how you mean? Or do you mean the frame around the bottom bracket kind of?

-Cyclist- wrote: ↑4 Oct 2024, 7:22pm

AndyB1 wrote: ↑4 Oct 2024, 6:37pm Just a thought - one end of the BB has a LH thread, the other a RH thread. I always look at a new one to check which is which. Easy to get it wrong and be tightening it!

Aha so they are basically quite similar to pedals? One left threaded and the other one right threaded or something like that?

Yes, but opposite. The left pedal is left hand thread, but the right BB cup, on British made bike, is the left handed one.
This is down to precession.

in the massage treatment, the ends of the BB shell are subjected to radial hammer blows. This is usually enough to loosen the bonds of corrosion in the screw threads, just beneath. I'm sorry, but I don't really understand your last question.

I suggest that you apply penetrating oil to both bottom bracket cups and leave it overnight to work. Remove the non-drive cup first - it is usually much easier.

To avoid the bottom bracket tool slipping and damaging the splines, clamp the tool to the bottom bracket either with a bolt through the tool into the axle or a big G-clamp with one end on the tool and the other on the opposing end of the axle [that's what I find normally works. You will probably need a much bigger spanner - a 1.2m long scaffold tube over the spanner should work.

Mike Sales wrote: ↑4 Oct 2024, 7:35pm

-Cyclist- wrote: ↑4 Oct 2024, 7:22pm

AndyB1 wrote: ↑4 Oct 2024, 6:37pm Just a thought - one end of the BB has a LH thread, the other a RH thread. I always look at a new one to check which is which. Easy to get it wrong and be tightening it!

Aha so they are basically quite similar to pedals? One left threaded and the other one right threaded or something like that?

Yes, but opposite. The left pedal is left hand thread, but the right BB cup, on British made bike, is the left handed one.
This is down to precession.

So the non drive side should it be removed by screwing clockwise or is it the other way around?
Any way to know which to screw which way?

thanks

mongoose wrote: ↑4 Oct 2024, 8:35pm I suggest that you apply penetrating oil to both bottom bracket cups and leave it overnight to work. Remove the non-drive cup first - it is usually much easier.

To avoid the bottom bracket tool slipping and damaging the splines, clamp the tool to the bottom bracket either with a bolt through the tool into the axle or a big G-clamp with one end on the tool and the other on the opposing end of the axle [that's what I find normally works. You will probably need a much bigger spanner - a 1.2m long scaffold tube over the spanner should work.

Aa sounds nice. Just have to find which way to screw. Clockwise or non clockwise on the non drive side?

thanks

Use one of these to lock the BB tool onto the unit and provide a firmer grip for your shifter.

-Cyclist- wrote: ↑4 Oct 2024, 10:37pm………..

Aa sounds nice. Just have to find which way to screw. Clockwise or non clockwise on the non drive side?

thanks

Non drive side is a normal screw thread; unscrew counter clockwise.

Driveside is “left hand” thread; unscrew clockwise.

Be careful with long levers, it’s possible to break stuff.

Google “freeze spray for stuck bolts” ……I just recently found this stuff, haven’t needed to use it yet

Eyebrox wrote: ↑4 Oct 2024, 10:40pm Use one of these to lock the BB tool onto the unit and provide a firmer grip for your shifter.

The tightening torque of the BB caps is normally 70N/m.
Using good grease on the threads preserve this value.
Otherwise, if there is rust in the threads it becomes 80-90N/m.

I had this problem too, on a Bianchi Vento 605 steel frame (1992) with old-style 80s and 90s Campagnolo BB cups, and I solved it with three things:

• BBT-4 by ParkTool: modified with three M5 holes in the handle, three M5 screws to anchor the handle to a two-meter long steel tube.
  Choose a diameter that allows it to fit into the tool handle without too much yoke, just a little interference, I mean
• Torque = Force * arm_length
  tools like the BBT-4 are designed for 70N/m, that means for 80-90N/m, a greater unlocking torque is needed, and the only way to get it is with a longer arm than the lever, so I used a lever with a 2 meter arm
• using the common bolt used to anchor the crank, I built carbonate discs, drilled in the center
  • (a) 1 disc, 4mm thick, dug (with dremel) to let the 3 small arms of the tool pass through, and with a 16mm hole, first to be inserted on the BBT-4 tool
  • (b) 1 rubber pad, circular in shape, with a 16mm hole, the second to be mounted on the BB
  • (c) 4 discs, 3mm thick, with a 16mm hole, to be inserted on the square pin
  • (d) 1 disc, 4mm thick, with an 8mm hole, in which to insert the screw that tightens the crank
  all these discs have the purpose of holding the release tool still, allowing you to safely use a 2-meter lever

BB-cup --- BBT-4(2m lever) --- (a) --- (b) --- (c) --- (d) --- bolt

Brucey wrote: ↑4 Oct 2024, 8:02pm in the massage treatment, the ends of the BB shell are subjected to radial hammer blows. This is usually enough to loosen the bonds of corrosion in the screw threads, just beneath. I'm sorry, but I don't really understand your last question.

Using a strong thermal shock, the extreme procedure for the last hope

The gentle radial hammer blowing is good. When even that treatment fails... I don't know, in the list of crazy things I've done, there's a slightly more drastic version.

I used a gas flame, temperature about 600C, blue flame, I heated each cap for a quick blast, less than a second, repeated twice, the piece reached 200 degrees in an instant (filmed on a IR camera), the metal is terribly heat conductive, then I poured a bucket of liquid water containing ice, at about 10C.

room temperature, hellish heat, freezing hell.

Unfortunately the situation is not favorable: aluminum expands more than steel, the caps are made of aluminum, while the BB box is made of steel (on a steel frame), just the opposite of what would be needed in this case, thinking of using temperature to loosen the grip.

So, during the thermal shock the cap expands more than the steel around it, however during the cooling phase there is the opposite movement, and this helps to detach the oxide on the thread, or worse... the grease that has cemented there are cases in which ... you use the wrong type of grease, you put it to protect the thread from oxidation, and the grease does its job, but then over time that type of grease becomes a sort of glue

It's a rather extreme procedure, it seriously ruins the paint, but... it has a good chance of unblocking the caps

Never seen brazed brass, but I think you have to be very careful though: if there are parts in brazed brass, you have to avoid that the flame reaches the parts, and you have to reduce the exposure time to the flame