Repeat topic alert!I (help with seized BB)

[Mossy]

Hello again

I've found a victim / friend willing to purchase my 95 Mongoose IBOC zero G in the hope of making space for my 2 builds. As part of the deal I agreed to strip the bike and give it a once over. No problem I thought!

The problem:

The bottom bracket has not been removed for 10 years so it's seized. I want to check that I'm unscrewing in the right direction for the following reason?

Please note that the BB fixed flange with shell is on the left (non-drive side) whilst a plastic removal ring is on the right (drive side). Never seen this before, but then again I've never paid any attention to this fact previously. All the other bikes / frames I have (GT, Kona, Orange) have the fixed flange on the drive side.

The BB looks to be a typical standard square taper Shimano cartridge type.

The plastic removable ring on the right drive side has been removed with ease by unscrewing clockwise. I assume that my left non-drive side should therefore be unscrewed anti-clockwise, but no joy this evening after spending 4 hours trying to shift it. :evil:

I've now left the damn thing soaking in penetrating oil etc. and will be finding some steel tube to give a little more leverage to the wrench. Also the BB tool has been bolt fixed into position to avoid slippage.

Please put my mind at rest. :roll:

Thanks, Mossy

 

[sic_nick]

Park tools website has it all

http://www.parktool.com/repair/readhowto.asp?id=94

 

[S8-Tom]

You might want to put the removed cup back in a couple of threads just to stabilise the other side when you remove it.

 

[Mossy]

Thanks for the link sic_nick and S8-Tom.

So it doesn't matter which side the BB flange / shell sits as the unscrewing procedure remains the same.

Brute force it is then! :x

 

[Rampage]

Plusgas from your local motor factors / engineering shop should work well.

Or you could try soaking it in Coke over night (genuine coke, nto cheap supermarket stuff.

Also, why does the bottom bracket screw in that way. Surely if both threads were reversed you would be
(sort of) tightening the BB with every pedal stroke, not loosening it?

 

[fatfixie]

if you have the genuine shimano hex shaped bb tool (or similar), then put the tool in a vice and use the frame as a lever

Has always worked for me

Andy

 

[Neil]

if you have the genuine shimano hex shaped bb tool (or similar), then put the tool in a vice and use the frame as a lever

Has always worked for me

Andy

Sounds a good idea - never had to do that for BBs, but removed plenty of cassettes like that.

 

[Mossy]

It's out! I feel like a dog with two d*cks

I invested in a 3ft length of 1.5" square tube, £1.85 from the local steel stock holders. Must admit the chap behind the counter looked a bit pissed with me stood there with a £20 note. Placed the tube over the wrench and wallop came off first time. Putting the removable ring back in position also helped.

Thanks for the great advice as usual.

Mossy.

 

[Andy R]

Also, why does the bottom bracket screw in that way. Surely if both threads were reversed you would be
(sort of) tightening the BB with every pedal stroke, not loosening it?

It's because of precession. You can demonstrate this by holding a pencil or something in your fist - turn the top of the pencil in a clockwise direction and notice which way the pencil actually rotates...

It's how you turn a fencepost to a slightly different orientation - want to move it clockwise? Then rotate it anticlockwise.
That's how my Dad demonstrated it to me anyway, when I was about 10

 

[petertreglown]

stuck bb's

glad the wrench extension worked, this is fairly common practice in the bikeshop workshop, our bar 'bertha' is a four foot long tube! often the blowtorch will be employed...watch out paintwork and cable guides. wurth make a freeing spray called rost off ice which is good for first attempts on stuck bolts bb's etc, very effective.