bottom bracket help

[wurly]

Quick question. is the chainwheel side usually a left hand thread?
I thought i'd ask first before increasing force.
Bike is late 90's GT

 

[SRS]

Quick question. is the chainwheel side usually a left hand thread?
I thought i'd ask first before increasing force.
Bike is late 90's GT

I have known it to be either from experience and type of BB.

However a comon question on pedals as pelow.

Sitting on Bike.
Left foot = left handthreaded pedal. Right foot = right hand threaded pedal.

 

[wurly]

Its still stuck. I borrowed a better quality splined tool as my cheap one was in danger of breaking.
The left side is definately RH, so its likely the chainset side is probably RH too?
I'm going to try again tomorrow.Its full suspension so i need to get a jack underneath as support.

edit:
I have just checked the almighty Sheldon Brown site and it would suggest that most modern production bikes are British ISO thread sizes and it says the left side is RHthread and the right side(chainset side) is LHthread.
Which is opposite to

'Sitting on Bike.
Left foot = left handthreaded pedal. Right foot = right hand threaded pedal. '

http://sheldonbrown.com/gloss_bo-z.html#bottom

I would have thought the BB would be trying to undoing itself??

Confused.......me

 

[Martin@e-bikeshop]

Hello,

Drive side is reverse thread, and non drive side is normal thread.
Normal thread being lefty loosy, rightey tightey..

Must have changed, off the top of my head; 200-300 BB's in my time. 99.9% reverse thread on drive side.

If you get stuck bolt the splined BB tool to the BB using a crank bolt and get a big breaker bar on it.
Also a bit of heat can help with a heat gun, get it quite hot and give it a sharp tug on the breaker bar.

It should 'snap' loose and unscrew by hand from there.

Regards
Martin

 

[oigoi]

I concur with martin I've always found the chainwheel (rh) side of the bottom brakcet to be a left hand thread therefore turn it clockwise to undo it.

Pedals are the opposite to the bb rh pedal = rh thread and vice vers

 

[wurly]

Ah thanks
very much....tools packed up and i'm in the warm now. It's nice to know i'm forcing it loose instead of tighter. (You both posted before my editing).

 

[oigoi]

I would have thought the BB would be trying to undoing itself??

Confused.......me

The reason the bb is not trying to undo itself can be understood if you imagine what is happening in the bearing.
Imagine you are looking at the chainwheel end of the bb axle and the bearing on that side as it is rotating clockwise in normal motion.
The balls of the bearings will also be rolling around but if you look at the motion of an individual ball within the bearing it will actually be rotating anticlockwise on itself
This anticlockwise rotation of the bearing balls will try and turn the outer race of the bearing in an anticlockwise direction hence a lh thread is used so it tightens itself

 

[grldtnr]

You don't say which type of BB is fitted ,if its sealed bearing unit ,no need to save it! cut through the nylon cup flush with the frame using a hacksaw, then address the opposite end with a hammer, out pops the cartridge ,then you can carefully cut away remainder of the cup, taking care not to damage threads.

replace with new sealed BB, they are tolerant of minor thread damage to frame.

Brutal ,but it works!

 

[jackhandy]

The reason the bb is not trying to undo itself can be understood if you imagine what is happening in the bearing.
Imagine you are looking at the chainwheel end of the bb axle and the bearing on that side as it is rotating clockwise in normal motion.
The balls of the bearings will also be rolling around but if you look at the motion of an individual ball within the bearing it will actually be rotating anticlockwise on itself
This anticlockwise rotation of the bearing balls will try and turn the outer race of the bearing in an anticlockwise direction hence a lh thread is used so it tightens itself

Thanks for the explaination - Like Wurly, it always seemed foreside-back to me (not that Wurly's foreside-back - that's me!), but now all is clear.
Must be something in Westcountry air that convolutes logic

 

[wurly]

There was something in the Westcountry air this morning. Plenty of expletives!
What a total b******d.
This is the worst job on a bicycle i have ever encountered

No way was this thing coming out without extreme force, hence me asking the question about the direction of thread.
After using a piece of tubing on my big adjustable wrench, i resorted to heat and a length of box section. Eventually it moved, but it need several turns before i could turn it by the wrench alone.

http://i219.photobucket.com/albums/cc224/gearhead188/upload/20130302_105308.jpg

http://i219.photobucket.com/albums/cc224/gearhead188/upload/20130302_110232.jpg

Yuk! what a mess. I'm holding it with a rag because it's still very hot.

http://i219.photobucket.com/albums/cc224/gearhead188/upload/20130302_110656.jpg

At least i can get a new one to stop the annoying clicking and fit a pedelec sensor for the speedict.
Thanks for your help everyone

 

[amigafan2003]

Install the new one with some copper grease on the threads.

 

[oigoi]

Yay the battle is won! I had to do one like this once on a bike that had been ridden on the beach quite a lot and the salt water had got in and corroded the thread quite solid. Amazing the difference it can make getting some heat on it just got to be careful with an aluminium frame it doesnt glow before it melts like steel does it just melts!