Bottom Bracket woes.

tufty

Retro Guru
I'm currently struggling with the extraction of a totally seized BB-UN71 from a Sunn frame. Bolted the extractor tool to the spindle, non-drive side, apply large spanner, nothing. Apply a metre of pipe to large spanner, ah, there she goes, it's starting to - oh. Bugger. I now have a non-drive side cup with removed splines.

In a fit of extreme optimism, try the drive side. Same approach, stopped short of achieving the same result.

Yes, I do know which way to turn them.

Lightbulb turns on above head. Bracket is dead anyway, why not separate the drive and non drive sides from one another, thus reducing stuckness.

Removed the spindle by the simple expedient of tearing out the dust seals and plastic bearing cages, pushing all the balls to one side and twatting the spindle with a big hammer until the balls drop out. Nasty. Then smash the cartridge housing, starting with a small punch through the bottom bracket drain hole, then using a 1/2" socket extension bar and a hammer to smash out the rest. Brutal, but the result is more or less what I wanted.

12 hours of penetrating oil.

Apply heat gun until bottom bracket too hot to touch, ice on drive side cup, tool in the big vice at work, use frame to get some leverage. Oooh, that's workin .... no. I now have 2 (separated) cups with stripped splines. Both of which are still apparently welded to the frame.

Do not want to take the grinder / drill approach. I like this frame too much, and although I have a steady hand, I don't want to risk buggering the threads any further. Plus, the bearing races are still in there, and they're as hard as hell. Let's go for chemical warfare. No caustic soda at work, but we do have some fairly caustic drain cleaner. It's caustic enough to remove the anodising from the cups, and start to pit them, but after 8 hours it's starting to lose its efficiency without any particularly severe damage to the cups. It's about 5% caustic. Bloody kid's stuff. It's health and safety gone mad, I tell you! I need something like 50%, the sort of mixture that boils itself as you mix it. I'll be working late tomorrow, but will send the missus out to get some caustic soda crystals

Replacement will probably be Origin8 or Velo Orange. The other options are all heavy, second-hand, or NOS "unobtanium". Anyone got any feelings one way or another on those?
 
I'm going to ask a daft question but which way are you turning?
I know you said you know which way but can you say as I've got a bb in in aa frame I'm struggling to remove too lol.
 
jgjones095":2hjm3jbg said:
I'm going to ask a daft question but which way are you turning?
I know you said you know which way but can you say as I've got a bb in in aa frame I'm struggling to remove too lol.

You always remove a bottom bracket toward to front of the frame :)

Carl
 
There's 3 main types of bottom bracket threading. British / ISO, Italian, and French. For a shimano BB, the drive side cup is marked with the threading. On an MTB, probably "BC1.37" which is British threading, 1.37", 24tpi

If you have a British / ISO or Italian BB, you turn "forwards" to unscrew, and "back" to install. Drive side is left-hand threaded.

French BB is "normal" threaded on both cups, so "forwards" on the non-drive side and "backwards" on the drive side.
 
tufty":3jdqk48s said:
I'm currently struggling with the extraction of a totally seized BB-UN71 from a Sunn frame. Bolted the extractor tool to the spindle, non-drive side, apply large spanner, nothing. Apply a metre of pipe to large spanner, ah, there she goes, it's starting to - oh. Bugger. I now have a non-drive side cup with removed splines.

In a fit of extreme optimism, try the drive side. Same approach, stopped short of achieving the same result.

Yes, I do know which way to turn them.

Lightbulb turns on above head. Bracket is dead anyway, why not separate the drive and non drive sides from one another, thus reducing stuckness.

Removed the spindle by the simple expedient of tearing out the dust seals and plastic bearing cages, pushing all the balls to one side and twatting the spindle with a big hammer until the balls drop out. Nasty. Then smash the cartridge housing, starting with a small punch through the bottom bracket drain hole, then using a 1/2" socket extension bar and a hammer to smash out the rest. Brutal, but the result is more or less what I wanted.

12 hours of penetrating oil.

Apply heat gun until bottom bracket too hot to touch, ice on drive side cup, tool in the big vice at work, use frame to get some leverage. Oooh, that's workin .... no. I now have 2 (separated) cups with stripped splines. Both of which are still apparently welded to the frame.

Do not want to take the grinder / drill approach. I like this frame too much, and although I have a steady hand, I don't want to risk buggering the threads any further. Plus, the bearing races are still in there, and they're as hard as hell. Let's go for chemical warfare. No caustic soda at work, but we do have some fairly caustic drain cleaner. It's caustic enough to remove the anodising from the cups, and start to pit them, but after 8 hours it's starting to lose its efficiency without any particularly severe damage to the cups. It's about 5% caustic. Bloody kid's stuff. It's health and safety gone mad, I tell you! I need something like 50%, the sort of mixture that boils itself as you mix it. I'll be working late tomorrow, but will send the missus out to get some caustic soda crystals

Replacement will probably be Origin8 or Velo Orange. The other options are all heavy, second-hand, or NOS "unobtanium". Anyone got any feelings one way or another on those?

Hack Saw 2 slots per Cup about 1/2" - 1" Gap, Gently prize the bit between the slots to break it away

Providing the frame is Steel and the Cups are alloy you will feel the difference when your through the alloy.

If you was in the Midland/Derby area I would quite happily do this for you if you didn't fancy it yourself (ive probably had to do this a dozen times and everytime its been 100% successful)

Carl
 
That is the other option. I don't overly like it in terms of potential thread damage, and the fact the bearing shells (and bits of the cartridge shell) are still in place makes it harder to do, no? The shells didn't want to come away from the cups, even when "encouraged" with the trusty punch / hammer combo.

Given it's a steel frame, I think I will stick to the chemical attack for the moment.

thanks for the offer, though. If you happen to be wandering through the alps, I have hacksaw blades :)
 
If you have an engineers vice ,putting the tool in that an turning the frame gives much more leverage. And if you can bolt the tool to the BB spindle that would hold it on just about through anything.

They will come out if you're manly about it ;)
 
On the drive side, that's what I did. With additional heat and cold. Enough torque to noticeably turn the vice on its axis, despite having been locked in place with a lump hammer. Result - disintegrated splines on the drive side cup.

This is the only time I've ever had so much trouble getting a bottom bracket out. Like you say, eventually they come out. It's not even a question of being manly about it - for bikes I have to turn my manliness down a bit as the bearings I usually spend any time removing are found here:

5-pylone_ligne.jpg


:)
 
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