I've a UN72 that I need to use, and both cups are (reasonably) firmly attached. I'm trying to work out how to remove one, as it'll be a press fit - would it be daft to screw it into the BB shell from the other side and then knock it our gently by the axle (with an old crank bolt fitted rather than hitting the axle direct). I'd need to make sure it was screwed in a decent way so I don't damage the threads, but without a puller I can't think of how else to do it. It's had a good dose of WD40 with no success.
Unsticking UN72 cups - advice
- Thread starter markoc
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Hitting the axle will put sideways pressure on the bearing and bearing race. They're not setup that well for that ;-)
Only something I'd do to get that bastard out as a last resort.
You only need/want the none drive side off (the one without the lip) , it should have some anti vibration/sticking compound in it.
Spray something that may help dissolve it more E.G. EWD40 as you've tried, though gt85 seems to work much better.
I'd then get a wrench around the inside and tap and work it off.
How can you fit it to tap it if both cups are on.
Only something I'd do to get that bastard out as a last resort.
You only need/want the none drive side off (the one without the lip) , it should have some anti vibration/sticking compound in it.
Spray something that may help dissolve it more E.G. EWD40 as you've tried, though gt85 seems to work much better.
I'd then get a wrench around the inside and tap and work it off.
How can you fit it to tap it if both cups are on.
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Ah just figured what you probably mean by backwards, axle end in on the NDS side. By all means try it, but only when it's a last resort or you just try it with a few gentle taps.
A vice tends to come in hand instead of a wrench to drop something through and get two edges.
A vice tends to come in hand instead of a wrench to drop something through and get two edges.
Sorry, should have been a bit clearer, tapping and hitting are different things entirely in my book! Tap it to break the goo/ corrosion holding it in.
Yes...hitting it hard will possibly pull the bearing off the tube, but that would require significant force, which would probably have it out the vice first!
But good to be clear and quite rightly pointed out.
Yes...hitting it hard will possibly pull the bearing off the tube, but that would require significant force, which would probably have it out the vice first!
But good to be clear and quite rightly pointed out.
Thanks for the quick replies - I don't have a vice (though am fast thinking one would be handy). Hadn't thought about the compression issue on the bearings if I give it a wallop - glad I asked! It's taken a while to find this BB so the last thing I want to do is damage it.
Will try GT85 and also might need to invest in a vice as holding it steady is the challenge.
Will try GT85 and also might need to invest in a vice as holding it steady is the challenge.
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If one one (NDS) is revered into the frame, then you can get a wrench (adjustable or better) around the inner or lip of the driveside cup and strike down on that.
Though a few taps on the axle is probably no more than a good ride down helvellyn.
The race will not come out as the axle and the shell are the races with big fecking balls between them. I was just thinking of sideways dinting on the race edges when you get carried away
Though a few taps on the axle is probably no more than a good ride down helvellyn.
The race will not come out as the axle and the shell are the races with big fecking balls between them. I was just thinking of sideways dinting on the race edges when you get carried away
Like others have said, don't go tapping the axle with any kind of blows.
The NDS cup should come off with a little piece of wood on the edge of the cup and some taps on alternate sides with a small hammer. Simply holding the BB in your hand at the DS cup should be enough to secure it.
The DS cup is a different matter. The press-fit is a much tighter tolerance fit, and using a piece of wood and hammer generally doesn't work. My method:
- Screw the BB in the shell, only the DS first, hand tight is good enough.
- Screw in the NDS cup, again hand tight is good enough.
- Lock the cup remover tool into the NDS cup with several washers and a crank bolt. The washer external diameter must be enough to cover the cup remover tool, and the internal diameter enough to let the axle through. A lot will depend on your BB remover.
- Gently unscrew the NDS cup. "Et Voila" the whole assembly will gently separate from the DS with no hitting.
You may need to fiddle with spacers and washers and/or play around with how much the cups are in the frame so nothing bottoms out. Good luck.
The NDS cup should come off with a little piece of wood on the edge of the cup and some taps on alternate sides with a small hammer. Simply holding the BB in your hand at the DS cup should be enough to secure it.
The DS cup is a different matter. The press-fit is a much tighter tolerance fit, and using a piece of wood and hammer generally doesn't work. My method:
- Screw the BB in the shell, only the DS first, hand tight is good enough.
- Screw in the NDS cup, again hand tight is good enough.
- Lock the cup remover tool into the NDS cup with several washers and a crank bolt. The washer external diameter must be enough to cover the cup remover tool, and the internal diameter enough to let the axle through. A lot will depend on your BB remover.
- Gently unscrew the NDS cup. "Et Voila" the whole assembly will gently separate from the DS with no hitting.
You may need to fiddle with spacers and washers and/or play around with how much the cups are in the frame so nothing bottoms out. Good luck.
The NDS cup should come off with a little piece of wood on the edge of the cup and some taps on alternate sides with a small hammer. Simply holding the BB in your hand at the DS cup should be enough to secure it.
Recently had a NOS, and it worked fine for me with some WD40 overnight.
Recently had a NOS, and it worked fine for me with some WD40 overnight.
fearfactoryüberalles
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Shimano's special material under the NDS cup causes this anomaly-I'd use some gentle taps, BB body firmly held in hand, put a screw into the axle and tap on it lightly, even with a rubber hammer- so far no wrecked BB using this method...
