Cartridge BB not screwing all the way in

othello

I'm having problems fitting a UN55 cartridge BB into a Cube MTB frame, and cannot work out what I'm doing wrong!

I've screwed in the right hand side all the way, so the flange is touching the BB shell. When I screw in the left hand side it only screws in 2/3's the way. It just won't go in any more. I can back off the right hand side a bit and then screw in the left some more, to even out, but that doesn't look like it should be right.

The bb shell is 68mm and the BB is 68mm.

I've fitted a few of these over the years and have never had this problem! Any ideas?

nicklouse

if the BB shel is not faced then when bottoming the drive side it can put the BB of center. so back it off. tighten in the ND side and then snug the D side up to the BB.

this is all presuming you have the correct BB.

othello

nicklouse wrote:

if the BB shel is not faced then when bottoming the drive side it can put the BB of center. so back it off. tighten in the ND side and then snug the D side up to the BB.

this is all presuming you have the correct BB.

Thanks, I'll give that a go. I've always done DS first then ND. But hopefully that will work.

othello

I backed off the drive side, and screwed the non-drive side all the way in. Then tried to screw in the drive side. It only got half the way down the threads before stopping.

It seems like the cartridge is not lining up precisely with the cup on the other side, or its coming up against something.

Does it need a trip to the LBS?

Levi_501

Are you meant to have spacers?

Are the threads dirty damaged part way down?

othello

Levi_501 wrote:

Are you meant to have spacers?

Are the threads dirty damaged part way down?

No spacers supplied, and as the shell is 68mm and the BB is 68mm I shouldn't need any.

The only thing I can think of is the threads. They are fine initially as everything screws in by hand. I'll get the LBS to take a look I think.

maringirl

Do check that the screws holding the cable guide in place under the bottom bracket are not sticking too far through and catching the bb as you put it in. If they are back them off put BB in and then tighten them up again afterwards. H\ave had this a couple of times.

othello

After a trip to the LBS it turns out I'm not a total muppet

The non-DS for the BB was the wrong one ! It was for a 72mm shell and not a 68mm, hence it being too long. Correct one put in and BB fits.