M950 XTR bottom bracket issue

[fattiman]

Took cranks off to clean, mounted them and now the bb won’t turn, have I broken something? They have the self extracting bolts if that’s relevant?

 

[d8mok]

Did you remove the BB or not?

Did you align the splines correctly by removing the self extracting caps first?

If it’s M950 and not M952 it could also be preload related

 

[2manyoranges]

rather difficult to break anything.
have you got all the things bak in the right order?

 

[ishaw]

It's probably down to the collars. The BB is designed to work with both 68 and 73mm shells so perhaps the collars have moved and you need to adjust them.

Have the spacers gone back the same way they came off?

 

[d8mok]

It's probably down to the collars. The BB is designed to work with both 68 and 73mm shells so perhaps the collars have moved and you need to adjust them.

Have the spacers gone back the same way they came off?

People also assume that because it works on 68 or 73 that the lock ring is used to space it rather using the spacers. Seen it so many times with the preload lock ring being used as a way to widen/ shorten

 

[fattiman]

I will take a look, can’t see anything noticeable at present, but confused. Nothing looks damaged.

 

[fattiman]

Still none the wiser, I literally just took the drive side chainset/crank off, cleaned it and put it back on. Now it’s seized solid.

 

[ishaw]

Do you have any pics?

 

[d8mok]

Still none the wiser, I literally just took the drive side chainset/crank off, cleaned it and put it back on. Now it’s seized solid.

Did you remove the self extracting bolt covers when installing them back on?

 

[ishaw]

I have seen some xtr cranks with marks on the cranks which could only have been caused by the arm binding on the inside of the BB. Not sure how this happens as the arms should not be able to do this unless there's something wrong with the splines and they've allowed the arm to be over-tightened I'm guessing.