Stuck Bottom Bracket

MickyMick

I'm looking for some info. regarding the bottom bracket on my Specialized Rockhopper (2003).

According to the spec. from Specialized, my bike uses a Shimano UN25 bottom bracket. I' m trying to replace this with the one that came with my new Deore LX Hollowtech II crankset but am unable to unscrew the current bottom bracket (UN25) on the drive-side as it appears to have welded itself to the frame i.e. there's a fair bit if rust!! I've sprayed it with wd40 and left it soaking overnight - hopefully this will help tomorrow.

Anyway to the question - I've been trying to ascertain that the drive-side should be turned clockwise to loosen it as most sites seem to state for shimano BB's, (just so i know how much force to apply)...the shimano site itself only allows you to view an exploded diagram ,no other info.

can anyone provide the info. i require or provide any help?

Cheers!

supersonic

Yes, it is a reverse thread on that side. Hopefully the WD40 will penetrate - and try a longer lever.

MickyMick

Thanks for the confirmation SuperSonic!

Fingers crossed the WD40 will penetrate...I'm heading up north (Sutherland) on friday for 3 days riding at Carbisdale, Golspie and Laggan so need to get the new crankset on quick sharp!

cheers,
M_M

bobtravers

Try to find some High performance rust penetrant... In Canada, we have this:

http://www.3inone.com/products/penetrant-drip-spray/

Spray with the straw, then wait 15 min...

Use a good ratchet 1/2 in socket and don't mind to put a lot of constant pressure, it should work... is your frame aluminium, steel or carbon??? Don't put rust penetrant on carbon frame, as it can damage it...

cunning-stunt

Clockwise and mallet..

nicklouse

it also helps to refit the non drive side cup finger tight to help keep thing from flexing.

please remember to have the BB shell faced so that the bearings of the new crankset are parallel to each other and perpendicular to the crank axle axis. (it is a job for the LBS).

form info and pictures can be found on Parktools.

MickyMick

Thanks for the info guys....bike is currently on a workstand is it best to place on floor?

abbots_mike

probably, most workstands wont be able to take the kind of leverage you will put in. on wheels with an assistant is probably best.

clanton

If all else fails you can try mounting the BB tool in a vice and then turn the whole bike (will probably need to strip most stuff off the frame for this to work, I had a bare frame when did this) around the tool ie using the frame itself as a lever. I did this after exhausting all the other methods on a long neglected steel frame, me turning the frame and a mate holding the frame down into the tool.

MickyMick

Cheers for all the advice guys.

I eventually relented and took it to my LBS. They managed to free it. Apparently it took two men pushing down on a 3ft wrench to free it!!

Have just installed the new crankset. Still to fit the new chain but it's looking like the 2 spacers on the drive side will be too much for my front derailleur i.e. it doesn't look like it will shift properly over the outer chainring...fingers crossed! i've got a 68mm bottom bracket and 3 2.5mm spacers fitted as per instructions. can one of the spacers on the drive side be moved to the left hand side if shifting is a problem? this would still give the 75.5mm distance required.

Also, stupidly managed to pulll my rear brake lever with no disk between the pads can these be pushed back or will i need to bleed? i have shimano xt 765's.

again thanks for all info and help.

nicklouse

yes you can play with the spacers.

and a clean something between the pads will seperate the pads.

More reading on Parktools.