[Fulton]

I am installing my evil chain guide right now. when I pulled out the bottom bracket, something really wierd happened. Please keep in mind that i have been a shop mechanic for 4 years, so I'm not a total idiot when it comes to installing BB's. Ok I backed off the non drive side cup about 5-6 full turns, then went to remove the liped drive side cup, and it came out. with out the bottom bracket. I am using an XT square taper, UN-72. I have lots of extra XT's (none the right length) laying around so I pulled some out, and sure enough, the drive side cup is fixed to the bottom bracket. Better yet, when i took out the non drive cup, the bottom bracket was stuck in it!?!? I can put it back together the way it is, but am I going to have problems with it coming loose or creaking??

 

[Micro-Sanjay]

I'm seasonaly an idiot...what are you asking help with? removing the stuck driveside BB cup?

If it is, I had the same problem and did something drastic when everything else failed...well, Intense did it for me upon my direction and to their dismay...

 

[DHiTone]

It should be fine. They are only a push taper fit - in theory a slightly better fit on the drive side than the other. With geneal age, wear, ingress of cack they can work loose.

I have had this happen to a couple of BBs. I just put the drive side cup in all the way and then wound the BB in from the other side and tightened as normal. Worked fine for an entire season of DH riding big mountains everyday. No problem.

Tone

 

[oldfart]

Yeah, what DHiTone said. Both cups do come off and the drive side is on more tightly. If its comes off I will clean everything up well and apply a little locktite of the red or blue variety to to the inside of the cups to keep it snug.

 

[bomberz1qr20]

Originally posted by oldfart
Yeah, what DHiTone said. Both cups do come off and the drive side is on more tightly. If its comes off I will clean everything up well and apply a little locktite of the red or blue variety to to the inside of the cups to keep it snug.

Or you can use my age old theory,

Put grease on EVERY part of the bike except:
chain
rotor
faces of a square taper BB

That includes grease on the inside of the cups, that way any microscopic amout of play won't mean squeeks and creaks.

 

[gravity]

Originally posted by bomberz1qr20


Or you can use my age old theory,

Put grease on EVERY part of the bike except:
chain
rotor
faces of a square taper BB

That includes grease on the inside of the cups, that way any microscopic amout of play won't mean squeeks and creaks.

uh dude...... ya gotta grease the faces of a square taper BB, otherwise the cranks creak the minute a single molecule of anything that isnt metal gets in there.

 

[bomberz1qr20]

Originally posted by gravity


uh dude...... ya gotta grease the faces of a square taper BB, otherwise the cranks creak the minute a single molecule of anything that isnt metal gets in there.

no no no NO

You NEVER grease the taper! It's essentially a press fit that your making, and if you grease it, it can actually damage the crank because the grease allows the crank to press in too far, widening the square hole in the crank! On a new crank install you clean the taper with a scotch brite pad and that's it. On a crank that's been greased you'll never stop tightening it.

This has been my experience and the same with many other mechanics I know.

Anyone agree?

 

[edoz]

Never, ever grease the square taper spindle. EVER! The first time you put it on, it will slide on too far and you will have ruined your crank arm.

 

[Shibby]

my friend who's been riding trials on the same set of LX square-taper cranks for 6 months would disagree. everytime he pulls em off (wrecked chainring or whatever), he greases the $hit out of the square-taper (Phil Wood waterproof grease). cranks are still goin strong.

stronger than mine did before i went to ISIS anyway.

 

[edoz]

Sorry, but the Barnett's manual and the bike shop owners who would have fired me if they saw me do that would take my side. if it works for your friend more power to him, but his cranks are on borrowed time.

 

[Shibby]

you forget that, for a guy who spends serious time on his bike, and takes big hits every once in a while, even the best square taper cranks are only good for a couple of years, no matter how well-maintained.

ISIS!

 

[bomberz1qr20]

Originally posted by Shibby
you forget that, for a guy who spends serious time on his bike, and takes big hits every once in a while, even the best square taper cranks are only good for a couple of years, no matter how well-maintained.

ISIS!

Well at least your friend is giving himself a quick reason to go ISIS soon enough! Those cranks should be doomed by now, he's lucky

 

[Shibby]

good lord.

anybody have any actual evidence that states that not greasing will improve the life of your cranks? if Barnett's told you to jump off a bridge, would you?

as it was explained to me by a few of the wrenches at my shop, the grease will tighten the fit of the cranks further, since it acts as "filler" in the miniscule gaps in the crank-bb interface. the crank sliding further up the taper doesn't make any sense, since it seems it would position itself the same regardless of the coefficient of friction of the surface of the taper... it was already established that it was a press-fit, not a friction-fit.

this isn't to say i grease my square-taper interfaces. my singlespeed's bb is bone-dry, actually, with a bit of loctite on the crank bolts. i'm just bringing in another case that i am informed of...

-- trying to keep it good-natured --

 

[Shibby]

another thought, this one from the ISIS website (isisdrive.com), regarding the use of grease in cranks...

"...The drawback of using grease on almost any interface is that it reduces the friction present between the mating surfaces, thus reducing the amount of load transfer through friction. Please refer to the instructions from your crankset manufacturer regarding the use of grease on the interface."

Granted, this is a spline interface, but the same thought seems to be applicable to the square taper.

This also makes sense to me... so the crank would deform faster since the load transfer doesn't go through friction. Hmm, I can see it both ways, actually! Werid...

 

[bomberz1qr20]

Originally posted by Shibby

as it was explained to me by a few of the wrenches at my shop, the grease will tighten the fit of the cranks further, since it acts as "filler" in the miniscule gaps in the crank-bb interface

This guy is smoking several different things never before placed in a pipe.

We need to start a new thread...perhaps a poll? Let's get a consensus cause I've been hearing the "no grease on the taper"
theory, and proving it in practice, for like 12 years now.

I have personally seen several destroyed cranks from greased tapers.
"Dude this thing just won't stay tight, I've cleaned it and re-greased it everytime I've taken it off..."
That's how it usually sounds.