White Grease All Over New Bottom Bracket- Blown Seal?
03-14-07, 10:55 AM
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White Grease All Over New Bottom Bracket- Blown Seal?
I just received a new bottom bracket Shimano UN-53 which was shipped to me via air mail from the States. One side of the spindle is covered in a pasty white grease. I've never seen this before on a new BB. Is it possible that a seal blew during shipping and this grease leaked out? If not, what is this mystery paste? Thanks.
03-14-07, 11:11 AM
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Square taper shimano bbs usually have grease smeared on the drive side taper. Saves you having to grease it yourself I suppose. Who knows why they don't grease the non drive side taper.
03-14-07, 11:25 AM
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Originally Posted by d_D
Square taper shimano bbs usually have grease smeared on the drive side taper. Saves you having to grease it yourself I suppose. Who knows why they don't grease the non drive side taper.
03-14-07, 11:39 AM
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Originally Posted by splytz1
Yeah, but... you're not supposed to grease the tapers.
(opens can of worms)
(opens can of worms)
I always grease the tapers. Learned this when I was a wrench at an LBS doing assembly. As part of the set up, we had to take off the crank arms and grease the tapers. This makes sure you get a good tight fit and it makes taking the cranks off easy as pie.
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Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1
03-14-07, 11:44 AM
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You Know!? For Kids!
Seems to me that if bearings are properly greased prior to inserting spindle, it would be next to impossible not to get grease on spindle. Presence of grease shows that spindle went through grease during assembly. Adds peace of mind to me. I lightly grease my square tapers prior to crank install BTW
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03-14-07, 04:34 PM
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Before you assemble the cranks on the bottom bracket axle, degrease the axle and crankset square heads thoroughly.
I don't have my Shimano reference manual here with me, but I do believe they advise against greasing the tapers as well.
Aluminum cranks typically do not require lubrication of this press fit. Aluminum by its nature is self-lubricating as it is covered with a thin layer of oxidation.
The primary reason behind this is chainline. Greasing the spindle or crank bolt threads allows one to push the crank further onto the spindle than you would otherwise, at the same torque level. That does two things, 1) ruins your chainline, and 2) ruins your crank by enlarging the hole.
09-20-10, 07:29 AM
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Anyone who has encountered an aluminum crank chemically fused to a steel spindle, requiring removal by angle grinder has learned that yes, you do need to grease the tapers.
09-20-10, 07:42 AM
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The comment that greasing them lets the crank move too far up the spindle and ruins both it and the chainline is incorrect unless you wildly overtorque the bolts and that can damage the crank, grease or not.
BTW, how did you find this thread? It's 3-1/2 years old.
09-20-10, 07:47 AM
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Ha - yes I just realized I resurrected a very old one by accident. Was searching for grease gun recommendations and got carried away reading through results.
BTW brand new shimano cranks come with grease (or more likely some sort of anti seize) pre-applied to the square taper holes, so I doubt the previous poster's claim that shimano advises against a greased interface.
BTW brand new shimano cranks come with grease (or more likely some sort of anti seize) pre-applied to the square taper holes, so I doubt the previous poster's claim that shimano advises against a greased interface.
09-20-10, 07:03 PM
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I've used antisieze instead of grease because I thought it was even better at preventing galvanic corrosion between the aluminum cranks and the bb spindle. Don't the aluminum, copper, and zinc particles in the antisieze act like sacrificial anodes at the interface?
I have seen fused-on cranks that had their removal threads tear out while trying to crank them off with the tool.
I have seen fused-on cranks that had their removal threads tear out while trying to crank them off with the tool.
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