# 595 bottm bracket facing



## vclune (Oct 26, 2006)

Is it recommended to face the bottom bracket shell on the 595, 585 or 486. Not sure about carbon bottom bracket shells compared to aluminum.

Inquiring minds need to know


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## Just Sam (Feb 24, 2004)

I was told yes when I bought my frameset.


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## rensho (Aug 5, 2003)

Whatever you do, make sure the threads are very clean. If you can't thread in the cups by hand, STOP! You don't want to know how I know...

Any good LBS would chase/face your BB for $15. These days, the BBs really don't need facing (no longer loose ball bearing), but chasing the threads is a good thing.


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## skritikos (Aug 10, 2005)

rensho said:


> Whatever you do, make sure the threads are very clean. If you can't thread in the cups by hand, STOP! You don't want to know how I know...
> 
> Any good LBS would chase/face your BB for $15. These days, the BBs really don't need facing (no longer loose ball bearing), but chasing the threads is a good thing.


I thought that the modern hollowpipe with external bearings bottom brackets need a perfectly faced BB! At least this is what Shimano says :idea: 


Stamatis


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## jimbonnet (May 9, 2005)

rensho said:


> Whatever you do, make sure the threads are very clean. If you can't thread in the cups by hand, STOP! You don't want to know how I know...
> 
> Any good LBS would chase/face your BB for $15. These days, the BBs really don't need facing (no longer loose ball bearing), but chasing the threads is a good thing.


I just put together a BMC frame that needed facing.. bad!

I don't think it can hurt anything to at least put the tool on there and see how bad it is. I think that is a myth that all good frames don't require it anylonger.. my opinion only 

--jim


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## rensho (Aug 5, 2003)

1st, it can't hurt, so i'll grant that every time.

It has to do with today's use of cartridge bearings. They carry the load radially, rather than the old school, loose balls, angular contacts.
If it weren't square, the BB would be too loose, or be too tight, but neither scenario would make good, circumferential, contact with the races.
Today, the cartridge bearing system has so much play in their seats, both bearing balls, and bearings into cups, that the squareness of the BB face would factor in such a minor way.

Just my 2c.

As mentioned above, I'll lose this argument every time.


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## hairscrambled (Nov 18, 2004)

rensho said:


> 1st, it can't hurt, so i'll grant that every time.
> 
> It has to do with today's use of cartridge bearings. They carry the load radially, rather than the old school, loose balls, angular contacts.
> If it weren't square, the BB would be too loose, or be too tight, but neither scenario would make good, circumferential, contact with the races.
> ...


I heard this today from a experienced mechanic - "It's not as important to face bottom bracket shells when using cartridge bearings".


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## C-40 (Feb 4, 2004)

*not so...*

The old style loose ball BBs don't have "angular" contact as opposed to radial. Both cartridge and loose balls carry loads radially and axially. Loose balls are not that sensitive to alignment errors, since both the cup and spindle have radiused bearing races. 

Chasing the threads, followed by facing the BB shell only insures that the faces of the shell are perpendicular to the threads so maximize contact with the face of the fixed cup or cups, depending on the BB design. This helps to insure that the cups or lock ring will not work loose while in use. It will NOT fix a right/left thread alignment problem. With internal threads, you only get one shot at correct alignment and size. A thread chaser will only follow the original thread path, cleaning out burrs or paint. If the tool was able to change the aligment, the thread would quickly become oversized if a significant amount of additional material was removed. A chaser can correct an undersized thread, but it should not change the aligment of the thread.

With many years of machining expereince, my opinion is that the crude tools used for hand facing may do more harm than good, if the mechanic is not experienced. I've never faced any of the three LOOK frames I've owned. I just carfefully remove the paint from the surface where any fixed cup will contact. It's fairly easy to screw in a fixed cup until it contacts a .010 inch feeler gage, then use .008 and .012 gages to check for misaligment. I wouldn't face a shell unless I found the face more than .002 inch out of square.


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## vclune (Oct 26, 2006)

*Thanks for the input*

That's the kind of reply I was looking for, Thanks.


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## rensho (Aug 5, 2003)

C-40, while i disagree with your point about the contact of the bearings, I do realize you're correct about the facing. The facing, now that I think about it more, has much more to do with the cups making better contact with the shell and keeping from working lose.
I should have realized the threads determine the axle axis and not the faces. DUH.


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## rkdvsm (Jul 15, 2006)

I thought you didn't need to face a brand new BB shell when you get a new frame. Can someone educate me on this???

Thanks.


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## C-40 (Feb 4, 2004)

*read the postings???*

Any frame might need facing, but IMO, one that needs more than the removal of paint from the faces of the shell should have been rejected at the factory. The need for facing can be verified with feeler gages, if you first remove the paint.

What you can't do with facing and chasing tools is correct a major misalignment of the threads. You can only square up the faces to match the threads and correct an undersized or otherwise damaged thread profile.


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## rkdvsm (Jul 15, 2006)

C-40 said:


> Any frame might need facing, but IMO, one that needs more than the removal of paint from the faces of the shell should have been rejected at the factory. The need for facing can be verified with feeler gages, if you first remove the paint.
> 
> What you can't do with facing and chasing tools is correct a major misalignment of the threads. You can only square up the faces to match the threads and correct an undersized or otherwise damaged thread profile.


Do you guys generally take this job to the LBS?


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## C-40 (Feb 4, 2004)

*yes....*

The tools are expensive; not something most people would invest in. 

http://www.biketoolsetc.com/index.c...c=Bottom-Bracket&tc=Facer-Sets&item_id=CU-007


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