Bottom Bracket Preload???
#1
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MADE IN HONG KONG
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Bottom Bracket Preload???
Ok, I'm spoiled by cartridge this and cartridge that.
How much preload should an old style, loose balls, cups and lock ring BB get? Should there be any play (up down) on the spindle? What is the best indicator that the cups are tight enough?
If this did not have such a nicely ground spindle (70's sugino) I would chuck it for a maintenance free UN-72.
Crunching is too tight ... right???
How much preload should an old style, loose balls, cups and lock ring BB get? Should there be any play (up down) on the spindle? What is the best indicator that the cups are tight enough?
If this did not have such a nicely ground spindle (70's sugino) I would chuck it for a maintenance free UN-72.
Crunching is too tight ... right???
#6
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MADE IN HONG KONG
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gosh, how did you guys use to adjust all that stuff all the time? The machining / honing has to be perfect to get rid of all the play at all locations for a full rotation. There is just a small (.0005?) bit of play at 9 oclock and no play else where on the non drive side and play in other areas on the drive side. With the crank on and fix wheel hooked up, it spins for quite a while. just wondering if I should set the cones closer?
#8
Originally Posted by poopncow
I mean I have to close my eyes and shake the crank arm to feel the play at the end of the arm.
What sydney said, but in more detail ;-) He's a minimalist ;-)
#9
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Originally Posted by poopncow
gosh, how did you guys use to adjust all that stuff all the time? The machining / honing has to be perfect to get rid of all the play at all locations for a full rotation. There is just a small (.0005?) bit of play at 9 oclock and no play else where on the non drive side and play in other areas on the drive side. With the crank on and fix wheel hooked up, it spins for quite a while. just wondering if I should set the cones closer?
Due to the gap in the threads, when you tighten the lockring, it will actually pull the cup outwards slightly, thus opening up some clearance. So... with the cup adjusted just perfect so there's no play, tighten it up an additional 1/16-1/8th of a turn, then tighten the lockring, which will pull the cup back out to the previous setting of perfectly smooth. Depending upon how square the facing is and how clean the threads, this additional amount will vary.
#10
Originally Posted by poopncow
gosh, how did you guys use to adjust all that stuff all the time? The machining / honing has to be perfect to get rid of all the play at all locations for a full rotation. There is just a small (.0005?) bit of play at 9 oclock and no play else where on the non drive side and play in other areas on the drive side. With the crank on and fix wheel hooked up, it spins for quite a while. just wondering if I should set the cones closer?
#11
JRA...

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Originally Posted by DannoXYZ
Yes, it's a little too loose if you have any play at any location at all. What will happen with that looseness is the load will be concentrated on a single ball or two at that point and the wear will accelerate. Better too tight with extra friction than too loose (because it'll wear into correct specs eventually).
Due to the gap in the threads, when you tighten the lockring, it will actually pull the cup outwards slightly, thus opening up some clearance. So... with the cup adjusted just perfect so there's no play, tighten it up an additional 1/16-1/8th of a turn, then tighten the lockring, which will pull the cup back out to the previous setting of perfectly smooth. Depending upon how square the facing is and how clean the threads, this additional amount will vary.
Due to the gap in the threads, when you tighten the lockring, it will actually pull the cup outwards slightly, thus opening up some clearance. So... with the cup adjusted just perfect so there's no play, tighten it up an additional 1/16-1/8th of a turn, then tighten the lockring, which will pull the cup back out to the previous setting of perfectly smooth. Depending upon how square the facing is and how clean the threads, this additional amount will vary.
https://www.yarchive.net/bike/ball_bearings.html
#12
When adjusting a loose ball type bottom bracket, I tighten the adjustable cup until resistance is felt indicating binding in the bearings, next back off the cup 1/8 turn or so to allow the bearings to spin smoothly. Lastly, tighten the lock nut.
Last edited by Nessism; 11-18-05 at 10:45 AM.
#13
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Everyone, Thanks for all the advice. You detailed explainations are well appreciated! Especially for clearing up the play thru out the rotation question. I will go back and tighten up the cup a little more to get rid of all play (yes will use the arms as a lever)
I used to adjust valve clearances on motorcycles and Datson Z cars and did machine work for a few summers. So I am very familiar with the effect of play in threads and how to compensate for it. Its good to have some experience
I used to adjust valve clearances on motorcycles and Datson Z cars and did machine work for a few summers. So I am very familiar with the effect of play in threads and how to compensate for it. Its good to have some experience
#14
Originally Posted by DannoXYZ
Due to the gap in the threads, when you tighten the lockring, it will actually pull the cup outwards slightly, thus opening up some clearance.
#15
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Originally Posted by bostontrevor
Unless, of course, in the process of tightening the lockring, you also turn the adjustable cup a little too. You need to play with it all a little bit and figure out where you want the cup to end up so that tightening the ring will tighten it up but also put it outward...just so.
#16
Nope, the pin spanner isn't designed for holding the cup in place, just removing it. You can bend or break the pins if you're not careful, or so I'm told. Not all cups take pins, either. I've got at least one that's just got a notch for a lockring spanner.
#17
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And the common lockring tools seem also need the crank arms removed to work.
Last edited by Yoyo2012; 11-02-17 at 12:20 PM.
#18
Don't make me sing!
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Start a new thread, and throw in some pictures. This discussion ended twelve years ago!
#19
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The guy you quoted hasn't logged into BikeForums since 2010...
#20
Passista


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It depends. If the crankarm is far enough from the cup and the tool pins are short (I ground them off on mine) it's possible. For the lockring I use a modified channel lock pliers.
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