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Tech question on old Dura Ace BB7400(4 posts)

Tech question on old Dura Ace BB7400johnnybegood
Dec 3, 2002 10:43 PM
Hey, remember these old bottom brackets, square drive, open bearings?? Well, I pulled a low milage one out of a bike that had been hanging in my garage for 10 or 15 years to sell it to a co-rider. The adjustable cup came out with 10 loose ball bearings whereas the fixed cup side has the balls in a bearing race. Does anyone know if the adjustable side should have a race too, and somewhere 10 or 15 years ago I failed to reinstall it and now cannot remember? If the balls are supposed to be loose, how many are there supposed to be. The race has 11 balls and I only had 10 loose ones. Does anyone have the original diagram they could post for me?? Thanks!!
re: Tech question on old Dura Ace BB7400rdbkr
Dec 4, 2002 8:48 AM
Those bearing "races" (I call them retainers) came with the bottom bracket and are used to make installation easier, but are not necessary. I used to install the bearings loose without them in my old bb (did the same with my headset too) before everything went cartridge.

You should be able to fit 11 balls in the cup. 10 balls were probably OK, but 11 is better.

Sorry, don't have a diagram for you. If you're looking for the races/retainers, Loose Screws has them (in pairs).

Look for item #4: http://www.thethirdhand.com/index.cgi?c=Bearings&sc=Retainer&id=49207704362
11 loose balls are more reliable!satanas
Dec 5, 2002 7:00 AM
If you can get decent quality balls, use them. (If you can't, but can get decent retainers (with 11balls/side) it's best to take the balls out and run them loose.)

The only good thing about retainers is that they are slightly quicker to assemble. OTOH, they can creak, break up, and generally have less bearings in them.

I would *always* use loose balls if there was an option to do so; when I used to work in a bicycle hire shop, we regularly replaced broken retainers with loose bearings. This ended the problem 99% of the time (unless the cups/axle were stuffed also).

DA 7400 BB's were very good quality; I wish I could buy some new ones now!
Luv them loose balls!rdbkr
Dec 5, 2002 7:42 AM
Sounds kinda nasty! Might be a good topic for a new thread.

That's exactly why I went with loose balls. My bb started to sieze up about 4 miles from home. Had to coast the rest of the way. Found out that the retainers began to deform and started to bind. Luckily, didn't damage the bb.

Do the same with the headset too, although only in the lower
cup, since it bears most of the load. Can add 2-3 more balls to spread the load out.

BTW: I think you can get the DA 7400 bb's at Loose Screws also: http://www.thethirdhand.com/index.cgi?c=Bottom%20Bracket&sc=Complete%20BBs&tc=Standard&id=960464121938 (#7)