PeaceByJesus

A neighbor has a new 20'' Kmart (Pacific) bike which the rear wheel locked up. Taking it apart reveals that the cup bearing (only one side has one) was mangled (likely over tightened from the source). The 9 bearings are 7/32, which is what some coaster brakes use, and I see these by for sale, as well as these (which may be the same), however I need to make sure the I.D. + O.D. are correct

The sizes I measured are O.D. 32mm (approx. 1.25'') and 24mm (approx. 15/16''), though these may not be precisely accurate. The places I have looked (Niagara cycle, Amazon and Ebay vendors) only list the package size. Queries to vendors or Amazon has so far resulted in they do not know, or do not reply.

The drive side uses 14mm loose bearings, which are easy to find.

9x7-32.Bearing
Non-drive side
Anyone have a clue as to what/where in order to replace these?

Andrew R Stewart 

The vast majority of Asian made coaster brake hubs follow either the Shimano or the Bendix/SunTour designs, to the amount that the retainered balls usually interchange. As the typical retainer ring has no markings (the days of numerically marked retainers seems to have left the building) the shop method is to try a visually similar bearing and see how it feels/fits with all in place.

Once again I find myself describing a situation where the "look up the numbers" hope is not likely to happen and instead the try "one and see" is more the usual. This requires access to more then one retainer size. This is, again, why a LBS is a valid place to get help from. We have a few bins of various retainers, maybe 15 different sizes of which only one will fit best. BTW the retainer's shape as it's body and fingers wrap around the balls can be a source of a no fit even if the ball diameters, number of and retainer ring rough (it is a stamped piece, not machined) OD all match. Andy

PeaceByJesus

Thanks for trying to help. This is not a coaster brake hub but a microdrive, yet maybe they use the same.
There is no local bicycle shop in this city (around here it seems I am the LBS, if for basics and free for labor by the grace of God), and have been slowly building a stock of bearings, so unless a LBS in another city is accessed maybe I will order the ones I am looking at and see if they work. Maybe I could actually use loose 7/32 bearings in place of the cup ones, but that can be problematic.

BTW, this may be helpful for some:

3,969 mm (5/32″) – steerer (fork) bearings and many pedals.

• 4,762 mm (3/16″) – front wheel hubs (2 times 10 balls – i.e. 10 balls at each side most often).
• 6,35 mm (1/4″) – rear wheel hubs (usually 2 times 9 balls) and cup and cone bottom brackets (2 times 11).
• 5,556 mm (7/32″) Campagnolo Record front hubs and some exotic hubs of other manufacturers (2 times 9 balls). https://bike.bikegremlin.com/2017/04...ng-ball-sizes/

EDIT: After all this, I found an old coaster brake assembly in the bottom of a storage container, which I did not find before, and sure enough there is a 7/32 cup bearing in there that is the same size (fits, with the same I.D. and O.D.), as the one that belongs to the microdrive (I had two wheels, so I had a good one to compare). Thank God for old parts! And which means the #89 cup bearings I saw on sale should be the same, though I no longer need one right now.

Having found a correct bearing the next step is to order 1/8 bearings for the other side (though 100 G25 bagged balls each of the following sizes: 1/8", 5/32", 3/16" 7/32" & 1/4" for $7.45, seems to be the best buy).

Thanks again.

wschruba

Wald, until recently, still posted the bearing retainers they "make" (assemble/repackage)...fits for older American bicycle parts. I believe they were one of the last holdouts with regards to the obsolete numbering system that Andy referenced.

Wheelsmfg sells a variety or retainer bearings, enough to work on most bikes, through their website. Your other option is fiddly, but successful in almost all cases: throw away the retainer and pack a full compliment/full compliment minus 1.

Andrew R Stewart 

Sorry I can't be of more help. I would not have made the assumption of a coaster brake hub if the description had been more detailed. Now understanding that the hub is a single speed (Microdrive, a brand/model name? Or a generic term?) I suggest you look at the hub shell cups for cracking at the ball track. Too tight a bearing adjustment can work harden the shell's cups and cause them to crack far sooner then needed be. Andy

Also the bearing design (contact angle) might make going to loose balls a possibility. This is the usual first go to for non IGH or coaster hubs that I service. Andy

PeaceByJesus

I have not found these at Wheelsmfg but since I was able to confirm (as explained in my edit to my prior post) that the #89 bearings that are for coaster brakes also fit the Pacific micro drive then I could just get them if needed.

PeaceByJesus

Being willing to help is commendable, and maybe this thread will help others in the future. Micro drive is a generic term for a type of drivetrain, mostly BMX and MTB, that uses smaller than standard-sized cogs.

As re cracking at the ball track due to too tight a bearing adjustment, that is warranted, since over tightening was apparently what caused the disintegration of the cup.

Thanks for the advice.