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ball bearing size for GT bmx hub?

Old 12-05-21, 01:56 PM
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rickpaulos
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ball bearing size for GT bmx hub?

took this hub apart and found 3 different size balls in it. 1/4" - 7/32" - 3/16". 14mm axle.
anyone know what the correct ball bearing size is?


right side cage.

left side:

Last edited by rickpaulos; 12-13-21 at 11:40 PM.
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Old 12-05-21, 04:28 PM
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Canít help out, but you might get a better answer on the GT owners FB page.
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Old 12-09-21, 03:18 PM
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It's tough to tell which one is which. But typically rear bearings are 1/4" in most rear hubs. You might want to check your front hubs to as I have a feeling the original owner got the bearings all mixed up for both hubs.
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Old 12-10-21, 03:37 PM
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Make sure you don't have one size on the drive side and a different size on the non-drive side. It looks like a std hub with freewheel. Hazarding a guess, the large bearings go on the drive side and the smaller ones on the non-drive side.
When a hub destroys itself like that, bearings can travel through the hub to the other side.

You need to remove the axle & freewheel and look at the cups and cones.
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Old 12-13-21, 11:39 PM
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After a bunch of trial and error...

The hub shell is threaded on both sides. freewheel standard 1 & 3/8" on one side, odd ball 1 & 3/16" on the other side (the side with the 16 tooth ACS FAT freewheel). The cups are different sizes. Smaller on the side with smaller freewheel threading. The cones are the same outer diameter but the bearing surface is cut smaller on one cone. and one cone is shorter. So left and right specific cones. 5/32" balls on both sides seems to work best. larger sizes have the balls running on the edge of the cones, not in the center of the bearing surface. About 15 balls on each side. Seems sensitive to having what I'd say is enough. Turned much smoother if I took out one. (kinda like a headset). 14mm axle x 1.0mm pitch. What the hardware stores call extra fine pitch (but they don't carry that anyhow).

The ACS FAT freewheel is noticeably fatter than normal single freewheels. I found out that ACS also makes left side drive specific freewheels. This ACS FAT seems better quality than the endless stream of bso single freewheels.
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