I don't know how your assembly is constructed, I suggest consult with Oldtimer Service. With any wheel bearings, it shouldn't have bearings inner race press fit, it is necessary to have the inner race adjustable. Original -28 loose ball bearings has a free moving inner race on one side where bearing play is adjusted with nut and locknut only. Because of that they are also made with a shallow angular contact path. Deep groove ball bearings isn't made with that, they are more sensible for side load so they need to be fixed different but still adjustable.  

I guess your hub is constructed in one of two ways. One is with a separate, loose distance tube used over the hollow axle inbetween the bearings inner race. In that case the hub should be able to slide out. Perhaps with a little gentle love tap on the hollow axle. Bearings inner race should only be slide fit on the hollow axle and outer race press fit in the hub.

If steps is turned on the hollow axle instead of a loose distance tube, then one bearing has to be pressed out of the hub together with the hollow axle.

I would prefer the first version, easier to disassembly the hub and it would avoid tamper with the hollow axle, that needs to be firmly and very secure screwed in the brake plate. 

If nothing is found to keep the distance fixed between the bearings, especially if the inner races are press fit on the axle, the hub is dangerous and should not be used as such, as deep groove ball bearings are not suited for the sideload that it may entail. The fixed distance will share and distribute the load equally 50/50 between the bearings, where if not, a tiny misalignment will load both bearings rapidly toward a premature fail.

When the bearing nut (or axle nut) is torqued, it presses against and lock the inner races together via the distance tube (or steps if so made) and by surface friction prevents them from turning. Same as most any car wheel bearing. Mind you, ball bearings has to have a specified sideplay, so the inner race bearing support or distance has to be made or shimmed to a very precise measure to allow that minimum of sideplay. No drag should be felt, turning the wheel when the bearing nut is torqued.

It is different with taper roller bearings as in the 29-31 hubs, except the complicated -31 rear hub, that's a chapter in it self. The taper roller bearings on the 101 should be adjusted to zero play and preloaded carefully a tiny bit, just so a very little drag is felt. Too much and the rollers will run dry. Too little and the rollers will vibrate and chatter in the race.

Hello again,

I have removed the hollow axle, which is constructed using a distance tube and stepped bearing holders (Photos and sketch attached) The bearing holders appears to be a press on fit on the hollow axle. The inner bearing is a hard push on fit. The outer bearing on the sprocket side is a push on fit with evidence of bearing retainer  used (locktite?) The bearing is 52mm, the sprocket side hub measures 52.06mm (2.3/1000 oversize) The brake side hub measures 52.00mm.

My thoughts are to eze the inner bearing holder to a slip on fit to allow for adjustment. Check the distance between the inner faces of the bearings on the hollow tube and compare with the inner faces of the hub (adjust if needed) Reassemble using suitable bearing retainer product on the outer bearing (Hub) Remove inner seal on the bearings to allow greasing via the hub grease nipple.

Any feed back would be appreciated.

Other option. There is a same size (52x15x25mm) Timken bearing available. This would require modifications to the hollow axle to suit. This bearing is narrower than the original Timkem which is 19.368mm wide. This would still require the outer bearing to be fitted using bearing retainer. 

Are the Timken bearings (#1779,#1729) the same in the front and rear hubs?

Thank you in advance for your comments/feedback.

Regards

Mark

Thanks Carl-Erik for your reply.

The Hub has the bulb on one side. The bearing is actually 6205zz (shielded both sides) which is a single row deep groove 15mm wide, narrower than the Timken In the photo the bearing does look wider then it is. The Timken #1779#1729 is 19.368mm wide.

I am not sure why they went with the ball bearing other then as you noted for maintenance. My preference would have been the Timken bearing to avoid the issues with preload on the ball bearing set up.

Some oil in the hub is a good idea to keep the seals lubricated. 

Thanks for your comments and advice