These BORG rim brake hubs are simple to service. Take apart for the following reasons

1) to replace bearing

2) to replace freehub body 

3) to add grease to freehub mechanism.

Bearing require changing when they are not longer smooth. When the bearings spin with noise they are worn. They will spin freely at this point but there will extra drag with rider load on the wheel. Bearing life should be long. 

Insert 2x 5mm allen keys into end caps. Normal right hand thread and undo. One end cap will undo.

Insert a 10mm allen key into the axle and with the other 5mm allen key remove the other end cap.

 

 

The freehub bearings should be removed with a blind or collet style puller and refitted. 

Freehub pawls and springs are a spare part and can be replaced.

To remove axle knock it out with a rubber mallet from the drive side. The nds bearing will push out of the shell.

 

 Use a bearing puller to remove drive side shell bearing and a bearing press to fit new NTN 6902 bearings. 

The freehub bearings are NTN 6802. 

Pictured here are shell bearing with contacting seals and a freehub with non contacting seals.

The hubs are made with the tight tollerances that NTN bearings provide. Therefore use of other brands of bearings while possible may affect bearing life and hub performance.