Originally Posted by
FBinNY
Less is better. Unless the hub has a solid barrier to prevent excess grease from filling the hub and directs all excess to the outside under a bleeder type seal excess grease will eventually pack the hub solid.
On my old GreaseGuard hubs (no brake) I could continue to inject grease forcing old contaminated grease out under the external seals until it ran clean. But I wouldn't try this with any hub that had internals other than the two ball bearings. IMO, 1 cc is probably plenty. Keep in mind that grease doesn't evaporate or get consumed, so if it's not coming out under a seal, each new application adds to what's in the hub.
Update: I used a 2 mL syringe which I filled up entirely with the red goop mentioned above (Red Line CV-2) and it went in much easier than I expected, considering how viscous it is. No spill-over, and now my rollerbrake has regained its modulation. However, it does drag a bit. Also, the "stopping force" has remained about the same, although now, thanks to the much improved modulation, I feel safer using the brake.
FBinNY it would seem that 2 mL of lube are enough for the rollerbrake. BTW, it's one of the lower-end Shimano models, for what it's worth. I suspect that the higher-end ones take about the same amount of lube, judging purely by the size of the case.