Originally Posted by
jerrysimon
Re the OLN of the Automatix its 120mm without the spacers. The two lock nuts on the non drive side are about 2.5mm each if I recall. The Brompton rear dropout width spacing is around 117mm so I needed to loose about 3mm. I removed one of the lock nuts and then had the other one machined down to about 1.5mm - 2mm and just used that. It means you have to "set" the nut to lock the hub together when you clamp it between the dropouts. You should be ok doing the same, though maybe have to spread your forks very slightly.
I'm in the same position here. I have a SRAM Automatix coaster brake hub and want to fit it to a folder bike. The folder is a Kansi and came with a SRAM T3 hub. The frame is aluminium and is similar in shape to the Dahon Mu, so the rear 'combined-chainstays-and-seatstays' are very short and stiff and won't spring apart much at all.. The Kansi frame and the SRAM T3 hub in it have a spacing of 117mm.
I measured the Automatix OLN as 120.0mm. The two 22m-wide L/H cone adjustment nuts outboard of the brake reaction arm measure 7.9mm for both together, so just about 4mm each. The single 17mm-wide locknut on the R/H side measures 3.3mm thick.
I was thinking in terms of finding the specifications for the locknuts and obtaining alternative, thinner ones. It hadn't occured to me to have the existing nuts machined down, but of course that makes more sense. Ideally I would lose the same amount on each side so as not to have to dish the wheel at all, but since there will be no rim brakes I guess 1mm either way won't matter much. If I take 1mm off each of the three nuts it should fit just fine. Alternatively, I could lose 1mm from each side and 'steal' the last 1mm by springing the frame.
But if you need to go down to 114 or so then perhaps you could lose one of the L/H locknuts and dispense with the R/H lock nut, simply setting the R/H cone in its fixed position using a medium-to-strong thread locking compound. (Locktite 638 perhaps?) Not ideal, but it should work OK, ...I think, ...unless I have missed something obvious (...?)