NUTS SYSTEM OF ADJUSTMENT
Will Coleman brought round the rear wheel for his 500 Triumph the other day, worried that the expensive taper-roller bearings would need to be replaced because they felt stiff and gritty. In my experience, taper rollers are amazingly resilient, so I hoped they were just adjusted too tightly and needed a wash out. Sure enough, the adjustment was too tight. The bearings cleaned up well and as we reassembled them it looked like we had saved Will a chunk of his budget.
I explained that taper-roller wheel bearings are supposed to be adjusted so that there is always a tiny bit of play at the wheel rim – usually 1/16in (I’ve had to take the owners handbook in to convince MOT testers in the past). So although I’d set the bearing to what I thought was near enough, it would probably need to be finally adjusted when back on the bike – but there’s where it got confusing. On my old Thunderbird, I’m sure there were two nuts, an adjuster and a locknut – but that bike had a gearbox-driven speedo. Will’s has a rear wheel drive box – and the adjuster nut is under the box, the locknut outside. With only a fraction of a turn difference between too tight and correct, I couldn’t tighten the locknut without the adjuster moving – how’s that going to work?
I think the answer is, that is how it works. I reckon you loosen the wheel in the rear fork, which frees the ‘locknut’ to move, a spanner on that also shifts the adjuster under the box and once happy you lock it all up again by pinching it between the fork ends with the wheel nuts. Will’s going to try it to see if it works...