QD stands for Quick Detachable and a QD bushing features a flange that connects the bushing (quickly!) to the sprocket. They also have a taper – usually 4 degrees, half that of a taper-lock bushing – that, along with the cap screws, provides a closer fit.
How to Install a QD Bushing
Installing a QD bushing involves the usual set of steps and precautions. Inspect everything for dirt, grease, nicks, scratches, and any other contaminant or imperfection. Do not apply lubrication or anti-seize. When it comes time to tighten the screws, use a torque wrench to stay within the rated limits and tighten the screws gradually, evenly and alternatingly. Fully screwing in one bolt before the others are at least partially tightened can create imbalanced pressures, which will lead to premature failure.
One added precaution is to maintain a gap of 1/8 – 1/4″ between the sprocket hub face and the QD bushing flange. This protects the sprocket hub from potentially damaging pressures.
A variation of the QD bushing, the QT bushing can be reverse mounted. These have six holes so the bolts can be installed from either side.
How to Remove a QD Bushing
“Quick Detachable” bushings live up to their name. Remove the cap screws and then insert screws into the removal holes. Tighten those screws (alternatingly, evenly, gradually) until the bushing loosens and you can take it off the shaft. If you need to, after tightening the cap screws in the removal hole you can tap on the sprocket hub to loosen the bushing.
MDS offers QD bushings for bore size from 1/2” to 4-7/16”, along with the following types: SD, SK, J, F, E, SF, SDS, SH, and JA. Not sure which one is right you? Let us know and we’ll make sure buying a QD bushing is almost as quick as installing and detaching one.