Why is the rear Q caliper dragging on my BMW?
The pads on my BMW RT appear to be constantly in contact with the disc, even after a full caliper strip and service. When it’s on the stand it is possible to turn the wheel, but you can hear the pads rubbing. If I then remove the caliper from the bike the pistons slide back reasonably easily. The brake fluid level is roughly midway between low/high and the brake pedal spring seems to be up to scratch, moving the pedal back when released. Ron Posse, Putney
Answered by Tez, Motorworksuk We’ve found that the original BMW rubber brake hoses break down internally after 10 years and don’t allow the fluid to return fully. Another possibility is that if the brake pedal position has been changed, it could be that when it returns to rest it is not allowing the master cylinder to release completely, therefore pumping pressure up, but not releasing it. If normal grease was applied to the caliper sliding pins during the service, the rubber dust caps could also swell and restrict movement.