Wings & Wheels offer disc brake conversion kits for a number of makes of gliders. Here's the ad for Schempp-Hirth gliders: http://wingsandwheels.com/conversion...mpp-hirth.html

I have no experience with these kits (and no connection to W&W). At one time I was considering modifying my LS8-18, but I've since found the factory brakes work well enough if you keep them adjusted properly.

-John, Q3