Dyna Glide ModelsSuper Glide, Super Glide Sport, Super Glide Custom, Dyna Glide Convertible, Super Glide T-Sport, Dyna Glide Police, Dyna Switchback, Low Rider, Street Bob, Fat Bob and Wide Glide.
If still under warranty go to the dealer they will replace the master cylinder. If not then just rebuild the master cylinder. My fxdls just got this problem recently and ended up getting worse due to brake master cylinder sticking a little. Easy fix.