I've said how terrible the brakes are on these boards regarding this particular model trike before and to the best of my recollection I don't think many agreed with me. Over the last two weeks my DR and SX have been run side by side through the Arkansas wilderness by my brother in law and myself and I've had nothing but brake failures on my DR almost constantly. This is the norm for this bike which has had brake issues from the very beginning and it's time to address it.
The only two bikes I've ever owned that have had brakes this terrible have both been Yamahas. My IT175 had front and rear drums which gave out completely after fording one river. It ruined the rest of the day. The DR has had an array of brake problems. Its first problem is the front brake is just too small, period. It is always working at maximum capacity and needs to be adjusted often. This is compounded by the fact that the rear brakes are doing so little to slow the machine most of the time so the already overwhelmed front brake has to pick up the slack. I wouldn't be sure what to do about the front just yet and would rather concentrate on the rear which is essentially ballast in factory form.
I've had two separate problems with the rear that seem to compliment each other quite nicely. One problem is in theory at this point, but at times there was no slack in my brake lever as if the brakes were already applied. This was because they were already applied. They were dragging even if they hadn't been applied, they were applying themselves. They would sometimes release but of their own accord, just whenever they felt like it. When they released the lever would pull normally again, then it was a matter of time before they would hang up once again. I had to roll backwards down a hill and they just would not allow me to. Upon disassembly it was found that the floating disk that rides on splines cut into the axle is too worn causing the rotor to "cock" on the axle and grab the brake pads who then assisted in holding the rotor in this cocked position as it rotated with the axle. Being out of town my solution was to put motor oil (I don't have any grease) on the splines and that solved that problem for now. Brakes were adjusted back up and better than ever. For a day.
The following day we got the bikes into some water. They could handle much more than we were in. The SX performed flawlessly. As a matter of fact I do believe it's been years since I've adjusted the brakes on the SX. I've not stopped adjusting the brakes on the DR ever. As soon as the brakes on the DR got wet they flew south. Just completely gone after a couple mild applications. Adjusted them up once again the next morning and got them a little wet again and just nothing, right to the bars with the lever. These brakes are completely useless and a waste of time as far as I'm concerned.
I don't have all the time in the world right this second, but when I can mess with it the only thing I can think of doing is converting the rear to hydraulic disk as opposed to the useless mechanical setup. I figure it should be easy enough to build a caliper mount and then just run one line to the handlebar. I'll have to make the rotor stationary instead of the floating setup it is now. I'm thinking I'll just cut two lands in the axle for circlips that will hold the rotor where it needs to be. Ta-daa! It's not going to happen tomorrow but it needs to get done.