Arg.. I am typing all this a second time after it disappeared...
Not to further muddy the water, but I also have a HVDA in my TR3.
To not have a shake/shudder the proper bronz(?) bushing must be installed into the end of the crank -under the flywheel. The early cars (like mine) have a deeper recess machined into the crank than the newer ones. Most use a short bushing. The bushing must be a snug fit onto the transmission input shaft, and also fit snug into the crank. If you put a later bushing into an early crank, it will slide forward too far, and the input shaft will not reach the bushing -ask me how I know... The bushing keeps the input shaft centered into the center of the crank, and aids smooth operation of the clutch.
Also, Herman sourced his clutch discs from the best sources he knew. But on at least one occasion, the vendor subcontracted the manufacturing of the discs to a cheaper manufacturing facility. One thing that happened is the retainer that holds the springs was reduced from a rectangular hole with beveled sides, to simply a rectangular hole without the beveled sides. This resulted in a plate that worked, but over time, the springs dug into the non folded sides, eventuality cutting far enough that the springs were no longer retained in the hole, and caused complete clutch failure (ask me how I know).
The second set of parts I purchased from Herman were on 3/23/16. The disc was $105.00, the (tr6 style) pressure plate $130, the long input shaft bushing $14.00. I'm sorry but I don't have the generic part numbers or sources. I also cannot find my pictures of the failed clutch compared to the new clutch. Before you install your new disc, I highly recommend you make sure the springs are retained by FOLDS in the plate, and not simple holes cut.
I enjoyed speaking to Herman, and he really knew his stuff. I love the HVDA, even tho I have had a few problems. If I can help in any way, please tell me how.
Jer