Sort of a postscript (larger than I originally thought) to my earlier post #5.
The way I wrote the post, it could be inferred that I might be promoting McLeod. I am not. I am neutral toward the manufacturers, in general. Brent's guidance on his experience retailing the various manufacturer's products and the subsequent customer experience is a good guide/litmus test for who you should be looking at and who you might want to give a pass to. Advertising notwithstanding, real-world customer experiences are typically the best litmus test.
Be circumspect about friction material and your intended use; friction material can profoundly change the character and usefulness of your clutch. The other be sure to check, check point is to make sure you have adequate clearance inside your clutch can for the stack height of your twin disc selection. At the two-disc level, they can virtually always be made to fit; it is just that sometimes the fitment process might take a little more effort.
Another thought that I should have mentioned earlier is for easier shifting at elevated engine speeds, smaller diameter discs have less rotational inertia and are easier on your transmission's synchros. That said, I use a 10.5-inch diameter disc with a TKO that uses Liberty's carbon fiber synchros and shift rails with Liberty's modified interlock timing. This is a big improvement in the TKO shifting experience.
To do a clutch upgrade, you will need to have your transmission out of your car. Once it is out, there will never be a better time to do the Liberty TKO shift improvement kit upgrade with their bronze shift fork pads, billet shift dogs, modified TKO interlock rails, carbon fiber synchros etc. With the advent of the TKX boxes you might want to get to Liberty on the shift improvement stuff sooner rather than later. At some point I would not be surprised to discover that they would stop offering TKO enhancements.
PPS
In order of easiest to most difficult to shift at elevated rpm, your pressure plate choices look like;
- Diaphragm
- Borg & Beck
- Ford Long Style
- Ford long Style w/counterweights
Anytime a clutch uses counterweights to lock up, it will be more difficult to shift at elevated engine rpms. Counterweights can appear in any of the four choices. Best to stay away from them. Dual disc clutches require less plate load because of increased friction surface area attributable to the second disc.