I don't have a problem with the different friction materials, or even the dual friction disc, they just need to be matched with a pressure plate that provides an appropriate amount of clamp pressure for that friction material and application.
The problem is the typical aftermarket manufacturer doesn't give you many choices when it comes to clamp pressure, they instead generally adjust torque capacity by varying the friction material. Since there are only a few common friction materials available, the step from one to another can be pretty big.
The typical aftermarket 10.5" diaphragm pressure plate has around 2800lbs of clamp.
......with an organic disc that's ballpark for around 500ftlbs.
......with a typical dual friction, now it's ballpark for around 650ftlbs.
......with cerametallic or iron disc, it becomes ballpark for around 820ftlbs.
So what do you choose if you have a street/strip car making say 550ftlbs, more than what the organic disc can reliably take? The next step up is dual friction, which has about 30% more clamp pressure than what is ideal for 550ftlbs. If you go for the cerametallic or iron disc it's even worse, about 64% more clamp than what's ideal for 550ftlbs.
Excess clamp pressure is what makes clutches act like on/off switches. The more excess you have, the worse it gets. The more excess you have, the more bog/spin you get, also the harder it beats on your drivetrain. Excess clamp pressure means higher than necessary pedal effort as well.
To me it would make more sense if we could choose the friction material for the application first, and then choose the clamp pressure to suit the application. Street applications would most always get organic single disc up to about 500ftlbs to keep pedal effort acceptable, organic dual or triple disc above that. Street/strip could step up to more aggressive friction materials that would be less street friendly but last longer under extreme conditions.
Diaphragm clutches are easier to operate for a given clamp pressure, and the clamp pressure stays in a tighter range over the life of the disc. Wouldn't it be nice if someone made diaphragms available in 200lb increments from 1200-2800? Not likely to happen.
They do make adjustable clamp Diaphragm, Long, and B&B pressure plates, so that's an option if you can find one with a suitable range.
What do I do? I'm a guy that likes to get more than expected out of common affordable parts. For my street/strip applications I take the common 2800lb PP, and then use my clutch hit control products to make that 2800lb pressure plate initially hit like a much softer 1800-2000lb unit, then transition to hold like a 2800lb unit. Softer hit on the drivetrain without giving up any of the holding power.
Grant
