There are several ways to get 5 clutch frictions in the front clutch of our trannies. Although several companies advertise, a 5 clutch direct clutch, the different ways of doing it make a HUGE difference in how well they hold up over time.
You sort of answered your own question when you said, why not add as many as will safely fit. 5 is easy to get, 6 is possible with a little work, and I'm sure 7 is possible, but you have a lot of other factors to consider than just number of frictions. The thickness of the steels themselves as well as the thickness of the steel in each friction disc is important.
When a clutch is applied, it slips ever so slightly as it comes on. During this time, enormous amounts of heat is created. Thicker steel aborbs the heat and doesn't reach as high of a temperature as when thinner steel is used.
It's the same concept as using a heavy front cover on Torque converters to dissipate heat if you can't keep the clutch from slipping. If the clutch isn't slipping, no excess heat is created and there is no need for a heavy cover, but that is another issue entirely.
One way of adding 5 clutches to the front clutch is to use the . 060" forward clutches instead of the . 080" front clutches.
But this is a cheap way of getting there because the only difference in these clutches is the thickness of the steel portion. I ran a setup like this for a while and the steels actually warped due to excessive heat. I have one hanging on the wall as a display.
The proper way of doing this is to use the . 085" frictions that are designed for the front clutch. They resist warping over time and will live longer than the thinner clutches.
Also, clearance in a clutch pack is often determined by the number of clutches. So as the number of clutches in a pack increases, the clearance should also increase to resist drag.
So, if you add clutches and also need more clearance, where does this extra space come from? The answer is either thinner plates or custom parts and expensive machining.
Even though several companies may have the same marketing hoopla, once you get into the finer details of the system there are right and wrong ways of accomplishing the same goals.
The reason this is so fresh on my mind is because I spent today playing with Cord's new automatic. It was stock this morning and I spent several hours scratching my head today trying to make this thing live without buying any special parts. I got 5 clutches in there, but there is a better way of doing it than what I did. But it didn't cost him over $150 for the entire rebuild. I can't wait to ride in it tomorrow to see how well (or poorly) it works.
I hope this answers your question,
-Chris
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