Originally Posted by hemienvy
Mad, the project I'm working on next little by little is a 430" big block that I want to be able to shift at 7000-7200.
I have read your posts and am impressed by your knowledge.
I'm inclined to keep these old clutches for, I don't know what, some mystery future use.
But realistically, for this particular deal, I will tell you, I'm planning a Richmond 6-speed with 3.54 rear gears.
I wonder if a Long plate with an organic disc might be the best compromise.
I say "street driven" but the car doesn't know if a 7200 RPM shift is street or race.
But it's not 9000 and it's not a 600 inch motor.
It can't be that hard a compromise...........



Dont get me wrong. I have zero issues with the Borg & Beck plate. It’s fine. It’s all the base pressure. If the car is under 3800 pounds you can use an organic disc and you only need 2400 pounds of base pressure. 600 pounds may not seem like much but that’s quite a drop.

Years and years ago when I was still using that cover and I was at 3000 pounds of base I was having issues shifting above 6500ish. I fought it for a while and I was told the firewall was flexing, the linkage was flexing and all kinds of other stuff. I raised the fingers .100 and that made shifting quicker but it still wasn’t happy.

At any rate, I got on the phone with some Stock Eliminator guy I met in 1981 at a National event. I don’t even remember his name any more and not long after I met him he passed away. He was the one that told me all that stuff can flex and move but what you don’t see is the cover itself flexing. The way the levers are mounted to the cover and all that pressure makes the cover flex. When the cover flexes it makes the clutch drag because the plate doesn’t come off the disc evenly.

At that point to get the pressure down, we ended up running 9 springs. Of course, everyone was sure the clutch would explode without all 12 springs in there but it never happened. And it made shifting a blast. Plus, parts breakage went way down.

My car was light enough and had enough gear that I eventually got all the way down to 1800 pounds (that was only 6 springs) and it just got better. Of course, with bite you could get between 75 to maybe 100 passes on a disc before it had to be changed out.

Then I went to the soft lock and that’s even less plate load.

I would look at a good organic disc and taking some of that plate pressure out. If nothing else, your left leg and knee will thank you.


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston