Technical Another question..... (clutch & pressure plates)

Does anybody make an Aluminum pressure plate? OR a light weight clutch that could be used on a street machine?
I'm wondering...........uh-oh...IF the assembly was made of Alum. it would be a good bit lighter than the standard steel units. Maybe not as light as an Alum. flywheel but still..........
Would dropping back to a 10" clutch vs an 11" clutch make a difference in quick revs? (I know----I know the gripping strength may be lessened all according to amount of HP and torque/weight/rear gear that is there.
More of a good 'bench-racing-question' really.......
6sally6

 

No street clutch that I'm aware of has an alum hat. In multiple disc units in racing where there is the need for adjusters and spring cups, alum and titanium is common. There is a formula to figure out mass versus diameter to determine if smaller is better. You still need so much disc area so the amount of area versus the pressure plate spring pressure is where the answer will be. I use the light weight flywheels more because I like the sound than the performance.

 

Are you thinking of the housing in a PP? Can’t imagine a steel one causing extra rotational drag, what maybe 1-2 pounds of weight?

 

I seem to recall hearing of an aluminum pressure plate made by I think it was Scheifer.

 

Me thinks you are onto something!
Yeah, I have been known to "over think" things too, a friend of mine would come over to check out my "Rube Goldberg of the month" and say "still trying to outdo yourself I see".
Carry on!

 

@studebakerjoe - I just sold one of these in the classifieds - it was a Schieffer and had an aluminum plate. Kinda neat set up.

 

Tell me about it!!...........
Aluminum pressure plate??!
Light-weight clutch??
I know about Alum. flywheels
6sally6

 

I’m not sure really. It came with a pile of parts I bought and didn’t have a clutch or flywheel with it. I’ve seen them on eBay also. Sorry, don’t know much about it!

 

Black Magic Clutches sell a “Defiant” 10” aluminum long style clutch. Ram clutches sell the same clutch assembly. Be prepared to $pend $ome cash.

 

The problem with aluminum is the higher rpm you need to get the car moving from a stop. The steel has lots of rotating mass and energy, when you release the clutch that energy is your friend. Not so much with the aluminum, the engine will try to die and you'll be on & off the clutch pedal trying to seek a balance to get the car moving.

 

Here's something to think about. Actual Racepak data collected from my personal 2525lb driver/car, with some rough calculations applied. Sbc power, but exact same car/trans/flywheel/clutch/gearing/tires. Also exact same heads/intake/carb/cam/compression. Only difference between these two engines was the rotating assy...

Scat cast crank (49lbs), steel rods, 1863g bobweight, WOT no-load rev rate of 8500rev/sec.
In 3rd gear @ 535rev/sec accel rate, 31.47ftlbs gets absorbed by the engine's rotating assy, 468.53ftlbs makes it to the transmission's input shaft.
In 1st gear @ 1975rev/sec accel rate, 116.18ftllbs gets absorbed by the engine's rotating assy, 383.82ftlbs makes it to the transmission's input shaft.

Scat F43 lightweight crank (42.1lbs), aluminum rods, 1492g bobweight, WOT no-load rev rate of 11,515rev/sec.
In 3rd gear @ 541rev/sec accel rate, 23.49ftlbs gets absorbed by the engine's rotating assy, 476.51ftlbs makes it to the transmission's input shaft.
In 1st gear @ 2217rev/sec accel rate, 96.27ftllbs absorbed by the engine's rotating assy, 403.73ftlbs makes it to the transmission's input shaft.

Comparing the two...
...both engines put out the same torque when operating steady state @ 5000rpm.
...same flywheel/clutch for both, only difference was weight of crank/rods.
...bobweight difference was about 3.27lbs, crankshaft about 6.9lbs. A little over 10lbs total.
...WOT 4500-5500 at 3rd gear acceleration rate, the lightweight rotating assy hits the transmission's input shaft with about 7.98ftlbs more torque.
...WOT 4500-5500 at 1st gear acceleration rate, the lightweight rotating assy hits the transmission's input shaft with about 19.91ftlbs more torque.

The Flywheel/clutch weight is typically centered farther from the axis of rotation than the crankshaft, making it an even more effective place to lose weight.

Grant

 

you can also look into a lighter weight driveshaft