Need help selecting a clutch

[Gerald Lewis]

Hi everyone, I've been running around in circles trying to decide on which clutch to get. I'm running a 470 low deck stroker, trick flow heads, solid cam I think 240/240 @50 and a rpm intake. Not sure on numbers since I haven't dynoed it yet.
I was looking at centerforce df and it seems like there's an equal amount of love/hate with that clutch.
Then I was looking at McLeod RST street twin and the McLeod super Street. Right now jegs has 10% off McLeod clutches. The rst looks nice but it's twice the cost of the others. Any help is appreciated, thanks

 

[SLOPAR72]

Hi everyone, I've been running around in circles trying to decide on which clutch to get. I'm running a 470 low deck stroker, trick flow heads, solid cam I think 240/240 @50 and a rpm intake. Not sure on numbers since I haven't dynoed it yet.
I was looking at centerforce df and it seems like there's an equal amount of love/hate with that clutch.
Then I was looking at McLeod RST street twin and the McLeod super Street. Right now jegs has 10% off McLeod clutches. The rst looks nice but it's twice the cost of the others. Any help is appreciated, thanks

Depends on what you are doing with the car.

The Twin Disk is a soft pedal with the clamping force of a dozen bears. Centerforce with the weights is OK too but I am not sure there is much of an improvement over an OEM setup.

For a street car I would probably do just a basic OEM clutch. If I was X Crossing or something road race worthy probably a Twin Disk. If I wanted to beat on it at the strip then an investment is in order for an adjustable clutch to get the car away from the starting line.

JW

 

[weedburner]

Ideally the clutch's holding power should be matched to the power you make, with very little reserve. Here's a simplified explanation- let's assume the engine makes 500ft/lbs and the clutch's capacity is 700 ft/lbs before it begins to slip. When you launch the car, that clutch is going to draw 700ft/lbs…the 500ft/lbs that the engine is making at wot plus another 200 ft/lbs of stored inertia energy that will cause the rotating assy to lose rpm. That extra 200 ft/lbs makes the launch more violent, but as soon engine rpm is drawn down to the point that engine rpm sync's up with vehicle speed, rpm ceases to drop and that transfer of an additional 200ft/lbs of inertia energy stops. The downside is that after you have lost the rpm and used that inertia energy, that spent energy then has to be paid back in full before the engine can recover the rpm that it lost. That inertia energy transfer which made the car launch harder initially now slows the car, as it reverses and some of the engine's power must be used to recharge spent inertia energy back into the rotating assy. In the end, that temporary 200 ft/lb boost did not actually net you any performance gain.

Why subject your transmission and drivetrain to that extra 200 ft/lbs if it doesn't net you anything?
What if that extra 200 ft/lbs of holding power gets you a broken transmission?

If a clutch with only 600 ft/lbs of capacity were used it would slip roughly twice as long, which means the car would be traveling faster at the point where rpm and vehicle speed finally sync up...much less bog. Not only does the transmission see less abuse, but the engine doesn't lose as many rpm after launch and after the shifts...the engine will be pulling from a higher average rpm where it makes more power.

 

[Gerald Lewis]

Ideally the clutch's holding power should be matched to the power you make, with very little reserve. Here's a simplified explanation- let's assume the engine makes 500ft/lbs and the clutch's capacity is 700 ft/lbs before it begins to slip. When you launch the car, that clutch is going to draw 700ft/lbs…the 500ft/lbs that the engine is making at wot plus another 200 ft/lbs of stored inertia energy that will cause the rotating assy to lose rpm. That extra 200 ft/lbs makes the launch more violent, but as soon engine rpm is drawn down to the point that engine rpm sync's up with vehicle speed, rpm ceases to drop and that transfer of an additional 200ft/lbs of inertia energy stops. The downside is that after you have lost the rpm and used that inertia energy, that spent energy then has to be paid back in full before the engine can recover the rpm that it lost. That inertia energy transfer which made the car launch harder initially now slows the car, as it reverses and some of the engine's power must be used to recharge spent inertia energy back into the rotating assy. In the end, that temporary 200 ft/lb boost did not actually net you any performance gain.

Why subject your transmission and drivetrain to that extra 200 ft/lbs if it doesn't net you anything?
What if that extra 200 ft/lbs of holding power gets you a broken transmission?

If a clutch with only 600 ft/lbs of capacity were used it would slip roughly twice as long, which means the car would be traveling faster at the point where rpm and vehicle speed finally sync up...much less bog. Not only does the transmission see less abuse, but the engine doesn't lose as many rpm after launch and after the shifts...the engine will be pulling from a higher average rpm where it makes more power.

That's a good point. I didn't think of it like that. So would I be fine with just a single disc in an 11 or 12" diaphragm pressure plate? I see a McLeod 11" with a sprung hub that says 3200 static pressure and a 12 inch with 2400 static pressure. Am I right to assume that the greater the static pressure the more torque it'll hold? I know the size of the clutch disc and facing material plays a big role in it also. I would go B&B but it's too much traffic here in Atlanta for that and I don't want a hammer clutch.

 

[AJ/FormS]

For street or?
What tires?
What rear gear?
Traction aider?
How heavy is the car?

For street and 295s or less, in an A-body,just about any old V8 set-up will work. Cuz if it spins, it don't need much to hold.
If you get too much clutch, even on the street,it will start to break stuff; like yokes, u-joints,crown teeth, and driveshafts.It will also beat up the cross-pin saddles on a cone-type.I haven't blown up any pinions or sidegears yet........But I really softened the hit after I broke stuff the last time.