alexandervdr

I am trying to find a light on the foot clutch for my 1964.
Does the 250hp spec C2 has the same clutch as the 365hp? If so, then I assume lower powered sbc could go along with lighter/lower pressure clutch plate than the one originally put in? I have a smooth driving style, don't like to rev up, no drag starts. Any recommendation?

65tripleblack

They all used the same, standard duty clutch. Any standard clutch from Hays, Luk, Ram, BWD (Borg Warner) will be sufficient. Centerforce flyweight system is a gimmick.

midyearvette

others will chime in on this im' sure...speaking from experience, the centerforce II, although expensive, has to be one of the lightest and best holding clutches out there...i have used them for years in many cars including our vettes with zero issues...jmo...good luck...

1snake

Get a complete Luk package from Carolina Clutch for less than $150. Luk makes most of the OEM clutches. I've used them in everything from stock small blocks to built big blocks and never had one fail and they have a very light pedal pressure like the originals.

Jim

kellsdad

alexandervdr,
The amount of foot pressure required to operate the clutch is a function of three things: the springs that have to be compressed (e.g., the pressure plate release springs), friction where the linkage pieces meet, and the geometry of the pedal and linkage system. Going to less than stock spring pressure may reduce the holding power of the clutch. Of course the linkage should be lubricated and in good working order. That leaves the geometry of the pedal and linkage system. The fundamental rule here is that anything you do to reduce the foot pressure on the pedal will require you to increase the distance the pedal has to travel to release the clutch. For example, it's theoretically possible to cut the pressure in half if you're willing to double the distance the pedal has to travel to release the clutch.

For practical advice, I'll start by assuming your clutch assembly works like my 1963 Corvette. If that is true, then there is an option described in the Shop Manual for repositioning a bolt on the clutch pedal bracket to "provide the precision feel of fast release and permits more rapid gear shifting." If the clutch in your car has this option employed, your clutch will require a heavier than stock pedal pressure. You can reduce the pedal pressure by going back to the stock pedal bracket configuration.

KC John

I totally disagree with this statement. I just went from a generic pressure plate (Hays, Ram, etc.) to a Centerforce II and the clutch is definitely lighter than it was. I've been using them for years and I think they are great for reducing pedal pressure.

The pressure used to make the bottom of my foot sore if I drove for too long with soft shoes on. I couldn't wait to change and it worked as expected.

alexandervdr

Do you happen to know the product code of the Centerforce II kit?

Thanks

midyearvette

now youre talkin'....go to jegs or summit and look for a 10.5 or 11 inch whichever you need
i can depress my clutch pedal by hand!.....wifey loves it too, but they are a bit pricey......

MikeM

The operative phrase here is "standard duty". I don't think Hays makes a standard duty clutch but Ram, Luk, Borg Warner and CenterForce do.

I could be wrong about Hays.

TC233

Woww I know 2 members that will like that info, this member with a bum knee and a buddy of mine here, thanks for this I did not know that. When I got mine it took 40 pounds foot pressure to push the clutch to the floor, at a long traffic light, my leg looked like it was having an epileptic fit.

1snake

The OEM, LUK 10.5" clutch in my 60 takes 12 pounds of foot pressure to depress. It holds great for 1 gear burnouts and has enough bite to squawk the tires going into 4th gear. It's a pleasure to drive in traffic and I have a bad left knee.

Jim

midyearvette

if your clutch was set for the quick release, you would readily know it as it takes most all of the travel out of the pedal.....everything works very closely to the floor and takes much more pedal pressure to work it.....

MikeM

Yep! That's the way they should work!

alexandervdr

At the end of the day, this is the only relevant number: anyone does better than the 12 pounds of foot pressure?

Rokndad

I'm nowhere near home so does anyone have a picture of this adjustable bolt geometry? I'm the other member Dennis (TC233) mentioned.

Mako72

I tried the CF Dual Friction years ago and had a vibration problem. The weights would not center, causing a vibration. I switched to a McLeod and only had slightly more pressure but the vibration was gone. In retrospect, I spent money to have my motor balanced at the machine shop when it was built and I don't want to hang a clutch on the end of the crank that has moving weights. That was MY experience but others have had luck with their CF DF's.

65tripleblack

There is a phenomenon, called overcentering, which most people here are familiar with. If anyone speed shifts at speeds of 7000-7500RPM, then overcentering can be a problem unless you:

1. Put a block under the clutch pedal to prevent travel to the floor, or
2. Adjust the clutch so as to allow maximum free play.

The idea is to prevent the Belleville spring of a diaphragm type pressure plate from overcentering at high RPM's by causing the friction disc to disengage, but not to travel any further beyond the point of disengagement.

The flyweights used by Centerforce will exacerbate this condition if it occurs on your vehicle because the flyweights will apply clamping force to the overextended Belleville spring, which actually forces it to further overcenter.

kellsdad

I couldn't find a good picture online, so I'll try to describe it in words starting at the clutch pedal and working up. The pedal is welded to an arm that goes up and bolts to the "clutch bracket assembly." This assembly is roughly shaped like a Y with the clutch pedal bolted to the bottom of the Y with two bolts. The arm of the Y toward the rear of the car has the stop that limits the rearward motion of the pedal as it is being released. The arm of the Y toward the front of the car is attached to the axle that allows the entire assembly to pivot when the pedal is pressed. The clutch rod connects to the clutch bracket assembly near the center of the Y.

According to the Shop Manual, the procedure to adjust the pedal release throw is:

• Disconnect the return spring
• Disconnect the push rod from the clutch assembly bracket
• Loosen the lower bolt on the clutch assembly bracket
• Remove the upper bolt on the bracket, rotate the bracket to align with the alternate hole, and install the upper bolt
• Discconect the push rod at the cross shaft, rotate 180 degrees and reconnect the push rod
• Reconnect the push rod to the pedal bracket and tighten all the bolts

The picture in my Shop Manual doesn't make it clear how this action changes the geometry. But as the pivot point is at the top of the assembly, it must either move the push rod away from the pivot and toward the clutch pedal, or it leaves the push rod where it is and moves the pedal closer to the pivot point. I suspect the latter.

Rokndad

Thx kellsdad. When I get the chance I'll crawl under there and take a look.

JohnZ

This thread is beginning to take on the flavor of "How many forum members does it take to change a light bulb?"; just get the proven LuK replacement and you'll be happy.