Three Pedals on the Floor: Different Strokes for Different Folks, Part II

Wayne Scraba

15 May 2014

In the first part of this series (SEE HERE), we began our investigation into two very different types of high performance clutches. The first (which we’re looking at here) is a single disc affair. But it has some twists. Instead of using a common diaphragm or Borg & Beck pressure plate, the McLeod setup we focused in on is a combination Long/Borg & Beck arrangement. It’s not new technology (McLeod pioneered this setup decades ago), but it still works very well, thank you. What you end up with in this curious mix of parts is the heavy-duty hat found in a Borg & Beck pressure plate, but with Ford style Long levers in place. More on this arrangement in the accompanying photos.

Backing up the package is a steel flywheel. It’s SFI approved. That means the piece passed a stringent rotational test (without disintegration or ever stress cracks). The last thing you need is floor and limb removal courtesy of a departing flywheel. And don’t laugh – it’s an ugly picture and it can happen all too quickly. That’s why high quality clutch components with SFI tags are extremely important.

The flywheel we showed you was a pretty light steel job at 25 pounds. You can get flywheels in plenty of different weights (typically 25, 30 and 40 pounds). The reason for having different weight options is due to the engine characteristics coupled with the vehicle weight. Honestly, a little 283 is going to need a bit more flywheel weight to move a heavy car than say a 427 in a something light like a Corvette.

So far so good. What follows is a more in-depth look at the pressure plate levers along with a look at how clutch disc technology has progressed. Bottom line here is, this “ain’t the Sixties” anymore. It is possible to mix old school proven parts with next technology.

The Ford Long style levers found on this McLeod pressure plate offer some big advantages over a standard Borg & Beck lever. The biggest is the fact they have quick ratios, and prove perfect for quick shifting. Equally important, the setup is extremely accurate and it just flat works on the street (and of course, the strip).

Here’s where modern technology meets old school: The “rag” or disc looks pretty conventional in the first photo – on the pressure plate side, it features an organic bonded, riveted face and sprung hub. Flip it over to the flywheel side and you’ll find the disc has a ceramic (segmented) puck bonded to the face.

What the multiple friction materials accomplish is to increase clamping power but at the same time, make the disc very “livable” on the street. It’s like having your cake and eating it too.

McLeod encapsulates three of the springs in the hub. They use a urethane material, which provides a dampening effect. This tends to reduce chatter in a sprung hub clutch disc. Basically, consider the urethane as a shock absorber for the sprung hub.

In Part III, we’ll dig deep into dual-purpose multi-disc clutches.