[DeTomaso] clutch?

[JDeRyke at aol.com]

In a message dated 11/25/08 12:21:46 PM, ehpantera at yahoo.com writes:

> I'm in the process of putting in a new clutch assembly. I would appreciate 
> an explanation of the differences and benifits between McLeod and 
> Centerforce. How well does the internal slave cylinder work?
> 
The stock Ford (or McLeod) clutch- called a Long-type or three-finger, uses 
three levers to depress the clutch against 6 or more rather stiff coil springs. 
To help hold even more torque at high rpms, there's often a blob of steel on 
the levers' far end which responds to centrifugal force and increases 
pressure. On a Pantera with a stock bellhousing, the lever weights won't clear the 
internal stiffening ribs and must be removed. The disengagement distance is 
marginal.

The Centerforce uses a single very large disc-shaped bellville spring to 
provide holding power with slots in the big spring providing the levers to release 
it. Due to the better leverages, a Centerforce will be easier to push in for 
the same holding power. Centerforce uses sliding weights in the slots forming 
the levers to add some centrifugal holding power, that do clear the Pantera 
bellhousing. Both designs work fine (with only marginal disengagement distance 
possible) and both weigh about 16 lbs but they use different bolt patterns and 
bolt sizes. So you must either redrill & tap an existing flywheel or replace 
the flywheel with a new one. This does give you the opportunity to add an 
aluminum flywheel, giving a little more power and drop some weight but costs quite 
a bit extra. Most aftermarket flywheels are stronger (and safer) than stock, 
and come pre-drilled for almost any clutch.

Annular throwouts work much more efficiently than the stock sliding lever and 
multiple bellcranks, all of which add friction to the system, and it drops 
some 8 lbs from the engine weight. They are typically much easier to push in due 
to the complete lack of sliding friction in the system. They will work with a 
stock clutch master cylinder and often increase the amount of disengagement 
you get, lengthening ZF synchronizer's life. They have two big disadvantages: 
first, if ANYTHING goes wrong, you must pull the ZF to correct it. Second, the 
initial setup is absolutely critical since the internal quad-seal is not 
designed to spin, only sealing linear motion. So when the bellhousing and transaxle 
heat up and expand, if there's not enough free clearance, the hollow piston 
starts spinning with the flywheel and wears out the seal in 50 or so miles, 
forcing a ZF removal and a tricky rebuild. They are also fairly expensive.
FWIW, I've had a stock Long clutch and annular throwout on Judys car for 15 
years and the combination is quite easy to push in. I had several problems with 
early design throwouts initially, but for the last 12 years its been fine. 
Good luck- J Deryke


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