[DeTomaso] Will a twin disk clutch with a Borg and Beck Long style pressure plate fit?

[Ken Green]

Jack,
 
    The whole point of the twin disk clutches is that you get twice the holding with the same spring force, so your observations on the damage caused by a stiff clutch are addressed by using a twin disk clutch.  People are using them in Panteras, Art for example, and they work, so there must be sufficient disengagment.  But, Art had a diaphram pressure plate, which I believe to be thinner than a B&B, L.  The one I'm looking at is rated for 900 ft-lbs.
 
    I realize that it has to fit to be useable, that's why I asked.  Someone told me that the stock pressure plate is B&B, L, so appearently they can fit, but I'm worried that the spacing added for the twin disks may be too much.
 
    The questions you raised are good, and I'll try to get answers. 
 
Ken

--- On Wed, 9/17/08, JDeRyke at aol.com <JDeRyke at aol.com> wrote:

From: JDeRyke at aol.com <JDeRyke at aol.com>
Subject: Re: [DeTomaso] Will a twin disk clutch with a Borg and Beck Long style pressure plate fit?
To: kenn_green at yahoo.com, detomaso at realbig.com
Date: Wednesday, September 17, 2008, 9:51 AM


In a message dated 9/17/08 9:05:50 AM, kenn_green at yahoo.com writes:


One is a race clutch that probably fits with no issues, but it's not clear that it's streetable.  The other is their Street Twin with a Borg and Beck/ Long style pressure plate and it looks like (from pictures on the Mcleod web site) that the pressure plate is spaced away from the flywheel to make room for the two disks, and it's nto clear to me that it will all fit inside a ZF bell housing.

Just 'cause its on sale doesn't make it a deal. Its also not clear that a stock Pantera hydraulic clutch system will have enough travel to release a twin disc clutch, since our cars barely have enough clutch travel to release a single disc; two discs will need twice the travel to even be marginal. So you might need some wholesale changes to get the thing to work as well as a stocker. This sounds like the solution to a problem no street guy has, and will likely wear out your ZF synchros faster than ever. 

FWIW, 'race' clutches usually have super-stiff springs to wear out your leg in traffic, and a disc with no marcel or shock-springs so you always get some chatter on take-off. Finally, stiff clutches react far more force into the block each time you step on the pedal, which wears out the small crankshaft thrust bearing. Then when the tiny bearing surface is gone, wear allows the crank to move fwd & back too much, bending the connecting rods. Con-rods won't take much bending before you saw the block in half when a rod fails at speed.
If you're convinced you really need such a thing, maybe for a foaming-at-the-mouth big-block or a big supercharger, I'd ask McLeods tech service guy what this clutch is rated for- 2200, 2400 or 2600 lbs, and what height or thickness is the complete assembly? I'd also ask them how the stiffness compares to their 'stock' 11" Long clutch. Borg & Becks are sometimes smoother acting due to the internal rollers but if the thing is too stiff to live with on the street, thats a definite drawback.  FWIW- J Deryke


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