[DeTomaso] Flywheel recommendation-long

[JDeRyke at aol.com]

In a message dated 1/20/08 7:24:16 AM, wkooiman at earthlink.net writes:

> By the way, while the (Fidanza) flywheel is very light, the pressure plate 
> is not. I have it all apart right now.  I'll put everything on a scale and 
> post the results.
> 
When fiddling with my 16-lb aluminum flywheel, I weighed an OEM Long clutch 
and got 16 lbs. Then I weighed a Centerforce and also got 16 lbs. The friction 
discs are virtually identical. I'm interested in what weights you find, Will.
> 
> ...What I really want to try is a small dual disc circle-track type clutch.  
> I know at least one person that is running Dennis Quella's racing dual-disc 
> on the street.  He doesn't have any problems with
> it.  There's no chatter, and it doesn't bog.
> 
Chatter and bogging are not the problem. The separation distance for a single 
clutch disc in a stock Pantera clutch setup is barely 0.040"- that is, 0.020" 
on each side of the supposedly free-spinning disc which   has a 'crush 
thickness' and wobbles. Adding a second disc means that the separation of each 
friction surface is now half what a single disc has- and that was marginal to begin 
with, unless you re-engineer the hydraulic system or the pedal ratio- or both 
at the same time. Even a long-throw slave doesn't truely give enough 
separation on most stock systems. Less disc separation means more drag on your ZF 
synchros each time you shift- and we all know how expensive THAT wear is to repair 


Dual-disc clutches are really meant for big engines with enormous torque that 
a single disc just cannot hold, or for pro-racing so one can run a small 
flywheel and lower the whole powertrain without a big flywheel dragging on the 
ground. Real racecars use 5" dual or triple-disc clutches with the oil pan 2" off 
the ground for a lower center of gravity. I'm told the commercial dual disc 
setups for Panteras (and 454 Corvettes) iare simply two std 11" discs on a std 
dia flywheel, so engine lowering isn't possible. 

IMHO, a modern racing Pantera would likely be running a GT-40/Mangusta-type 
6-speed ZF which will lower the powertrain some 4" for better handling. The 
only street DeTomaso on which a dual-disc clutch & smaller flywheel really makes 
sense is the Mangusta- which in stock form with 50-series tires does sometimes 
drag its 157-tooth flywheel. But a 5" or 5-1/2" dual disc sprint-car system- 
good for 700 bhp- costs around $2500, so I've yet to meet a 'Goose owner 
interested at that level. A small diameter flywheel automatically means a 
relocated, reverse-running starter strapped alongside the ZF in a custom bellhousing, 
and a custom oil pan with custom engine & ZF mounts. There's probably more 
special parts needed that I haven't thought of. I'd be glad to help if someone 
really wanted to dig into such a neat engineering project- at your garage & on 
your car, not ours! FWIW- J DeRyke 





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