[DeTomaso] Clutch Options-long

[JDeRyke at aol.com]

The DeTomaso bellhousing fits so closely around the flywheel & clutch that 
ANY clutch you use should be checked for protrusions before bolting it on. The 
3-finger Long clutch cannot have centrifugal bob-weights on the levers or they 
will crash into and break the cast inner bellhousing braces on the 1st 
revolution of the engine. All Mustang clutches have bob-weights. Centerforce 
diaphragm clutches don't have protrusions but fit close enough that a snap-in plastic 
cover on the upper vent hole will not stay in place. 

Centerforce clutches use 3/8" dia shoulder-bolts-with stand-offs, and a stock 
flywheel is tapped 5/16", so either a new flywheel is needed with 
Centerforces or a good machinest to retap your old flywheel. Using 5/16" bolts in 3/8" 
holes guarantees a sloppy fit and vibration. Using 3/8" shoulder bolts with no 
stand-offs will leave the clutch loose on the flywheel with the bolts tight. 
Finally, there are several bolt patterns possible with various clutches, and 
redrilling/retapping a flywheel correctly is tricky. Some aftermarket flywheels 
have several patterns drilled & tapped but the hole diameters needed also vary.

Third, once you've assembled everything, the disengagement distance at the 
flywheel (with clutch pedal flat to the floor) must be at least 0.040" as 
measured with a feeler gauge thru the access hole in the bellhousing (engine OFF). 
This means that disc is only 0.020" clear of both flywheel and clutch, which is 
not really enough but is the best we can do in a Pantera with all-new stock 
parts. 

A too-thick clutch disc will make it all but impossible to get any release at 
all. A long-throw slave cylinder will increase the disengagement measurement 
a bit. Worn over-center linkage under the dash (L-models only) will reduce the 
disengagement distance, as will a sloppy fit of the slave in its bracket on 
the bellhousing, or a master cylinder that internally bypssses pressure. All 
this effort is to prevent extra clutch drag and wear while shifting your 
expensive 35-year-old ZF synchros. 

You will likely need to readjust the lever at the bottom of the slave 
cylinder one or more splines on the shaft going into the bell housing, in order to 
prevent the throwout bearing from constantly riding on the clutch. When you do 
this, its possible for the lever to hit the bellhousing in an area not easily 
visible. Unless the bearing is a constant-contact type, it will quickly wear 
out if there's no free play- also wearing out the clutch fingers on either type 
of clutch. Because replacing the throwout or pilot bushing is such a chore in 
a Pantera, I advise replacing them anytime the bellhousing is removed.

When replacing the pilot bushing inside the crank, check it first with a 
magnet. Many "bronze" bushings these days have iron filings in them to make them 
cheaper, and such a bushing will wear the ZF shaft nose, as will a roller 
bearing if it siezes 6 months later

Unless you've done this stuff before, or are an excellent trouble-shooter 
with lots of spare time, I really advise you to buy a whole package from one of 
the vendors, rather than trying to piece something together from the hot-rod 
shops that may save you $15 initially but cause $eriou$ problems later. With a 
vendor, when things go wrong you've at least got someone to call for answers or 
warranty claims.   IMHO, this is NOT a simple job; good luck- J DeRyke



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