[DeTomaso] Clutch Options-long

[Paul - Home]

This won't get you more clutch disengagement (the 0.040" that Jack is 
talking about).  This can give you more free play before the throwout 
bearing hits the clutch.  But you can also get this same (throwout 
bearing to clutch) clearance by properly adjusting the slave cylinder 
and the stop.

Paul
#9270

cengles at cox.net wrote:
> Dear Jack,
> 
> Dumb question: I have been told that one *could* take the throwout bearing (I think that's right....) and have a machinist remove .030" off of it. This is supposed to a) have no detremental effect on the bearing and b) provide extra clutch-flywheel disengagement room, perhaps in excess of .050-.060". Is that true? Seems like an attractive modification, so there must be some downside to it.
> 
> Easily fooled, Chuck Engles
> 
> 
> 
> ---- JDeRyke at aol.com wrote:
>> 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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