[A4] A4 clutchless shifting
tyson at up-times.com
Fri Apr 20 02:33:53 EDT 2007
By sitting at a light with your foot holding the clutch pedal you are doing
serious damage to the clutch system.
First of all, there is a bearing that is placed between the clutch fork and
the pressure plate - the throwout bearing. Some cars have a puller-type
system rather than a pusher system, but they too have a bearing there, its
just called a different thing. Anyway, this bearing is designed and
lubricated for short periods of rotation, for a second or so as you shift.
Holding the clutch down keeps this bearing engaged. It is not designed for
that wear, it is not actively lubricated and its internal lube overheats and
causes it to fail. Sitting at a 5 minute light, you are likely causing
enough wear to it to equal 500 or more shifts. The bearing itself usually
costs $20-45 on most cars, but to replace it, either the motor or the tranny
has to be removed, which costs in excess of $600 on most cars.
The second problem is that clutch disks do not move all that much when the
pedal is depressed. The space between the flywheel and the clutch when you
push the pedal is hardly wide enough to fit a piece of paper in. As a
result, there is still some friction between the flywheel and the disk. Not
enough to make the car move or spin anything, but still enough to make heat.
This heat will build up in the friction surfaces of the clutch (which is
effectively a big glorified brake pad) and cause it to glaze - or harden.
This in turn makes it brittle and the glazed layer (which is much more slick
and does not engage as well) will flake off. Ever overload and fry your
clutch by revving too high and dumping it? Then even after you let the revs
calm down, the clutch still won't grip? That's the glazed surface not having
enough grip to engage.
Either way, if you are in habit of sitting with the clutch pedal down, get
out of it!
Technical Manager, Uptime Technical Solutions LLC.
tyson at up-times.com
From: Rocky Mullin [mailto:caliban at sharon.net]
Sent: Thursday, April 19, 2007 11:19 PM
To: Tyson Varosyan
Cc: 'Doug Hill'; a4 at audifans.com
Subject: Re: [A4] A4 clutchless shifting
On Apr 19, 2007, at 11:17 AM, Tyson Varosyan wrote:
> Your friend has issues is he wore through a clutch in 1-2 years!
> Unless he
> was competitively drag racing (which means that he has issues
> anyway) he
> needs to re-learn how to drive a stick and get rid of bad habits.
> With the
> quality of stock clutches on these cars, I would be surprised that
> even "bad
> driving" would cause this kind of wear. He was either dragging a
> lot or he
> is one of those people that hold the clutch down at red lights.
is that how it's supposed to be? i pull it out of gear and let the
out at stops, but mainly out of laziness.
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