Date:         Tue, 18 Oct 1994 18:44:38 -0700
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         wabbott@townshend.Corp.Megatest.COM (William Abbott)
Subject:      Re: Syncro Estasy, spins, ABS


> >BTW, the Synchro is an amazing option. With studded snows it is an 
> >awesome winter-mobile.  Could use ABS, though, as my wife found out in a 
> >little spin out last winter.  
> 
> (Actually, the syncro doesn't need ABS since the viscous coupling tends to
> distribute even braking force equally between the front and the rear of the
> vehicle.) 

	Distributing braking force and ABS are two different things.
ABS, usually, moitors wheel speeds and modulates the brakes to prevent
any of the wheels from locking up. When it senses a wheel slowing down to
a stop, it momentarily releases brake pressure on that wheel. Typically,
ABS is fitted to 2WD vehicles, like my Corrado, but my friend Kevin has
rear-wheel-only ABS on his GMC 3500 4WD. As the name suggests, it keeps
the rears from locking, but doesn't affect the fronts. I'm not sure it
works when in 4WD, and that brings us to the Synchro.

	As I understand 4WD, with limited-slip differentials, the wheel
speeds are all related to each other. You can't stop one wheel and have
the other three turn, or break one free and spin it. The effect is much
like ABS but not exactly the same thing. You can loose traction, but you
can't get too far from it on or two wheels at a time.

	So you can spin a 4WD vehicle, but you have to loose traction
on all four wheels to do it. Most typical spins are conducted by locking
the rear wheels, which lowers their coefficient of friction compared to
the fronts. If the driver holds the brakes on, the fronts, having more
traction and thus generating more slowing force, will try to get behind
the rears.  

	On days of amazing rain, I've gotten my Corrado sideways by 
stomping on the brake and turning the wheel, but it takes effort and 
if you just let up, it goes straight.

	I remember reading that a Synchro cannot be towed, since the
drive train can't be disconnected and the system doesn't like to driven
long distances with power flowing in from the wheels. This suggests that
the Syncro is always in 4WD. Is that true?

	Cheers!
	Bill

(What do you call a 4 humped camel in Jiddah? 

A Saudi Quatro!)