Date: Sun, 19 May 2002 00:40:49 +1000
Reply-To: Andrew Jack <andrewxp@AJ.DNSALIAS.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Andrew Jack <andrewxp@AJ.DNSALIAS.NET>
Subject: Re: anti-sway bar (longish)
Content-Type: text/plain; charset="iso-8859-1"
John,
A diff lock goes a long way to eliminating the shortcomings of a sway bar
off road. Basically, by locking the diff you will still have traction even
if one rear wheel is unloaded or in the air. As mentioned by Dave
Carpenter, the sway bar does not limit *total* wheel travel, just
independent travel. You could still come unstuck (literally) if the surface
is slippery and two driven wheels would give you progress, but one is
insufficient.
Robert Keezer's example was good, but did not cover the case where there may
be changing levels on the road, and for example the left front and right
rear wheels are up, and the right front and left rear wheels are down. With
limited articulation, this can result (if stopped) in the vehicle
see-sawing or pivoting on a line left front/right rear. A sway bar will see
this happening earlier, which was my originial point. Even a four wheel
drive (without difflocks) will be stuck. Your diff lock would save the day,
with the proviso, as stated above, that one driven wheel can provide enough
traction to extricate the vehicle.
As for when the diff lock should be engaged, IMHO only when traction loss is
imminent and at the lowest practicable speed. In most cases, except when
very slippery, the diff lock can be engaged once you become "hung up" and it
will save the day - this method also has the advantage of the vehicle
letting you know "I'm almost at the limit". My Audi 80 quattro has a
pushbutton diff lock that automatically disengages when the speed rises
above 15mph. A diff lock has the effect of trying to make the vehicle go in
a straight line if both wheels on the locked axle have traction - ie loss of
steering effectiveness. This is even more pronounced with a front diff
lock. If the diff lock is engaged on a high traction surface, axle torquing
could cause something to break (probably the most expensive component).
As an example of how a diff lock can be used, a couple years back I was at a
ski resort, and we had a decent (for Australia) dump of snow (10-12" IIRC).
The access roads and main carpark were duly plowed, but not the carpark I
was in (along with several full size 4WDs and a few 2WDs). We needed to
reposition the vehicles to fit a few more in, and the 4WDs manouvered with
much wheelspin, sideslip, snow flying everywhere, foul language and general
lack of control. The 2WDers witnessed this and stayed put. I decided, ok,
I'll get out of the carpark and let the other guy in (Honda Accord, with
chains), then bring my car (Audi 80 quattro, no chains) back after he's
finished fooling around. So, without any fuss, I proceeded to exit the
carpark. On a steepish slope I engaged the diff lock as there was (slight)
side slippage. The Honda then couldn't even make it 10' into the carpark,
despite chains, lots of run ups and cussing. I then proceeded back into the
carpark, again no fuss thanks to the diff lock (& AWD) and parked where I
had been before. A crowd of onlookers, who had been there from the start,
was totally amazed by how in control and effortless my maneuvering was
compared to the 4WDs (messy) and the chained 2WDs (ineffectual) and several
looked at my front wheels and said "how did you do that without chains and
in an ordinary car?".
In regards to articulation, in this context, I was refering to each wheels
ability to "touch(ing) the ground at the same time", but more specifically
relative wheel travel - ie a sway bar reduces articulation - or relative
wheel travel - between the linked wheels.
Andrew
----- Original Message -----
From: "John Clemens" <jbclem@earthlink.net>
To: "Andrew Jack" <andrewxp@AJ.DNSALIAS.NET>; <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, May 18, 2002 9:09 AM
Subject: Re: Re: anti-sway bar
> Andrew,
>
> I'm just seeing this thread and your answer brings a few questions to
mind:
> I have an 2 WD '83 Westphalia watercooled with a transmission converted
to
> have a vacuum operated locking differential(from a Syncro). How do you
> think it would work on bad roads with a rear sway bar and the diff lock
on.
> How about on the highway? By wheel articulation do you mean the fact that
> all wheels are touching the ground at the same time?
>
> John
>
>
> ----- Original Message -----
> From: "Andrew Jack" <andrewxp@AJ.DNSALIAS.NET>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Friday, May 17, 2002 1:47 AM
> Subject: Re: anti-sway bar
>
>
> > ----- Original Message -----
> > From: "Robert Keezer" <warmerwagen@HOTMAIL.COM>
> >
> > >I think that you can only gain by adding a anti-sway bar.
> >
> > Except if wheel articulation is important to you. Probably more of an
> issue
> > in a Syncro, but if you are trying to drive a 2WD on rough tracks this
> just
> > puts you further behind the (all wheel drive) eight ball.
> >
> > As usual, it's a compromise. I would rather put up with the rock'n'roll
> > (and drive accordingly) on road, and know that I have full wheel travel
> when
> > in semi off-road conditions.
> >
> > Andrew Jack
> > Australia
> >
> > '92 T3 Syncro
> >
>
>
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