Date:         Wed, 7 May 1997 23:03:05 -0400
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         kelphoto@mail.bright.net (mark keller)
Subject:      Re: Clarification on Handling of Vanagons

David,
        I'm by no means an expert, but this stuff does fascinate me.  I
agree that the  westy's I drove, all early 80's models, seemed to be softer
than the, I think, 400lbs of weight added would seemingly account for.
4400 vs 4800lbs. I feel that the short wheel base, 95 inches might
contribute to your reporting a  differnt feeling with respect to cornering
on the Westy chassis vs your Wolfsburg chassis. This short distance from
the tire to the polar axis, the rear wheels, requires the front tire
sidwall to be stiffer, more ply or a lower profile, 60 series, than a tire
on a 10 or 15 inch longer chassis.  The longer the distance the greater the
leverage.  So with the added weight of the camper, the tires are at even
more of a disadvantage, with respect to generating cornering force. About
the springs and sway bars.

 Do they make an air shock for the vanagon? Again another article spoke
about increasing the spring rate on the rear by torqing a ratchet type
device, but I think it was a pre vanagon article.  Does the vanagon have
the same type of gizmo?

In your responsem to me you said

"On smaller/stiffer sidewall tires in the front only - this can cause very
>bad handling.   Reason is that  the slip angles of the front and rear tires
>will then be different, and this will cause one one end or the other to
>grip and start lateral force sooner in the initiation of a turn than the
>other end.
>This effect is most pronounced when the front end tires have a larger slip
>angle than the rear (as when I put on snow tires in the winter),  but I've
>also experienced very vague handling with the reverse condition also.
>With an extreme mismatch it feels like balancing a broomstick.   The
>extreme example that is always cited is putting on radials in the front and
>bias-ply in the rear (makes the car undrivable)."

       I don't completly understand your explantion. I wanted to ask what a
slip slip angle is? I talked with a mechanic friend who said that it is the
Attitude of the body on the suspension. Ie one end of the vehicle higher or
lower than the other.  He offered to get a copy of the information to me so
I have not seen it yet?

       I'm not sure if my saying that smaller tires up front is being
interpreted the way I had intended. I felt the low profile tire ie a 60
series vs a 70 series, of the same brand was a second choice I did not give
much thought to other ramifications. In this specific application,the
change would be a 1/2 inch or less of change in the height of the chassis.
I would think that various loading conditions, including the weight of a
full vs a empty tank of gas 100lbs would vary the height by 1/2" or so. So
I wonder if the tire change in height would pratically have an effect in
terms of vehicle sway.

        I understand that Syncro cannot have different size tires because
the rotational speed differential would engage the system. But If this slip
angle is related to the vehicle's attitude, the syncro's front attitude is
1 1/2" higher than the rear, and I think the whole chassis sits an 1"
higher overall, for offroad clearance?, than a 2wd vanagon. Also the
Syncro's chassis moves the spare tire and gas tank rearward. Probably more
offroad reasons. Although with the added weight of the front end drive
train the move makes good sense for controlling the cg fore and aft.



On my previous car a 72 240Z, I ran XZX's front and rear for at least a
100K. But I noticed that the Front Tires really were undersized for the
weight of that large 6 cyclinder engine.  I eventualy put 195 60/14 MXL's
on the front only and kept the 175 70/14 xzx's on the back.  I ran this way
for a 100K or so with wonderful results. The front tires here rear were 23
1/4" Tall and the rear were at 23 5/8" Tall The tire height change only
raises or lowers chassis by 1/2 the amount, since only half of the tire's
diameter is beneath the axle. This set up worked very well for some
different needs.  One was that Z's were very light in the back, an putting
a wide tire back there was trouble.  Less weight per sq in, coupled with a
cg nearly over the engine itself.  I've seen quite few totaled Z's that
"spun into power pole backwards"  By keeping the orginal treadwidth in the
rear, I never spun the car, for lack of traction in the wet. The bigger
front tires likewise were much better suited to the weight of the motor and
a cg position very far forward of polar axis, ie rear wheels.  The car
handled very neutral in over/understeer.

 So back to the tires. Ideally four tires of the same height and ply rating
seem to be a good choice. But I's still consider a 60 series tire up front
to help improved the vehicle's ability to generate cornering force. As a
intermediate test, ie, only havig to buy two tires, vs four. to see how
they improve or degrade the suspension tuning.

Mark
91 Carat Wolfsburg
>
 87 Wolfsburg (lowered
>suspension, which I think is superb for a van.   I think they changed
>something for the 90 Westy and I'm trying to find out what it is, since the
>87 with double the miles and worn suspension bits handles much better that
>the Westy.
>
>On increase in height of center of gravity - I've driven my 87 with more
>than 150 lbs of plywood on top (yeah, I know you're only supposed to put
>100 on the rails), and it is my recollection that it was sluggish, but not
>unusually so.
>
>I'm starting to suspect that the 90 Westy just has softer springs than the
>87, but I also suspect that the sway bar is smaller than it should be, and
>I'd like to  get one of you folks with good-handling late Westys to measure
>the diameter of your sway bar.    Mine is 21 mm (measured under the
>undercoating.)
>
>
>
>Dave
>
>At 12:58 PM 5/3/97 -0500, mark keller wrote:
>>        The information I wrote concerning the handling differences of a
>>vanagon and a vanagon camper were a response to a message I read, but
>>trashed to soon, on the list.  The owner had just purchased a camper and
>>was curious why the camper handled differently than his regular camper. In
>>that message he asked about various ideas he was considering. Tires,
>>swaybars and etc. That is the  context in which I was addressing my
>>thoughts.
>>
>>        But since the endorsing statements of overall handling has been
>>made, I would wholeheartedly agree. I have absolutely loved the handling of
>>vanagons, from the first test drive. Since I just bought my first one,
>>after seven years of looking and driving at many different vanagons and
>>vanagon campers, I thought the two best were a 80 with new gas shocks and a
>>87 Wolfsburg. My opinion of course.
>>
>>        One gentleman wrote the my suggestion of 1" smaller tires on the
>>front axle was "just plain DANGEROUS". While I don't know of his rational,
>>I would't hesitate to do it on my vehicle. I do know that different tires
>>sizes on the same axle is a no no, I have not heard of it being dangerous
>>on the front or rear of vehicle, as long as the tires are of the same size
>>on each axle.  I'm sure there is a practical limit as to how much
>>offsetting differnce you have.  Dragesters seemed to have quite a bit, but
>>they don't corner, except for right at the end when they turn off of the
>>strip. A varity of tuned suspension set ups utlize the offset in either
>>tire height or width to accomplish specific goals for the vehicle.
>>
>>        So, my suggestions were merely a starting point for the individual
>>who was considering, and asking for ideas on how to improve the handling on
>>his camper vanagon.  I would believe he understands that "porche" like
>>handling is not the goal of this excersise, but to merely do what he can
>>with what he has.
>>
>>        Sorry to apparently offend fellow vanagon owners with the
>>impression that the vanagon and vanagon camper is somehow not a excellant
>>driving vehicle as is.  I believe the vanagon to be a world class machine,
>>bar none. And incedently, I agree that any other van that I have driven
>>falls way short in the total package of enjoyment to drive and
>>functionality.
>>
>>Mark Keller 91 Carat
>>
>>
>>
>>
>>
>>
>>