[Vwdiesel] Spring Notes

[James Hansen]

Roger sez:

I think they are going for the soft cushy ride impression on that first test
drive in order to sell the vehicle.  My 4WD Toyota
4Runner is the same way, they all have spring sag some number of years down
the road.  I would imagine in their early consumer
testing, they probably get 100 comments about the how the ride could be
smoother to the one comment wondering how the soft
springs will hold up over time.
-___
True enough.  The thought of someone imagining that a truck should ride
smooth makes me smile, but that's what has driven the marketplace for some
time.  To make them ride nice, they removed the truck parts, and added car
parts until the ride was nice.  Driving my Pop's Duramax is like a cruise in
the family sedan... impressive until you crawl underneath.  Gone are live
axles, leaf springs, big hairy chunks of iron that made trucks capable of
hauling loads over anything passable etc. Now we have pavement queens.  Big
powerful impressive pavement queens, but realistically, the suspensions are
made for pavement, not what the adverts would have you believe... the image
of the businessman driving his F-150 on the weekend in the Best Buy parking
lot wearing starched and pressed plaid workshirts with airbrushed
sweatstains and artistically applied dirt smudges always persists in my
mind's eye.  Yeah, I'm a bit of a cynic.
Certainly a softer spring will move more, and wear faster than a heavier
spring.  In a passenger car coil spring (a dual rate where the coils are
different end to end), the lower rate end will wear faster.. translating to
a better ride- the lower rate end sucks up the small bumps and the higher
rate end only comes into play when the other end is compressed.  It's more
complicated than that, but that's more or less how they work.  That bit
Mark2 posted was pretty good but a little confusing mebbe to some.  (The
bulk of my experience and investigation has been on rated racing springs
that are single rate). Taking some of the coil out of the picture with a
spring rubber is perfectly valid- it's no different than cutting the spring,
which raises the rate of the remainder (back to factory), and adding ride
height spacers to get back to your desired ride height. Doing this without a
spring rate tester is hit and miss to some extent... or doing a lot of
calculations, and making some assumptions...er... guesses.  The higher
divisions of the race world use spring rate testers on each spring after
every race to asess the wear (loss of rate) and determine whether to re-use
or replace the spring. This way, you know exactly what rate the spring is
before installation and the repeatability of suspension setups is
accomplished
more below
---.


One nice thing with leaf springs (like the rear of the VW pickup) is you can
add leaves on to them, likewise on my Toyota, I did
the same.  In fact on my front axle, I am running a "worn out" set of stock
leaves from the rear of an '83 pickup and the "worn
out" stock leaves from the rear of my '85 4Runner and the combination is a
wonderful spring:
	http://www.4crawler.com/4x4/4R_suspension-III.shtml#Front

Can't really do a lot with coils.  I do run a pair of old "heavy duty" coils
on the front of my '82 pickup and added a rubber
coil spacer twisted up as high into the soft part of the coil as possible
and they do pretty nice.
_______

I like your suspension setup.   I've added leaves to some of the the farm
trucks to compensate for wear as well.  It works. I've tried re-arching and
that just goes away over time, adding leaves is the better long term
solution for older stuff in my opinion too.  Gonna have to do the rears on
my VW truck one day soon.  Ever thought of air bags?  I've kicked that
around for the caddy... remove leaves, use the leaf spring as more of a
locating device and use air bags to maintain suspension height and ride
quality with varied loads.  In theory it seems like a good idea... Ignoring
costs that is.

I know a guy that runs stock springs from an assortment of different cars
and trucks on his street stock.  They are cut down to ride height, a total
mish mash of (dare I say it?) hillbilly engineering that has been arrived at
by years of experimentation and trial.  He kicks ass on the track. It really
annoys some of the more technical crowd.  Sometimes it just works.
-James


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