chassis re-enforcement v.101

[brianm@earendel.org (brianm@earendel.org)]

et al in this discussion 
the front of our cars are a box.

warning ascii art use a fixed font like courier

______________
|            |\
|            | |
|            | |
|            | |
|            | |
|____________|/


pretty much that is the structure you start with
now add the tires

______________
|    ooo     |\
|            | |
|            | |
|            | |
|            | |
|____ooo_____|/

and remember that without the lower K bar this hole thing flexes quite a 
bit. if your in doubt get a 2 cardboard boxes with the same kind of 
ratios the A1's have.

Tape the larger box shut. (passenger compartment w/ the door shut)
but on the front box cut the top and bottom off.

y
^
|
|---->x
up(z-axis)
____________________
|          X|       |
|          X|       |
|          X|       |
|          X|       |
--------------------

This is pretty much the basics of any car. except convertables.and rear 
engine cars BUT were worried about A1 VW's.
now think about applying tortional strain around the X axis.  (is this the 
right verbage ME's?)

so now make a channel that attaches the lower portion of the front box 
together. along the bottom.(the H's)

____________________
|          X|   H   |
|          X|   H   |
|          X|   H   |
|          X|   H   |
--------------------

But now remember that its not that easy. cause in our cars. the front box 
is actually smaller on the bottom than on the top and SHORTER too.

Blowup view of what it really is without the K bar.

TOP 
__________________________
|          X|            |
|          X|            |
|          X|------|     |
|          X|            |  
|          X|            |
|          X|------|     |
|          X|            |
|          X|            |
--------------------------

A more accurate Tope view
_____________
|           | 
|           |\____________
|          X|            |
|          X|            |
|          X|------|     |
|          X|            |  
|          X|            |
|          X|------|     |
|          X|            |
|          X|            |
|           | ------------
|           |/
|           |
-------------



Side ( without the frame rails)
____________________
|                   |
|                   |
|                 __|
|                |  |
|\               |  |
| \              |__| <-- front Core support the top portion of it is 
|  \_____                 for decoration not Structural integrety
|________]
|
   ^^^^^^ frame horns

entire side simplified
|----------------------|                      
|                      |
|                      |__________
|                      |         |
|                      |_________|
|                      |  
-----------------------



Front ( i know its now 100% symmetric but thats ASCII art for you...
_______________
|             |
 \  |     |  /  
OOO\OOOOOOO/OO  <--- front core support cross member
    o     o 
    ^^^^^^^ <---frame horns



So now the question becomes. does the front end twist about the 
X -axis and why. basically because its a thin walled structure that is 
designed to flex. that saves weight. Its a trade off. the other problem is 
that the box is easily flexed in the Y-axis direction. ie. up and down in 
the plane of the screen. because the rigidity isnt there. So what does 
adding the upper strut brace do in the ENGINE bay. it adds a top to your 
front box. the lower brace was added so that you at least had a bottom to 
your fron box.. sort of. I am intimately familiar with this structure as i 
have remove and replaced 4 motor in the last 2 years. and with out any of 
the motor or suspension the front end is really flexible. 

so the upper stut bar provies a top to the front box helping to kill the 
x-axis rotation and the y-axis wobblyness (not a real work).
So if your trying to kill body roll from flex aka sway..

so the upper strut bar keeps the front box from becoming deformed

with the bar
_______
|     |
|     |
-------

without the bar (exaggerated)

  /    /
 /    /
 -----


Brian
EE not an ME.. anybody wanna poke holes in it go for it

82 2.0L topless bunny ( engine #3 in 2 years)
88 16v aka skateboard
84 0v. makes looking at it easy.
90 90q20v



tape em together where the X is.
and the front 
On Wed, 25 Dec 2002, Scott F. Williams wrote:

> Dave, how on Earth can any stress bar reduce "sway"? What exactly do you
> mean by that word, anyway. :^) Are you referring to the elimination of roll?
> That's the job of the coil springs and anti-roll bars (a.k.a. "sway"bars).
> The upper strut brace (stress bar, etc.) simply keeps the strut towers from
> moving apart from each other. However, the tendency to roll in corners is
> not reduced a bit.
> --
> Scott F. Williams
> NJ Scirocco nut
> '99 Subaru Impreza 2.5 RS
> Mazda 323 GTX turbo "assaulted" vehicle
> Golf GTI 16v "rollycar"
> ClubVAC: "Roads found. Drivers wanted."
> 
> Dave wrote:
> > I don't know what Shine would say about it but I think
> > the braces add a little more rigidity and less sway in
> > hard cornering.  This has just been my experience.
> 
> 
> 
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