Open question about 4000 Strut bars Jamex?

[cody at 5000tq.com]

Quoting Mark R <speedracer.mark at gmail.com>:

> Really it depends on the quantity.  I'd presume we'd do
> powder-coated cold-rolled steel as opposed to 304 series stainless. Most
> bars are powdercoated CRS.  Most of the tubing we bend is much larger
> diameter... so if we want mandrel bends, I might have to farm that part
> out.  Quantity will be king as far as price, since we'd need:
> 1.  Tubing; setup and cut to length.
> 2.  Tubing bends (setups)
> 3.  Tower base plate (x2), program and CNC punch.
> 4.  Deburr tubing ends and base plate.
> 5.  Weld bar to base plate (fixture)
> 6,  Powdercoat.
> 7.  Nutsets and hardware.


I have a suggestion to really improve the design. I'm sorry if this  
has already been noted, I haven't been following the thread until just  
now.

The bar should be arranged so it can bolt to the firewall at some  
point towards the center. If you just run the bar across to the strut  
towers then you are bracing them to each other... that way the stress  
is distributed to each helping prevent flex, but in doing that it is  
also flexing the tower that would be otherwise less stressed. If you  
bolt the bar to the firewall you prevent the bar from moving at all,  
meaning the towers will be forced to stay stationary, rather then flex  
together.

Heres an example. You are at the track in a hard left corner. The RF  
wheel is loaded most and flexing the top of the strut tower outwards,  
away from the center of the car. The LF wheel is experiancing very  
little stress due to weight transfew, so it's tower is right where it  
should be. Now you add a typical strut tower brace. When the RF strut  
is loaded in the same corner it tries to flex outwards again, but  
since it is tied to the un-stressed LF tower by the bar it doesn't  
flex *AS MUCH*, but as it does flex it pulls on the brace and the LF  
strut tower, causing flex where there was none before. If the brace is  
secured to not only the sturt towers, but also the firewall, it  
prevents either tower from "pulling" on the other and makes for a much  
stiffer chassis.

Basically a typical strut bar will cut flex in half, whereas one  
bolted to the firewall will almost eliminate it all together.

-Cody Forbes
http://www.5000tq.com