[DeTomaso] Engine Bay Brace question

[Mad Dog Antenucci]

Again, outstanding work Gary.....as you said when you have a budget or a Pantera there are allot of compromises. 
Add a street driven Pantera and the list gets longer.

Well done.


 
Mad Dawg Antenucci 
Team Pantera Racing 
The 1st & still the only vintage race team in open road racing 
www.teampanteraracing.com




________________________________
From: GW <gow2 at rc-tech.net>
To: JJD1010 at aol.com
Cc: detomaso at realbig.com
Sent: Tue, December 22, 2009 5:25:51 PM
Subject: Re: [DeTomaso] Engine Bay Brace question

Yea, there are a couple goals and everything is a compromise as was said.

To sum it up I made a drawing. First comparing the ladder bar to a 
truss/bridge is really not looking at what the bar does. A truss would 
be fine if you were going to stand on the brace or drive a car across 
the top.

In the top example "A":

http://www.rc-tech.net/cars2/panttransam/1905/rollladder.jpg

There are 2 main forces on the bars. One coming from suspension 
compression pressing up on the spring/shock. The second being side 
loads. These are the main 2 loads being dealt with. These forces on the 
ladder bars are in compression for most concerned. Not that there are no 
other forces but these being by far being the main forces. The wheel 
wells have a tendency to flex or pivot at the frame like a hinge. With 
out the ladders in the ladder bar having more then one bar would not be 
terribly effective in stopping this; little more then a standard bar. To 
stop this hinge effect the bars must be locked so they form a ridged box 
so to speak.

The ideal box would be a "X" as in example "B". This would be more stout 
then is really necessary, would be heavy and take up a lot or extra 
room. The point of the cross braces is not to make the brace a bridge 
but to stop the bars from moving side to side.

Example "C" is the compromise I used. The compromise gives me room for 
my slave cyl. Even though it is moved in a couple inches the tubing is 
so stout if this thing goes off a cliff I doubt this will be compromised.

In photos of old race cars some times you see a cross brace in the 
engine bay such as the one in example "B". This of course is obviously 
ideal to limiting the open card board box effect in the trunk. I thought 
about putting one in but I am on the fence. I can always add one.

What I ended up with is example "C"; a roll bar which attaches to the 
roof line and then comes back and mounts next to the upright attachment 
with everything tied together with 11g plate.


This is not a full race car. I hope to track it. There are some areas I 
have addressed and others I have not but this is where I chose to draw 
the line. This still leaves me room to build an aluminum trunk tub.

Gary




JJD1010 at aol.com wrote:
> True, however, engineering is usually an optimization of variables and I  
> believe Gary is saying this set up will likely serve it's intended purpose  
> based on the forces at this point. 
>  
> Jeff
> 6559
>  
>  
> In a message dated 12/22/2009 10:23:13 A.M. Central Standard Time,  
> arkoch at earthlink.net writes:
>
> While  there are some benefits in adding the two "45" degree members to 
> the top  and bottom braces to stabilizing the two horizontal braces, the 
> effects  are minimal as compared to employing the triangulation rules of 
> truss  design.
>
>
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