Re: [alfa] Re: roll barred

[Richard Welty <rwelty@xxxxxxxxxxxxxxx>]

On Fri, 03 Oct 2003 20:35:03 -0400 SHartDP@domain.elided wrote:

>  I am building a 6 point cage for what will be my semi daily
> driver and play toy.  I'm not sure I will do any sanctioned racing other
> then a club fun day so I don't think I have any set rules to abide by
> (not that my design would fail any tech inspection).

actually, we're fairly constrained in what designs we can accept in the
SCCA. excessive cleverness in bracing designs dooms some cages, as do
unnecessary bends in main hoops and front braces.

a good example is using an x arrangment in the braces going back from
the main hoop. we expect them to run straight back, typically to the shock
tower directly behind them. some clever engineers figure out that an x
arrangement is actually stronger. we don't accept the x braces; while
theoretically they're stronger, such a design requires much more careful
fabrication and execution, and if it's botched, it's much weaker.

likewise, in a forward brace from the main hoop, you are allowed two bends
in current SCCA cage rules, typically one at the top of the windshield to
break down to follow the a pillar, and one at the bottom of the windshield
to go to the floor. more than 2 bends are only permitted in certain
circumstances, and only if the cage is built of the next larger sized
tubing.

only 4 bends are permitted in the main hoop; two at the top, and two mild
ones in the middle of the verticals. the angle of the middle bends is
severely constrained.

>  Anyways - do most
> people run mild or DOM cages at .095 wall or are they thicker?  .095
> wall is allowed for main cage in chromoly only in SCORE rules so most
> guys run .120.  Is .120 overkill or too heavy for the poor little alfa?

i should think that 1.5 x 0.095 DOM is probably fine. for SCCA, you'd want
1.5 x 0.120 or 1.75 x 0.095 for ITB, but the 1.5 x 0.095 works for GT and
production (i'm presuming your GTV, weighing in at a little under 2500 lbs.)

richard
-- 
Richard Welty                                         rwelty@domain.elided
Averill Park Networking                                         518-573-7592
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