RE: [alfa] Re: installing roll bar on Spider

["Brian Shorey" <bshorey@xxxxxxxxx>]

> While Skip is very right in saying that a street roll bar will not do
> much for you in an actual rollover (though I would prefer to have one
> than not) he does go a bit far with his statement that it is for looks
> only. There is actually a noticeable handling difference upon addition
> of a street (or any) roll bar due to the increased stiffness.

I don't see where the stiffness is added with a roll bar of any height.

The flex in the Spider is across the door openings (fore and aft), and the
roll bar (race or street) is entirely behind the plane of the rear part of
the door opening.

Over it's lifetime, My Spider has had a street bar, a race bar, a race bar
with a fore/aft brace, and a chasiss stiffener.

The results with the street and race height bar were nil, in terms of added
stiffness.  The chassis stiffener made a noticeable difference, the fore/aft
brace made the most difference.

Pictures of the current installation can be found here:

http://www.shorey.net/ItalianCars/EbonySnake/Rollbar.htm

Basically, you've got to add support across the door openings if you want to
increase the stiffness of a Spider.

I think Skip is right.  Further, technically you really don't want to be
bolted in with shoulder harnesses if you've got a rollbar that doesn't
protrude above the top of your head.  If your rollbar isn't going to keep
your head from hitting the ground when you're upside down, then you really
don't want your body held firmly in that upright position.

 As for installation assistance, here ya go
> http://spider.noshirtnoshoes.net/4kq/barpix/install.html
> Let me just apologize in advance for my... sense of humor.
> Oh, and that
> wire that I drilled through - it turned out to be quite important, so
> allow me to reinforce the suggestion to plan your holes carefully.

I'm not an expert, but there's a couple of things I'd consider changing.
First, I'm not sure of what the effect is of bolting a bar on top of carpet
is.  It might seem nice and snug now, but over time, as the carpet
deteriorates, the result might be some slack in the base mounting hardware.
I think the common practice is to raise the carpets (or rubber mats, or
whatever), bolt the rollbar metal against metal, then cut the carpets to fit
around the base of the bar.

Second, I don't know what the effects are of bolting the harness to the bar.
I think it's considered acceptable to use the bar as a guide for the belts
(you absolutely want to make sure that the belts don't pull 'down' on your
back), but I think you really want to make sure the belts are secured to the
base of the vehicle, not the bar.

I could be wrong about either of these, I'd be curious to hear from the
rollbar and cage experts in the group.

bs
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided