Hi,
If you want an SCCA (or other organization) compliant roll bar, you
should get a copy of the rules. I mention this because rules vary from
time to time and specs vary between clubs. I will add that the SCCA specs
should give you a safe roll bar.
That being said, the SCCA requires that you have a 5 point bar, that is
to say a four point with a diagonal cross brace. There are further
stipulations in the rule book about what materials to use. Important
points are: mandrel bent 1.5 inch tubing (for your application) .120 thick
steel, I forget the spec, but the rules are very specific about what
material and how it should be welded etc. Oh, and no crimp marks from
when the tubing is bent!!!
Now, you did not specify if you wish to autocross only or if you intend
to road race. In the former, you need just a roll bar. For the latter,
you need a more substantial "cage".
There are a couple of choices for bars: 1. you can buy a kit that needs
some welding and a lot of it bolts in and 2. find a local race car
fabricator and have them bend/weld you a bar.
Autopower makes a bolt-in kit for TR6, I'm sure they have something for
TR250. Note, however, that the SCCA Solo II compliant bar will not allow
propoer operation of the convertible top on your car. Bummer. You might
be able to talk with Autopower about a custom kit, particularly if you
are not a "big guy". The reason I mention this is that most clubs have a
spec about how far above the driver's head the bar must extend.
One word of coution: don't scrimp on the bar. If you drive the car at the
limit, you want real protection. Otherwise don't bother installing a bar
at all. It turns out that the reason for the 5 point bars is because
there are crash situations where the main "hoop" can collapse and the
diagonal cross brace reduces the chances of that type of failure. Believe
me, you don't want a roll bar failure if you are strapped in with a full
harness!
have good _safe_ fun,
rml
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