Prefab Roll Cages

[EvilCamaro]

Has anyone ordered any of these prefab cages from
http://autoweldchassis.com/index2.ivnu ?

If so, how was the quality/fit?

[Bryce]

there stuff looks really good. but no prefabbed roll cage will be exactly the way you want it. especially if you want it to be tucked against the roof and follow the roof line to the trunk. but if i was to buy a prefab roll cage i would buy it from them .

[Bryce]

make sure you buy the DOM or chromoly the ERW will not pass inspection at NHRA. Im not sure about SCCA but I think they require DOM as well.

[67speedfreak]

make sure you buy the DOM or chromoly the ERW will not pass inspection at NHRA. Im not sure about SCCA but I think they require DOM as well.

That is not true. By the rules minimum wall thickness for NHRA is .120 wall. DOM tubing is a consistent .120 and will pass no problem. EWR's wall thickness is not consistant thruout and .120 EWR would fail. That is why these companies use .134 wall EWR to make sure it will pass the sonic test.

We use only .120 DOM for all our cages. It is lighter and will pass tech. Most production companies have gone with ERW because it is cheaper.

Brian

[EvilCamaro]

Yea i am probably just going to go with chromoly. Thanks guys.

[Twentyover]

From the current SCCA rule book Section 9.4.F.1


'1. Seamless or DOM mild steel tubing (SAE 1020 or 1025 recommended)
or alloy steel tubing (SAE 4130) must be used for all
roll cage structures. Alloy and mild steel tubing may not be
mixed. ERW tubing is not allowed."

From http://en.wikipedia.org/wiki/Tubing_(material) Manufacture
Main article: Tube drawing
There are three classes of manufactured tubing: seamless, as-welded, and drawn-over-mandrel (DOM).

Seamless tubing is produced via extrusion or rotary piercing.

Drawn-over-mandrel tubing is made from cold-drawn electrical-resistance-welded tube that is drawn through a die and over a mandrel to create such characteristics as dependable weld integrity, dimensional accuracy, and an excellent surface finish.



Many other sanctioning bodies such as NASA do permit ERW in som classes.

For ME, the ultimate question is, what fraction of the cost of the roll hoop or cage is raw material and how much is labor. On my car, labor was the huge content, so the decision to use DOM was a no-brainer

[BAD68GTO]

Very nice thread to read, and getting ready for a 6 point in my 68 GTO, but since the frame needs to be cut to box it in, I think I am going to farm it out to a local professional.

[Bryce]

something else to consider. NHRA allows a 30* bend in the main hoop support (the bars that go to the trunk) but SCCA and NASA do not allow this bend.