kepani

i tried a search on this topic but found noting. pardon my search skills...

i'm looking at the autopower 4pt race rollbar for an itr. however, there are two options as to the material of the bars; erw (electric resistance welded tubing) or dom (drawn over mandel tubing).

can anyone in a nutshell describe the main differences between the two types? the dom rollbar is ~$35 additional. i'm just trying to see if there are any benefits in the dom since it is a little more expensive.

thanks!

kepani-who needs a rollbar soon before exblow4.

AdamITR

DOM

jc836

The tall and short of it is real simple-the SCCA and NASA rulebooks now require DOM tubing be used in all New installs for competition cars. You must read the rulebook for the type of event you plan to use the car for to be sure that you meet the minimum requirements for the car weight and so forth. Personally, I would not use anything other than DOM even in a Solo or autocross type car-it is simply not worth the difference in cost. BTW: a really important item to have for tech inspection is a manufacturer's certificate showing the materials used.
If you want to get real technical on the material-it is still a form of mild steel tubing. How it is formed into tubing determines the difference in types. There are actually several versions of DOM available. The typical is drawn over a mandrel from stock and the resulting seam is sealed and smoothed (simple explanation). Another version is made by piercing a billet and extruding it over a mandrel (Shelby process).
By comparison ERW is made from flat stock that is drawn thru a die and the seam is welded. The seam edges are not smoothed and forced to seal against themselves in the same way as DOM. The 3rd version of DOM I am aware of starts with ERW and is taken thru the process again.

There are articles on the WEB and you can contact several companies to learn more. I donated my father's manual from National Tube (McKeesport, PA) to a library-so try searching that resource. USX may still have manuals available from their plants for those that are interested in metallurgy.

Footwork

ERW stands for Electric Resistance Welded. This is a mild steel tubing that started out as a flat sheet of steel, formed into tubing and welded.

DOM stands for Drawn Over Mandrel and it is actually ERW tubing that has gone through a second process that shapes and smooths the tubing so that the walls are more uniform. This in turn makes the tubing stronger than the original tubing.

http://www.ioportracing.com/faqs.htm

Catch 22

Galvanized fence posting.

Don't laugh. It has actually been done.

DsITR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Catch 22 &raquo;</TD></TR><TR><TD CLASS="quote">Galvanized fence posting.

Don't laugh. It has actually been done.</TD></TR></TABLE>

you forgot exhaust pipage...

...crush bent


...and bamboo/duct tape

Kepani, you are better off going w/the DOM bar.. so you don't have to *upgrade* later.

sorta like buying the lowest rated helmet possible, and then buying a new one every year.

kepani

the question is answered - i will be getting the dom race rollbar.

thank you all for the rollbar lesson(s). safety should always be first when it comes to road racing.

kepani

IP2GSR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Catch 22 &raquo;</TD></TR><TR><TD CLASS="quote">Galvanized fence posting.

Don't laugh. It has actually been done.</TD></TR></TABLE>

Not to hi-jack this too far ......

In a previous life I wrenched on a C fuel dragster. One guy shows up with a dragster made from water pipe (black pipe), complete with threaded couplers to make the full lenght since the 10ft sections were the longest he could buy from the hardware store. I'm still amazed he had the *****, or stupidity, to climb in that thing. From memory it had a big block 427.

Dave
#72 ITS GSR