I have a Miata with a roll bar welded in, the guy I got it from said the bar is SCCA legal (material and size tubing), I WANT to add a front section, and try to make an ITR car. But I want to make sure my bar is good, anyway to tell if it's legal?
I have a Miata with a roll bar welded in, the guy I got it from said the bar is SCCA legal (material and size tubing), I WANT to add a front section, and try to make an ITR car. But I want to make sure my bar is good, anyway to tell if it's legal?
Look in GCR.
Find minimum thickness and diameter for your car's weight.
Measure diamter, drill test hole and measure wall thickness.
BUT, no Miatae are classed in ITR....so....you mean S? or A? Not that this matters to the allowed tubing sizes.
NC Region
1980 ITS Triumph TR8
Oh, oops, is it ITU or something? Regional class for cars that are not classified in any other IT class. My car is not legal for SM or ITA
No problem. Yes, it will either be in ITO/E or U.
Shouldn't affect cage thickness though. Check the GCR on that for yor car's weight and then check your diameter and wall thickness.
NC Region
1980 ITS Triumph TR8
Drill and a micrometer of some sort....
NC Region
1980 ITS Triumph TR8
Simon, to measure the thickness of a tube, drill a small pilot hole. then with the "stick" end of a vernier caliper, measure the depth of the hole when it hits the other side. Then take the "fork" end and measure the outside diameter. Subtract the first measurement from the 2nd, and you get the tubing wall thickness.
Tim Linerud
San Francisco Region SCCA
#95 GTL Wabbit
Convert from GP to GTL
http://www.timlinerud.com/racing/index.html
racer_tim @ yahoo dot com
Sounds like this car doesn't have a log book. Someone please correct me if I'm wrong, but IIRC, to get a log book now the tubing must be DOM, not ERW. Not sure if there's a reliable way to tell the difference.
Marty Doane
ITS RX-7 #13 (sold)
2016 Winnebago Journey (home)
Thanks Tim, I will do that
As for it being DOM, that is also a concern, I think he said it's DOM, when I got the car the rules were for DOM only anyway for new cars, so hopefully that's what it is. Worse case I could just sell this bar and get a new cage...
Simon, if I rember correctly you are a teenage young man. < That's good struff. In the future if you have time before buying something ask questions on this site so that you don't end up buying stuff thats' not usable or that's illegal.
Trust me there is plenty of stuff that I look at that I think
Have Fun ; )
David Dewhurst
CenDiv Milwaukee Region
Spec Miata #14
Yes, well I am twenty now, but have been posting here since I was sixteen under a different name I dont know why I can't log in anymore. Simon Tibbett was my old user name (even though that's me! ) I got the car to autocross and do PDX stuff, but I just cannot hold back, I HAVE to go wheel to wheel!!!
Last edited by Simon T.; 03-24-2008 at 05:53 PM.
Good private garages (non-dealer) with a decent assortment of tools should have a borescope. My son has one, but it is in Bakersfield CA.
Last edited by RacerBill; 03-25-2008 at 12:22 PM. Reason: addl clarification
Bill Stevens - Mbr # 103106
BnS Racing www.bnsracing.net
92 ITA Saturn
83 ITB Shelby Dodge Charger
Sponsors - Race-Keeper Data/Video Aquisition Systems www.race-keeper.com
Simpson Performance Products - simpsonraceproducts.com
Simon,
ERW usually has a seam that you can see and feel running down it's length. DOM should be smooth all around. And be careful drilling the inspection hole. If you hit the inside of the bar when you drill through, you could put the measurement off.
Good luck.
Joe Camilleri
HP Scirocco
Check out the VW Club Racers Facebook page: http://www.facebook.com/group.php?gid=309326556818
A paper clip can be used when you don't have a boroscope...
1st thing to do would be to sand off the paint around the entire tube. If you see a line, you can be 50% sure it's ERW. I've had DOM with an exterior line before, so now it's time to drill your 3/16" inspection hole - on the oposite side of the line. Stick the paper clip end into the hole & feel around. ERW has a pronounced weld seam. You'll know it if you hit it.
Scott Rhea
Izzy's Custom Cages
It's not what you build... It's how you build it
Performance Driven LLC
Neon Racing Springs
Just for reference, DOM (Drawn Over Mandrel) tubing *IS* ERW (Electric Resistance Welding) tubing, cold-drawn run through a die or mandrel after the ERW process in order to improve inner surfaces and dimensional (primarily wall) consistency.
Seamless tubing is a whole 'nother animal. CDS (Cold Drawn Seamless) is made from a solid bar that is cold-drawn over a die/mandrel.
The process that Scott describes is valid, as you're looking for any evidence that the welded area at the seam is not consistent. ERW tubing will be slightly different where the rolled strip was welded, whereas DOM will be consistent all the way around.
GA
Bill Etherington
NNJR Tech
Well I bought the car over a year ago, and don't know how to get in touch with him, the bar was custom made, he said by a guy who does SM cages. It looks good, and the welds look good.
But here is the deal, it did not have a harness bar, and I got one welded on, meaning I have the one that he cut off sitting here, so I have a piece of the tubing off the car with two open ends. So can I just look in it, and look for a weld down the middle? Or is it just a line?
If the wall thickness is consistent, and there's no indication of a weld other than visible discoloration, then it's probably DOM.
If, however, you can run your fingers around the inside and you can "feel" where the weld is, it may be ERW.
Bookmarks