rficalora Rob Ficalora Willis, TX (2764 posts) Registered: 10/24/2007 02:46PM Main British Car: '76 MGB w/CB front, Sebring rear, early metal dash Ford 302 |
What gauge for roll-bar mounting plates?
I'm making a dual hoop roll bar. What gauge steel should I use for the plates at the ends of the tube and the under car plates?
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Re: What gauge for roll-bar mounting plates?
3/16" minimum but 1/4" would be better. I suggest you go to SCCA.com and read thru the rule book in the roll cage section. It tells you about minimum thicknesses, and lengths of sides, diameter of bolts, etc. Those minimums are there for safety, so they are a good guide to follow even if you don't plan on racing.
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MGBV8 Carl Floyd Kingsport, TN (4511 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: What gauge for roll-bar mounting plates?
SCCA says .080" minimum thickness for the plate, but this is welded to the floorboard. The norm seems to be 1/8" or 3/16". the 1/8" is the usual if it must be bent to conform to the floorboard. A roll cage is normally using 1.50"x.095" DOM tubing for cars under 2500lbs. Personally, I would use 1.75"x.095" DOM for the main hoop & the smaller tubing everywhere else.
If you are just building a Boss Frog style double hoop bar, they use 1.75"x.125" tubing for the main double hoops & 3/16" for the plates. [www.bossfrog.biz] In an accident, one's body moves around an extraordinary amount. Make sure that your head will not ever contact the roll bar. |
Re: What gauge for roll-bar mounting plates?
.080 is only for welded in plates. He specifically said plates above and below, so he is talking about bolt in plates. Minimum for bolt in is 3/16", but 1/4" would be better. Grade 5 or better hardware.
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BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: What gauge for roll-bar mounting plates?
I think SCCA specs 3/16" for bolt-in, and really anything thicker that does not go to a separate frame seems rather pointless. Nothing on an MGB shell is anywhere close to that thick, even on the front subframe, so it's very difficult to spread the potential load out beyond the edges of the plate anyway. Possibly a better approach would be stacked and welded plates of lesser thickness and increasing size to spread the load while also spreading the bending moment inwards past the edge of the plate. The risk with 1/4" is that the stiffness of the plate will concentrate the load at the edge and cause it to tear the metal it is attached to.
Jim |
MGBV8 Carl Floyd Kingsport, TN (4511 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: What gauge for roll-bar mounting plates?
Correct, Todd. I did lookup the Boss Frog specs, though. ;)
If I ever build a bolt-in roll bar/cage this is the way I will do it. Edited 1 time(s). Last edit at 04/13/2016 01:58PM by MGBV8. |
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BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: What gauge for roll-bar mounting plates?
Pretty slick Todd, what are you using for a bender?
Jim |
Re: What gauge for roll-bar mounting plates?
JD2. Great bender. Very rugged construction. Its' built a couple dozen or so cages and roll bars and its still as good as new. Wish I could say the same for all the tubing notchers I've gone thru. This cage and car is the first race car I have ever built where I ignored the rule book. I want to build the safest fastest car I can. The cage attaches in about 30 different spots, and is basically the structure of the car. There are many more bars to come, but not until after I install the driveline and cut away anything that interferes with its installation. When its done, it will basically be a GT1 car stuffed into a TR7 shell, and it will be registered and just barely road legal.
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BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: What gauge for roll-bar mounting plates?
Which model? Manual or hydraulic? You clearly know what you are doing with it. Very nice work.
Jim |
Re: What gauge for roll-bar mounting plates?
Pretty sure its a model 3. Whatever the newest version was 15 years ago. Its a manual bender, but I could add air or hydraulics to it easy enough. Never found it to be a problem slipping a 2" by 4' pipe over the handle and bending it that way. I have a steel stand that I can either mount to my shop floor or to the wooden deck of my trailer. Most of the time I back my truck up to the trailer and use the tailgate as a bench. I have a pipe vise that mounts in my trailer hitch and extends up level with the open tailgate. Pipe, pipe cutter, and notcher sit in the truck bed. Bender sits beside it on the trailer. Easier to bend long pieces and not have to worry about moving everything out of the way in the garage. Plus, its just nicer working outside. Being able to mount the bender to the trailer also makes it portable. I can go to where the car is if I have to. If you are going to buy a bender make sure you get one with a degree wheel and a magnetic pointer. Have plenty of spray lubricant to coat the pipe with where it slides thru the mandrel. Magnetic levels and angle finders are nice to have too.
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BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: What gauge for roll-bar mounting plates?
I'm in.
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DiDueColpi Fred Key West coast - Canada (1365 posts) Registered: 05/14/2010 03:06AM Main British Car: I really thought that I'd be an action figure by now! |
Re: What gauge for roll-bar mounting plates?
We're having a "bender" at Todds?
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