Bodywork, Paint, Interior, Trim, & Wiring

discussions about bodywork, paint, interiors, trim, audio, electrical components, wiring, etc.

Go to Thread: PreviousNext
Go to: Forum ListMessage ListNew TopicLog In


rficalora
Rob Ficalora
Cypress, TX
(2305 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
What gauge for roll-bar mounting plates?
Posted by: rficalora
Date: April 09, 2016 08:07AM

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?


tr8todd
Todd Kishbach

(315 posts)

Registered:
12/04/2009 07:42AM

Main British Car:


Re: What gauge for roll-bar mounting plates?
Posted by: tr8todd
Date: April 09, 2016 08:26AM

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.


MGBV8
Carl Floyd
Kingsport, TN
(3106 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: What gauge for roll-bar mounting plates?
Posted by: MGBV8
Date: April 12, 2016 08:54AM

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.


tr8todd
Todd Kishbach

(315 posts)

Registered:
12/04/2009 07:42AM

Main British Car:


Re: What gauge for roll-bar mounting plates?
Posted by: tr8todd
Date: April 12, 2016 03:12PM

.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.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5198 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: What gauge for roll-bar mounting plates?
Posted by: BlownMGB-V8
Date: April 12, 2016 05:39PM

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
(3106 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: What gauge for roll-bar mounting plates?
Posted by: MGBV8
Date: April 13, 2016 01:51PM

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.

http://www.britishracecar.com/BritishMotorHeritage/BMH-Witney-J.jpg

http://www.britishracecar.com/BritishMotorHeritage/BMH-Witney-I.jpg



Edited 1 time(s). Last edit at 04/13/2016 01:58PM by MGBV8.


tr8todd
Todd Kishbach

(315 posts)

Registered:
12/04/2009 07:42AM

Main British Car:


Re: What gauge for roll-bar mounting plates?
Posted by: tr8todd
Date: April 13, 2016 02:55PM

That looks a lot like the plates I welded in on my MGB roll bar. Wherever possible, carry the load with additional plates on a vertical surface, and it goes without saying, put the plates where the metal is the thickest if possible. Here is the cage I'm working on at the moment. Car is getting a LS3 from a 2010 Camaro.
DSC04053.JPG
DSC04054.JPG
DSC04055.JPG
DSC04056.JPG



BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5198 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: What gauge for roll-bar mounting plates?
Posted by: BlownMGB-V8
Date: April 13, 2016 06:09PM

Pretty slick Todd, what are you using for a bender?

Jim


tr8todd
Todd Kishbach

(315 posts)

Registered:
12/04/2009 07:42AM

Main British Car:


Re: What gauge for roll-bar mounting plates?
Posted by: tr8todd
Date: April 13, 2016 07:26PM

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.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5198 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: What gauge for roll-bar mounting plates?
Posted by: BlownMGB-V8
Date: April 14, 2016 10:52AM

Which model? Manual or hydraulic? You clearly know what you are doing with it. Very nice work.

Jim


tr8todd
Todd Kishbach

(315 posts)

Registered:
12/04/2009 07:42AM

Main British Car:


Re: What gauge for roll-bar mounting plates?
Posted by: tr8todd
Date: April 14, 2016 11:54AM

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.


MGBV8
Carl Floyd
Kingsport, TN
(3106 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: What gauge for roll-bar mounting plates?
Posted by: MGBV8
Date: April 14, 2016 01:22PM

Let's all go to Todd's house for a roll bar bending party!


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5198 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: What gauge for roll-bar mounting plates?
Posted by: BlownMGB-V8
Date: April 14, 2016 03:12PM

I'm in.


DiDueColpi
Fred Key
West coast - Canada
(1191 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
What if the Hokey Pokey really is what it's all about?

authors avatar
Re: What gauge for roll-bar mounting plates?
Posted by: DiDueColpi
Date: April 14, 2016 08:06PM

We're having a "bender" at Todds?


Sorry, only registered users may post in this forum.