PDA

View Full Version : I think I have it figured out...real roll bar



TR6BILL
12-03-2008, 07:34 PM
I have a "Faux Roll Bar" like so many have. I have found a source of 1"x3" steel rectangular tubing that I think I can weld to a 1/4" steel plate below the the body where the faux bar bolts, and weld it to the frame in front and back of the spring tower. Shouldn't be a problem if I can MIG the whole thing together in place, even strengthen the spring tower in the process. And add only about 5 lbs to the whole setup. Whaduya think?? Once in place, just suck the whole thing down to the new brace with some grade 8 bolts and ride assured that I have at least a little protection.

roofman
12-03-2008, 08:12 PM
Here is an idea


https://www.barris.com/gallery_cars/TV_MovieCars/gallery_alvinsacorn.html

BryanC
12-03-2008, 09:00 PM
I think that sounds like a good start. What you propose helps with the vertical load when you're on your head. If the Jolly Green Giant picks up the car and puts it down on its top, you would be in good shape. The next question is about the side and fore/aft loads that you might encounter in the real world. If the car rolls on its side, you want a diagonal brace (say top left to bottom right) to keep it from folding (maybe your bar already has this - many don't). If you roll over and then slide along on your top, it would be good to have some fore/aft bracing also. Most bars have four points so there is some fore/aft bracing already. The final piece is some padding on the bar so that when you get hit you don't get killed by hitting your head on the steel tube. With the frame pieces you mention plus the bracing and padding, you should have a reasonable roll bar (I assume it is at least about 1.75" OD tube with at least about 0.095" wall thickness).

Bryan

PeterK
12-03-2008, 10:16 PM
I have a "Faux Roll Bar" like so many have. I have found a source of 1"x3" steel rectangular tubing that I think I can weld to a 1/4" steel plate below the the body where the faux bar bolts, and weld it to the frame in front and back of the spring tower. Shouldn't be a problem if I can MIG the whole thing together in place, even strengthen the spring tower in the process. And add only about 5 lbs to the whole setup. Whaduya think?? Once in place, just suck the whole thing down to the new brace with some grade 8 bolts and ride assured that I have at least a little protection.

I was thinking of more like 2x2 square tubing. Otherwise great. But I agree that you need to triangulate the two mounting points with 2 more. It should add a good stiffness to the chassis too.

tdskip
12-03-2008, 11:26 PM
Are you gugs suggesting additional bracing for a bar like this?

https://sparrowbritishauto.com/2006%20Aug/TR6%20Rollbar.jpg

BryanC
12-04-2008, 06:47 AM
That's a dead link - just a red x. The Moss Motors picture of a TR6 roll bar looks OK. It has some fore/aft bracing and lateral bracing that extends from the top of the main roll hoop. Some bars are simple hoops with a couple of little rearward braces that aren't even at the top of the main hoop. Those would not be my first choice.

Bryan

PeterK
12-04-2008, 08:15 AM
Personally, I prefer the four legs to be on two different planes: the main hoops on the rear floor behind the seats, then anchored underneath. And the support legs bolted through the rear shelf and then supported to the frame.

The main hoop of the bar in our 3A is anchored on the sloped rear floor and reinforced underneath with 4x4" 1/8" plates. The legs mount to the rear inner wheel wells and also through 4x4" 1/8" plates above the rear tires.

The bars that anchor all four legs on the parcel shelf (like tdskip posted) just don't seem to provide strength unless the legs are continued undeeneath to the chassis. Also there is no diagonal bracing of the main hoop to prevent it from folding.

I sold this one on ebay a few years ago when I changed my mind on the design. It's nicely braced, even has a harness bar but I didn't like the hoop and legs sitting together on the shelf.

racingenglishcars
12-04-2008, 08:58 AM
Just go to the source
https://www.dasu.dk/media/filebank/org/reglement_9_bilag1_appendix_j_2008.pdf