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 |
Sticker shock
Went to visit a guy who makes roll cages to get an estimate on a roll bar sort of like this one. There were a bunch of 4x4's and a couple of drag trucks at the shop and the work they do did look good... but I wasn't prepared for a $750 estimate. The idea was to have the basic shape of this one but have it tie in at the floor on both sides in three planes (floor board, vertical panel behind the seats, and side of the frame rail). In the middle it'd attach to the trans tunnel. And it'd have angled braces going back to the battery shelf and forward to about the middle of the seats (enough to keep it from folding but not so far forward that it'd make it hard to get in or out). After thinking about it, the price is probably fair considering the fabrication required for all of the places it'd tie into the car but it's still way more than I was prepared to spend. Plan now is for me to make the brackets and then have Matt (the guy who does the roll cages) just bend the pipe for me.
|
roverman Art Gertz Winchester, CA. (3188 posts) Registered: 04/24/2009 11:02AM Main British Car: 74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L |
Re: Sticker shock
Rob, If you do the fitting and welding, should save a substantial amount. Local off-road fabricator, quoted me $5./bend. You may want to shop webbsites like S&W Race Cars, for materials and bends. Good Luck, roverman.
|
Re: Sticker shock
Rob what size of pipe and wall thickness is appropiate for a roll bar? There are no shops here in Calgary that do mandrell bends, but there is a shop that has a machine that will do fairly smooth bends and they can do tubing up to 1.5" diameter. I do not know what the wall thickness is. Is 1.5" diameter tubing big enough for a roll bar?
If this was good enough for a roll bar I would consider getting them to do the bends and then getting my tig welder friend to weld it up for me; his welds are lot prettier than my welds. Cheers Byron |
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 |
Re: Sticker shock
I'm no expert. NHRA requirements that I saw are below. My plan is to go with 2" x .118 (or as close as I can get locally) for the main hoops and 1.5 x .118 for the angled braces. I'm confident 1 3/4 would be fine for the main hoops, but i think the 2" will look better.
If you're thinking of making one, be sure to read up on them. A roll at that's not done to where it won't fold over on you can be more dangerous than no roll bar at all. Also, to protect your head it'd have to be pretty tall. Pull a string from the fender about 6-8" from the headlights to behind the seats. Angle the string up high enough to clear your head by a few inches. That will show how high it needs to be to protect you assuming the windshield collapses and the front sheet metal gets bent down an inch or two. Net is you're not likely to get the sort of protection you'd have in a race car but can get some margin of safety I think. NHRA rules... A roll bar is required in any convertible running 13.49 seconds or quicker in the quarter mile, and in other cars beginning at 11.49. The roll bar is accepted in vehicles running as quick as 10.00 second e.t., provided the stock firewall and floorboard is intact, other than for installation of wheel tubs. The rollbar must be constructed of minimum 1 ¾ inch o.d. x .118 inch wall mild steel tubing, or 1 ¾ x .083 chrome moly tubing. If the floor and/or firewall has been modified, then a full roll cage is required beginning at a 10.99 e.t. A full roll cage is required in any vehicle running 9.99 seconds or quicker, and any vehicle running 135 mph or faster (regardless of e.t.). The roll cage must be constructed of minimum 1 5/8 o.d.x .118 mild steel tubing, or 1 5/8 x .083 chrome moly tubing. |
Moderator Curtis Jacobson Portland Oregon (4576 posts) Registered: 10/12/2007 02:16AM Main British Car: 71 MGBGT, Buick 215 |
Re: Sticker shock
Drag racing rule requirements are quite different from road racing. Frankly, I think SCCA's rules make more sense for a street-driven British sports car. The second part of this article includes a summary of them, plus commentary:
[www.britishv8.org] |
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 |
Re: Sticker shock
I'd forgotten about that article but it's a good one. I still plan to do a dual hoop one, but want to read the SCCA rules to learn a bit more.
|
Jim Stabe Jim Stabe San Diego, Ca (829 posts) Registered: 02/28/2009 10:01AM Main British Car: 1966 MGB Roadster 350 LT1 Chevy |
Re: Sticker shock
I have provisions for a roll bar in my car and actually had one made up for it but it was ugly and I thought it detracted from the lines of the windshield and the car. What I found from trying lots of shapes is that for the bar to look good it had to be too short to provide any real protection (especially with no helmet) and that made it too close to my head which could result in serious injury if I were hit. The original bar was well braced fore & aft and diagonally and removable and I still have all the mounting points in the car so I could add a functional bar later if circumstances demand one but for now I will make blanking plates that will close the holes in the body and be flush with the surface and (hopefully) will not be that noticable. Having a restriction that prevents me from taking the car out on a road course as fast as the car should be is probably a good thing.
|
|
Jim Stabe Jim Stabe San Diego, Ca (829 posts) Registered: 02/28/2009 10:01AM Main British Car: 1966 MGB Roadster 350 LT1 Chevy |
Re: Sticker shock
Rob, and anyone else contemplating a roll bar
Here is some interesting reading on the safety of roll bars for non helmeted passengers. Lots here but worth going through. [corner-carvers.com] [corner-carvers.com] |
MGBV8 Carl Floyd Kingsport, TN (4511 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: Sticker shock
Yeah, I know. Makes me want to remove my roll bar every time I think about it.
Speaking of bolt-in roll bars, anyone think they can actually be made strong enough to really be useful? |
Moderator Curtis Jacobson Portland Oregon (4576 posts) Registered: 10/12/2007 02:16AM Main British Car: 71 MGBGT, Buick 215 |
Re: Sticker shock
The problem with these discussions is there's such a broad range of installation variables and also such a broad range of accident scenarios. Even the OEMs can't agree on priorities when it comes to safety.
Almost every car on the road weighs more than an MGB, has a higher center of gravity, and is much taller all around... so I figure compared to other drivers we should worry more about being crushed and less about flipping over. I fear being t-boned in an intersection. That's one reason my cage has three extra side-to-side tubes (in addition to the two hoops and the diagonal behind the seats.) It also has bars across the door openings. Yes, perhaps in a rollover I might crack my skull. On the other hand, I may have the safest MGB on the planet for in-town driving. (Bonus: extra stiff chassis!) SCCA has accepted bolt-in cages in Showroom Stock classes for two decades, so apparently bolt-in can be made to work. Can you fit doubler-plates underneath the floor? Can you weld-in mounting plates (under the carpet) and then bolt to them? Almost any car modification can be done well or done poorly. |
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 |
Re: Sticker shock
You guys are slowly convincing me to forego the whole idea... but right now I still want to do one.
|
roverman Art Gertz Winchester, CA. (3188 posts) Registered: 04/24/2009 11:02AM Main British Car: 74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L |
Re: Sticker shock or left field ?
One "might" consider the oem roll bars showing up on roadsters these days ? BMW , Porsche roadsters and even Mopar comvertables have them, and have swapped to other vehicles. Cheers, roverman.
|
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: Sticker shock
I wanted to put one in my RD but I wanted the height to be adjustable and the main hoop to be removable. It got put on hold when the motor needed replaced. But the only reason I wanted it was to be able to drive it on the race tracks. Aside from that in my opinion it is pretty much a bother.
Jim |
Re: Sticker shock
If you take the time and build it right, they really are not that intrusive. You have to have everything around so you can measure and test fit to make sure they fit. I have a couple of the TR8 roll bars that are commonly sold on the web. Both were removed and tossed aside because they fit so poorly. I built new ones for the cars owners that actually fit and didn't limit seat travel.
|
|
socorob Robbie La (173 posts) Registered: 09/17/2009 04:42PM Main British Car: 1963 Sunbeam Alpine Series 2 Ford 2.8 V6 |
Re: Sticker shock
The ones in the oem roadsters these days are all called show bars. No rollover protection is implied. They are mainly for looks.
|
Moderator Curtis Jacobson Portland Oregon (4576 posts) Registered: 10/12/2007 02:16AM Main British Car: 71 MGBGT, Buick 215 |
Re: Sticker shock
Quote: Maybe. However, how they're marketed has more to do with our litigious society than with the design and construction of the bars. They could be made to meet the very letter of FIA, SCCA, and NHRA rules and the sales literature still wouldn't promise lifesaving protection because doing so would invite lawsuits. |
roverman Art Gertz Winchester, CA. (3188 posts) Registered: 04/24/2009 11:02AM Main British Car: 74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L |
Re: Sticker shock
Not being a structural engineer, I still suspect these so-called , "show bars" are better than "air", in a roll over ? " Mojave Mile" rules will consider some oem. rollover designs, "if" the engineering is provided by entrants. Cheers, roverman.
|
HealeyRick Rick Neville (489 posts) Registered: 12/19/2007 05:01PM Main British Car: 1963 Austin-Healey 3000 Ford 5.0L |
Re: Sticker shock
Another consideration for street bars is the secondary impact of your head and the bar. In a race car, you're helmeted and belted in with a 5 or 6 point harness, cinched down tight. Even still, there's going to be some movement during a rollover. With a standard street bar, you probably will have a 3 point shoulder belt at best and if your bar is low enough to allow the use of a convertible top, your head is extremely likely to smack the bar when you roll. And don't think that pool noodle insulation wrapped around the bar is going to be sufficient.
|
Moderator Curtis Jacobson Portland Oregon (4576 posts) Registered: 10/12/2007 02:16AM Main British Car: 71 MGBGT, Buick 215 |
Re: Sticker shock
Quote: That argument makes sense on cars which don't have headrests or that have headrests set way too low... The B-pillar (i.e. the steel column between door glass and side window) on an MGB GT is further forward than anyone would put a roll hoop. Just to the side of the driver's head! Maybe MGB GT owners should fear their B-pillars. |