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MG MGB GT V8 Factory Originals Technical - Why we need quaility rollbars
Carl Floyd

That's just about how it works too! And get this, the stickier your tires, the better your chances of turning turtle.

I think we should follow up this post with a bunch of links to whatever roll bars are available for the MGB. I'll start it out with a couple that I've found with a web search. No particular recommendations, but I'll point out if I see one I particularly like.

Note the hoop for attachment around the driveshaft tunnel
Hoops to full cages, not cheap, but probably reasonable.
Another full range of similar products.

Here's some info on SCCA requirements: 1-3/4" DOM (1/8" wall I believe) and a full race cage basically. But I'm looking for a simple hoop that will work with the soft top and preferrably one that is removable. I'd prefer not to have to bend one up myself, but if it comes to that I expect I can do it. IIRC bolt together joints need a 6" section of telescoped tubing and a I'm not sure of the bolting requirements.
Jim Blackwood


You've seen mine. No diagonal bar & not near tall enough. I'm gonna have to mod a soft top along with parts from the packaway frame to clear a taller rollbar.

Looks like this Autopower racing rollbar requires removal of the passenger seat.
Carl Floyd

Great video, a good lesson to learn for us all. That was a closed car, imagine what would have happened in a roadster with only the windshield frame to support the car. The guy's last comment might well have been a lot different, or at least never spoken.
Bill Young

I have been in a rollover where the roof collapsed somewhat and I can tell you that being unceremoniously dropped on your head has it's drawbacks, such as a back muscle spasm that was with me off and on for the next 15 years before easing up enough that it only comes back now during periods of unusual stress. I'm really grateful for that too, but it never really goes away entirely. On the bright side though, it did demonstrate that the human neck is wonderously flexible, something else that I'm very grateful for. A rollbar would have helped, but then, how many I-H Travelalls do you see with a rollbar of any sort? Having the seatbelt on would have helped too, relying solely on the steering wheel and shifter to stablize oneself in a high speed roll is not a recommended proceedure, even if it was successful up until the roof gave way. Now trying something like that in an MGB would be pure madness even with the seat belt because the windshield frame is made of cast aluminum and we all know what happens to cast aluminum when it is deformed and the collapse of that windshield frame would be much more sudden and troublesome than the collapse of the Travelall windshield frame and roof. However, not having the SCCA mandated 2" height above the helmet (and full cage) would not necessarily be a death sentence in a rollover. You might only end up with a severe muscle spasm or something.

Anyway, Carl the SCCA rulebook does allow slip joints for removable bars (roll bars that is ;) so concieveably it might be possible to add extenders as a removable joint in the main hoop whereby one could raise the bar on track days and lower it for street use. Might make the bracing a little tricky but it sounds like it could be done.

Jim Blackwood

And in the UK

Geoff King

That's actually a pretty good looking roll bar. But does it allow access to the battery boxes? It looks like the center mount would interfere.

Jim Blackwood

A good point Jim, it wouldn’t be a problem with the later 12v cars but it’s shown fitted to a 72/73 and it looks as if the centre mount would be on top of the battery box cover.

Geoff King

There are a couple of decent looking roll bars here but how many would actually hold up in a roll over? Would a bolt in roll bar be up to the task? Just curious.

-- Scott
Scott Costanzo


I rolled my 74.5 MGB with the following roll bar
I was playing with tire pressure and had the pressure up round 40PSI when I rounded a corner and the back skidded out. Sliding backwards and sideways off the road I hit a bolder with the right front drivers wheel and the car flipped over.
As it started to go over I buried my face in the passengers seat. Once the car had settled my first thought was *#$*#4 I busted the windshield I had just installed. Next thought was to be careful not to let the seat belt go and land on my head. Once I had managed to get the seat belt off and was laying in the dirt under/in the car I was trying to figure out how to get out. The doors wouldn’t open because the vent windows were stuck in the dirt. I didn’t want to kick the door open and wreck my car???? Wreck my car!! It was already wrecked, I booted the door open and climbed out just as 2 cars I had passed rolled up.
End result 2 small cuts and $5000cdn later. New front drivers fender, new hood, new door skin, new windshield, new drivers glass and 1 rear quarter panel
So yes they do work, and they saved my life.

Bruce Mills

There are three critical considerations: How the bar is made, how it is attached, and what sort of rollover. The Classic Roll Bars product, according to their testing, is very strong and able to withstand the expected forces of a rollover with minimal deformation, but in an extreme case *any* roll bar could be made to collapse. We can't insure against all possibilities though, just the more probable ones, given the expected use. A bar that meets SCCA specs, attached solidly to the car with load spreading attachment points can be expected to do the job it was designed for. Yes, it can save your life.

Jim Blackwood

Bruce I have a very very similar roll bar. I can't tell you how many times people have called it nothing but a "bling" bar! A while back I even offered $1k donation if guys wanted to put together a car for rollover test. No one would take me up on it. All they wanted to do was talk about how roll bars like that would do absolutly nothing for a car. I am glad to hear it worked for you!

Gary Walker

gw mr

The location of the attachment points could be a little better but it's certainly better than no bar at all. Moving the main attachment point outward so that it is adjacent to the wheel well arch would be a better attachment point, but even better is the root of the sill box which is layered and reinforced IIRC and having the plate bend over the edge of the box would be better still. Moving the brace attachment outwards to the frame box section would likewise give a stronger attachment point, but then internal tubes for the bolts could be an issue both there and at the sill boxes. Your bar was aparently designed to be an easy install and not interfere with the top but it could easily be strengthened by adding supplimental mounting plates, a modification worth doing in my opinion. In a simple and relatively slow rollover it will probably protect you. In a barrel roll, maybe not.

Jim Blackwood

Hey Carl,
have you thought of replacing the top frame with a roll bar and just leave the header rail attatched to the top like the old Bs. this way you can keep the O.E. top and have enough room over your head to pass regs. I haven't thought much about how the roll bar would look but it's an idea if you want to make a bar yourself.
Evan Amaya

"the SCCA rulebook does allow slip joints for removable bars (roll bars that is ;) so concieveably it might be possible to add extenders as a removable joint in the main hoop whereby one could raise the bar on track days and lower it for street use."

Jim, that's a novel idea! I may explore that one further.


I was thinking along those lines. Using the rollbar as the rearmost part of the frame. Then modding a stow-away frame to somehow still support the middle of the top.
Carl Floyd

I've been having a good look at the SCCA rulebook, not because we can expect to comply with it's provisions in any way short of a full roll cage, but because it provides a good guideline for what should and should not be done. The text on removable sections is particularly illuminating.

The requirement for a slip joint, aside from a close fit, is that there be 8" of overlap and that the tube bottom out in the joint, and that two 3/8" bolts secure the joint. Minimum tubing size for a 2500lb car is 1.5" DOM with a .095" wall thickness.

There is also a requirement that the main hoop be one continuous piece.

Within these guidelines several possibilities come to mind. Such as for one, a permanently installed base having the rear braces and an angular cross brace but with a removable main hoop. Not strictly in accordance with SCCA policy, but if the legs of the main hoop extended to the mounting plates there would be little to complain of. And here's the kicker. Let's say you have a 4" difference between "below the top" and "2 inches above the helmet" and solved that problem by using a pair of 4" removable plugs for the main hoop to bottom out on? Remove the plugs and it fits under the top. That means straight and parallel uprights but it should work, and it should be plenty strong. What to make the plugs out of and how to best remove them are open questions.

Jim Blackwood

This thread was discussed between 15/08/2006 and 23/08/2006

MG MGB GT V8 Factory Originals Technical index

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