Legal roll cage setups in trucks

[aventino68]

Most of the stuff I see on here doesn’t have the rear bars coming down from the top of the cage through the roof or the rear glass. NHRA and SCCA say rear roll cage bars must be within 6 inches of the top bar. I hate these and want to avoid these on my 56 pickup but how to do this and stay legal. I see a Petty bar might be an option but no-one on here has these.



How do guys get cages that don’t appear legal certified in trucks?

[Sbeck09]

I think you are seeing the fairly relaxed nature of autocross rules shine through here. I've never really had them ask much about my cage in various "street" cars. Time trial road course stuff isn't much more strict. Most classes don't even require a cage at all.

Wheel to wheel is a different story. There isn't a work around. Those bars have to be there for that main hoop to not end up in your lap. So unless you are building an all-out race truck, I wouldn't even bother adding the down bars if you don't like them. And a Petty bar would totally screw you on a passenger so bear that in mind too.

[aventino68]

Ok, thought that sadly might be the case. Was wondering if there’s a way of redesigning the cage and strengthening in the cab or the front tubes to allow the rear tubes to come through at tray wall height back to the rear suspension and be hidden. Sounds unlikely and the rear tubes kill the truck look a little. Keen to do track stuff like Thunderhill 25 hr as well as autocross.

[Sbeck09]

I have seen a number of trucks that run rear bars from the cab to the rear suspension area just below the rear window. This allows them to be hidden under a bed cover. Just doesn't really do much to help in a rollover situation.

[aventino68]

I’m thinking I’ll contact the SCCA and see if I can have a removable Petty bar that I could put in for road racing and take out when I have a passenger. That should get the truck past scrutineering.

I’d run the rear lower bars as well to tie in the rear suspension and strengthen the chassis.

[cornfedbill]

Most sanctioning bodies require 2 fore-aft bars that are at least 30 degrees from vertical and within 6 inches of the top bar. I think some bodies will allow these to mount forward of the bar.

From SCCA General Competition Rules (GCR):

Cars must have 2 braces extending to the rear from the main hoop and attaching to the frame or chassis. Braces must be attached as near as possible to the top of the main hoop (not more than 6 inches below the top), and at an included angle of at least 30 degrees.

The SCCA rules can be downloaded from their site.

Be careful NHRA rules don't always meet road racing requirements. I found this to be the case when building a roll bar for the Sandhills Open Road Challenge. The Big Bend Open Road Race has even stricter requirements (it is a faster race).

Read, read, read, is all I can say.

You could make removable rear bars. Our roll bar was removable. We used some connectors I got from Summit Racing for the rear supports. They are billet Chromoly.

[Adam_T]

Sorry to hijack but just wondering about the safety of roll bars like he's originally talking about. If you had a main hoop with the door bars but No back bars would it be dangerous in an accident? Going to add a harness bar to my project and was thinking of just doing a full hoop mainly for looks but don't think I really want to do the rear bars.

[Sbeck09]

Sorry to hijack but just wondering about the safety of roll bars like he's originally talking about. If you had a main hoop with the door bars but No back bars would it be dangerous in an accident? Going to add a harness bar to my project and was thinking of just doing a full hoop mainly for looks but don't think I really want to do the rear bars.

The simple answer is that it's better than nothing, but won't ever be ask strong without the added support. Doesn't sound like that's a big deal in your case.

[aventino68]

I was thinking of seeing if an engineer can use this clause:


On cars where the rear window/bulkhead prohibits the installation of rear braces (Porsche 914, Pontiac Fiero, etc.) the main hoop should be attached to the body by plates welded to the cage and attached to the stock shoulder harness mounting location. There must also be a diagonal bar connecting the top of the main hoop to the lower front passenger side mounting point (“Petty bar”). Some cars built for racing in other recognized sanctioning bodies may be granted a waiver of this rule; however they must show proof of compliance with the current published rules for their class.

If they can design a cage that’s strong enough with a removable Petty bar then I’ll go that route, otherwise I’ll see if I can use removable rear bracing. Sounds like I need to look at the open road racing requirements too.

Which makes me wonder, can you have a road legal vehicle that you can use for anything from autocross to 1/4 mile to open road racing and it’s pretty much legal in all?

[cornfedbill]

Which makes me wonder, can you have a road legal vehicle that you can use for anything from autocross to 1/4 mile to open road racing and it’s pretty much legal in all?

That depends on how fast you plan to run. Some classes do not require any type of rollover protection.

That said, I would make every effort to build a safe and effective roll bar in a pickup. They do not have much roof structure.

The Petty bar and attachment to the body is not a bad compromise. It's not the best, but is better than nothing. Can you run diagonal door bars that attach to the main loop at around shoulder height to offer some support?

[aventino68]

That depends on how fast you plan to run. Some classes do not require any type of rollover protection.

That said, I would make every effort to build a safe and effective roll bar in a pickup. They do not have much roof structure.

The Petty bar and attachment to the body is not a bad compromise. It's not the best, but is better than nothing. Can you run diagonal door bars that attach to the main loop at around shoulder height to offer some support?

Thats what I was thinking too. I've also stumbled across the cages built for the large truck racing and the Paris Dakar Off Road Race. They use extensive bracing in the cab that doesn't extend rear of the cab. But looks like it would prevent deformation of the cab when needed. So I'll see if there's a combination of all of that which would pass scrutineering with the SCCA. I'm assuming a weight penalty I can live with in additional cage structure vs just having the rear bars. Still think I will use lower rear bars to triangulate back of cab at tray level down to rear suspension area.

Not sure how quick it will run, I'm hoping to have a little play with the aero, more for stability than anything else.

[stangreen]

Thats what I was thinking too. I've also stumbled across the cages built for the large truck racing and the Paris Dakar Off Road Race. They use extensive bracing in the cab that doesn't extend rear of the cab. But looks like it would prevent deformation of the cab when needed. So I'll see if there's a combination of all of that which would pass scrutineering with the SCCA. I'm assuming a weight penalty I can live with in additional cage structure vs just having the rear bars. Still think I will use lower rear bars to triangulate back of cab at tray level down to rear suspension area.

Not sure how quick it will run, I'm hoping to have a little play with the aero, more for stability than anything else.

On my 55 F100 when I was doing the cage NHRA Tech told me the only way not to have rear cab bars is to put a promod cage around the driver I did not want that many bars around my head because this is my daily driver so I decided to do the cab bars I did a 12 point cage put a few extra bars in it also

[Sbeck09]

I'm actually excited to see all the wild looks on people's faces when I roll up to a light in my lowered old truck with cage bars coming down. Sure makes a conversation piece.

[Vimes]

I was looking at doing a roll cage in my own truck, but found in my research that it's not a good idea in your street car. The reason is, if you're not wearing a helmet and are in an accident, instead of your head bouncing off padded interior parts it's bouncing off unforgiving steel bars. Something to think about. I'd like a roll cage in the truck I'm building, but now am not sure on what I can do with this since my truck will be a street/strip vehicle.

[cornfedbill]

I was looking at doing a roll cage in my own truck, but found in my research that it's not a good idea in your street car. The reason is, if you're not wearing a helmet and are in an accident, instead of your head bouncing off padded interior parts it's bouncing off unforgiving steel bars. Something to think about. I'd like a roll cage in the truck I'm building, but now am not sure on what I can do with this since my truck will be a street/strip vehicle.

That is why it is very important to design your cage properly. We put a roll bar in my son's HHR for open road racing. We dropped the seats and set the roll bar in a position that it was not possible to hit our heads as long as we were belted in properly. It took a lot of work and extra planning. We felt safe in it at the speeds we were running. Our class limited us to a maximum of 140 mph.