Charley Hoyt

Here are some pictures of my latest project…. I am having a roll bar fabricated and installed in my convertible widebody. The purpose of this roll bar is to allow me to participate in HPDEs. I did not intend to make something that is SCCA or NHRA legal….But I do want to be reasonably safe.

My requirements for this design were straight forward: 1)I have to be able to drive to the track with the top up, 2) the top of the roll bar needs to be about two inches over the top of my helmet, 3) The roll bar needs to be far enough from my head so that it is safe to use on the street without a helmet, 4) The roll bar needs to be at least as safe as a coupe, and hopefully more safe.

The forward support that attaches from the top center of the bar to frame near the passenger still needs to be installed. Hopefully it will be ready to go to be powdercoated by the end of the week.

If you want to see more pictures of the fabrication process check out this thread http://forums.corvetteforum.com/c6-t...post1571897731

Han Solo

You might should have read this first.

http://www.nasaproracing.com/hpde/index.html

Charley Hoyt

Thanks. I checked with our local operators about the design prior to installation and they approved it. So hopefully I won't have any problems. When I get to the point that I am competitive I will have to go with another solution...because, quite honestly a hoop as described in the attached document for HPDE isn't much (if any) safer then what I have.

fatbillybob

That makes me cringe! If that bar ever sees service you will die because that bar is totally unsuported rules or not. Especially since you are doing it yourself at least consider making a bolt in removable head tube bar from the top of the rollhoop going to the lateral frame rail/door sill by the front of the door opening. This way you will get some support of the rollhoop and even pick-up a little side support.

AU N EGL

Charlie

we applaud you for the effort and work you have done, however please check with the clubs you wish to drive with. PCA and NASA have good tech rules

NHRA legal roll bars are not acceptable for HPDEs. and any roll bar must pass SCCA, NASA pr PCA rules too be allowed on track days or HPDEs.

To give you some ideas about the NASA tech rules. ( please download NASA CCR for specifics )

Main Hoop
One continuous tube with no more then four bends not to exceed more then 180* +/-10*
( I see six bends in your main hoop )

Diagonal Brace
At least one (1) diagonal brace shall be used in the same plane as the main hoop. One
end of the diagonal brace shall attach to the corner, or horizontal part, of the main hoop
above the driver’s head, within twelve (12) inches of the driver’s-side corner. The other
end of the diagonal brace shall attach to the mounting plate (or to the main hoop as
close to the mounting plate as practically possible diagonally opposed to the driver’s head, passenger floor
( Diagonal bracing not mounted from behind drivers head to passange side floor )

Rear Braces
The main hoop must have two (2) braces extending to the rear. The braces shall be
attached as near as possible to the top of the main hoop, and no more than six (6)
inches below the top. The braces must not contain any bends*. There must be at
least 30 degrees between the plane of the main hoop and the plane of the rear braces.
The main hoop rear braces shall be installed to form no more than a one hundred five
(105) degree angle or no less than a seventy-five (75) degree angle with the main hoop
when viewed from the top. The main hoop braces may be mounted at the rear shock
mounts or suspension pickup points
Not installed yet.

many other rules, not address in this short overview:
- tube thickness to wt of car
- mounting plates
- mountng plates to frame
- welds
- bolts
- tube bends and crimps
- padding
- etc.

Clearance ( broom stick rule)
In open-top cars, the top of the main hoop must be at least 2” above the driver’s helmet, and the plane formed by the top of the main hoop and the top of the front hoop must be above the driver’s head in both closed and open top cars.

PCA tech rules
http://www.pca.org/portals/cr/PCA-CR...ule%20Book.pdf

being a convertible you will need to run with the top down at all times

Plus a convertible will need race seats, harness systems and arm restraints.

Unfortunate just putting in a roll bar does not allow one on a track with any club.

Clubs need to protect their liability and their participants, so rules are made. And most clubs use the PCA rules

Then again, it is your car and your safety, but many of us don't believe that you will pass any PCA or NASA tech rules to run HPDEs.

From the pictures you have posted I would not pass this roll bar for our event.

davidfarmer

While I personally believe "sleeving" 1 3/4" tubing with .120 2" tubing is pretty darn safe, I don't think anyone will ever allow this setup when applied to the main hoop

Charley Hoyt

Thanks for the help...It is appriciated. It is not shown in this post...but, there is a little more information in the attached post.....There is a Petty bar that will be attached that goes from the top center of the bar that goes to a welded pad on the frame in the passenger foot well (near the door sill). Also, I am not fabricating the bar myself. I have a roll bar fabrication shop doing the work. The mock up work was done in my garage to help visualize the design concept and ensure that the removable section would fit in the trunk.

Charley

Charley Hoyt

Thanks AU N GEL, I do appreciate the advice from the forum experts. Realistically the safest way to go is to have a roll cage. Any non-cage options have considerably more risk. I checked with my local event operator and they said that they will allow this for their events.

With that said. I researched the SCCA rules prior to developing this concept and although the design concept is primarily mine, The fabrication, installation, and final design has been done by a professional roll bar fabricator. When I studied the SCCA rules it became obvious that a roll bar that meets all of these requirements would not be possible in a convertible. For example, If the roll bar is going to be 2" above the drivers head you can't have a solid main hoop tube (and have the roof operate). The compromise was to fabricate a joint that is solid steel and extends into each end of the bar. It gets welded to the bottom bar and extends several inches into the upper bar. It then gets bolted to the top bar with two grade 8 bolts. This area should be stronger then bar itself (although it will be less flexible).

Another example is the number of bends...This was the minimum number of bends possible to actually attach to the frame. I have seen a couple of designs without the bottom bends.....but, if done that way there is no frame structure to attach to.

The bar is two inches above my helmet.

I do appreciate all of the guidance and I agree with you that I hope I never need to use the bar. This definitely does not meet the SCCA rules for a cage. I would have if it were possible with this car. I was working to make a bar that is as safe as possible given the constraints of the car...and the fact that this isn't a track dedicated car. I am aware that there will be a time where I will need to step up to a full cage car.

Charley

davidfarmer

many have gone before you in establishing that a roll-bar cannot be built that will allow a functional top (and be high enough). Ironic thing is that you CAN do a full cage, as cage rules don't require the bar to be 2" above your head.

Charley Hoyt

Agreed. I know that it is not possible to make a roll bar that meets all of the SCCA requirements, so in doing trade studies on options I attempted to come up with a compromise that is as safe as possible. My goal was to be at least as safe as a coupe without a roll bar. I also had a goal to not make the situation worse. It is bad enough to flip a car...I didn't want a poorly designed roll bar complicating the situation. I am hopeful that this design will meet these goals.

I have read enough posts and seen enough pictures to realize that the safest way to go is to have a full cage. But, unfortunately that was just too far of a jump for me right now because that also means that a track dedicated car is required (not a problem), and a truck, and a trailer, and a place to store a trailer. I am hoping that this configuration will safely get me through my novice year.

Thanks again for the comments I appreciate the input.

GettReal

David, I actually have a vert that is a track car and has a 6pt bar welded in. It allows the roof to be functional and when I am in the car with my helmet on I still have 1-2" of clearance. It IS possible, however I had the best of the best build mine

Charley, is there a reason you went to a removable bar? is it because you just dont want the bar in there all the time? Also, where and how will the rear braces be mounted?

Im a vert guy looking to help another vert guy if I can.

Charley Hoyt

Thanks. I appreciate the help. Can you send me (or post) some pictures of your roll cage? I could probrobly learn quite a bit.

I am not currently planning on any rear supports....Just a petty bar going from the top center of the top bar to the frame in the passenger foot area. I could not figure out an acceptable method to install rear braces without cutting into the hard boot. The vertical bars are supported at mid height though....

Charley

davidfarmer

Gettreal,
ou are either really short (no offense intended), or have a really low seat. I built a main hoop that "touched" the C5 roof, and it was even with my head with a helmet on, OEM seat. The only way I could have made it work would have been to sit so low that visibility would have been an option.

And as you say, 1"-2" isn't enough, as standard rules for a convertible with bar require 2" of clearance. A full cage is the only option for keeping a convertible AND be technically legal.

NTMD8R

Getreal,
your profile says you have a C5.

In your post, are you talking about the C5, or do you now have a C6 which has the 6pt cage ?

I had a custom bar built/installed in my C5.






But a C6 is a whole different scenario.

GettReal

hehe, no offense taken at all.. I am 6'1 and I just went to the garage, put on my helmet and tightened myself in with my harness. The difference between my helmet and the softtop is 2 1/4".

I am using raceseats that are side mounted and pretty much sit on the ground and since im not really short, visibility isnt an issue I know you have heard of Powell Raceshop (who did all the roll cages in corvette challege cars) they did my bar and literally have it to fit within mm's all over.

I also saw this rollbar for a c6 vert. Im not crazy about the bottom bar curving behind the waterfall like that. I saved the link because I have a friend here who tracks his C6 vert but only at certain events.

http://forums.corvetteforum.com/c6-t...installed.html

And Yes I have a c5 not a c6 but I went through the exact same thing when I did mine, everyone saying things arent possible.

AU N EGL

No padding ?

Charley Hoyt

I saw this design but decided against it because the main hoop is very close to your head which would require a helmet to be worn on the street to be safe. My bar is six or eight inches further back compared to this one. Also the bar cant be high enough to have 2 inches of clearance and still be under the roof (with a stock seat)

Charley Hoyt

Here are the pictures of today's progress. This is the connector that allows the top bar to be removable. Unfortunately when the shop installed these the discovered that the tubes on the removable bar were not straight enough so they are going to have to remake the upper bar.

On the bright side this gives me another opportunity to change the cross bar support configuration....any recommendations?

Thanks,
Charley

minitech

Isn't the 2 inch rule measured with a broomstick across the top of the bar and windshield pillar top? There should be 2 inch clearance from the driver's helmet.

GettReal

Good question, every event Ive been to, nobody has actually checked