Street safe roll bar?

[Damn True]

That was sorta my question initially. Gotta admit...I didn't find the street-centric cage thread when the question came up.

I suppose we could move the stuff related to my cage. Or you could pound sand. Your call.

[Wiggawam]

Originally Posted by blainefab

You can leave the downtubes there - they meet the angle requirements. The car should benefit from adding X bracing to the shock towers - land the tubes on the shock tower right next to the transverse, rather than on top of the transverse.

I'll second this. If it was my personal car that's how I would set it up.

[blainefab]

Originally Posted by Bossbill

Point of order...does your cage build go into the Street cage thread or here? Or combine the street cage thread into this one?

IMO splitting True's build into the 'street safe roll bar' thread makes a lot of sense. To me, 'roll bar' = street, and 'cage' = race, each with some very different constraints that affect the build. Both threads are aptly named, both would be active threads.

[CP86SVO]

Originally Posted by blainefab

The car should benefit from adding X bracing to the shock towers - land the tubes on the shock tower right next to the transverse, rather than on top of the transverse.

Would the X bracing go from the shock tower to the harness mount junction or the downtube junction?

I most likely be putting in a NHRA type side bar as a compromise instead of a full cage in the near future.

TIA

WS

[Wiggawam]

Originally Posted by CP86SVO

Would the X bracing go from the shock tower to the harness mount junction or the downtube junction?

I most likely be putting in a NHRA type side bar as a compromise instead of a full cage in the near future.

TIA

WS

I would join it to the downtube junction. The more triangulation you can get the better, I prefer to never have something joined in the middle of a span. The weight penalty would be inconsequential since this is already a street car. Tying it into the upper junction will also benefit the rollover protection you were originally looking for by creating another load path downward.

[blainefab]

Originally Posted by CP86SVO

Would the X bracing go from the shock tower to the harness mount junction or the downtube junction?

I most likely be putting in a NHRA type side bar as a compromise instead of a full cage in the near future.

TIA

WS

For street/track cars I've been putting a single diagonal in the plane of the backstays - drv top to pass shock tower. It mostly lines up visually with the main hoop diagonal so interferes less with rear visibility than a full X. Our visual situational awareness on the street is a lot more casual than on the track, so fewer sight line distractions are better.

To increase the rigidity of the chassis with no impact on rear visibility you could put an X down low, from the bases of the main hoop to the shock towers.

[Ken Rahaim]

Originally Posted by blainefab

IMO splitting True's build into the 'street safe roll bar' thread makes a lot of sense.

Gents,

Hold off on anymore discussion about True's stuff and give me a day or two to split out the posts. I'm in NYC at a conference so I can't get to it now. True's already given me the relevant posts.

[Ken Rahaim]

Originally Posted by Ken Rahaim

Gents,

Hold off on anymore discussion about True's stuff and give me a day or two to split out the posts.

Posts split out. Resume discussion.

Alan (or anyone), give me a PM shout (sooner, rather than later) if you see the discussions in either of these threads drifting from their topics. Thanks.

[SN65]

Originally Posted by Damn True

SNIP.... It's pretty easy to flip the wiper motor over onto the inside of the cowl to make room for the crossbar.

SNIP....

If space for the windshield wiper motor, etc, is an issue, just convert over to a cable drive system and you can locate the motor pretty much anywhere. Also the wiper gear drives are very, very small allowing for installation in very tight quarters.

Good luck with your project, it looks like you are developing a pretty nice plan of attack.

[Damn True]

Originally Posted by SN65

If space for the windshield wiper motor, etc, is an issue, just convert over to a cable drive system and you can locate the motor pretty much anywhere. Also the wiper gear drives are very, very small allowing for installation in very tight quarters.

Good luck with your project, it looks like you are developing a pretty nice plan of attack.

There is an itty-bitty Chrysler motor that'll work just fine. I'll need to fab a bracket to hold it inside the cowl but it shouldn't be too tough.

[JohnK]

Originally Posted by blainefab

..Now, the door bars... Those things meet the letter of the rule, but I'd not give them a pass. My metric on door bars is: 'can a corner of a car touch the driver without bending the cage?'

Let me ask a general question about door bars in an OT application... the NHRA style door bars:

(Example image, ignore the fact no diagnoal is shown)

The single diagonal from the main hoop down to the floor under a-pillar aren't allowed by any rule for OT competition in general (SCCA, NASA).

But, in an HPDE application, would it have any value at all in absorbing some energy in the event of a side impact or additional dead weight? (Mild steel, not chromoly)

The example is a 4 point roll cage is being installed following AI rules but the car is only being used in HPDEs. A full cage will be added at some later point.

The builder suggests adding the door bars (swing out's even) as being better than no bar at all and very inexpensive to do at the time of roll cage installation/fabrication.

Worth doing or not?

[Ken Rahaim]

Originally Posted by JohnK

Let me ask a general question about door bars in an OT application...

Question is more apropos in this thread...

[blainefab]

Originally Posted by JohnK

Let me ask a general question about door bars in an OT application... the NHRA style door bars:

But, in an HPDE application, would it have any value at all in absorbing some energy in the event of a side impact or additional dead weight? (Mild steel, not chromoly)

The builder suggests adding the door bars (swing out's even) as being better than no bar at all and very inexpensive to do at the time of roll cage installation/fabrication.

Worth doing or not?

IMO if the car is still a street car, then skip the door bars. Routing a door bar inboard of the inner door panel/armrest puts it right up against the drivers arm, where it can affect steering input, or whack the driver in a street incident. If it's a modern car, it will have an engineered side impact structure in place.

If you do go ahead with it, make it low - lower than NHRA spec, to get it away from the drivers elbow. There's a pic earlier (post #47) in this thread of a 2pc triangulated door bar that may be useful. The rear part of the map pocket was trimmed to fit.

Swingouts would be the worst possible setup - the floppy joint at each end would negate some of the desired rigidity of the structure, and be much more hazardous to the driver - if the pin was not in place, for example, in a side impact the bar could bend enough to escape the stop plate, and whip into the driver.

Keep in mind that no matter what door bars are installed now, when it's time for a full cage, they'll likely be cut out and replaced with a structure using the space freed up from gutting the doors.

[JohnK]

Alan,

Thanks for the input. I decided to forgo the side bars for now based on that input. The more I thought about the arm being so close to the bar, the more the idea grew on me.

Much appreciated. At some point, I'm going to a full cage but I'm picking the car up later this week with the 4 point and shock tower cross bar set-up.

I will post some pictures up later as there were one or two "I misplaced the rule book" moments I have some questions about. Don't think their serious but a 2nd expert opinion wouldn't hurt.

John

[pcrussell50]

After reading this thread and giving lots of consideration to the whole roll bar/human head/street use and padding stuff, I've made my peace with the idea of putting a 4-pointer into my hpde fox mustang, a large factor being that I almost never street drive it anyway except to and from track events.

I have two remaining questions:

First, I was never sure whether the common Autopower and MaximumMS kits are even effective from the standpoint of the main hoop pushing through the thin sheet of the floor. I am not averse to paying a proper fabricator to reinforce as neccessary if "push-through" is otherwise a legitimate concern.

Second, last time I looked, Maximum sells both their own and Autopower. Anyone have opinions as to which they'd choose in my case?

Fwiw, I'm somewhat comforted by the fact that the 911gt3 I just saw yesterday at Heathrow airport had a factory installed 4-point style cage. And did I not see any padding on those bars?

[Greensix]

Originally Posted by pcrussell50

After reading this thread and giving lots of consideration to the whole roll bar/human head/street use and padding stuff, I've made my peace with the idea of putting a 4-pointer into my hpde fox mustang, a large factor being that I almost never street drive it anyway except to and from track events.

I have two remaining questions:

First, I was never sure whether the common Autopower and MaximumMS kits are even effective from the standpoint of the main hoop pushing through the thin sheet of the floor. I am not averse to paying a proper fabricator to reinforce as neccessary if "push-through" is otherwise a legitimate concern.

Second, last time I looked, Maximum sells both their own and Autopower. Anyone have opinions as to which they'd choose in my case?

Fwiw, I'm somewhat comforted by the fact that the 911gt3 I just saw yesterday at Heathrow airport had a factory installed 4-point style cage. And did I not see any padding on those bars?

I used the MM main hoop to build my cage off of and it worked out pretty well. It could be a little wider but it isn't a gross gap or anything. The foot plates are pretty large but I felt safer adding in lots of side plates to tie into the body. Made the chassis a good bit stiffer as well. The reason I just used the hoop is that I wanted to make sure everything on it was NASA legal for AI. If you don't have that concern, I think the kit they have works great as an HPDE roll bar. I have no experience with Auto-Power other than I can't remember anything bad I have ever heard about them.

[JohnK]

I was happy with the way the roll bar came out overall but the some of the finer points about the diagonal being one piece, its connection to the same node as the down tube at the top hoop, and the fact the down tube should have terminated on the floor/shock tower before the cross bar went in, were slightly off from the rule book and pictures I left behind.

If I'm not mistaken, I still believe this bar meets the AIX rules in all aspects and I think the boxed in shock towers rectifies the down tube terminating on the cross bar.

Input welcome.






I chose not to take the main hoop to the floor because the rear seat mount cross beam was so stinking beefy, seemed to make sense to mount it there.

John

[JamesC]

I know it has been put out there before in this thread and others, but plenty of modern OEM vehicles that pass safety standards and such have roll bars (jeep, Mercedes, and first gen 4Runners come to mind), not all of them even have padding so its seems that its not impossible to integrate a roll car into a street vehicle safely.

I am not asking for any of the engineers here to release proprietary data, but obviously there is some design guides and validation processes that allow this to happen. I was hoping we had some people on here that had incite into that.

While it is quite possible that the roll bars that meet these standards may not meet the specs required by many race classes, but I would love the see the information and the design process that is needed to do this.

Do we have any engineers on this board that specialize in automotive safety design?


EDIT:

Just to be 100% clear I don’t want this to turn into another podium for a knee jerk safety lecture. What I am looking for is the processes that are used to design and integrate a roll car into a street car safely.

Here is an example of what I am thinking of:

I am GUESSING one such design guide would take something 95 percentile male sitting height (about 975mm) and perform a sweep of head and make sure it is X inches away from roll bar in each crash scenario that is required for a design guide.

I ASSUME there is then a validation process to prove that the design works as needed.

[weargle]

Watch your roll bar mounting points. Exhibit A: What happens when the main hoop punches a hole in the floor pan?

[Glenn98ZM6]

condition of the driver?

[Bossbill]

Article on car build (rather tatty article).

Could the driver have survived? (Glenn98ZM6 beat me to it).
on edit -- 2nd pic shows a guy in the same color suit as indicated in car pics.
If that's him I'd be marching down to Car FX and asking for another body in white -- for someone else to finish.

2nd edit -- there was a passenger!

[Drew Manzella]

Originally Posted by Glenn98ZM6

condition of the driver?

Judging by the colors the driver is wearing I'd say his condition is "Standing in the far left of the 2nd pic".

Also - Car FX is owned by a guy named Will Williams. A quick Google search finds us this pic of Russ Williams - no doubt the son of Will Williams and also looks an awful lot like the guy in the 2nd pic - which makes it that much more plausible.

EDIT: Zooming in makes it look an awful lot like that is a bolt-in rollcage:



Is that just torn metal/shit or are those bolts coming out of the feet of the main hoop?

[SteveL]

Originally Posted by Glenn98ZM6

condition of the driver?

What about the passenger??

[JohnK]

Nice job with the blow ups Drew. Thanks. It does look like a bolt bar. There was a magazine article on these cars just recently I've got to go find. Might have more detailed pics of the bar.

Looks like driver/passenger got out thru the trunk? Don't see any jaws of life action on the roof for the extrication.

Great sequence capture by that photographer for sure. Great find Weargle.

[Bossbill]

Originally Posted by JohnK

There was a magazine article on these cars just recently I've got to go find.

Uh, post 141?

Dec 2009 issue (which has no cage details -- I just looked).

[rstoff]

In one of the pictures on the bottom of that article, it appears that it had no more than a simple 4 pt. bar.

[SHOboy]

Originally Posted by JohnK

Looks like driver/passenger got out thru the trunk? Don't see any jaws of life action on the roof for the extrication.

Still wondering about the condition of the passenger. If they got out the trunk I'm wondering what seats were installed (fixed back or not?) and how they got clearance to get out.

The interior pic in the article suggests the stock seats may still have been in place, but the first pic in the series looks to me like the back of a race seat sticking up.

Tall driver, too. If there were no injuries they both dodged bullets big time.

[SoundGuyDave]

Agreed. AND it looks like a drag bar at that. I looked through the pix, and I couldn't see either a harness bar or a diagonal... Granted, neither of those would have influenced the outcome of that crash, but...

I have an Autopower 4-point bolt-in bar in my S197, and after looking at those pix, I suddenly feel the need to reinforce the front mounting points...

Does anybody think it would be enough just to weld in a larger floor pad, and connect that to pads welded to the rear seat vertical sheetmetal and the rocker sill? I'm thinking of essentially a horizontal floor pad, and both lateral and longitudinal vertical pads, all connected, and then drop the bar on that.

[blainefab]

Originally Posted by SoundGuyDave

I have an Autopower 4-point bolt-in bar in my S197, and after looking at those pix, I suddenly feel the need to reinforce the front mounting points...

Does anybody think it would be enough just to weld in a larger floor pad, and connect that to pads welded to the rear seat vertical sheetmetal and the rocker sill? I'm thinking of essentially a horizontal floor pad, and both lateral and longitudinal vertical pads, all connected, and then drop the bar on that.

Dave - can you post pics of the base of your main hoop - interior and exterior?

[SoundGuyDave]

Alan,

It'l take a few days to strip the interior out (car still has full interior, carpet, panels, etc.), but the jist of it is that it has a fairly small pad, roughly 3"x4" that lands on the floor panel right at the corner of the footwell for what would be the back seat passenger. Fairly tight to the pedestal mount for the rear seat, which I believe is structural, and very close to the sill, as well. This pad is drilled with three 5/16" holes and bolts through the floor pan, with a backing plate of the same dimension on the other side. There is easily enough vertical clearance to slide a 3/16" steel pad underneath the interior pad. If you need pix, I'll take them, but that should give you an idea.

I will admit, I wasn't really thinking about rollover protection so much as I was having a solid seatback brace and a place to mount the harnesses, but after seeing those pix.... Yikes.

[barraza]

Originally Posted by JohnK

Looks like driver/passenger got out thru the trunk? Don't see any jaws of life action on the roof for the extrication.

The doors don't look particularly bent up. I bet they just opened them and rolled out.

They were VERY lucky.

[JohnK]

Originally Posted by Bossbill

Uh, post 141?

Dec 2009 issue (which has no cage details -- I just looked).

Nyquil has me slowed down for the night and I didn't make the connection. Thanks for checking the article.

[Tob]

Some random notes:

- looks like the Griggs arm held up (Watts and LCA's did too)!
- zoom in on the second to last photo. Looks clear to be a bolt in cage. You can also see that the floorpan stretched downward before the 'reinforcement' plate tore through
- 'The family behind the business'

http://tulsacarfx.com/carfx1/index.p...d=14&Itemid=61

[gt40]

Originally Posted by Tob

- zoom in on the second to last photo. Looks clear to be a bolt in cage.

Yep! This says its an Autopower 4-point cage.

[Larry]

A roll bar, yes. An endo bar, clearly not.

For lakes racing, those are required to be welded in, and to a much larger plate. And after seeing these pics, there's going to be a lot more than just plates at the bases of anything I'm involved with. Damn...

Lucky, too.

Edit for clarification: There was likely nothing wrong with the roll bar itself. The anchoring method / installation was obviously inadequate for the intended purpose.

[SoundGuyDave]

Most likely either this:



or this:




It's NOT the "road-race" version, since there's no diagonal.

Any way you look at it, with a car that built up (600hp, griggs torque arm and watts link, etc. etc. etc.), they should have put a full cage in it. If you look at the pictures of the other two cars, neither of them have any sort of bar in them, so they could easily have made this a full-on track car.

[SteveL]

2008 Car FX #12
The Wildest: A Racecar Made Legal For The Street

[Bill Cosby] Right [/Bill Cosby]

I've seen safer Ricer builds than that roll bar...

[StanIROCZ]

I'm surprised the factory roof structure of a modern car like that would cave so easy.

The front floor pans (where the base of A-pillars terminate) in F-bodys are almost nothing: 20 ga sheet metal spot welded to the rocker. And the rocker in a 3rd gen (maybe a 4th gen too) is basically a tube of 20 ga, and mine was rusty. Neither one of these is an adequate base for a cage.

For this reason I strongly believe in the gusseting like Alan does between the A-pillar bar and the door frame:


Also for that matter, the main hoop and everywhere else. The more integration the better. Sheet metal loaded in bending is weak. Sheet metal loaded in shear can be very strong. I also believe in the thinnest mounting plates allowed per rules since the weak spot isn't the plate, it’s the sheet metal that it is welded to.

It is too bad that CMC and other stock-like classes don’t allow more ties than they do.

[Glenn98ZM6]

Originally Posted by StanIROCZ

I'm surprised the factory roof structure of a modern car like that would cave so easy.

The front floor pans (where the base of A-pillars terminate) in F-bodys are almost nothing: 20 ga sheet metal spot welded to the rocker. And the rocker in a 3rd gen (maybe a 4th gen too) is basically a tube of 20 ga, and mine was rusty. Neither one of these is an adequate base for a cage.

For this reason I strongly believe in the gusseting like Alan does between the A-pillar bar and the door frame:


Also for that matter, the main hoop and everywhere else. The more integration the better. Sheet metal loaded in bending is weak. Sheet metal loaded in shear can be very strong. I also believe in the thinnest mounting plates allowed per rules since the weak spot isn't the plate, it’s the sheet metal that it is welded to.

It is too bad that CMC and other stock-like classes don’t allow more ties than they do.

accually Stan, the 4th gen has its front sub-frame under the A piller bar which is very different than the 3rd gen which has it towards the trans tunnel.

i do agree w/ your take on the plates between the cage and chassis. but the biggest improvement would have to be the bar in the center of the a-piller down to the top door bar.

i'm really shocked anyone walked away from that.

[Glenn98ZM6]

this shot here does not show any front half cage, just a main hoop.