Q: Roll Cage designs & Photos

#21

Here is a pic of the cage we plan to do in Simon’s car (note that a few of the tube junctions are not quite accurate as far as actual location yet). A typical design but with a few extras here and there. Missing from the pic is the cross member between the rear down tube attachment points and then the clambshell gussets in the door X’s, the A pillars at the dorr X, the A pillars at the windscreen crossmember, and possibly in the main hoop X.

I’m still contemplating a lower X from the upper rear door bar/main hoop interface back to the rear down tube mounts. Those are mounting to the trunk floor where the spring perches are located so I can’t triangulate back from the lower rear X/main hoop interface.

Anyway, as with all McMahan cages, the execution will be no less than phenominal. Car gets dropped Tuesday, should be back the 1st week in Dec and then the rest of the teardown can commence. Reassembly should start early Jan with a final completion around mid Feb. If all goes well, testing in March, track in April!

simons_cage_isoview_sm.jpg680x533

#22

regarding the additional lower rear X - there is some ambiguous language in the rules about the cage being for safety and not rigidity. When I asked my NASA Regional Director how he interpreted that, after we talked about different configs, he said that he would consider the second X to be just for rigidity, and hence, not compliant. I’m sure this is a grey area.
cheers,
bruce

#23

leggwork wrote:

[quote]regarding the additional lower rear X - there is some ambiguous language in the rules about the cage being for safety and not rigidity. When I asked my NASA Regional Director how he interpreted that, after we talked about different configs, he said that he would consider the second X to be just for rigidity, and hence, not compliant. I’m sure this is a grey area.
cheers,
bruce[/quote]

Of course I’m not really interested in challenging the rules or the officials so much but I have to say that this is a ridiculous one. The cage, by definition, is more safe the more rigid it is. Any properly placed extra tube, for the most part, will increase rigidity and therefore overall safety. The cage is not designed to be a crushable structure, minimal deformation from an impact is the goal.

We’re not trying to push the rules or get into arguing about it but I will say that when I design a cage it is with safety in mind, I do not want any compromising here. If someone challenges a cage because of extra tubes then so be it but that’s pretty weak.

I’m not saying that you are, I understand where you’re coming from. Trust me I deal with people pointing out rules wording issues everyday but something like this is just stupid and silly. To be really anal, any tube other than the basic 6 or 8 pt stucture is "extra" and could fall into this category so where’s the limit?

I want the car to be very safe, the last thing I want to think about is whether the cage held up.

#24

just FYI, this is the section of the NASA rules I was mentioning. I’d be willing to bet that a fellow competitor in Spec E30 wouldn’t protest the second X, but who knows.

[quote]15.6.2 Intent
Chassis stiffening is a side benefit of a good roll cage system, but it is not the intent of these rules. Parts of the cage deemed by the Chief Scrutineer, to serve no practical purpose other than chassis stiffening may be considered in violation of the intent of these rules (Note: Some class rules allow for chassis stiffening.). The Chief Scrutineer may order the removal of said parts, or require that the vehicle owner redesign, reconstruct, and re-certify the roll cage if warranted. The removal or redesign of the cage, whole or in part, to comply with these rules, does not imply that penalties will not be issued for violating the intent of these rules.[/quote]

Another interesting part of the rules is that we can make the cage compliant with SCCA, IMSA or Grand Am rules if we have a copy of those rules to present. Not sure what additional allowances that might enable. Too bad it doesn’t mention BMWCCA because the "Additional Reinforcement" is allowed rule was added this year.

[quote]15.6.1 Purpose
The basic purpose of the roll cage is to protect the occupant in case of a rollover or a collision. It must be able to withstand the weight of the car landing on the roof. These rules apply to all classes, unless otherwise superseded by the class rules. Vehicles homologated by, or built to the specifications of, SCCA, IMSA, and Grand AM must conform to these rules, or may conform to their respective current class rules for roll cage requirements. It is the responsibility of the driver to have these (non-NASA) rules in his/her possession.[/quote]

I don’t know what the process is for requesting CCR modifications but it would be nice if this area wasn’t so gray.
cheers,
bruce

#25

leggwork wrote:

[quote]just FYI, this is the section of the NASA rules I was mentioning. I’d be willing to bet that a fellow competitor in Spec E30 wouldn’t protest the second X, but who knows.

[quote]15.6.2 Intent
Chassis stiffening is a side benefit of a good roll cage system, but it is not the intent of these rules. Parts of the cage deemed by the Chief Scrutineer, to serve no practical purpose other than chassis stiffening may be considered in violation of the intent of these rules (Note: Some class rules allow for chassis stiffening.). The Chief Scrutineer may order the removal of said parts, or require that the vehicle owner redesign, reconstruct, and re-certify the roll cage if warranted. The removal or redesign of the cage, whole or in part, to comply with these rules, does not imply that penalties will not be issued for violating the intent of these rules.[/quote]

Another interesting part of the rules is that we can make the cage compliant with SCCA, IMSA or Grand Am rules if we have a copy of those rules to present. Not sure what additional allowances that might enable. Too bad it doesn’t mention BMWCCA because the "Additional Reinforcement" is allowed rule was added this year.

[quote]15.6.1 Purpose
The basic purpose of the roll cage is to protect the occupant in case of a rollover or a collision. It must be able to withstand the weight of the car landing on the roof. These rules apply to all classes, unless otherwise superseded by the class rules. Vehicles homologated by, or built to the specifications of, SCCA, IMSA, and Grand AM must conform to these rules, or may conform to their respective current class rules for roll cage requirements. It is the responsibility of the driver to have these (non-NASA) rules in his/her possession.[/quote]

I don’t know what the process is for requesting CCR modifications but it would be nice if this area wasn’t so gray.
cheers,
bruce[/quote]

Agreed. I might think that the wording is pertaining to specific classes they are trying to limit but I don’t know all the NASA classes by any means so I could be way off.

Anyway, attached is a pic of the cage we are likely to do. Only thing missing are a few clambshell gussets in the A pillar tubes at the top of the windscreen.

Cheers.

simons_SE30_cage_rev2_sm.jpg680x525

#26

Jack, how many cars is Elephant building? Just Simons? Will you race it some? Thanks in advance, Robert Patton

#27

I think the tube joining the two rear plates would be considered a weld-in rear shock tower brace and hence illegal.

I went through the same ordeal with the Northern Cal regional directors regarding cage design. I wanted to do all the same things you are proposing, but had to remove some stuff. Ultimately, those are the guys ruling on compliance, so if they say no, there’s not much you can do. They’ve also heard all the same arguments you’ve made and won’t budge on it. Sucks, I know.

#28

traqrat wrote:

[quote]I think the tube joining the two rear plates would be considered a weld-in rear shock tower brace and hence illegal.

I went through the same ordeal with the Northern Cal regional directors regarding cage design. I wanted to do all the same things you are proposing, but had to remove some stuff. Ultimately, those are the guys ruling on compliance, so if they say no, there’s not much you can do. They’ve also heard all the same arguments you’ve made and won’t budge on it. Sucks, I know.[/quote]

The rear tubes do not go to the shock towers, they go to the trunk floor where the spring perches are located.

Like I said, I’m not trying to argue or to push any issues, this is how I would do any cage with limited allowances. The cage is about safety and the stiffness/rigidity it adds are by products. I’ve inspected dozens of cages this year for many classes and I would not want to ride in some of those cars even though they meet the minimum requirements. I guess my minimum standard of safety is higher than most. If I ever have to walk away from a totaled car I hope I can say thank God for the cage!

#29

Patton wrote:

Hey there Sheriff. Right now just the one for Simon. I’m not sure if I’ll race it or not, I’m going to be busier next year with BMW CR than I was this year I think. I’m hoping to hit the track once or twice though, we’ll see. I really wish I could get enough time to race at the Nationals, I’ve got tons of seat time at MO so I think it would tons of fun. Remains to be seen though…

#30

Jack,
Here is picture of my cage by the rear shock towers.

You can find links to pics of my cage in this thread:
http://spece30.com/component/option,com_mamboboard/Itemid,68/func,view/id,1310/catid,9/limit,10/limitstart,0/

The way I, and my cage builder (very reputable around SF bay area) read the rules, cage is legal as per SpecE30 rules. Note that I said “I� and not the NASA / SpecE30 officials so take it for what is worth. When I posted the pics of my cage nobody protested it… I don’t consider it “stiffening� of the chassis since I am not tying it to the spring perches, and for safety, etc each ‘point’ ties three bars. Also per rules rear “strut� bar is allowed, so I don’t see this as a problem. Will see what officials say once I get on the track ( and if someone will protest it).

BTW, what’s the software that produced those nice drawings of your cage?

Igor

#31

Igor,

That’s a CATIA V5 solid model that I created using Jack’s input and
what I know McMahan likes to do. That last version of the cage
weighed in at 166 lbs. It’s not an exact model as I used my car with
full interior for some preliminary dimensions.

Actually if I had more time on my hands I could put a lot of the E30
on CAD and design a bunch of stuff. I’ve got camber plates designed
already so I may try to do some adjustable Spec E30 ones. I don’t sell
stuff though I just design. :wink:

-Carlos.

#32

clopez98m3 wrote:

[quote]I may try to do some adjustable Spec E30 ones. I don’t sell
stuff though I just design. :wink:

-Carlos.[/quote]

Carlos,
Thanks for the info.

Not to long ago, and just before I got my plates, I had a conversation with Jack about “state of the camber plates� for the E30 (and spece30) – quality, fitment (spl?), dealing with companies that make and sell them,….if you design them maybe Jack can sell them?

Igor

#33

well, now that you mention it … :wink:
I just noticed from an earlier comment in this thread that only a bolt-in shock tower brace is allowed … Seems like it would be less expensive to allow a weld-in bar like you have. Carter?
9.3.8.10. Any bolt-in strut or shock tower brace is permitted, unless specified in these regulations.

cheers,
bruce

Igor wrote:

[quote]Jack,
Here is picture of my cage by the rear shock towers.

You can find links to pics of my cage in this thread:
http://spece30.com/component/option,com_mamboboard/Itemid,68/func,view/id,1310/catid,9/limit,10/limitstart,0/

The way I, and my cage builder (very reputable around SF bay area) read the rules, cage is legal as per SpecE30 rules. Note that I said “I� and not the NASA / SpecE30 officials so take it for what is worth. When I posted the pics of my cage nobody protested it… I don’t consider it “stiffening� of the chassis since I am not tying it to the spring perches, and for safety, etc each ‘point’ ties three bars. Also per rules rear “strut� bar is allowed, so I don’t see this as a problem. Will see what officials say once I get on the track ( and if someone will protest it).

BTW, what’s the software that produced those nice drawings of your cage?

Igor[/quote]

#34

Igor wrote:

[quote]Jack,
Here is picture of my cage by the rear shock towers.

You can find links to pics of my cage in this thread:
http://spece30.com/component/option,com_mamboboard/Itemid,68/func,view/id,1310/catid,9/limit,10/limitstart,0/

The way I, and my cage builder (very reputable around SF bay area) read the rules, cage is legal as per SpecE30 rules. Note that I said “I� and not the NASA / SpecE30 officials so take it for what is worth. When I posted the pics of my cage nobody protested it… I don’t consider it “stiffening� of the chassis since I am not tying it to the spring perches, and for safety, etc each ‘point’ ties three bars. Also per rules rear “strut� bar is allowed, so I don’t see this as a problem. Will see what officials say once I get on the track ( and if someone will protest it).

Igor[/quote]

Igor and all:

No one at Spec E30 is obligated to look at photos and tell a driver if his car is legal or not. If I show a police officer a photo of me speeding, and I speed, and I get a ticket, it wasn’t the officer’s obligation to tell me not to speed.

The rule specifically allows a bolt-in shock tower brace. Your brace is clearly welded to the plates that are welded to the rear shock towers. I suggest you look at the CCR, rules 15.6.13 to 15.6.14B.

If you think there might be a problem with Spec E30 Rules compliance, ask the Spec E30 Regional Director at your next race. For sure, you’ll be allowed to race but a change might be required before the next race weekend.

Carter

#35

Sure, I agree that no-one is obligated to tell me (or anyone else) if I am in compliance of the rules or not just by looking at posted pictures. However I would of expected that in the spirit of the new series and comradely which is going on that someone would say something about it, a la “Hey bud, you might want to rethink this…� or some other friendly comment (I don’t think that we are, and hope to never be, at the point as some other series are regarding competitor’s car compliance). I want to build the car to the rules right off the bet – one of the reasons when I posted the pictures was to share the joy of my progress as well as to show what has been done and draw (constructive) criticism and suggestions. Clearly if I wanted to hide something I would not posted the pictures. Beside dozen cars that have been build around the nation for the new series that is trying to gain momentum, the rest of us are trying to figure out how to do it – and one way is to discuss it here, hence a lot of posts regarding rule compliance and progress of work among other things.

[ /rant off]

When I and my cage builder read the rules it seemed that my cage is in compliance. I will contact my regional director (M. Mills in CA right?) and see what he has to say. If my cage is out of compliance I’ll fix it before my first race.

Igor

#36

Igor:

I posted in a bit of a hurry late last night and didn’t want to sound snappy.

Yes, we want all new drivers/car builders to post photos and reports about your progress. We enjoy reading about others’ progress.

Regarding your cage, Mike is certainly the best among the Spec E30 officials, when it comes to these things.

Carter

#37

I’ve read over the rules, done my homework and have developed the final design for my cage.

The car will be delivered to the cage builder this weekend. So if any of you see any glairing rule infractions… please feel free to call them to my attention.

Thanks again for all of your input and suggestions.

#38

Update: Based on the comments from previous posts I contacted my regional Spec E30 dir (who in turn also contacted NASA tech for the region) and I got a ruling regarding my cage legality:

There is nothing wrong with the downtubes on my cage, however the welded in bar from one shock tower to the other was deemed illegal.

I have to cut it out and can use bolt-in tower brace if I want to.

Regards,
Igor

#39

I can vouch for the quality of the IE rear brace, if that helps.

#40

scottmc wrote:

[quote]I’ve read over the rules, done my homework and have developed the final design for my cage.

The car will be delivered to the cage builder this weekend. So if any of you see any glairing rule infractions… please feel free to call them to my attention.

Thanks again for all of your input and suggestions.

[/quote]

Sheet metal gussets like the ones you have in your doorbars are not specifically allowed by the NASA rules. They only allow reinforement tubes. I would contact your NASA regional steward and make sure it is legal before having those done.