School me on full roll cage pricing

[PatientZero]

Aren't S bends a no-no?

 

[Fabman]

Aren't S bends a no-no?

Its certainly not what I would prefer.

 

[bob]

Yes, the devil is in the details as they say. The SCCA CCR reads a lot like the tax code and just as confusing.
I was 100% sure by reading the rules that my car needed a .120 cage but a phone call to the head tech inspector said .095 was good. I didn't believe him so I made him send me an email stating it....just in case it came up later.

FWIW, I think SCCA is very clear and lenient. I'm just a home DIY guy with some minimal fab skills (I have accumulated 4 welders) and built 3 racecars and had zero problems getting cages stamped and logbooks issued.

 

[Fabman]

FWIW, I think SCCA is very clear and lenient. I'm just a home DIY guy with some minimal fab skills (I have accumulated 4 welders) and built 3 racecars and had zero problems getting cages stamped and logbooks issued.

I have seen some pretty sketchy stuff out there for sure, I have no idea how some of it passes.
Personally I'd rather err on the side of caution than to have something rejected and have to start all over or spend thousands on modifications to pass inspection like an earlier poster in this thread had to do.
Not to mention being responsible for someone getting hurt in a poorly crafted cage.
I'd hate to be that fabricator or the guy that signed it off. Everybody suffers there.
I read the rules, call for clarification when needed, do my very best work and follow instructions to a tee.
But that's just me...

 

[Apex Media]

Lemme know the next time you're down in SoCal and you can be my guest to karate chop it into small pieces. Don't mind me videoing

I too would like to witness that lol

 

[Apex Media]

I have seen some pretty sketchy stuff out there for sure, I have no idea how some of it passes.
Personally I'd rather err on the side of caution than to have something rejected and have to start all over or spend thousands on modifications to pass inspection like an earlier poster in this thread had to do.
Not to mention being responsible for someone getting hurt in a poorly crafted cage.
I'd hate to be that fabricator or the guy that signed it off. Everybody suffers there.
I read the rules, call for clarification when needed, do my very best work and follow instructions to a tee.
But that's just me...

The more i read what you post the more comfortable i am choosing you to do the cage. Lots of knowledge on this forum. glad i joined it

 

[Fabman]

The more i read what you post the more comfortable i am choosing you to do the cage. Lots of knowledge on this forum. glad i joined it

I like to say that "I may not be the best or the brightest, but I don't know anybody that cares anymore or tries any harder than I do".

 

[Tonymustang302]

Get a room you two

 

[bob]

I have seen some pretty sketchy stuff out there for sure, I have no idea how some of it passes.
Personally I'd rather err on the side of caution than to have something rejected and have to start all over or spend thousands on modifications to pass inspection like an earlier poster in this thread had to do.
Not to mention being responsible for someone getting hurt in a poorly crafted cage.
I'd hate to be that fabricator or the guy that signed it off. Everybody suffers there.
I read the rules, call for clarification when needed, do my very best work and follow instructions to a tee.
But that's just me...

Yes that's good but you can do things like err on the safeside like you said go 120 wall vs 095. Also unless for sure purpose build you never know where the car will be or how rules change. If lets say 3000lbs is the cut off for 095 vs 120 wall and the min weight is 2700 then 095 works but the guy might switch class or even within a class could breach 3000lbs. And need 120. There isn't an issue unless you get protested or crash with serious failure. Cage design is always a compromise. Even safety in cage design is a compromise that most drivers either don't care or don't appreciate the risk.

 

[Dave_W]

Back in the 90's, there was a guy in Albany who built cages as a side job, and used his day job engineering knowledge to do finite element analysis to optimize his designs. With (much) faster computers and open source FEA software nowadays, I'm wondering if more cage builders are doing something like that. Could be some knowledge to be gleaned from Formula SAE teams on FEA-based tube structure design.

 

[bob]

Back in the 90's, there was a guy in Albany who built cages as a side job, and used his day job engineering knowledge to do finite element analysis to optimize his designs. With (much) faster computers and open source FEA software nowadays, I'm wondering if more cage builders are doing something like that. Could be some knowledge to be gleaned from Formula SAE teams on FEA-based tube structure design.

I seriously doubt it. I started learning about cage design because the typical builder had no idea why he did what he did. The average builder isn’t an engineer nor clued in on FEA. Often the answer was that’s the way we’ve done it for 20 years. No one is dead so it must work having no clue about sample size. Once I went to a famous Porsche race shop for a possible cage. The guy was saying he like “beefy” welds. Stronger Yada Yada. I go see his shop and see an progress cage. Well yeah he needed beefy welds to fill the gaps of his poorly coped tubing! That was the 3rd builder I looked at. Then there was the pro puffing his chest out he only did cages by TIG. I saw his very pretty perfect petite welds with minimal to no filler rod. These welds were a thing of beauty. His welds were perfect to seal an oil tank but totally inadequate for strength and toughness. I decided to do it myself. Just because you pay a pro does not mean the guy knows what he is doing. But that said there are many good builders once you start to float in the racer circles. Problem is the guy looking for his first cage is often not clued into the guys who know. imo owners need to learn about cages their lives depend on it. Learn about compromises. Learn about fixed seats vs. sliders. Floor mount seats vs welded seat frames welded to the cage. NASCAR bars support at the sill? Side impact attenuators vs. full NASCAR bars? How about intrusion plates? containment seats!

 

[Fabman]

Computer programs have come a long way, we certainly didn't have anything like that when I started building cages 40 odd years ago, but careful study of successful designs by "pros" and the constant building and repairing of wrecked tube chassis stock cars and you get a pretty good idea what works and what doesn't. I'd love to have used a solid works program but when I started out I was making balsa wood chassis and testing torsional rigidity with a dial indicator and a fish scale.
Crude but effective.

 

[blacksheep-1]

Phoenix does cages, remember last year when Amy wadded up her gen4 Camaro at the runoffs? Well they built here new car (and she finished second by a fender) they built her a custom cage, she complained about hitting her head getting in the car, they put a bend in the side bar, she needed more leg room, they built it in, there are extra roof bars in case the car lands on a post, there is a whole lot to say for a custom built cage. You have basically 2 choices, (within the rules) you can buy a cookie cutter cage and build it yourself or have someone else do it, or.. and this will be a lot more expensive, have someone build a TRUE custom cage that fits you. Don't get sucked into the "custom cage" that is no better than a cage in a box, if you are paying the money it will require your participation fitting the car to you. and it won't happen over night. Compare Amy's 4th gen or Fabman's car to a cage in a box and you'll see what I mean.

 

[bob]

Phoenix does cages, remember last year when Amy wadded up her gen4 Camaro at the runoffs? Well they built here new car (and she finished second by a fender) they built her a custom cage, she complained about hitting her head getting in the car, they put a bend in the side bar, she needed more leg room, they built it in, there are extra roof bars in case the car lands on a post, there is a whole lot to say for a custom built cage. You have basically 2 choices, (within the rules) you can buy a cookie cutter cage and build it yourself or have someone else do it, or.. and this will be a lot more expensive, have someone build a TRUE custom cage that fits you. Don't get sucked into the "custom cage" that is no better than a cage in a box, if you are paying the money it will require your participation fitting the car to you. and it won't happen over night. Compare Amy's 4th gen or Fabman's car to a cage in a box and you'll see what I mean.

I'm a cage builder for myself. I have been offered jobs to build people cages but I already have a day job. Rob is right. There is lots of participation needed with a custom cage. IMO the seat is critical and 1st basic. Everything is build around the seat. Too many cages are built and the seats mounted inside. During the build I soft mount my seat and build the cage around it. Over the couple months of my build I might have that seat in and out of the car 50 times. Every cage I build the seat frame is part of my cage vs. Seats mounted to floor on sliders. I want my car to be able to crumble around me. It's a compromise. It's my car custom fit for me and no one else drives it. You cannot do that so easy if making a car for multiple drivers.

 

[bob]

I don't know if I mentioned this before but I'm an old racer. When I built my 1st cage X driver's door bard where popular. Then attempts at nascar bars were hot maybe 15 20 years ago when HANS started to get popular with amateurs. About the same time we started seeing driver's crashboxes in the vette C5R pro car but we amateurs were screened out of the technology like we were when all the pros used HANS and we amateurs were wearing nothing or early wright strap devices and issac piston head and neck restraints. My latest build end of 2019 I was able to buy the nascar impaxx foam to build a crashbox. So my current design is reduced size nascar bars supported with a sill tube (often left out) and intrusion plate. These elements help to contain the impaxx foam and spread energy. Monocoquing a full containment seat and driver's crash box is the best an amateur can do today. There are lots of compromises and things to consider. You need a good builder. Amazingly on any weekend we are crashing. At Runoffs last week about every race lost a car to a crash of some kind. Very rarely is anyone hurt. The chances of getting injured in your streetcar seems much higher than the most questionable tech passing racecar.