Aluminum Roll Bar?

[javadog]

Originally Posted by Flieger

Which is why you have double-butted tubes on things like bicycle frames.

Those aren't welded... at least not the good ones.

JR

[kach22i]

Found it, and yes it was just the practice stuff.


Update: building a roll cage

Originally Posted by widebody911

We did some practice bends on 'cheap' ERW stock, but still managed to blow though a bunch of the expensive stuff. I can salvage some of the mis-bends to make smaller pieces. All my friends are getting DOM tubing paperweights this xmas.

I had a little of the 'pull' issue when I removed my improvised door bars - I got a little bit of 'twang' when I cut them off and the door gap changed.

I also found this as far as terms:

Steel Conduit Pipe Manufacturers & Supplier ISI marked Punjab India

Q : What are other terms used for Steel Conduit pipes?

The following names are often used in international parlance as a synonym to Steel Conduit Pipes:- Black Steel Tube, Electric Resistance Welded (E.R.W.) Steel Tube, MS Tube, Screwed & Socketed Steel Tube or just Steel Tube etc.

Some good FAQ's on this site:
http://www.ioportracing.com/faq/rollbar.htm

What is true is that Chrome-Moly is stronger than DOM and DOM is stronger than ERW.

I'm a bit puzzled by the 3,500 lb rule.............is there a typo in there?

[wayner]

Originally Posted by LJ851

This 917/10 chassis including rollbar must be a horrible idea then, being all aluminum....

From most reports, I don't think it was even a great race car chassis let alone a cage with any sort of protection.

I remember how I used to think that anything from the factory was good, but then I read about the innovative pressure gauge that they installed on the frame so that the driver could detect the moment it cracked so he could return to the pits.

Even the factory was still learning.

[Flieger]

Originally Posted by wayner

From most reports, I don't think it was even a great race car chassis let alone a cage with any sort of protection.

I remember how I used to think that anything from the factory was good, but then I read about the innovative pressure gauge that they installed on the frame so that the driver could detect the moment it cracked so he could return to the pits.

Even the factory was still learning.

They did not have a pressure gage for the driver to read. They had a fitting that they could put a gage on after the race and pressurize it. During the race the only pressurized tubes were the ones carrying oil.

If you think that frame is scary, think about the Le Mans winning (!) Magnesium (!) frame for the 1971 917K.

[Flieger]

Originally Posted by javadog

Those aren't welded... at least not the good ones.

JR

My point is still valid. Yes, there are lighter materials out there, ones that don't need to be welded.

[javadog]

Originally Posted by kach22i

Some good FAQ's on this site:
Roll Bar & Cages - Frequently Asked Questions


I'm a bit puzzled by the 3,500 lb rule.............is there a typo in there?

I wouldn't recommend that site. No good info. They seem to confuse readers with a discussion that talks about the material type and interlaces it with the production method. There's other useless crap there as well.

No typo. Some race cars are actually that heavy.

JR

[kach22i]

Originally Posted by Flieger

If you think that frame is scary, think about the Le Mans winning (!) Magnesium (!) frame for the 1971 917K.

In the previous post with the practice cash in the rain at 250 km/hr (155 mph), that frame/body/design allowed the driver to survive.

Even if I could get my steel bodied / aluminum bumper 911 up to 155 mph, I have sincere doubts about my chances of survival - even with a steel roll bar.

[kach22i]

Originally Posted by javadog

No typo. Some race cars are actually that heavy.

Why would the rules mandate the weaker ERW (conduit) be used on the heavier +3,500 lbs cars?

I would think that a heavier car would need more strength not less (more strength like DOM or Chrome-Moly).

Same reasoning also allowed me to think that a light weight roadster from the early 1900's could get by with a laminated loop/hoop of wood. Although at the time they favored ejection (no seat belts) as the preferred method of accident survival.

[javadog]

Originally Posted by Flieger

Welding also reduces 4130's strength significantly. Which is why you have double-butted tubes on things like bicycle frames.

Originally Posted by Flieger

My point is still valid. Yes, there are lighter materials out there, ones that don't need to be welded.

No, it's not. Do some research into why bicyle frames are made the way they are... They are brazed. This is done at lower temperatures than welding and their are several advantages that come from this method of construction.

While you're at it, read up on welding 4130. You have some misconceptions there, also. You might be surprised at what you learn. Understand that 4130 was originally intended to be gas welded. There are advantages to that. Modern welding methods change the nature of a 4130 welded joint and you need to understand what role is played by the type of welding used, the type of filler rod used, the size and shape of the weld filet, the use (or not) of pre- and post-weld heating, etc. etc.

It's a complex subject and not well understood by most people, including a lot of welders.

JR

[javadog]

Originally Posted by kach22i

In the previous post with the practice cash in the rain at 250 km/hr (155 mph), that frame/body/design allowed the driver to survive.

No, he was just really lucky. They did not intend for the frame to break like that. That crash wes very early in the testing of the 917 and Piech was running the program. His first concern was weight, followed by his second and third concerns, which were also weight.

Porsche race cars (like many of that period) were not safe at all. If my memory is any good, they didn't even tell the drivers of the magnesium-framed 917 that they were using that material in the frame, until after the race.

The first race car they built with any decent safety was the 962. Even the 956 was a killer. I still remember the day Stefan Bellof died in one.

JR

[javadog]

Originally Posted by kach22i

Why would the rules mandate the weaker ERW (conduit) be used on the heavier +3,500 lbs cars?

Maybe because they are using a larger diameter tube, thicker wall, etc.

You can't make blanket statements like they do, about roll cages and their suitablity for cars based on weight. Each sanctioing body will have specific rules and even these may change over time. They may also conflict, in that a cage legal for one race series would not be legal for another, unless changed.

If you are building a car for a particular series, the rules will generally specify the minimum sizes and types of tubing to be used and most will have some guidelines on what sort of design is needed.

JR

[NYNick]

And I thought it was just a simple question I originally posted….

[cgarr]

All my welded joints are normalized same as we do with fuselage tubing. It takes some time to heat everything back up but really the only way to do it.

[javadog]

Originally Posted by NYNick

And I thought it was just a simple question I originally posted….

Poke around here a while:

Untitled Document

You too, Max.



JR

[javadog]

This may be easier to digest:

American Welding Society - Welding Journal

[kach22i]

Originally Posted by NYNick

And I thought it was just a simple question I originally posted….

Hang the heretic!..........he's back.

Just kidding.

I've learned a few things, new week though and it's time to move on.

[Augustus]

Aluminum has high tensile strength, but once you over-stress it, it breaks, cracks or tears. There is a reason you never see race cars with aluminum cages or roll bars.



You need to rethink this. It's your life on the line my friend.

Porsche used an aluminum roll bar in their 1969 911 GTS.

[70SATMan]

Originally Posted by Augustus

Porsche used an aluminum roll bar in their 1969 911 GTS.

It was also optional on the early STs. Same design as the steel but, in ALU.

[kach22i]

This 914 makes some repeated use of aluminum.

914-6 GT Troutman Truck
Detailed Photos
August 8, 2011
Gunnar Racing

Aluminum strut holds the tank in. On most other GT's this strut is steel

Plexiglas rear window and aluminum roll bar. That's right, aluminum.

Porsche 904
http://cobraferrariwars.com/porsche-904.html

The diagonal black tubular braces running from the top part of the roll bar hoop back toward the rear shock towers is not original, but most of the vintage-raced original 904s have added this for safety -- a stronger roll bar. We had the original rear body section parallelogram hinge mechanism, but it was awful and so replaced it with a crude but practical aluminum tube brace. I don't know whose idea it was to paint the motor fan shroud red, but so what. The wheels are all steel whereas the originals were magnesium/steel.

[proffighter]

Aluminum cages are used often here in Europe, I have a FIA approved HEIGO



Here I posted the document:

Looking for ideas and/or pictures of drilled out parts

Weight difference is quit big, steel cage is 34kg, same in alu is 18kg

Material is AlZnMg 1 F 35, steel would be 460