Rally Chat
Don\
Welcome! Log In Register

Advanced

some good roll cage buidling guides

Posted by Littlelina 
Forum List Topic List Start New Topic
Page 6 of 13    Pages: Previous1234567891011NextLast
Newer Topic Older Topic
Tim Taylor
Tim Taylor
Professional Moderator
Location: Oakland, CA
Join Date: 02/02/2007
Age: Midlife Crisis
Posts: 622

Rally Car:
Mazda 323 GTX
Tim Taylor
Re: some good roll cage buidling guides
November 16, 2011 11:49AM
some injur-nears have taken entire classes on metallurgy and welding...

FYI: T45 for cages is just an artifact of the British racing industry. It is a good cage material because it has similar yield strength to 4130 chromoly but also better ultimate strength so it will deform and absorb more energy before it breaks. It's also damn expensive because by virtue of being a niche alloy used mostly by british aerospace companies and cage builders. Most of continental Europe uses 25CrMo4 or 15CDV6 instead because it's much cheaper and does the same job.
Please Login or Register to post a reply
john vanlandingham
John Vanlandingham
Godlike Moderator
Location: Ford Asylum, Sleezattle, WA
Join Date: 12/20/2005
Age: Fossilized
Posts: 14,152

Rally Car:
Saab 96 V4
john vanlandingham
Re: some good roll cage buidling guides
November 16, 2011 12:37PM
To all you Chrome moly experts and your truly bizarre claims that chrome moly is "brittle".....

Cars have bodies AND cages, both of which have some strength, together if done will is stronger than the the 2 thing separate...

Motorcycles have only the frame....

Very light weight, very strong since the intended use of at least moto-cross bikes is like way way insaner in NORMAL use that wimpy little roll overs....

Knowing the normal stresses are quite severe, and that the expected life span is pretty high:

Why the hell would 4130 or similar be the material of choice if it was "brittle"....??????

The one word that spring to mind when I think of chrome-moly steel is TOUGHNESS.
I am feeling too shitty to argue this. back to bed.


John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.
Please Login or Register to post a reply
heymagic
Banned
Senior Moderator
Location: La la land
Join Date: 01/25/2006
Age: Fossilized
Posts: 3,740

Rally Car:
Not a Volvo
heymagic
Re: some good roll cage buidling guides
November 16, 2011 02:00PM
If I remember correctly...

T45 is British and homolgated by the MSA . T45 is not approved by the FIA for home construction.

So if an old cage FIA cage is sold and has homo papers it is allowed, no papers then it has to meet the FIA rules, not the MSA rules. So T45 is no good in this case. CDS can be used without papers depending on thickness and construction. A real homolgated car from say 1987 can be built with the older designs using CDS (not DOM or Cro-Mo or T45) of the prescribed dimensions. That could change as time progresses so I advise against it.Clear as mud eh??

Many of the "cute" homolgated designs are not very strong and fail due to being too lite. Someone swore under oath and testing they were ok. Prolly an engineer with a law degree and political aspirations.

Saving 50 or 70 lbs in the average rally car is a total waste of time as most people never approach the driving limits that would actually make a difference at. New tires are a better investment. Better seats are a better investment. Make the cage hell for stout so when stoopid shit happens you have a chance to be around later and lie about whos fault it was...

Building a cage to anything other than FIA or RA specs will get you a seat in the spectator area at RA events, just so ya know. No Halo Hoop, no Vbars, no skinny tubing.
Please Login or Register to post a reply
DaveK
Dave Kern
Senior Moderator
Location: Centennial
Join Date: 07/11/2008
Age: Midlife Crisis
Posts: 1,085

Rally Car:
Compact M3 & Evo IX
DaveK
Re: some good roll cage buidling guides
November 16, 2011 02:07PM
Quote
Cosworth
This is weird because my 93 civic was log booked by RA late last year with a SD cage kit with papers but is obviously past its homologation. Mike during the back and forth emails told me that if its an homologated kit then its fine as long as its not modified. Adding bars would void the homologation.

How did you get papers from the cage manufacturer if the cage is past its homologation expiration date? Which manufacturer did you purchase the cage kit from? I was under the impression that once the homologation date is passed that they no longer can provide the homologation paperwork...so instead provide MSA certification (which I was told wasn't good enough for an RA/NASA logbook unless the cage met 253 specs on its own i.e. thick enough steel).

Dave
Please Login or Register to post a reply
Doivi Clarkinen
Banned
Elite Moderator
Location: the end of the universe
Join Date: 02/12/2006
Age: Possibly Wise
Posts: 1,432

Rally Car:
1980 Opel Ascona B
Doivi Clarkinen
Re: some good roll cage buidling guides
November 16, 2011 04:58PM
Quote
john vanlandingham

Yeah, like every single time I would crash my Huskies or KTM or Maico with chrome-moly frames, I'd throw it away. I crash like 6-7 times in one turn in a practice session in heavy rain one day in about an hour period, but remembering what Dave would say here 26 years later, I ran back and threw the frame away.
Maybe the Chrome Moly Dave has used doesn't have those alloys which gives the chrome moly that I am used to its well known toughness and resistance to cracking...


And at the time, neither Husky, KTM or Maico did any post weld treatment.
Stick it in a jig, mig the fawk outta it , pull it out and paint them.

I asked about in the garage mods or repair "Just MiG it"

But to be fair, those guys were injur-nears and I think Dave thinks about the same thing about Injur-nears as I do...

Ok, I guess I have to clarify things a little bit. I'm talking about big crashes with big impacts that may or may not visibly deform the cage. Not a light roll in a ditch that just wrinkles the roof or laying your bike down in the mud.
Please Login or Register to post a reply
Doivi Clarkinen
Banned
Elite Moderator
Location: the end of the universe
Join Date: 02/12/2006
Age: Possibly Wise
Posts: 1,432

Rally Car:
1980 Opel Ascona B
Doivi Clarkinen
Re: some good roll cage buidling guides
November 16, 2011 05:07PM
Quote
Cosworth
Quote
john vanlandingham
And at the time, neither Husky, KTM or Maico did any post weld treatment.
Stick it in a jig, mig the fawk outta it , pull it out and paint them.

I asked about in the garage mods or repair "Just MiG it"

But to be fair, those guys were injur-nears and I think Dave thinks about the same thing about Injur-nears as I do...
CroMo if not heat treated after its been welded is no stronger than mild steel. I see it at SCCA club races in GT1 and GT2 cars where weekend fab shops make suspension components in CroMo but dont know any better. The result is failed components and the drivers being blamed to hitting curbs too hard. Even them slow talkin, moonshine drinkin, dip spittin southern boys in the NASCAR garages here in RaceCity USA, know to at least throw the torches on the part to give it some treatment before they're dun fixin to put it on the car.
CroMo yes its more britle like Dave said ONLY if not heat treated post welding.

Dude there's a good thing about those injur-nears that non injur-nears or self made injur-nears never have. Is the study of metalurgy to know and understand the properties of materials. C'mon John, weld it and paint it??? In that case just save the money and use mild steel, and leat it will start bending before cracking.

And this is my whole point, how many builders CroMo cages in rally cars really properly heat treat (normalize) all the welds in the cage when they're done? Some welds are pretty hard to get to to do that and would probably result in warped sheet metal in a few locations, too. I'm not saying CroMo can't be done properly, look at off road racing trucks. Those are built tube frame CroMo and are beat on worse than rally cars but they are properly done and heat treated after welding.
Please Login or Register to post a reply
Doivi Clarkinen
Banned
Elite Moderator
Location: the end of the universe
Join Date: 02/12/2006
Age: Possibly Wise
Posts: 1,432

Rally Car:
1980 Opel Ascona B
Doivi Clarkinen
Re: some good roll cage buidling guides
November 16, 2011 05:32PM
Quote
john vanlandingham
To all you Chrome moly experts and your truly bizarre claims that chrome moly is "brittle".....

Cars have bodies AND cages, both of which have some strength, together if done will is stronger than the the 2 thing separate...

Motorcycles have only the frame....

Very light weight, very strong since the intended use of at least moto-cross bikes is like way way insaner in NORMAL use that wimpy little roll overs....

Knowing the normal stresses are quite severe, and that the expected life span is pretty high:

Why the hell would 4130 or similar be the material of choice if it was "brittle"....??????

The one word that spring to mind when I think of chrome-moly steel is TOUGHNESS.
I am feeling too shitty to argue this. back to bed.

Actually, toughness is a word I would attribute to DOM more. It can take a few hits and not be compromised. CroMo work hardens. Just the act of bending it makes it more brittle in that area. Can it be heat treated and normalized? Yeah, but how many people do that properly. And John, I just don't think you're understanding the terminology here or something. CroMo does have a higher tensile strength than DOM. That's why it is a good choice for things like motorcycle frames and suspension components. It's very stiff and doesn't "give" easily. You don't want a bike frame to bend very easily. However, the point CroMo does finally fail it will be more prone to fracturing or breaking as opposed to mild steel which will bend (at less force than the equally sized CroMo piece.) I have to put the caveat "equally sized" because in reality the CroMo tube is almost always going to be thinner since that's one of the reasons for using it. You can use thinner and lighter tubing with CroMo than with mild steel to get comparable strength. Actually, even so the CroMo is probably a bit stiffer but it will break at it's failure point, even when properly heat treated.

My point is CroMo is a very good choice for certain components but for roll cages maybe not so much. You can't always control or really even check how properly the welds were done, and also a bit of "give", like DOM will provide, is actually a good thing in a rollcage. (And no, I'm not talking about collapsing, I mean energy absorbstion and dissipation.)
Please Login or Register to post a reply
A1337STI
Alex Rademacher
Mod Moderator
Location: Reno,nv
Join Date: 09/10/2007
Age: Midlife Crisis
Posts: 686

Rally Car:
93 GC with an 01 RS swap!
A1337STI
Re: some good roll cage buidling guides
November 16, 2011 05:52PM
DOM Steel appears to make a much easier (cheaper and quicker) tech process than Cromo would require.

as interesting as the debate is .. how is it relevant to giving Lina advice on her build? she can't go Cromo and get it log booked , so end of discussion (in terms of helping her cage build)

cutting holes in the floor/ taking the roof off, are both options she could go with and get booked. probably more worth while to debate options that still result in a log book....

smiling smiley

Like door bars, (i'm not a cage builder or welder) but even looking at cars all log booked in the same year, i see some are much easier to get in and out of, and some are very hard to get in and out of. a local rally crosser is in mid process of installing the safedrives / auto power roll cage kit .. and his door bars are really damn high and his A piller support is a little far back. that = very very hard to get in and out... probably the worst i've seen. not sure if you can get failed to get a log book with a cage that meets the rules ,but is too hard to get in and out of, but if so , he might have that happen.
sad smiley
Please Login or Register to post a reply
alkun
Albert Kun
Professional Moderator
Location: SF Ca.
Join Date: 01/07/2008
Age: Possibly Wise
Posts: 1,732

Rally Car:
volvo 242
alkun
Re: some good roll cage buidling guides
November 16, 2011 05:58PM
Yeah, once you get the helmet and the horse collar on, it gets really hard to get through the door, then add being on a 60 degree angle with the ass of the car sticking out of the giant ditch...
Please Login or Register to post a reply
Jon Burke
Jon Burke
Mod Moderator
Location: San Francisco, CA
Join Date: 01/03/2008
Age: Possibly Wise
Posts: 1,402

Rally Car:
Subaru w/<1000 crashes
Jon Burke
Re: some good roll cage buidling guides
November 16, 2011 06:13PM
Quote
Doivi Clarkinen


Ok, I guess I have to clarify things a little bit.


not really, most of us knew what you were talking about.
Please Login or Register to post a reply
phlat65
Sean Medcroft
Senior Moderator
Location: Edmonds, Washington
Join Date: 02/12/2009
Age: Possibly Wise
Posts: 1,802

Rally Car:
Building a Merkur
phlat65
Re: some good roll cage buidling guides
November 16, 2011 10:10PM
Quote
Doivi Clarkinen
Quote
phlat65




Rally Mexico. Sure looks like it flexes alot to me, and that is just the weight of the car, no violent roll.

Holy shit.

Yeah, no doubt. Would you want to roll that car off the road into the trees and stumps? Not me.
Please Login or Register to post a reply
john vanlandingham
John Vanlandingham
Godlike Moderator
Location: Ford Asylum, Sleezattle, WA
Join Date: 12/20/2005
Age: Fossilized
Posts: 14,152

Rally Car:
Saab 96 V4
john vanlandingham
Re: some good roll cage buidling guides
November 16, 2011 10:14PM
Quote
Doivi Clarkinen
Quote
john vanlandingham
To all you Chrome moly experts and your truly bizarre claims that chrome moly is "brittle".....

Cars have bodies AND cages, both of which have some strength, together if done will is stronger than the the 2 thing separate...

Motorcycles have only the frame....

Very light weight, very strong since the intended use of at least moto-cross bikes is like way way insaner in NORMAL use that wimpy little roll overs....

Knowing the normal stresses are quite severe, and that the expected life span is pretty high:

Why the hell would 4130 or similar be the material of choice if it was "brittle"....??????

The one word that spring to mind when I think of chrome-moly steel is TOUGHNESS.
I am feeling too shitty to argue this. back to bed.

Quote

Actually, toughness is a word I would attribute to DOM more.

You might but is a specific term in metal world



Quote

It can take a few hits and not be compromised. CroMo work hardens.

Oh, Really

Quote

Just the act of bending it makes it more brittle in that area. Can it be heat treated and normalized? Yeah, but how many people do that properly. And John, I just don't think you're understanding the terminology here or something.

Yeah thqat's probably it, I am using terms used in metallurgy.


Quote

CroMo does have a higher tensile strength than DOM.

Yep
Quote

That's why it is a good choice for things like motorcycle frames and suspension components.


Nope. It's high tensile strength allows the use of much thinner wall for equivalent strength
Quote

It's very stiff and doesn't "give" easily.

Actually the bend modulous of all ferrous materials---including iron---area ll the same----fatigue resistance does vary though.

Quote

You don't want a bike frame to bend very easily.

Oh, really?
We better go rewrite some 40+ years of history then.

Come on Dave, take the hat off and thing about the things made out of CrMo tubing and you'll see the stuff all has to be strong---kinda rigid but tolerate endless blows and tweaks and flexing for long periods of time..

Kinda off topic this whole thing..
The Euros have always been looser with safety rules than we have, maybe the sheer number of lawyers has something to do with that:
Country Lawyers Population People/Lawyer

US: Lawyers: 1,143,358 Pop: 303MM People per/Lawyer:265

New Zealand: Lawyers: 10,523 Pop: 4MM P/L 391

Spain Lawyers:114,143 Pop: 45MM P/L:395
Italy Lawyers:121,380 Pop: 59MM P/L:488
UK Lawyers:151,043 Pop: 61MM P/L401
Germany Lawyers:138,679 Pop: 82MM P/L: 593
France Lawyers:45,686 Pop: 64MM P/L: 1,403

Read more: http://wiki.answers.com/Q/What_country_in_the_world_has_most_lawyers_per_capita#ixzz1dvqi3vDM


Clearly the cage failures we saw in these Plow-drive things were simply going too thing and the material failing, they should have just thrown away the shell every 2 events if they were really serious. They weren't they were just playing, and as long as it looked marvelous that was it.

And sorry all you experts I will maintain my belief those men I knew, Bror Jauren, at Husky since the 60s to the 80s, Peter and Nans Maisch, sons of the founder at Maico and the engineer I was parked next to and chatted with all day from KTM that the didn't normalize the frames, just plain MiG---and they worked very good, flexible as they were. They were telling me what they did in production and World Championship bikes--since they used production parts. They had no reason to all lie separately..

Dave in mid/late 70s wheelbase on 500 class bikes, then maybe 400-440cc, could stretch nearly 40-45mm on hard acceleration. Frame flex.
No noticeable work hardening even after years of hard use.


John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.
Please Login or Register to post a reply
Rallymech
Robert Gobright
Godlike Moderator
Location: White Center Seattle
Join Date: 04/27/2008
Age: Possibly Wise
Posts: 1,292

Rally Car:
91 VW GTI 8V
Rallymech
Re: some good roll cage buidling guides
November 16, 2011 10:24PM
Use DOM. Stop talking.


Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.
Please Login or Register to post a reply
Tim Taylor
Tim Taylor
Professional Moderator
Location: Oakland, CA
Join Date: 02/02/2007
Age: Midlife Crisis
Posts: 622

Rally Car:
Mazda 323 GTX
Tim Taylor
Re: some good roll cage buidling guides
November 16, 2011 10:34PM
Gawd you all fail at metallurgy...

Lina, Talk with Michel before you start cutting and bending because he's going to inspect your cage. If you need any cage gussets let me know because I have boxes of them.
Please Login or Register to post a reply
john vanlandingham
John Vanlandingham
Godlike Moderator
Location: Ford Asylum, Sleezattle, WA
Join Date: 12/20/2005
Age: Fossilized
Posts: 14,152

Rally Car:
Saab 96 V4
john vanlandingham
Re: some good roll cage buidling guides
November 16, 2011 11:12PM
Quote
A1337STI
DOM Steel appears to make a much easier (cheaper and quicker) tech process than Cromo would require.

as interesting as the debate is .. how is it relevant to giving Lina advice on her build? she can't go Cromo and get it log booked , so end of discussion (in terms of helping her cage build)

cutting holes in the floor/ taking the roof off, are both options she could go with and get booked. probably more worth while to debate options that still result in a log book....

smiling smiley

Like door bars, (i'm not a cage builder or welder) but even looking at cars all log booked in the same year, i see some are much easier to get in and out of, and some are very hard to get in and out of. a local rally crosser is in mid process of installing the safedrives / auto power roll cage kit .. and his door bars are really damn high and his A piller support is a little far back. that = very very hard to get in and out... probably the worst i've seen. not sure if you can get failed to get a log book with a cage that meets the rules ,but is too hard to get in and out of, but if so , he might have that happen.
sad smiley

You're right, but misinformation has spread as computer use has spread. Words mean whatever anybody wants them to mean 5.1 is HIGH gearing and 3.08 is low., CrMo---for decades was noted for its toughness, now its suddenly "brittle". Guys that have no clue what is being discussed now "know" what is meant even when those who have worked with these materials for 40 years day in and day out don't know--from the "explanation" what is meant.

Everything is now "like whatever".


John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.
Please Login or Register to post a reply
Page 6 of 13    Pages: Previous1234567891011NextLast
Newer Topic Older Topic
Forum List Topic List Start New Topic
Sorry, only registered users may post in this forum.

Click here to login