some good roll cage buidling guides

on cutting holes in your floor to weld the top of your cage.

That's how my cage was done, and Guy Light signed off on it.

I mean really , you are going to worry about cutting a hole in the 1/32th thick sheet metal of the floor, even after you put on a 1/4 inch plate ?

Yes technically the floor is stronger when its 1/4 inch + 1/32 compared to just 1/4. but the holes that were cut to drop my cage were fairly small .. i think he maybe cut 2 inch holes, but then put on like a 6X6 1/4 inch plate.

if your cage is done right your seat is mounted to your cage, if the cage pushes through your floor its taking the seats with it, in which case you haven't lost any room from the top of your cage to your head. sure your car is ruined but you are A-OK.

My cage was done by a good welder. no bird poop in any of the welds.


If you do take your car into someone . just find someone who has done several log booked rally cars, and you should be fine.

but if you are going to do it yourself that's cool too. just put a tech/scrutineer on speed dial and get handy with an image hosting website.

design, take lots of pics, host on site, show to tech. start your main hoop, take lots of pics, host , show to tech, etc...

how long until you are on stage ?

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Reamer
I dont think they trust the welding process on T-45. Dom welds can be looked at and have a good idea if the strength is there. T-45 welds can look awesome and break from an improper weld.

Every body in America seems afraid of law suits and base rules on if if if what ever happens were done. This is just what Ive found when I asked the same question.

I've seen some pretty shitty looking welds on DOM cages that passed tech inspection.

Don't all the T45 cages require that you send a welding sample back to the cage manufacturer that they stress test? I know mine did. If that doesn't pass muster, they don't mail you the FIA certs.

Also not sure if MIG vs TIG plays into this at all (I'm not a fab guy and don't know much about welding), but I remember reading people going on and on about how you've got to TIG T45 and when you do, you must normalize the thing by baking the car and bringing it back down to room temp easily. I contacted the guys from Custom Cages and they say to MIG it with a wire that you buy with the cage.

Dave

Oh for crying out loud, not the cro-mo vs. mild steel debate again.


I just have to point out that with a really stout vice and a big lever, I can snap apart a nice cro-mo bicycle frame like it was glass, while an 30 year old Schwinn Varsity can be bent back and forth all day and tied into a pretzel.


Not saying cro-mo is bad, its just way more tricky. What are the rules for welding a cro-mo cage? Mig? Special wire? Seems to me the trade off for that 70 lbs. is a way shorter lifespan. No one is really planning on using a WRC car for more that 2 years, right? Anywho don't evos weigh over 3000 lbs? Thats like a 2.3% difference!


PS dont take it wrong Dave, you are my hero for your daring quests on PP.

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

Yup - looks like it moves a fair bit.
It is probably safe to assume that it is supposed to do that...

so i picked up a few pieces of "ceiling wire" in order to mock up and help shape my bends. I got some advice from an old timer hot rod builder today and of course he was totally confused by the regulation for dom tubing vs chromoly... go figure. Im pretty sure chromoly is outlawed because its way more difficult to maintain safety/quality control of the welds & during inspection, and chromoly is brittle compared to mild steel.
he said it shouldnt take me more than ~45 minutes to get the main hoop shaped up. what do ya'll think.
also, was planning on making some cardpaper versions of my "cage feet" thingies.
are the ones shown in the wrx car on previous strings of this discussion what I should be going for? cuz they look beautiful the great thing about my soon to be rally car is the almost "no rust" condition I got it in. it was a former show car in the 80s or something and it was a little sad pulling down a perfectly good headliner - but not really - I love the way cars looked when they are strippped! makes much more room for the 'vision' of what its gonna look like once completed I just hope I dont go grey before that happens :-/

Yeah, 45 minutes sound right........

I know my cage builder probably spent the whole 1st day fitting the main hoop and forward bars properly.......

He spent the time fitting it to the body so tight, it is stitch welded to the A pillar, and the B pillar with out using gusset plates. It is not as easy as it looks.

those are some nice-ass MIG welds!

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DaveK

I'm still curious about the reasoning that DOM is the preferred material vs. T45 (or other chromoly) when the rest of the world seems to think T45 is just fine.

Dave

CroMo weighs the same as the same size and thickness DOM per foot, it's just that the rules allow you to use thinner wall tubing with CroMo. CroMo is a harder, stiffer material but it is more prone to embrittlement and cracking. You really have to know what you're doing to weld it properly (which is one of the main reasons it's use is discouraged here.) Even just putting a bend in it work hardens it and makes it more brittle there. Then add in the complications of welding it and normalizing it properly. Then when you do crash it, it's far more prone to failure and cracking. CroMo cage that has been rolled but not obviously damaged or deformed should really be thrown away. I would never feel comfortable racing a car again with a CroMo cage that has been stressed and potentially compromised like that. I remember in 2003 looking at the Prodrive rental car (the car Mark Lovell drove in 2001) at the parc expose before the start. There was a crack next to the weld where the rear stay connected to the rear strut tower a third of the way around the tube. If I'd have been a scrutineer at that event I would have pulled the logbook and not let the car start. This is the "mighty" Prodrive and even their T-45 cages were cracking apart.

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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.

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phlat65




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

Henning is quite a bit fatter than Petter....

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Doivi Clarkinen

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DaveK

I'm still curious about the reasoning that DOM is the preferred material vs. T45 (or other chromoly) when the rest of the world seems to think T45 is just fine.

Dave

CroMo weighs the same as the same size and thickness DOM per foot, it's just that the rules allow you to use thinner wall tubing with CroMo. CroMo is a harder, stiffer material but it is more prone to embrittlement and cracking. You really have to know what you're doing to weld it properly (which is one of the main reasons it's use is discouraged here.) Even just putting a bend in it work hardens it and makes it more brittle there. Then add in the complications of welding it and normalizing it properly. Then when you do crash it, it's far more prone to failure and cracking. CroMo cage that has been rolled but not obviously damaged or deformed should really be thrown away. I would never feel comfortable racing a car again with a CroMo cage that has been stressed and potentially compromised like that. I remember in 2003 looking at the Prodrive rental car (the car Mark Lovell drove in 2001) at the parc expose before the start. There was a crack next to the weld where the rear stay connected to the rear strut tower a third of the way around the tube. If I'd have been a scrutineer at that event I would have pulled the logbook and not let the car start. This is the "mighty" Prodrive and even their T-45 cages were cracking apart.

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...

---

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.

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FunctionAuto
Interesting, because a year ago I contacted Mike about installing a homologated cage from Custom Cages in my 95 impreza and he said that homologation ran out and it would not pass in RA.

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DaveK

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wvonkessler
You are wrong on this. It does not need to be built to meet the specifications for new homologations per RA rules. It has to be built to its homologation specifications. This per Mike H on a '96 E36 build using a SD CDS multi-point weld-in kit that is being built by a buddy.

Have to be careful here. I asked about putting a Custom Cages T45 kit in my Compact and was told it wouldn't fly because it was beyond the homologation date.

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.

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I was told that you could start with a homologated cage if you added bars to bring it up to current spec...but the tubing thickness and diameters would need to meet the spec required in the 253 diagram, basically meaning the homologation had nothing to do with the cage being legal.

Dave

Looks like there's some confusion with all of this. At the events I've been to, they check the cage sticker and the FIA papers and its express lane after that.

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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.