phlat65 Sean Medcroft Mega Moderator Location: Edmonds, Washington Join Date: 02/12/2009 Age: Possibly Wise Posts: 1,802 Rally Car: Building a Merkur |
To pull the main hoop bar forward would also require collapsing it, and with a X in the main hoop that is going to be tough. There is a lot more at play than just terminating loads in straight lines, with a mid stay.
I think the mid stay is a good idea though. |
Josh Wimpey Josh Wimpey Senior Moderator Location: VA Join Date: 12/27/2006 Age: Midlife Crisis Posts: 649 Rally Car: Sneak the Golf |
Removing the rain tray makes it a bit easier but still a pain ____________________________________________________________- One. Class -- 2WD www.quantumrallysport.com http://www.facebook.com/home.php?#/pages/Quantum-Rally-Sport/281129179600?ref=nf |
ronerickson Ron Erickson Junior Moderator Location: Fenton, MO Join Date: 11/27/2012 Age: Settling Down Posts: 6 Rally Car: 1986 VW Golf GTI |
Roger that. Already removed it. Finally found photos of your setup on the diesel car. That's going to be hard to weld around! |
deaner Dane Aura Ultra Moderator Location: Caldwell, ID Join Date: 07/07/2013 Age: Settling Down Posts: 346 Rally Car: PS4 controller |
Taking both those things(light and heat) into consideration. I still don't effing know hahaha. I suppose whatever color I pick Ill bitch about anyhow for one reason or another.... Thanks for the insight. |
The thinking above about the X is a good thought but there are 2 factors not considered above that allows the bending of the vertical partion of the main hoop that is not prevented by the X: 1) The main source of 'extra material' for this bending is the outward bend that exists in practically all main hoop vertical sections that is put there to have the main hoop tight to the B-Pillar. That by itself provides enough extra length of the main hoop vertical to be pulled forward to allow for many inches of inward bending on the side bar. This main hoop vertical section bending becomes partly torsional which helps a bit but not much. 2) Now let's build a cage with a perfectly straight vertical section of the main hoop between the upper and lower attach points of the X: there would have to be some EXTREMELY high tension exerted by the X brace on the main hoop veritcal section to limit bending of the main hoop vertical section. For no bending of the main hoop vertical section, the tension would actually have to be INFINITE, which we all know ain't reality. What will really happen with this theoretical cage is that the main hoop veritcal section will start to bend (which it HAS to do BEFORE the upper and lower X-brace points try to resist), and the upper and lower X brace points will move towards each other under the load which allows more bending. But this is a minor factor compared to that listed in 1) above. So the main hoop X-brace is not enough of a factor to do much except under extreme bending situations; the side bar bending is far beyond what is acceptable by the time the X-brace comes into play. (Assuming all else holds together...) EDIT to add: Now one brace that does do you some good is the diagonal brace between the half lateral and the main hoop vertical section by your helmet. It is not as good as moving the side bar out but it is the kind of aid that slows the process and helps the 'side bar in tension' theory work a bit better. Edited 1 time(s). Last edit at 12/03/2013 08:31AM by starion887. |
Hey Josh, It'll certainly help in a moderate side impact, but it still depends purely on tension on the side bar to prevent too much inward bending. IMO, not as good as extra space to start with. Eventually, the side bar will stretch and start to yield. And the welds sure have to be good and the joints gusseted, even at the main hoop, IMO. I would prefer to use this with the double-U side bars as the typical X joints will see increased tension forces. Everyone needs to grasp that depending on tension in the side bars in any form is limited. For any straight member between 2 support points, for the straight member to remain straight under a side force, the tension force in the straight member has to be infinite.....(really!)......which we all know is not going to happen. The straight member always deflects to start the loading process, and either bends (yields) and stretches or the support points move, or both. |
Sean Edwards Junior Moderator Location: Arlington WA Join Date: 11/17/2010 Posts: 82 Rally Car: Celica |
I remember posting photos of a cage we were working on, & we bent the door bars outward towards the door. I remember being crucified for the outward bend, something about there being more leverage to brake the weld with the doors bars being bent outwards. this still doesn't make much sense to me.
hard to tell from this photo of the bend. The bars were straight just fish mouthed to bow out towards the door. I also remember people having a problem with the roof spreader bar having two bends in it, saying that it would be stronger if it was straight, regardless of the gusset. But I also see on here people preaching the importance of having the cage as tight to the pillars to not obstruct the view. what gives? |
NoCoast Grant Hughes Senior Moderator Location: Whitefish, MT Join Date: 01/11/2006 Age: Midlife Crisis Posts: 6,818 Rally Car: BMW |
Your roof is the style that seems popular on west coast thanks to Jackson Rally and Dirty Impreza.
I do a straight but kinked bar across between the two. The first BMW pic has the bars bowed outwards also. I've heard negative and good about that style. People like to debate what is better, what is safer, etc. to infinity. Take the intersecting vs. dual V style door X. The intersecting was almost exclusively the only style of X you would see until the Lovell/Freeman accident at Oregon Trail where apparently had the massive internal injuries not killed them, the intersection at the X broke and severed the femoral artery (so I have heard) and from that point on people started saying, "the X should be two bent bars so they can't break and impale your leg." Really what they should have been saying though is, "we need gussets." Both styles have their benefits and disadvantages. Some people way smarter than me have said that the dual V can be stronger but should have a larger and thicker gusset to prevent them from seperating. Regardless, your cage is fine Sean. Grant Hughes |
BJosephD Brian j Dyer Infallible Moderator Location: southern maine Join Date: 05/01/2009 Age: Midlife Crisis Posts: 381 Rally Car: 04 Rocky Mountain MTB... |
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Dazed_Driver Banned Mod Moderator Location: John and Skyes Magic Love liar Join Date: 08/24/2007 Posts: 2,154 |
So what about these then?
Design number 1 is a thought I had after seeing that silver cage a couple posts up. The bottom bar is only slightly bent, what if you used a sill bar and a v? I personally have style 3 in the neverending story, I mean rally car. I feel designs 2 and 3 are probably the "best" followed closely by 4, and then 1 last. Wouldn't the angles of the triangle created in the door bars matter? Or when its pushed sideways, vs trying to "compress" the triangle, the angles no longer matter? Welcome to the cult of JVL drink the koolaid or be banned. |
NoCoast Grant Hughes Senior Moderator Location: Whitefish, MT Join Date: 01/11/2006 Age: Midlife Crisis Posts: 6,818 Rally Car: BMW |
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Reamer Jeff Reamer Senior Moderator Location: Marlette, Michigan Join Date: 08/14/2010 Age: Midlife Crisis Posts: 489 Rally Car: Subaru |
I think 1,2,3 and 4 are RA legal? Isnt Nasa the one that requires a sill bar?
First rally 2013 Rally car type AWD subaru Total rallies as driver 6 Total rally cars built 2 Total rally cars caged 3 Total rally cars repaired from offs 4 Total years racing exp other then rally 19 yrs Like 31motorsports on FB! Check out 31motor sales on ebay for used Subaru parts |
Dazed_Driver Banned Mod Moderator Location: John and Skyes Magic Love liar Join Date: 08/24/2007 Posts: 2,154 |
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modernbeat Jason McDaniel Mod Moderator Location: Dallas, TX Join Date: 12/14/2007 Age: Possibly Wise Posts: 401 Rally Car: 1963 SAAB Historic, 1995 Impreza Open Light totaled at WRC Mexico, 2005 STi Pikes Peak winner |
Rally America has "required" a sill bar since 2006.
As of today, Rally America rules allow the old style 2006 cage ("X" in main hoop, sill bar, one additional door bar, A-pillar bar), a holomologated cage or an FIA cookbook cage from either DOM or CDS. FWIW, the FIA cookbook cage does not require a sill bar, and only requires a single door bar for cars built after 2006. I've had arguments with RA scrutineers about this as my car was built with an X-bar in the door, but no sill bar. But when you show them the actual rules, they don't want to read them as they know what's best. I had to have Hurst call the scrutineer to straighten him out and now my logbook has a letter in it from Hurst saying my cage is legal. Jason McDaniel Edited 1 time(s). Last edit at 12/08/2013 12:21PM by modernbeat. |
alkun Albert Kun Senior Moderator Location: SF Ca. Join Date: 01/07/2008 Age: Possibly Wise Posts: 1,732 Rally Car: volvo 242 |
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