Roll Cage Questions and Picture Samples.

[xxobuick]

We are building A 1936 Buick Coupe for the Production Coupe and Sedan Class, XX0 Engine.  The rule book states that you have to have the cage protect from the bottom of the driver.  Does this mean you have to have bars going under your seat, that attach to the side rails?  Also it states that you have to have the cage extend in front of the drivers feet.  Does this mean you have to have bars that attach to the front hoop, and therefore extend to the frame at a diagonal in front of the drivers feet?  I am looking at Figure 1 of Page 25 of the 2009 rule book, and It appears to be a 6 point rollcage, that has no bottom protection.  Is there any more diagrams I can look at for clarification?  I am using 1.625" Chromoly tubing, .095 wall.

The 1936 Buick Century Coupe has a X frame, and it is not like the frame turns into an x, there is still two frame rails that go the length of the car, then seperate rails create an X. Here is a photo:



Would these cages be legal for what we need?



Or this minus the bolt in part:



This is the car we are using:

[xxobuick]

In the rule book states head cage is needed to be Incorporated into the cage.  Something like this?

[xxobuick]

Also since we are using a 4130 Material cage, I would assume that you need to tig weld the cage with 4130 filler rod?  No mig welding correct?

[Joe Timney]

Never use 4130 rod on chromemoly...the weld will be too brittle. Use S70 or S65 rod, it is a triple clean coated mild steel rod. S65 is hard to find. If you use 4130 rod, heat treating will be mandatory. Don't forget the gussets.

[57 ranchwagon]

Is there a particular reason you are using chrome moly. Mild steel is cheaper easier to use and more forgiving. Just my thoughts for what there worth. As for the funny car style cage that will have to be one bad xxo class car to need one per the rules but its never a bad Idea to over engineer in the safety dept. Best of luck Sam

[RichFox]

Your pictures look very much like the pictures in the rule book so I would guess all of those cages will work. however the "Funny Car" type cage also meets the lateral movement requirements. See page 24. As such I would want to build that type of cage if it were my XXO car. I don't believe you need a underseat bar in a car that has it's OEM stock floor. Which I am guessing you have. If you have fabbed a floor then it is my understanding that yes you do need a bar beneath the driver to keep him and the seat from exiting out through the floor in a very bad roll over. As always answere you get here are interesting but carry no weight when you get to inspection. PS I really like XXO/VGC type Buicks. They have a build section here. How about some pictures? I made a fuel injector for a Buick eight. The owner hasn't run it yet. If it works for him maybe we can talk. half of it worked on my banger.

[John Burk]

Why do roll cages for production bodies look like the main purpose is to hold the roof up in a crash with driver protection added on ? All that tubing with nothing to retain the driver's torso on the right side but the seat .

[RichFox]

I think those are very old pictures and perhaps the Association should consider new drawings that more closely represent todays roll cage.

[Cajun Kid]

Why do roll cages for production bodies look like the main purpose is to hold the roof up in a crash with driver protection added on ? All that tubing with nothing to retain the driver's torso on the right side but the seat .

Maybe they assume the use of a "containment seat" and lateral head and neck restraints ?

Charles

[willieworld]

the purpose of the roll cage is to keep the car and cage from crushing in on you---if it does that then it did its job---your suit - helmet-gloves -boots -sfi padding--seat belts - seat -window net-fire system--hnr should keep you safe inside the cage----                                willie buchta

[jl222]

Also since we are using a 4130 Material cage, I would assume that you need to tig weld the cage with 4130 filler rod?  No mig welding correct?

  You might get Carroll Smith's book ENGINNEER TO WIN gives some advice on welding 4130 including preheating to 400 deg and heating the immediate area after welding to 1200 deg somewere between cheery red and dark red and cooling in still air.

    JL222

[xxobuick]

Ok, So can you mig weld with actuall Argon, not flux core on the 4130 cages?  The rule book does not specify which type of welding is needed.  We are using chromoly because it is stronger.  4130 .095 wall is tougher to bend than .120 dom tubing, therefore stronger?  Plus if we do set a record with this car, we will turn it back into a street rod, and build another cage for a modified xx0 class.  So we do not want the extra weight in the car for when we make it a street rod. 

[Milwaukee Midget]

Plus if we do set a record with this car, we will turn it back into a street rod, and build another cage for a modified xx0 class.  So we do not want the extra weight in the car for when we make it a street rod. 

Correct me if I'm wrong, but you're looking at, what, maybe 100 lb's difference for a complete cage?  In a drag car, sure - but a street rod? 

You're likely to be pulling half of the tubes out if you take it back on the street again.

A beautiful car - great choice for a racer.  Thanks for this thread, and keep us posted on the build.

Chris Conrad


 

[xxobuick]

Tubing is bought, and a done deal.  It is tougher and if something goes wrong, I like toughness.  I know there is guys runing 4130 cages in scta events. 

[57 ranchwagon]

Just a word of caution it is stronger but more brittle if welding is not performed properly chances of the joints breaking and not bending are much higher than mild steel failing. Not trying to talk you out of anything just making you aware it really should be tig welded.(heat temper of the joints) Looks like a cool project keep us updated. Sam