Q's about modifying the cage in my C5 vette - tall driver

[moespeeds]

Hi guys, I'm trying to make some modifications to the cage in my C5 FRC to fit my 6'3" frame. Apparently the guy this cage was built for was much shorter. It looks like they originally built this thing under the main hoop/B pillar, then later cut it out. I need to get this sucker up higher, as you can see in the pictures I'm not even close. My intention is to use a combination of raising the cage, and lowering the seat/mounts to get the room I need. I am an experienced fabricator and welder, though this is my first car cage.

 

Barely 1/2" between my helmet and the upper plane of the cage.

 

 

First off I'd like to raise the forward most attach points a full inch. I can build plinth boxes to set them on, but I only have about 1/2" until I hit the A-pillar/windshield frame. Am I permitted to trim the bottom side of the A-pillar to make the clearance I need?

 

 

 

Secondly, am I permitted to build 1" plinth boxes under the rearmost attach points, or would I have to install new downtubes? I don't see anything in the rules against this, but want to make sure.

 

Also, I slid the cage as far towards the driver's side as possible to make more room between the side of my head and the side hoop. I foolishly notched the sheet metal in the lower part of the b pillar, not realizing that this is against the rules. While you are allowed to penetrate this area, it states that you cannot notch it. So what to do? Can I weld a patch over the open portion of the notch? This would return the lost strength.

 

See the notch at the lower nascar bar:

 

 

And my last question. Ideally I'd like to cut away the floor completely where the seat rests, and get rid of the cheap stamped seat mounting straps that Chevy uses. I would fabricate 3/16" straps, braced and welded to the frame and trans tunnel, then span between them with sheet metal, sealing off the floor and dropping the seat at least 1/2". I see that the rules state that I cannot remove the stock seat straps, or the final layer of floor? What's the deal with that, as with the corvette the floor is barely a single sheet of fiberglass thick in some areas. If I kept the stock seat straps, could I still remove the fiberglass between them if I sealed it with sheetmetal welded in place?

 

Thanks in advance for any advice.

[kbrew8991]

you may want to mention what class you're trying to build toward as that may shape some answers / approaches people might recommend

[moespeeds]

St2

[Cobra4B]

As you know from looking at my pics the main hoop is way too low. You can also cut the top layer of the floor out to lower the seat about 5/8".

 

Mine - Carlos at Autodynamix did an excellent job creating exactly what I wanted. I took him the car with the roof loose and b-pillar already cut out. I told him to make me the roomiest C5 cage ever and took him 10 pages of pictures of other C5 cages.

 

[moespeeds]

you may want to mention what class you're trying to build toward as that may shape some answers / approaches people might recommend

 

 

Are the rules for full cage construction class specific?

 

Doesn't look like too many guys here do their own cages. Is there a way I can get this to a tech inspector?

[ILIKETODRIVE]

you may want to mention what class you're trying to build toward as that may shape some answers / approaches people might recommend

Are the rules for full cage construction class specific?

NASA CC&R have guidelines for basic cage geometry but some classes have superseding rules that allow certain cage additions without penalty.