Cage/Helmet Clearance

[lake_harley]

Started constructing and planning the roll cage for my FED. Driver was here today and we mocked it up with him in the car, helmet on, with 2" of clearance over the top of his helmet. To that we added the thickness of SFI padding to be installed. Called S&W race cars where I bought my chassis plans and talked to a tech. He said there's no actual minimum but to have enough clearance for some head movement, and not so tight to hamper doing a quick get-out in an emergency. So, am I on the right track with 2" between the helmet and the roll bar padding? It seemed to me that too much clearance would be as bad as not enough.

I'll appreciate thoughts.

Lynn

[tcoupekyle]

I don’t know but…. I have about 1inch between my helmet and pads in mine and it seems to be fine

[tcoupekyle]

It looks like more in these pics but my helmet will touch the padding pretty easily if I move around.

https://photos.app.goo.gl/k7mFA2SeYw8PLmsD6

[lake_harley]

Thanks for the replies. Based your examples of closer fitting cages, I might "tighten up" my cage a bit. Your examples verify what the tech at S&W had to say.

I can't stand the looks of a big tall, gangly-looking cage, but certainly didn't want to compromise safety by thinking too much about only looks. My driver is a tick over 6' but I'm only about 5'9". In talking it turns out both of us wear 34" inseam pants so his extra 3" of height is mostly in his torso which made sense considering the headroom I had sitting in the car. When I sat in the car with the rear cage tube mocked up I had a GOB of headroom and would have looked like a gnome sitting in it.

Thanks gents. Now I have some info the move on in an informed way.

Lynn

[wideopen231]

You want to fit comfortably,but not loose. When checking it is best to have full suit on.It make huge difference.

[janjon]

Should harness stretch on impact be a consideration?

[wideopen231]

As tight as we have belts that should be nothing. Now if you wear them loose tighten them .

[fuel749]

Started constructing and planning the roll cage for my FED. Driver was here today and we mocked it up with him in the car, helmet on, with 2" of clearance over the top of his helmet. To that we added the thickness of SFI padding to be installed. Called S&W race cars where I bought my chassis plans and talked to a tech. He said there's no actual minimum but to have enough clearance for some head movement, and not so tight to hamper doing a quick get-out in an emergency. So, am I on the right track with 2" between the helmet and the roll bar padding? It seemed to me that too much clearance would be as bad as not enough.

I'll appreciate thoughts.

Lynn

There is an actual minimum listed in the SFI spec.  Either 2 or 3 inches I can't remember and it doesn't really seem to be enforced

[JEFF/21C]

Always make sure your belts are tight, I've seen people hurt when they flipped and belts were not tight enough.you should set-up your cockpit with all your safety equipment on, street clothes are not the same!

[Supercat]

If you are planning to do a seat pour(foam) take that in as part of your measurements.

[lake_harley]

Did a 2nd fitment today with the driver wearing a driving suit (3 layer Sparco) over jeans. Decided to shorten the back "spine" tube of the 5-point cage by 1/2" which will leave 1"-1 1/2" clearance after allowing for the thickness of SFI roll bar padding.

I am going to bend a different spine tube with a bit tighter radius which will allow a longer tube between the front and rear hoops without the cage sticking W-A-Y forward of his helmet. With the rear tube I had the connector between front and rear hoops would have only been maybe 2" long. Leaning the rear hoop back a bit further by having a tighter bend radius on it will also put the rear hoop in a better position, like more out directly to the side of his helmet. I plan to have the front of the front hoop 3-4" out from the front of the helmet, measuring at about the top of the visor opening. I think I read somewhere in regulations that 3" is a minimum, and I believe that was to the front of the front hoop.

If you read anything wrong into what I have tried to describe, please call me out on it and correct me. I want to do this right. To me, it's the most important part of the whole chassis.

Lynn

[gregm784]

As tight as we have belts that should be nothing. Now if you wear them loose tighten them .

it really depends on how the belts are set up in relation to how you're pulled into the seat. If everything is right, you'll only move an inch or so.

[lake_harley]

Belts should be here in a couple days. I ordered UltraShield 3" belts but with a 2" buckle so there's less bulk right in the driver's lap. Also, ordered them with pull-up adjusters on the lap belt so the driver can tighten it well themselves in the confines of the cockpit.

I've begun an initial assembly of the car just to see that everything is going to play nicely together before blowing it apart again for paint, etc.

Lynn

[samotorsport]

I had a chat with a SFI inspector about this same topic in the jr dragster.
He told me on a hard tail 2 inch clearance, on a swing arm chassis 1 inch.
But this was for RED juniors . Don t know if the same rule applies for FED .

[THE FRENCHTOWN FLYER]

I think SFI specs for dragster / altered are 3" clearance above the helmet to the roll cage.