17 replies to this topic

[DavidNJ]

Talking to Kirkey, a seat to fit my shoulders will be 28" wide, 14" to the side of the seat centerline. Will that fit in a Spec Miata?

The dimensions similar to the picture below, but 28" instead of 25" wide.

Attached Files

•  Seat.png   369.98KB   0 downloads

[Johnny D]

FYI,

http://mazdaracers.c...otch-out-panel/

 

Also there's a search feature upper right if you want to look up past threads, but you're always welcome to ask.

 

J~

[DavidNJ]

Thanks...I'm sure that will be needed also.

 

Talking to Kirkey I need a custom seat. Their standard 16" seat is designed for 20" wide shoulders. Even the 18" (which is too wide on the bottom for me and based on the post I'm wondering if too wide on the bottom for an SM) is only 22". I'm 23"-24". That will be a 28" wide seat at the shoulders. 

I was too big for an NA/NB/NC street Miata. If I sat upright my arm is over the door. Same problem in the current Mini Cooper. I do seem to fit an ND. I ended up in an S2000 where I barely fit. In an SRF my shoulders rub the fiberglass on both sides and the forward rollover bar brace hits my forearm when turning the wheel over 45° or so.

 

Which is why I'm concerned that a containment seat that fits me may not fit an SM.

[Johnny D]

No your not too big for a Miata.

http://mazdaracers.c...oor-drop-panel/

 

found this when i did a search (there was more, hint, hint)

http://mazdaracers.c...ing/#entry88013

 

J~

[DavidNJ]

A few people using the Kirkey 71, one using the Kirkey 45 which is what I planned to use. The issues were questions on mounting and brackets. Jim Drago appears to make universal mounting brackets, Kirkey has there own. There are dropped floor panels, but other than providing space I don't think they can be used for seat mounting; the seat needs to be mounted to something structural or the cage; I used to having a cradle coming out from the cage.

 

The seats are all available custom built. Most of discussion involved the fit of the stock sizes or getting clearance for tall drivers. 

 

None that I've found deal with the width of the seat. If someone measures 14" to left from the seat centerline, were will the end point be?

The closest I found is this article, were a Kirkey 71 and cage is being fitted to a Miata. From the picture it seems to be a very tight fit. My seat, custom built, will be 4" to 6" wider.

 

BTW, how do does a driver get into and out of a containment seat in a Spec Miata? It looks like the steering column would be in the way, even with the wheel removed. Can the column be shortened?

[Bench Racer]

First, what is your weight, height, waist size? There are some pretty big boys driving Spec Miata, 6' 4", 300 plus pounds.

 

Second, before you do squat, go to the track or Spec Miata shop and sit in several different Spec Miata. It sound like your shooting in the dark.

[DavidNJ]

I am shooting in the dark...as far as I can tell the nearest shop is over 4 hour round trip and will be a few weeks. I tried that with the SRF and it was a bit fruitless. My butt fits fine, but my shoulders were a no-go. 

 

Height and weight is interesting...I'm 5-10, which shouldn't be a problem, and 275...which is a little problem, but really only for the lap-belt. 

 

The problem is the width of my shoulders. As I said, I don't fit a stock NA/NB/NC Miata or Mini and I'm a tight fit in my S2000. The picture says it all: the containment seat can be a tight fit by itself and we are looking at a custom seat that will be wider in the shoulders. My shoulder measurement is 23". A Kirkey 16" seat is set for 20". The widest 71 is a 17" which would be for 21". The 45 is a bit wider.

 

Since I plan to buy an existing car, the cage won't be a blank sheet of paper. Maybe the car pictured doesn't have the optimal cage for that seat.

This is a picture of the cage: 

 

This is Denny Steyn's cage:

 

Maybe the seat in the first one is too far back or the rear hoop isn't inclined enough to the rear? Very small differences when buying a used car with an existing cage.

[Dave D.]

Where in NJ are you? I have a shop in Central NJ (South River) and maintain a few SMs for friends and also serve as the Chief of Race Tech for NASA Northeast.I do not really advertise myself as a SM shop for a few reasons, however I usually have a few SMs at the shop at any time between my own,customer's and friend's cars. I have one in the shop now getting re caged with a floor drop. It might be much easier for you to look at a car in person.

   RE:Seat mounting. The floor drop is made with .060 sheet steel which is much thicker than the original floor material and is a great mounting surface for the seat. PM me for contact info......

 

Dave D.

[DavidNJ]

Where in NJ are you? I have a shop in Central NJ (South River) and maintain a few SMs for friends and also serve as the Chief of Race Tech for NASA Northeast.I do not really advertise myself as a SM shop for a few reasons, however I usually have a few SMs at the shop at any time between my own,customer's and friend's cars. I have one in the shop now getting re caged with a floor drop. It might be much easier for you to look at a car in person.

   RE:Seat mounting. The floor drop is made with .060 sheet steel which is much thicker than the original floor material and is a great mounting surface for the seat. PM me for contact info......

 

Dave D.

 

PM sent. You are fairly close by.

This is a picture of a roll cage mounted seat from an old Circle Track magazine: 

 

The text with it said: "The primary point of emphasis when mounting your seatbelt and racing seat inside your car is that the mounts should never connect directly to the car’s frame or sheetmetal. Both the seatbelt and seat should mount to a “seat hoop” that is connected to the rollcage. This way, if the driver takes a side impact that is strong enough to move the ‘cage, the seat and harness will move with it. The idea is to protect the driver from being injured by his or her own rollcage."

[38bfast]

A cage design that the main hoop start off the top of the rear bulkhead will move the main hoop rearward about 2" giving you a lot more room for seat options.

[DavidNJ]

A cage design that the main hoop start off the top of the rear bulkhead will move the main hoop rearward about 2" giving you a lot more room for seat options.

 

What would the door bars connect to?

[Bench Racer]

A cage design that the main hoop start off the top of the rear bulkhead will move the main hoop rearward about 2" giving you a lot more room for seat options.

 

 

What would the door bars connect to?

SCCA GCR

 

D. SIDE PROTECTION Two side tubes connecting the front and main hoops across both door openings are mandatory. Tubes that are welded to any part of the same mounting plate are considered to be connected to one another (see 9.4.E.3 below). NASCAR-style side protection or one bar bisecting another to form an “X” is permitted. Door side tubes may extend into the front door. In Improved Touring, Spec Miata, Touring, and B-Spec the door window glass, window operating mechanism, inner door trim panel, armrest, map pockets, wiring harnesses for door locks, windows, power mirrors, seat wiring, etc., and inside door latch/lock operating mechanism
GCR - 117
9. Cars and Equipment
General
may be removed and the inner door structural panel may be modified, but not removed only if the door bars extend into the door cavity. The stock outside door latch/lock operating mechanism shall not be removed or modified unless specifically authorized in the category rules. All categories except Production and GT shall not remove or modify stock side impact beams unless specifically authorized. E. ROLL CAGE ATTACHING POINTS 1. Improved Touring, Spec Miata, B-Spec AND Touring (excluding T1 and T2) classes–The roll cage must attach to the vehicle structure within the passenger compartment in a minimum of 6 points and a maximum of 8 points as specified in these rules. Roll cage may not pass through any structural member, except Miata rear main hoop braces may pass through the package tray. 2. All other classes–There is no limit on cage attachment points. The roll cage shall be integrated into the frame or chassis. 3. Mounting Plates a.  Mounting plates welded to the structure of the car shall not be less than .080 inches thick nor more than 0.25 inches thick. The maximum area of each mounting plate in the Improved Touring, Spec Miata, and Touring classes shall be 144 square inches. Plates may be on multiple planes but shall not be greater than 15 inches on any side. b.  The thickness of mounting plates bolted or riveted to the structure of the car must not be less than the thickness of the roll hoop or brace that they attach to the chassis, and must be backed up with a plate of equal size and thickness on the opposite side of the chassis panel. The maximum area of each mounting plate must be 144 square inches. Plates may be on multiple planes but shall not be greater than 15 inches on any side.

 

pm 38bfast for more info

[38bfast]

Upper bar attaches to main hoop. Lower door bar attaches to a plate welded to the bulkhead. Look at the East Street cages or V2 motorsports cages. I think a few other builders are starting to do this as well.

[DavidNJ]

Is this on the shelf? (It is the best/only picture I could find of that detail). Doesn't attaching two lower door bars to a bulkhead count as two additional attachment points? Isn't that putting a lot of responsibility on that bulkhead to hold car, something it doesn't designed to do? Can some of the same effect be achieved by installing the rear hoop at angle of incline of the read bulkhead?

 

Umm...a question about the fit of a containment seat is becoming a new cage. 

 

This will require a re-evaluation of my cost structure. I was planning on getting an existing car and changing the seats and belts. This seems to indicate it may need a new cage. We are getting out of the intended price range, especially considering the limited racing opportunities in the northeast (another thread, with lots of concurrence). 

[DavidNJ]

Is this a correct picture? Is it considered the same attachment point because it is on the same 144 sq in plate?

 

 

Does this one meet SCCA rules:

Attached Files

•  SM Cage 05.jpg   59.82KB   1 downloads

[Bench Racer]

Yes and yes provided they meet the rule 15 inch and 144 square inch.

[38bfast]

There is conciserable structure in that area of the car to mount the main hoop. Actually more structure in that area then mounting it to the floor pan. Many of my larger drivers have had to go down this road to fit in the car. It also pushed them into a new build because they could not find a used car with this cage design.

[DavidNJ]

Yes and yes provided they meet the rule 15 inch and 144 square inch.

 

I'm not sure about the second one, which is on an NC.

I did find this picture: