Frame and Body Design For Seating

[Wbulk]

Sorry, this is going to be a little long. I am just about done building my car so I have been looking for my next project. It may be another Cobra or not. As part of the process, just one of the issues I have been evaluating is seating position in the car. It’s tougher for bigger guys to fit in these cars. What got me on to this was I have a friend that has a Kirkham and I was riding in it at the track one day and I noticed that I sat lower in his car than mine. This made it so you are not having to look through the top bar of the windshield. Anyway after doing some measuring I found the difference in this case was the cowl rolled up higher from the doors than mine by about 1 ¼” right in the middle of the seat. This caused me to start looking at other manufacturers and how their bodies and frames differed. An example of which I was at a car show recently and there where two Shell Valley cars next to each other. I guess over the years they had used two bodies, so one rear deck cowl ramped up quicker than the other, making it look like the driver was actually setting lower in the car. This also affects things like how the roll bar looks. I then ran across a You Tube video on Pacific Roadsters that sparked my interest of how the various manufacturers address the issue or not.

I then started contacting the major companies and asked for specific measurements of their cockpit, and most of them sent them to me. I got to tell you that was very enlightening. I then started searching for pictures of these manufactures frames to see if it was the body or frame that was causing the difference in the measurements. Lone Star even did a You Tube video on all their measurements. I would highly recommend that anyone that is looking at building a car go through this process. It’s not just if you fit but where your head is for taller torso guys. Being 6’ 2” if I had gone through this process I would not have bought the car I did, even though the measurements are very similar to some of the major brands. In the end I found the two major factors were either a dropped floor pan or a body that has a cowl that ramps up higher. I am not going to go into all the other factors that effect which is best but I like the frames that are strong and have no cowl shake. The ones that when you go over a dip in the road the gaps do not change in the doors. No question in my mind that for a ladder frame ERA has one of the best, but there are others that are very good to.

Over the years I have e-mailed Barry McGill, Fiberglass 34 Coupes and Cobras by McGill Manufacturing, who use to be partners in B&B, which is the car I own. He had asked me what I would improve with the car if I could. I really respect companies that do this. Another company that did this was Hurricane, which has resulted in a better car. I had sent Barry a list of items, and then got onto this issue. He said he was interested, and I had sent him pictures of various ways to accomplish the seating. I have never bought anything from Barry nor I have I met him is person.

I guess he took this issue serious and had been working on improving his frames to get a better seating position. A few days ago he sent me some pictures of what he is doing to improve the Cobras he builds. One thing for sure, he is an excellent welder and fabricator, and I really respect the guys that actually work with their hands.

I think anyone that is in the market should consider this issue when evaluating brands. These are the pictures Barry sent me of how he has dropped the frame seating down 1”, while maintaining a very strong frame.

[wolf k]

I could not agree more, I am 6'2'' and with minimal seat foam in my racing style seats that are mounted directly to the floor, I still feel that I am sitting high in my ERA. In your research did you find any manufacturers that install the seats down between the frame rails? The frame rail in your photo looks like a good way to gain an inch.

[john chesnut]

I am 6'2", 34 inch inseam, and weigh 230lbs. I built my Cobra frame to wrap around me so that I could sit as low as possible and have as much leg room as possible. The frame height is 5 inches. The floor thickness is 1 inch. In this picture the seat is mounted 3 inches above the floor. I see through the windshield, well under the top frame rail and fit well with the soft top installed.

[mreid]

I'm 6'4" and 225 with a 36" inseam. I ordered my Kirkham with a dropped driver footbox and a racing seat. I haven't installed the racing seat as I fit fine with the regular seat pushed as far back as possible and bolted directly to the floor (no adjusters). My line of site forward is a few inches below the top of the windshield frame.

Wbulk, if you have all these measurements, why not post them in a table for all to see?

[Bill E]

The CR address this problem almost 30 years ago by expanding the car. Lowering the foot box and ramping the floor for the seat. The problem with that is (it is no longer a cobra clone.) A lot of people take offence with that. Me I don't care. I would rather have a car that works better and can be driven every day. Not something that makes me feel like I am driving a roller skate with a big engine. For me when you raise just cowl the car looks blocky. I have built a lot of cars for Big and tall and for the very small. moor than any one else, and I can tell you no one sits the same in a given car. What works for one guy will not be right for the next. These cars are like shoos. So every car we do is built to the guy that owns it. Build your car to fit you. Barrys Frame looks good.

[Luce]

Lone Star drops the floor pan to the bottom of the frame rails gaining you 4".

[G-Pete]

1 inch drop on a 3 inch frame (289 FIA) - that relates to a 4 inch frame as a 2 inch drop. Combined with Kirkey seats very nice low seat position. Last picture is my wife (5'10"). Very little difference between hers and my shoulder height Me 6'1" 200lbs inseam 33 inch.

The straight view is about the half of the windshield...

[Wbulk]

mreid, I was thinking about doing that but it may be the apples to apples thing. Some companies did not respond exactly to the questions I asked. This is the e-mail I sent to the companies:
I am looking for my next project . Can you give me some measurements of your 427 cobra?
Length and width of the cockpit at the top of the cowl.
Height from the floor to the top of the door at the latch point without carpet.
Length from the brake pedal to the intersecting point on the floor where it meets the back panel without carpet.
Height from the floor to the bottom of the dash.

When I got into this and after seeing the Youtube video Lone Star did for me I realized I should have asked for some additional measurements.
LS427CockpitMeasurments.mp4 - YouTube

One thing that I just remembered, a lot also depends on how the body is mounted to the frame. I have a similar frame to what Barry is building but not with his new modifications. My body comes down on the frame more than my friends Kirkham, about 2" down. So the body on the Kirkham actually sets higher on the frame than some. Plus the fact that the Kirkhams rear cowl ramps up higher and quicker than mine. I give that as an example becasue the fit in the Kirkham is better than my car and from looking at the others measurements, better than most. So, it's not just the frame, or if the frame drops where your are seated, but also how the body is mounted on the frame. I have been saving pictures of all the manufactures frames I can to compare and see how that affects the seating. It's interesting to me how it all comes together. For example may friends Kirkham roll bars are 14" high at the center of the rear cowl, mine is 15". But from the floor mine is actually a 1/2" lower than his. From the floor to the cowl at the center of the seat his is 1 1/2" higher than mine.

Where the body mounts on the frame also affects wheel opening design. You can see how they vary a little on ERAs site.
Compare car profiles

Good seating design appears to be a little here and a little there and it all works. It appears on this issue, some few may have it right on, but most don't have it all coming together just right. It is amazing to me that some of these cars have been built for sooo many years without trying to improve on this seating height issue. Then there are all the other design and quality issues. I think if more buyers ask the companies about this issue more might try to improve on theirs.


John and G-Pete thanks for the pictures. I really respect guys that do their own fabrication.

My evaluation continues!

Wayne