Seat upgrades

[rdorman]

I wanted to open serious discussion on the fiberglass buckets that some of us sit on in our Cobras.

My car is an old Unique. The seats are NOT comfortable for any extended period of time. I should note that Unique seats not only have improved since mine was built but there is yet another newer version coming out that is promised to be more comfortable. Bottoming out is common. Bottom to soft and of course no latteral support. Some of this is inherent to the fact that the seats try very hard, and generally succeed, in looking like the original seats. Personally, I would like to keep it that way.

Topics:
- Foam IFD, Density, type and placement
- Crash worthyness
- ungrade the funtion and keep the form

Foam.
Looking around here is what I have found. You Foam experts, jump right in! You can not use just one foam and come up with a comfortable seat. each area depending on loading requires a different type of foam.

The latest of which is the 'memory' type foam. Sold under a bunch of names such as Temper, Confor and of course, just plain memory foam. I have read that a number of people of bought memory foam pillows, etc and stuffed them in the seats. Problem is that the memory foam that is made for bedding and pillows seems to be way to soft for proper support for a seat base. Even a bit soft for the back.

This leads to Indentational Force Deflection (IFD). IFD, basically put, is a measure of the firmness of foam, expressed in pounds required to compress a sample (8" in diameter if I remember correctly on a 15"x15" sample) 25%. IFD of memory foam mattresses and pillows seem to be in the 10-15 range where a seat base requires something in the 27-35 range for the center section and north of 40 for the side and thigh support. The arrangement seems to allow the seat to 'surround' and support better. Back IFD range from about 27-35 for lumbar and kidney area as well as outside the body area for latteral support and roughly 18 IFD up the middle above the lumbar and between the lateral. Sound about right there foam experts? Of course these numbers will vary according to personal taste and use.

The hot ticket seems to be to use a foam such as Confor (high density and good IFD range, or any sutable memory foam) in layers over and below non-technical urethane foam. For instance. I thin layer of very soft foam (<10) over soft layer of Confor (about 26), over a medium firm layer of Confor (about 34) over a shaped non-technical foam of a equal or higher IFD rating with an even higher rating to the sides and front edge of the seat all wrapped in 1/2 dacron. Minimum base thickness seems to be about 4" not including the dacron. So if you use 1/2" soft non-tech over two 3/4 layers of Confor plus 2" of firm non-tech with the side and front being and inch or two higher, and firmer, I would think you would have it! I might even cut out a section from the seat cushion base (in the case a piece of plywood) directly below the tailbone to allow for additional 'travel' and avoid bottoming out on the tail bone. Should add that extra little bit of comfort.

Now for the back. Similar construction to the base but much lower IFD numbers because the load is greatly reduced. The memory type foam is probably over kill here EXCEPT in the lumbar kidney area where you need a firmer high density foam. Again start with a thin very soft layer followed by a slightly firmer layer of say 26 in the lumbar and lateral areas with 18 IFD in the middle. Sound about right?

Crash. Seems to me that could be improved. Any one ever been rear ended seriously with a glass bucket type construction? Running into something head on your belts are keeping you in place but being hit from the rear the seat is now acting like a belt. Would the glass bucket hold up? What about a welded aluminum pan on the inside of the bucket and that is what you bolt through? Easy, cheap and light.

Brings me to function. The seats are very low back and of course have to lateral support. Short of totally changing the appearence, what can be done. Seems as though carefull use of various foam IFD and density will take care of some of the lateral support issues. How about a little over stuffing? A little taller and a little more base length perhaps? Not a bunch, but enough to make a difference. Head rests. I wouldn't want to leave them on all the time for appearence sake but for those road trips it would be nice. Not to rest the head so much but more to help in a rear end collision. Seems to me once removed two little chrome grommets where they slide into the top of the seat would not look to bad. You could even use black grommets and at a glance wouldn't even notice.

You may have guessed by now I am already thinking of next winters project. Even though of course I haven't finished last winters project yet! I have already dropped the hint on the seat heaters with the wife and if I am in knee deep on this project then perhaps Santa will be good to me. Hell, lumbar bladders are only $40 as well! Hmmmmmmm.

So, seat designers. Any out there? And no, I do not want to go buy another set of seats. That is the easy way. what would I have learned by doing that?

Rick