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

[rdorman]

Doesn't any one know about this stuff?

Some updates from a post I put on another site:

"The temper for pillows and bedtops is really to soft for automotive use. The best prices I have found so far are at http://www.mcmaster.com/. The temper they sell goes under the trade name of Confor. Currently, the hot ticket (at least for someone my size, 5'10 170) seems to be a thin layer of Yellow (CF40) or non-technical foam with a IFD of <15 (multiply mcmaster's compression rating of psi @ 25% by 50 to come up with a approximate IFD), over a layer of pink (cf42) over blue (cf45) over non tecnical foam of about 40 IFD. This seat should not bottom out and be comfortable. Wrap the whole thing in Dacron. I would go with 1/2", 1", 1" and 2" thicknesses respectively. The non-technical foam should have a desnity between 2.5 and 4 pcf (pounds per cubic foot).

To put some of these to real world numbers for Confor (just the one peice of confor, nothing else), for a seat pad 3-4" thick you should use cf42(pink) for 115 pound person, cf45(blue) for 170 pound person and cf47(green) for a 200+ pound person or a 170 pound person in hot and humid conditions. This will not bottom out, offer excellent dampning and shock absorption (you won't feel like you are setting on a mini-trampoline. The approximate IFD for these is 30, 35, 60+ respectively.

This is for the seat CUSHION ONLY. The number for the back are greatly reduced since the amount of weight supported is greatly reduced. Additional perspective is that the IFD for pillows and bed tops is in the 10-15 IFD range so you can clearly see just how thick the pad would have to be to support the weight!

Remember, this stuff is temperature and humidity sensitve. The warmer and "wetter" it is the more compliant it is. 50 to 120 is considered it normal range. Above that it is VERY soft, below that it is very firm.

So no someone go out and try it! I have to many projects going as it is to get to it before next winter!

Rick"

[clayfoushee]

Rick,

Sounds like you've done a lot of research....impressive. But, from practical experience, I don't agree that the Tempur is too soft for automotive use. I used a Tempur lumbar pillow placed over the standard foam in the Unique seat. A few weeks ago when it was in the mid-70's I took a 2 hour cruise, where I was in the seat continuously with no bottoming out or discomfort. When I did that before, I was in serious pain.

[rdorman]

Just passing along what the industry experts are saying!

Temper is NOT to soft for automotive use. Just as an FYI for everyone tempur is just a brand name for viscoelastic foam. Comes under many names.

The Tempur that is used for beds and pillows is very soft because it does not have to support the amount of weight, for a given area, that a seat cushion in a car does.

You can absolutely put Tempur pillows, etc in your seat over the other foam and realize a benefit. It WILL feel better.

BUT, some of the folks I have seen do it with the pillows and matresses toppers have ended up with a 9" thick seat cushion! To thick for my tastes.

This stuff is rated at how many pounds it takes to compress 50 sq inches 25%. That is an 8" circle. Obviously, the more you compress it the more you weight it takes. So you can take a soft peice of greater thickness and no bottom out. The amount of weight required to compress the foam is fairly linear when it comes to viscoeleastic foam.

I will give you a example. Confor CF40 (viscoelastic) with an IFD about twice that of the typical pillow or matress cover takes about .3 psi to compress 25%. By the time you get to 70% that is now 1.5 psi. An increase of five fold! So to compress this foam 70% you would have to put 150 pounds in a 8" round area. I would imagine that be about a 400 pound guy! Above just below 80% deflection (compression) the scale becomes vertical and the foam basically becomes non compressable.

Using a little math you can see that you could use any degree of softness foam in a seat and yeild acceptable results. But it is not what is recomended from the industry.

Lets work it. Lets say the old a$$ cheaks have most of the weight on two 8" circles and that the weight is 150 pounds. Lets use a 6" slab of pillow type viscoelastic (such as one person did) and give it a IFD of 15, a good but firm pillow number. That piece for our two circles will support 30 pounds at 25% deflection or a compression of 1.5". Of course, the more you sink into it the more the circle grows! This is only 1/5 of the weight that we are applying. From the previous example you can see that it would take a 70% deflection to increase the IFD five fold. So our 6" hypothetical pad is now 1.8" thick. Still not bottomed out! However, we are now in the point of the depression curve where the product is rapidly becoming 'solid', non compressable. In effect, bottoming out. On bumps in the road and such.

Again, this is all based on industry information and not personal experience which is why I started this thread!

So as you can see, you can use viscoelastic foam in darn near any firmness and you will see a benefit!

Rick

[clayfoushee]

Rick,

I'm not disputing what you or the experts say. I was talking purely PRACTICAL experience with a 3" thick Tempur (visco-elastic) lumbar pillow in my seat cushion over the old foam with my body in it. I also know I was very uncomfortable in that same seat without it.

People not reading your post carefully might mistakenly conclude that it's not a good solution, when in reality, it helps a lot, and is VERY easy.

It's easy to see from the numbers you published, it's still going to be compressed close to the bottom, but it's a vast improvement.

[rdorman]

I see your point Clay! Yes folks, pretty much no matter what viscoelastic foam you put on top of your current foam will yield an improvement!

It is just in my nature to spend 100 hours researching screwing in a new light bulb and until I have met that commitment I am not happy!

Rick

[clayfoushee]

Rick,

That's why it's great to know people like you!!!!! Saves people like me a lot of time!!!!

[MidOHasp]

Rick, one cool way of screwing in a new light bulb I like (and I'm sure you've tried this before) is this: (PS this works best in a room directly beneath an attic)

If you build a stand that is approximately 6" shorter than the ceiling in the room with an adjustable diameter rubber circular clamp, you can hold the lightbulb firmly in place. Next, go up into the attic and cut out the ceiling around the fixture..................

[rdorman]

This might help people in their decision. I was just pricing out the cost. Looks like about $150 for all new foam per seat!

Sams Club pillows look real nice after that number!

If I could get the Weavers to send me a bucket, then I could experiment and return it to them. Perhaps a new extra cost upgrade. I don't know any one that would not have thrown in an extra three bills for a huge increase in comfort.

I wonder what their new seats are like?

Rick

[rdorman]

Originally posted by MidOHasp


Rick, one cool way of screwing in a new light bulb I like (and I'm sure you've tried this before) is this: (PS this works best in a room directly beneath an attic)

If you build a stand that is approximately 6" shorter than the ceiling in the room with an adjustable diameter rubber circular clamp, you can hold the lightbulb firmly in place. Next, go up into the attic and cut out the ceiling around the fixture..................

I had some thing similar in mind. Cut down on carpel tunnel from changing light bulbs. But I was going to motorize the sockets to thread/un-thread using a bi metal spring to hold the bulb. Place the bulb in the holder, press the button (or better yet, use a clapper. You know "clap on, clap off"), an voila!

On second thought the clapper idea may not be a good one. I can just see every bulb in the whole house falling out of the ceiling every time American Idol is on.

Rick

[Rich]

Rick,

When I first installed my Corbeau Classic seats, I was peering over the top of the windshield. I took them back to the place I bought them from, an upholstery shop, and they removed about 2.5" of the seat foam and added a .5" thick gel pack. The seats are very comfy and I look thru the windshield, not over it.

[rdorman]

Thickness and height are one thing I would like to tackle as well. I am only 5'10 and look more or less level with the top of the wind screen. I want to keep the thickness to a min. and perhaps even come up with a reasonable way to drop the base without having to give up the slide adjusters.

My passenger side seat had a lot of the base foam removed because he was 6'4! I drove 2000 miles home on that uncomfortable slab. Good thing I had a hemriod cushion to set on!

Rick

[MidOHasp]

Originally posted by rdorman


On second thought the clapper idea may not be a good one. I can just see every bulb in the whole house falling out of the ceiling every time American Idol is on.

Rick

Originally posted by rdorman


Cut down on carpal tunnel from changing light bulbs.

I can think of other ways to cut down on carpal tunnel, Rick...

[rdorman]

First would be to stop spending so much bloody time in the Forums!

Can't you just picture it though. Sitting there watching the tube and clap for something and every bulb in the house falls out of the socket. Guess I will also have to market a candle that lights itself when you clap. No, fire hazard. Hope about a clapper flashlight? I think I am onto some thing now. Create a need or desire and you can sell millions of any thing. Even rocks.

Rick

[MidOHasp]

Fart activated air freshener... or exhaust fan!

Thbbbbbppppppt! ................. *whirrrrrrrr*

[rdorman]

We need to go into business together!
Rick

[Jeff 427]

Rick

I too, thought that the Tempur pillow/mattress material was not dense enough for a good seat cushion. I was in Brookstone about (3) months ago and saw that Tempur makes a "seat" cushion for use on an office chair, etc. It seems like a much "firmer" material. I took down the part # and put it in a safe place, I guess its too safe because I can't find it !!!!!!!
What I remember is it was about 16" wide by 19" long and about 1 1/4" thick with a rounded front and square back covered in a cloth like fabric. It was like $80.00 a cushion. Seems a little pricey but if it works, its Cheap !!!
I would remove the cloth fabric from the cushion and put it in between the stock Unique foam and the leather. I don't have my Unique yet (Picking it up at Homecoming !!!! Yea !!!!) so I can't speak from experience. What do you think? Are you going to Homecoming?

[clayfoushee]

Jeff, that's exactly what I did, and it works well for me.

[rdorman]

Heh Jeff. First post! Welcome. Yep, there are lots of companies selling memory foam pads for backs, seat cushions etc. And I would imagine that they are stiffer or have a higher IFD. I am pretty sure that the density of memory type foams is naturally high so they would also retain their shape and body well.

Great to hear about your new Unique. You choose wisely grass hopper! No, unfortuniatly I will not be at home coming. I would love to go. I think it might be interesting for every one to see how well the cars hold up after more than 18 years! But with DVSF, etc I am just BOOKED until later in the summer.

So Clay, you DO have Tempur made for a seat

Rick

[decooney]

Rick,
I experienced the same thing with my Unique that I had. Good to hear they are planning for a revision. I ended up redesigning the bottom cushion, cutting a notch out of the plywood bottom to intentionally allow for sag, and building a frame for the bottom to extend depth in order to add more foam and a booster section in front for your legs; so it was not flat. Went from like 3" to 5" thickness, using very dense memory type foam. It was a major improvement, but it could have been even better. If I had it to do over again, I would look for entirely new seats more engineered for comfort and holding since comfort is a big part of the ride quality. Good Luck.