Back From Oregon

Back From Oregon

Instead of just going to Bend to work, I continued out to the coast to visit my mother, brother, and sister who live in one of the small coastal cities there. I'll have some pictures in a day or two--but right now, I am exhausted. I left at 6:15 AM this morning, and arrived home about 8:15 PM. Adding to the exhaustion, I have discovered that I am too dense for the Jaguar's seat on long drives.

This is not the first car seat where this has been a problem. Remember that density of an object goes up with the cube in linear dimension, so a person who is 10% taller, all other factors being equivalent, will be roughly 33% heavier (1.1 to the third power), and have about 21% more buttocks area (1.1 to the second power).

It turns out that a lot of car seats are designed to give a bit in the middle of the bottom cushion--but not so much on the edges of the bottom cushion. The theory is that people who are fairly small in height and width are also pretty light--so if the seat gives a bit in the middle, they sink in on the test drive, and this gives that cushy feel that many people expect. If you are a good bit heavier, you are generally a good bit larger in all linear dimensions, and the weight is distributed across not just the middle of the cushion (which has a lot of give) but also the sides of the cushion (which are usually better supported).

On several cars that I have owned, including my 1978 Camaro Z28, my 2000 Impala LS, the Jaguar X-type, and to a lesser extent, my 2000 Corvette, I have found that, to my shock and amazement, I am apparently considerably heavier for my dimensions than the average customer for whom these seats were designed. I am not a body builder, by any means, but I seem to be much more muscular (and thus denser) for my height and dimensions than normal. (Which is not bragging--it's a bad sign about the average person's level of condition!) It is quite common for people to underestimate my weight by 20-30 pounds--and thus, I'm a good bit heavier for the amount of seat that I cover than normal.

As a result, I sink into the less supported part of the bottom seat cushion much more deeply than the average person with the same number of square inches, and after four or five hours, I started to develop pain in my legs just above the knees. Because my rear has sunk lower than normal, the seat cushion puts excessive pressure on the legs in this spot. After six hours in the car, I start to develop pain in my lower back, for reasons that aren't quite as clear.

Now, car makers know how to solve this problem. I can remember being astonished the first time I sat in a Mercedes. The seat was extremely firm--enough so that I am sure that more than a few "luxury" car buyers were so turned off by the first five minutes that they simply refused to consider it. But ride on a firm car seat for a while, and you start to appreciate it.

Back in the late 1970s, Chevrolet would (if you asked nicely, and were on good terms with your dealer) let you order their sedans with many of the special parts used for police cars and taxis (using the Central Office Production Order list, instead of the Regular Production Order list). At my encouragement, a couple of friends ordered up a Malibu and an Impala with the police car parts. Some of these were performance items: enhanced versions of the sport suspension; quicker shifting automatic transmissions; pursuit tires designed for continuous high speed travel. Some of these were durability enhancements for the peculiar needs of pursuit vehicles: stiffer engine valve train parts for durability; even heavier duty versions of the wheels, cooling system, and oil cooler.

One of the most unexpected parts was the heavy duty front bench seat in my friend Eric's Impala. The standard Impala had a steel bottom to the seat--but with cut outs where the driver and passenger bottoms would be--to make sure that the seat had some give when you first sat down in it.

The heavy duty bench seat that came with the 9C1 package had a solid piece of steel at the bottom of the seat--and what a difference it made! Probably because the average police officer (in spite of the nasty stereotypes of them as donut munchers) is in much better physical condition than the average Chevy buyer, those cutouts weren't there.

I drove Eric's Impala on a number of occasions for prolonged periods of time--and even if I was a little tired when I got into it, I was wide awake after I started to drive it. Like those stiff Mercedes seats, it actually made me more awake, and more alert than I would have been otherwise. At the same time, when I sat in the front passenger's seat, which was also correspondingly stiff--I would nod off immediately--probably for the same reason that a firm mattress lets you sleep so well.

I've done similar stuff before to some of the aforementioned car seats, using the densest foam rubber that I could find to reduce the play in the center of the bottom seat cushion, and the results, while not perfect, have at least been better. As an expedient, somewhere in eastern Oregon, I stuffed a rather stiff blanket under the driver's seat to reduce that sinking feeling. It wasn't perfect, but it did make some slight improvement.

Anyway, one of tomorrow's tasks is to figure out how to make a proper corrective assembly for the Jaguar's driver seat so that it handles dense driver's like myself. It looks like the frame will allow me to machine a couple of crossbars out of aluminum channel that will substantially reduce the opportunity for the unsupported part of the cushion to drop. If it works well, perhaps ScopeRoller will have a new product to sell!