Friday, February 4, 2011

Driver's Seat Modification

Some time ago, I mentioned that I was going to modify our 2001 26.5' LD driver's seat. It was shutting off the circulation in my legs just behind my knees because the height of the front of the seat bottom cushion relative to the cab floor. Moving the seat forward or back and adjusting the seat back throughout its recline range made no difference. Also, for my 6' 200 lb frame, the back of the seat bottom cushion is too low for a comfortable (to me) thigh angle relative to the floor level and, the seat back adjustable lumbar support is four to six inches too high. Even with the lumbar support retracted as far as possible, I have an almost one inch gap between my bum and the seat back cushion.
I should mention that this posting really applies to the later LD's which have the front seats mounted to Ford supplied stands and not to the earlier pedestal mounted seats. (I found the earlier ones very comfortable.)

Anyhoo, I started out by getting the box stand mount front seat specifications from Ford. Our LD seats are within the Ford Specs but there is quite a bit of room for modification to improve comfort within those specs. I removed our driver's seat and took apart most of the seat bottom assembly. The metal seat bottom frame is built in such a manner that it restricts the amount of comfort change one can make. While the aft part of the seat bottom cushion is supported on springs, the front part of the seat bottom cushion is supported by a formed, curved piece of metal which prevents the front of the seat cushion from compressing as much as the rear of the cushion. This exacerbates the uneven `ride height' of the seat bottom cushion and prevents the front of the bottom cushion from pressing too hard on the knee end of my thighs when sitting in the seat with foot on the gas pedal.

As a result of the above, it was clear that the amount of change needed for me would require a complete rebuild of the seat frame.

Changing out the seat would be an easier solution. However, I did remove a melon slice shaped piece of the seat bottom cushion, cut level to the cab floor, measuring one inch in thickness at the front of the cushion and tapering down to zero about five inches into the cushion. I cemented the cushion together with spray on upholstery cushion cement and reattached the seat bottom upholstery to allow for the thinner cushion front. It takes a close eye to see any difference between the two front seats.

This modification made about one half of the change needed to make the seat really comfortable for me but did change it from a one hour seat to a two hour seat. I can live with that.

I should note that I've tried a number of loose cushion shapes without much success. The thing that did make a difference was TEMPORARILY putting a two-inch piece of plywood on the cab floor behind the gas pedal. (TEST ONLY - DO NOT IT FOR DRIVING) That is what convinced me that the front of the seat cushion was not compressing enough to allow my knees to get low enough to comfortably use the gas pedal over extended driving.

Searching the internet, I've found others have complained that their SOB Ford based Class C's with Ford box mount seats have the same type of drivers seat bottom discomfort.

My recommendations:

A. Unless you are very experienced at automotive mechanical and upholstery work, do not try to modify your driver's seat. The amount of change is just too great.

B. If you choose to replace the seat on your late model LD, be very sure that you get one that:

1. Fits the Ford Box mount (not the older pedestal mount) and only buy one that you can return it if it is not comfortable to you – sitting on a new seat in a store is not a good test in this instance,
as the real test will be your right leg's relationship to the seat and the gas pedal when the seat is installed in your LD.

2. Accepts the Ford seat belt Pyrotechnic Tightening Device.

If you don't like the seat comfort in your earlier LD with the pedestal mounted seats, you might try the Camping World for FlexSteel's armrest-equipped, reclining Van Seats. We had those in our last Ford E350 Class C and they were very comfortable for us.

The seat cushion modification, along with extensive cruise control use and rest stops every 90 minutes or so, worked well enough on our recent 1800 mile sojourn to Salt Lake City and back that no further seat changes are planned.
Contributors: Don McGlothen 11/1/03
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