If you are over 6 foot tall, more than likely you feel cramped when driving your early Mustang. Being 6'2", I needed more leg room to comfortably use the clutch pedal. After a little research and thought on the subject, I did a couple of things so I could better enjoy driving my car.
First I lowered the seat pan (platform) as per this article
from Mustangs Plus. Lowering the seat pan is optional if you do not want to do any serious modification to your car.
Next I relocated my seat tracks more rearward through the use of some flat steel bar stock, which was readily available from a local welding fabrication shop. This method does not modify the basic structure of the car and allows for the use of the factory floor pan access holes found under the car:
Here is a picture of how the original seal tracks bolt to a typical seat:
Note the brackets on the upper left of the picture. These are a completed pair of seat track extensions..
The seat tracks can be removed from the seat by using a large #3 Phillips screwdriver. If the bolts are very tight, a hand held impact driver may be required. Here are the parts that you just removed:
You will not need to modify any of these original parts, except maybe the rear most stud on each track. More on that later in the article.
To create the seat track extensions, I used 5’ of 5/16" x 1 ¼” thick low carbon flat steel. This was enough material to modify all 4 seat tracks of my Mustang.
First I cut the steel into 4 sections, each being 15” long, which will allow for up to 3” of additional seat travel:
If desired, you could cut them to just 14” if you only want 2” of addition travel, which was all that I really needed.
Next I drilled several holes in the flat steel, using the factory seat track as a template:
A pair of holes were first added in the soon-to-be seat track extensions to allow bolts to be inserted into the original seat pan holes. I countersunk these holes and installed a 5/16" x 18 thread flat head cap screw into each of them, with the heads being flush to the top surface of the track:
The flat head bolts and the countersink are needed so that there will be no interference with the tracks movement fore and aft. I welded the heads of the cap screws into place and ground the welds flat. The welding is required because you will not be able to insert a tool onto all the heads once the track is assemble to the extension.
Next I drilled another pair of holes 2” to the rear of the first set of holes. This will allow for 2” more leg room. I also drilled another pair of holes 3” away from the first (countersunk cap screwed) set. This would give 3” of leg room for an extra tall driver. In my case, I found that I did not need this extra travel.
I also needed to drill extra holes to clearance the rivets found on the seat tracks. Normally they are embedded into the carpet and do not cause a problem:
Notice how the parts fit together. Here is another shot:
I discovered that the spring retaining bracket of one of the seat tracks interfered with the travel. For this I used got fancy and used a mill to notched some clearance for those brackets:
You could probably do the same thing with an angle grinder. Once you are satisfied with the fit of the brackets to the seat tracks, they should be painted. Because part of the extensions will be seen when installed, it would be best to paint them the same as your carpet color. Lucky for me, my carpet it black and that is what I went with.
Reinstall the seat tracks to the seats using the original hardware. With some new 5/16” nuts and lock washers, install the new extension brackets to the seat tracks. You will notice that you will have 4 studs sticking down out of the bottom of the assembly. Three of these studs are no problem. The fourth stud will require that you drill 2 holes in your seat pan (for each seat) in order to create the a place for the original seat track stud since it is now relocated. You will not need to drill through the lower floor pan, just the upper pan. The holes will need to be large enough for the afore mentioned nut and bolt to pass through:
The pencils show where I drilled the two 5/8” diameter holes:
The stud passing through the new hole:
The corresponding holes are shown cut into the carpet:
You should now be able to reinstall the seat back into the car using the original nuts. Initially I did not use the long U shaped carpet protecting washers, but later added them to the front in order to create a little more tilt to the seat.
The following photo shows what the front of the seat looks like after the mod with the seat in the rearmost position. They are not as noticeable as they appear in the photo since the color matches the carpet.
You will not see the remainder of the extension when looking in the car. The rearmost part of the extensions hangs out over the rear floor space and is hidden by the seat. As mentioned earlier, I felt it necessary to shortened the rear studs somewhat to prevent accidents should a rear seat passenger stick his foot up under the seat.
My new seat location is absolutely wonderful after doing the 2 above modifications. I can comfortably reach the clutch and brake, plus I like the steering wheel at more of an arms length. The manual shifter is just in my reach when it is shoved forward. Due to the seat pan drop, I can comfortably wear a helmet and not rub the headliner, whatsoever. About the only negatives I find with this installation is that the dash is farther away and that means I must lean forward to start the car, turn on the wipers, the headlights, or adjust the radio. Also, if you have the deluxe retractable seatbelts, there is not enough room for the retractor to mount—the stock type seatbelts fit just fine. I still believe that the added comfort far and away overcomes the negatives.