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Drill new seat mounting holes?

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  • Drill new seat mounting holes?

    I saw on the forum some discussion about horn repair, and moving the steering column by loosening the two screws underneath on the column bracket. Can someone describe this process and the pros/cons of doing it?
    Like some of you, I’m a big guy, 6’4”, and struggling to get comfortable behind the wheel. I’ll likely go with the custom-rail method of moving the seat, but it would also be helpful to be able to move the steering wheel closer to the dash. I see no discussion of this in the shop manual.

  • #2
    I believe your steering wheel is fixed in position by the length of the steering shaft. Moving the column adjusts the gap between the steering wheel and the shift collar. In my opinion your best bet is to offset the seat rails. These pictures are how I did it and gained 2 inches. I used 1/4 inch steel. Welded in new studs with a two inch offset and welded this to the base. If you want more photos let me know. The studs look crooked but that's just camera angle.


    • #3
      Keep in mind that there should be two sets of holes on the seat mounting frames. If your seats are mounted in the rear holes mount the seats in the front holes. That should put the chair a bit further back away from the steering wheel, but give anyone in the back seat with less leg room. But then again, how often do you have anyone in the back seat anyway? Here is a pic of what my seat bottom looked like. You will see two holes top and bottom about 2 inches apart. If the seats are in the back holes, put them in the front holes and see if that helps. A PO had put a black plastic bag under the seat to catch all the dried up foam that was all over the carpet under it.

      Ray Clark - Squarebirds Administrator
      The Terminator..... VTCI #11178
      Contact me via Private Message for my email address, or Call (Cell) 210-875-1411


      • #4
        Thanks to you both. I definitely plan to try relocation to the other factory hole, but do not think it’ll buy me enough room. I’ll likely have to go with P38’s method to gain a few inches. I don’t mind cutting down on back seat space.

        P38, have you ever considered producing and selling those extension rails you made? You’d have your first customer here. I don’t have a welder or even a supply store near me to buy the proper size steel strips. But if I had the rails I could find someone to weld them to the seat frame.


        • #5
          TZTony - 1 inch by 1/4 inch strips sold in 3 foot lengths sold by Lowes, Home depot, Tractor Supply, Aubuchon Hardware etc etc. Let me know how you make out.


          • #6
            That's where I got mine and $25 to weld them in place. Im 6'3", made a big difference..


            • #7
              Today I unbolted my driver’s seat in prep to move it back. I had planned on using P38fighter’s method of welding bolts to a metal strip and welding the strip to the seat frame. (I can just move the seat to the forward factory hole, but that won’t buy me enough room to fit behind the wheel.) Since I don’t weld I’ll have to find and have someone do it for me.

              Now that I have the seat out, however, I’m wondering if I shouldn’t just drill new bolt holes in the floor, two inches behind the factory holes? I can put nuts/washers to seal the old holes and just use the new with large fender washers to grab onto a wider area of sheet metal. This would be less permanent in case I ever want to move the seat back to the original holes, and much easier as it eliminates the need for welding and extra rails permanently grafted onto my seat.

              There doesn’t seem to be any extra reinforcement in the area of the factory holes that isn’t there two inches back. I suppose having those forward holes might result in a slight structural weakening, but I can fit a washer in them and bolt them up. I don’t think that just based on this modification the seat would rip out of the floor In the event of a crash (and with no seatbelts, that would be the least of my concerns anyway).

              Does anyone see any issues with this that I might be missing? There are no fuel or brake lines or anything in that area that would prevent me from drilling new holes.


              • #8
                I would not make new holes in the floor. Your seat bolts are engineered to safely hold the seat under all conditions.
                I would not WELD to your seat rails, either. Welds tend to break out with vibration.
                I would BOLT new 1/4" X 1" steel extension strips through the rails with at least three grade 5 (or better) 1/4"-20 bolts with nylok nuts. I'm a big guy as well.

                My latest project:
                CLICK HERE to see my custom hydraulic roller 390 FE build.

                "We've got to pause and ask ourselves: How much clean air do we need?"
                --Lee Iacocca

                From: Royal Oak, Michigan


                • #9
                  Thanks for the advice, SimplyConnected. However with the TBird, the seat rails sit directly on the floor sheetmetal. Unless I’m missing something, if I were to bolt extensions to them, either the bolt head or nut would stick out the bottom and bend the rail when I tighten it down. Also, the headroom is an issue as well, and any rails I add, no matter how thin, would bring my head closer to the headliner. My hair already touches as it is!


                  • #10
                    Dave, have been watching this post since like Tony I am large for my age! Any way to use bolts for seat extensions without raising the seat too much? Maybe carriage bolts to hold the seat rails to the extensions? Getting in and out I am already starting to wear out my new upholstery. Thanks, Al


                    • #11
                      I decided to go the bolt-in method, for ease (no welding) and the ability to reverse or alter the results in the future. It worked very well.

                      I used custom-made extension rails made of the 1/4" inch steel and this size did not add much to the lack of headroom. I also added a few washers up front; to make up for the bolt head in hole #2 (see below) and to rake the angle of the seat back a bit. It actually gained me a bit of headroom. This method used only the existing floor holes with no need to drill new holes through the floorpan. One only needs to carefully measure the distance between bolt #1 and #3, and be sure to use grade 8 bolts/nuts.

                      This method involves three bolts/holes per rail as follows:

                      #1 - front hole - this is the hole drilled through the extension, which sticks out (in my case, two inches) beyond the factory frame rail in the front. You can customize this to any length you desire (until you hit the reat seat!). This bolt goes through the existing front floor pan hole and into the front hole drilled on the extension rail. I also added some washers between the floor pan and the extension rail to raise the front a smidge. It requires a new nut and lock washer.

                      #2 - middle hole - this hole was drilled through the extension rail to line up with the factory hole in the seat...the one with a factory welded-in nut. The extension rail was bolted to the seat frame using this hole. This bolt does NOT pass through the floorpan. The bolt faces up and is bolted to the seat frame before positioning seat in the car. The bolt head will rest on the floorpan and add a tiny bit of height - the washers I added to bolt #1 raised the front to the same height, thus relieved the stress that this bolt head would place on the extension rail if the front bolt was tightened down without washers.

                      #3 - rear hole - This hole requires drilling through the extension and drilling a new hole in the seat frame. It passes through the floor pan (using the existing floorpan rear hole), the extension rail, and the new hole in the seat frame. A new nut and lock washer is placed on it, which required reaching in through the rear of the seat with a box wrench to hold the nut while the bolt head under the car is tightened.

                      The careful measurement comes in between bolt #1 and #3, as the distance between them must match the distance between the front and rear floorpan bolt holes. #3 only has to line up with one of the two factory holes in the front of the seat frame.


                      • #12
                        Tony, if you have any pictures of what you just described above, can you send them to me so that I can post them for you?

                        Ray Clark - Squarebirds Administrator
                        The Terminator..... VTCI #11178
                        Contact me via Private Message for my email address, or Call (Cell) 210-875-1411