Sunday, March 23, 2014

Why so High?

So ever since I reupholstered my seats and replaced my seat foam with the new, high-density seat cushions, I've have to duck down a bit to look below the upper windshield frame to see the stop lights.  Also while crawling in and out of the car, my right thigh would get stuck under the steering wheel.  I bought a LeCarra 15" steering wheel thinking that since it's an inch smaller diameter, my problem would be solved but alas, no. The wheel has no dish so it sits closer to the dash and thus my legs again so I'm back where I started.   They make smaller 14" wheels but I like the look and feel of the 15" and don't want to spend another couple hundred bucks on a new one.

So what to do?  I could have done a "seat track mod" (link opens a Word document) which extends the seat tracks back a few inches but  that would put me further back from the already-too-close-to-the-dash steering wheel so I'd have to have my arms stretched out all of the time.

I'd considered cutting the frame of the seat itself an inch or so but then I'd have to re-upholster my seats and, if it didn't work out, would be out a seat frame and would have to buy another.  I'd considered buying a used frame to modify but couldn't find one for under a hundred bucks online plus shipping and there were none available locally.

So, my solution was to drop the seat platform.  This has been done much for coupes and fastbacks because they use separate left/right platform panels and also don't have the wide inner rocker of the verts which is probably why I was unable to fine a web site or reference to somebody that had already done it.

Worst case, in the event of failure, I'd have to patch my seat pedestal back to it's original configuration.  So, I set off on my mission into the uncharted territory of convertible-seat-platform-modification.   Poor Ol' Rusty.  She didn't think she'd have to feel the bite of the cutting wheel again so soon.  She'll get over it though.  On to the surgery!

First, I removed the steering wheel and then crawled under the car and removed both front seats.  This was followed by seat belts, the door sill plates, the center console, and finally, the well-worn (and dirty!) carpet, and finally, the underlayment.  The RAAMat was was not removable so I worked around it.

Seats out

Sill plates out

Seat belts and center console out


Finally, the seat platform was fully exposed and ready for modification.  I made a contraption from an L-shaped straight edge with calipers clamped flush to the base.  This allowed me to take accurate measurements of the platform height at various points along the floor.  My goal was to drop the platform exactly one inch.  The convertible seat platforms have L-shaped reinforcement brackets welded at the seat mounting holes.  These brackets extend about an inch below the top of the seat platform on all four corners so allowances had to be made to avoid them.   So, I first scribed a line an inch below the top of the seat platform followed by another line one inch below that line.  This became the area to be removed and was marked with masking tape in preparation for the cutting wheel.  Prior to cutting, I installed the seat to ensure that if the seat dropped down an inch, that the side of the seat would still clear the tunnel section of the seat platform.  It proved to have just enough clearance so I covered all of the interior surfaces around the platform to protect them from spark burns.

The back edge of the seat platform

The front edge of the seat platform

Measuring the drop

1" cordoned off for deletion

Testing the seat to tunnel clearance

All protected and ready to cut.

After I had cut the primary lines on the front and rear surfaces of the platform, I opted to leave the rocker side of the platform as one piece rather than cutting it off and welding in a patch.   This required me to remove the plug welds of the rocker edge overlap and pry it up.

I agonized over where best to cut the tunnel side for some time until I decided it would be a place far enough in towards the tunnel that, when the seat dropped and inch, it would clear the tunnel edge.  Once all cuts were completed, the platform top could be popped off of the base.

Front of the platform "after the cut"

Platform-to-rocker overlap needs to be freed.

Rear of the platform after the cut and after freeing the rocker overlap.

Never thought I'd see this again.  Note the media blast walnut shell that's been trapped inside since 2008.

Now that the inch of material was removed from the platform front and back, I had to come up with a method to reattach the top to the base.  Unfortunately, due to the fact that the front and rear of the platform are angled, the base is about an inch wider than the top.  I had actually planned that this would happen and was considering just filling the gap with strips of sheet metal.  However, once I started examining the situation more closely, I determined that if the angle of the both the top and bottom were increased, they would eventually mate again with the bonus of a drop of another 1/8" or so.  I did so, keeping in mind the alignment of the seat platform seat mounting holes vs. the access holes in the floor.  Upon completion, I tack welded the top back onto the base and test-fit the seat in the newly position platform.  What I found gave me one of those smack-self-in-the-forehead moments.  The seat hinges would not clear the inner rocker!  DOH!

I left the garage, to have a beer and park myself in front of the TV in a fit of self-loathing for having missed something so obvious.  That night, laying awake in bed, I knew what had to be done.  The rocker had to go!  Well... not go really, but a clearance cut would have to be made.  It just remained to be seen how much.

After measuring the seat hinge positions all the way forward and all the way back, I had determined the range of motion.  Then test fitting the hinge cover, I figured how far down and outward the cut would have to be.  Fortunately, it wouldn't have to be all the way down to the seat belt mounting bracket welded inside the inner rocker.  So, I marked the cut and chopped away the offending inner rocker.

I was happy to discover that the section that I had removed fit very nicely when reversed to fill the hole so I primered the now-inside side of the patch and welded it in.  Then I just had to cut and weld in two end-cap patches and grind the welds down.

I test-fitted the seats again, this time with the hinge covers installed, and was satisfied with the newly gained clearance.

Test fitting the top to the base.

Tack welded top to base.

Uh-oh.. seat clearance issues.  Yeah, the hinge covers were broken.  Need to order new ones.

Marked for "adjustment"

Opened up

Patch ready to go back in.

Ready for welding

Fillet patches for the ends.

All welded in.

Cutaway complete.

Test fitting seat rear position.

Testing front position.

Having solved the seat-clearance issue, and welding in the platform all permanent-like, all that was left was to fill the gaping wide chasm between the tunnel section and the platform.  I just used an old patch-making trick and stuck several layers of masking tape in the hole and marked the edge.  The tape could then be peeled off, cut around the marked edge, and stuck onto a piece of sheet metal to transfer the shape.  I used my Harbor Freight electric sheet metal sheer which, surprisingly, cut the 14 gauge sheet metal very nicely even though it was only rated for 18 gauge.  The patch was then test-fitted and fine-tuned until it eventually fit the way I wanted it to and then welded in and ground down along with all of the other welds.

Finally, the exposed weld surfaces were re-primed with DP74LF and then painted Gulf Stream Aqua.

Top and bottom mated.

Marking out the tunnel-to-platform filler patch

Using the template to mark the sheet metal scrap

Cut out and ready for trimming

Platform drop welded and ground down.

Painted and ready for carpet.

The seat was then re-fitted, confirming that the fit was still good and I just needed to put it all back together. So, I took a good look at the old carpet and "Old" is a very good description.  The rubber foot mat was cracked, the original red coloration was still visible, it was covered with old stains, and then there was the conspicuous lack of jute padding.  What ever shall I do!?

Stay tuned for "Carpet Diem".  Coming soon to a blog near you.


  1. Ahhhhh.....brilliant work Alex! Real pro stuff there and a brave execution with everything in the interior in place! Bravo!

    1. Thank you sir! Yeah, I was checking behind the "curtains" every few minutes to make sure no sparks were getting by. The welding had me the most concerned but I only managed to catch the butyl sound deadener alight a couple of times.

  2. Brave is an understatement. I'm rarely glad I'm only 5'8" - but this is one time that I am :)

    That was one bit of courageous surgery!!!


  3. Now we know why there isn't a reference on how to do a convertible. That is a lot of work. Just watch, now there will be dropped seats in convertibles showing up everywhere. See what you started?

    1. Ha! I'm not sure that anybody else would want to do this or at least not to the extend I did as I was trying to preserve the structural integrity of the seat platform since the Ford engineers had decided that it was necessary in a convertible in the first place.

  4. Alex, that's some impressive work there. I'm reminded of what a member of the street rod club I belonged to long ago once said; "You're finally done working on your car when you sell it." On the bright side, you not only have a better seating position, but you can replace your carpet and other bits now. :-)

    1. Thanks Dennis! I've actually been driving around for quite awhile since I performed this change and I have to say that I really like it. It's nice not to have to scrunch down to see below the windshield frame when I'm at a light. And you're right, it was an optimal time to update some... stuff. Stay tuned!

  5. Thanks for this post. I was just getting ready to cut my seat pans on my 67. Having gone through a previous iteration of mods from hell trying to fit BMW Recaros in a previous 67 vert, I didn't want to make the same mistakes, so I checked the hinge clearance, and found the problem BEFORE I started cutting. I searched VMF, and found nothing about lowering seat pans on a convertible, but found this post.

    Curious, if everything's still good a couple of years later? Anything you'd have done differently now?

    1. Hi gregseek1st,

      I'm still happy with the seat position. I'd like to do the passenger side because having one seat higher than the other is more noticeable than I thought it would be. However, tearing the interior apart again and cutting and welding don't appeal to me. I wish I would have done both sides at the same time. LOL!

  6. I am 6'5" I have my top seat riser out (doing tje frame and floor. I should probably do this mod...I am used crouching down to see traffic lights.