Lowered seat pan - a few notes

I’m writing this post to offer a wee bit of info for anyone ordering a pan-based speedster who is considering an option to have the seat pans lowered.  This is based on my limited experience only, so emphasis on wee.  Like wee wee.  Feel free to add or critique, anything that helps future searchers learn something about this topic is a welcome addition.

Why lowered seat pans?  For a taller person, the primary benefit is to provide more room beneath the steering wheel, and to place your head, and eyeballs and eardrums, a bit lower while seated.  

I am 6’ tall, my torso is a touch long, and because of issues with my lower spine I tend to sit tall in just about any seat.  When I was getting serious about buying a speedster, I had the good future of test driving two speedsters owned by SOC members.  In both instances, the effort to enter and exit was a bit more difficult than I would like while negotiating around the steering wheel, although by itself this was not a deal breaker.  I was a little more concerned about free movement of my legs while driving (safety) and the need to splay my legs outward a bit to avoid the steering wheel (comfort).  I realized that a relatively short test drive wasn’t enough time to let me become accustomed this new experience, but I decided more room would be welcomed.  (And yes I realized a tube-framed build from IM or Beck might be another way to solve the issue, but price, availability and registration in California complicated those choices for me).  When seated in both speedsters my eyeballs were about even with the top frame of the windshield which was a bit annoying - I  found myself scrunching down to see beneath the frame or raising my head to see over.  This tall position also placed my ears and hat closer to wind turbulence, and the top portions of the dash gauges were obscured by the steering wheel.  I could probably live with any of these inconveniences, but I wondered if all together they would be enough to reduce my overall joy of speedster ownership.

I then had the pleasure of sitting in and briefly driving a VMC speedster that was built with the lowered seat pan option by someone who is 6’ 3”.  I immediately liked it.  Entry and exit was much easier, I was looking through the windshield, and I could see the gages.  So when I ordered my VMC speedster I asked for the lowered seat pan modification (which Greg describes as a 1” change).  I also stuck with the standard steering wheel option, and not the larger diameter banjo wheel.

Eleven  months later I am happy to report I very much like what the lowered seat pans did for me.  Entry and exit is clearly much easier.  My leg position while driving is much better (foot/toe room is still not ideal but not much can be done about that aside from proper driving shoes).  The horizon is comfortably below the windshield frame even when sitting upright.  All good stuff for me.  I would even say the benefit seemed to be more than just 1” of gain for some reason, and a bit more than I needed.

The downside?  I can think of three; reduced ground clearance, seated position may be too low for passengers or guest drivers (my wife sits so low she has second thoughts about driving this car - not sure yet if that is a plus or minus), and maybe resale value (which is something I hope I won’t care about for many years, and who knows it could turn out to be a plus).  A forth possible negative is that a lowered seat pan may limit the ability to lower the overall stance of the car - the combination of a lowered seat pan and lowered ride height might reduce ground clearance directly under your rumpus a bit too much.  Ok I came back to edit and add a fifth possible downside.  The floor of the cabin just forward of the seats is scooped out a bit.  This may complicate fitment of floor mats as they will need to negotiate a central valley just in front of the seats.  I’m facing this issue now, so I may add to this post later if I come up with a solution.

Here is a photo showing the approximate ground clearance of my as-built speedster.  I’m holding the tape measure beneath a bolt that secures a seat rail, this one being on the outboard passenger seat rail at the aft end of the rail.  The aft seat rail bolts were worst case (lowest to ground) as compared to the forward seat rail bolts and seat belt anchor bolts.  

I seemed to have lost my 6” scale, so excuse the tape measure.  It measures a short 5-1/2”, and this is with the rear tires on my Marty G rug, so actual clearance is probably close 5-1/4” or a tad less.  I have no idea how this compares to other speedsters or coupes, but I assume this represents about a 1” reduced clearance compared to what I would have enjoyed without the lowered seat pans.  That is a big decrease if expressed as a percentage.

Side story next, my effort to regain a little ground clearance.

Seeing the bolts extend three or four threads beyond the nut made me think I could regain a touch of ground clearance be either using slightly shorter bolts, or by reversing the bolt so the bolt head was on the bottom (if there was enough room for the nut).  I abandoned the bolt reverse option after finding that this bolt, a carriage bolt, was staked (pressed?) into the fixed seat rail and would take more efforts than I was prepared to give to remove it, let alone shorten it and reverse it.  The next photo shows the staked carriage bolt - this bolt is captured, and to removed it the staked tabs would need to be cut off.  (The tabs as I call them didn’t appear to be a separate piece, but I could be wrong)

I decided that the amount the seats had been lowered in my car was actually more than I needed, so I added some thick fender washers (in addition to the washers already installed by VMC) between the fixed seat rail and carpet to raise the rails, which raises the bolts and effectively makes the bolts sit flush with the lower edge of the nut on the bottom of the car.  I now sit about 1/4” taller while seated and have gained about 1/4” of ground clearance.  This didn’t really accomplish much, but I thought it was worth a few hours of effort and it was an acceptable trade-off for me, and allows my wife to sit taller as well. The nuts are fully threaded onto the bolt, the nylon locking bit in the nut is mostly if not fully threaded.  This gives me full strength even though no threads extend beyond the nut.  In my opinion the strength of this connection is not as important as the seat belt anchors, as long as the nuts don’t loosen.  I’ve marked my speedster calendar to regularly check snugness of the nuts on the underside.  By the way, I reversed the seat belt anchor nuts so the head of the bolt is on the bottom, and the nut is in the cabin - this provides the same strength but is perhaps a bit more unsightly in the cabin, if anyone made the effort to look.

Here is an after photo.  I’ve added some notations to help better identify how the seat pan is modified for anyone curious about this.  It looks to me that the seat area is cut on three sides of a rectangle, the forward bit left intact.  The resultant diving board is then pushed downward, more so at the aft end by about 1”.  New sheet metal is welded in place around the perimeter to support the lowered pan, kind of like a paint roller tray.  The seat rails are attached to this lowered section.  Seats still have free movement forward and back.

That’s about it, but because I took a bunch of photos I’ll throw in a few to round out the story.  I realize this info is already known by the majority of members, but for newbies like me, I’ve found basic information like this very helpful. I guess I’m feeling a need to try and give back.

How to remove a speedster seat:

1. If you have heated seats, disconnect the electrical connectors that should be sitting beside or behind the seat.

2. Grab and lift the seat cushion at the back edge.  It will remain attached at the front (at least mine did), and if you have heated seats there will be a wire running from the back to the seat cushion, you may need to feed the cable to allow the cushion to be raised.

3. The four bolts that secure the seat to the sliding seat rail are now revealed.  Remove the nuts.  

4. Lift the seat off of the bolts.  This may need a bit of finagling, and it may be helpful to remove the washers that were under the nuts first (just remember to use them upon reassembly).

This reveals the seat rail assembly.  Notice each bolt has a washer that was under the seat.

Here is a photo showing the end of the lower fixed rail.  This was mine as-built (three washers under the front, one washer under the rear bolt).  I placed additional thick fender washers ( ~1/4”) beneath the rails at each corner.  This is what raised my seats canceling a bit of benefit of the lowered seat pan (yep I did that), but also raised the carriage bolts to slightly improve ground clearance.

One more thing, this was mother-in-law approved, even though she could barely see over the dash.