Modifying or Replacing Seats

From NSX-Wiki

[AW, CM] When removing the seats, it's a good idea to cover the console and sill with a blanket or towel, since it's easy to scratch things with the seat's mounting lugs.

The seat is quite easy to remove: four 14 mm-head bolts at each corner, and one 17 mm-head bolt attaching the shoulder strap. Unplug one electrical connector and lift the seat out of the car. Pretty neat. Bad news is that there's no real info in the shop manual other than how to remove the thing. No disassembly, etc.

[BRH] Sorry for the delay in this post, I was able to solve my headroom problems on the track by installing Sparco Pro 2000 racing seats. I had them mounted on flat brackets so they sit flush to the floor and with the seat cushions removed I gain about 4 inches of headroom. The problem with this setup is that while the seats work great on the track they are IMO not comfortable enough for everyday use. Approximate cost per seat was $550 plus the cost of getting the bracket fabricated....the work was done by Mike Busalacchi at T.A.D.Motorsports, (847)550-8116.

[AW] I just spoke to Mike at T.A.D. who indicated that he would sell additional brackets for approximately $100 each. Mike quite reasonably may want purchasers to assure him that they will use this setup off-road only, etc., as one would expect with any track-related or competition equipment.

As I understand Bryan Hunter's installation, the seat position is fixed by its mounting bolts, although of course you can have several mounting hole positions if, for instance, you need to change drivers.

I will be looking into mounting a seat like this but with slider brackets so that they are adjustable in real time. Mike suspects a 1" seat height increase from doing this, which would still net a 3" improvement in seat height, which is a huge improvement.

Making the Seat Bottom Removable

This procedure is documented in the manual and one of the service bulletins. It easy and takes about 1/2 hour. A couple people have asked me to describe the process, so here goes.

Remove the Driver's Seat:

• You probably want the seat-back all the way forward (vertical) for this.
• Move seat forward all the way.
• Pry up the two ~1" circular black plastic bolt covers w/ screwdriver, and remove two bolts at each rear corner.
• Move seat rearward all the way.
• Remove two bolts at each front corner (axis is about 30 degrees down from horizontal).
• Watch out for the worm screws that run along under each side of the seat. They're covered in black grease.
• Tilt seat toward center of car, exposing underside.
• Free harness from white plastic clip (pry apart with small screwdriver) and unplug wiring harness.
• Pry out cover over seat/shoulder belt bolt; remove bolt.
• Carefully remove seat from car. Towels covering the threshold are a good idea.

Remove the Seat Bottom:

• Invert seat on a clean surface (e.g. cardboard).
• Unclip seat back upholstery from seat back by pulling down on long white clip. Alternative: cut the hooks off the clip, since it will probably break anyway (and there's a service bulletin on this problem that replaces them with some removable $2 black plastic rivets after drilling four holes).
• Unclip seat bottom from now-exposed lip of seat pan. This may take some levering.
• At front of seat remove four black "rivets" holding "tongue" of bottom upholstery to pan. They may break; don't worry they cost about $2 ea. and aren't really needed anyway.
• Turn seat upright.
• Pull seat bottom foam up and away from pan, and where it is glued across the pan in three places cut it away from aluminum pan with an Xacto knife or razor or other sharp knife right at the surface. You will be cutting just the very bottom surface of the foam (~1/32") so you're not doing any damage here). An alternative *may* be to dissolve the glue with acetone, but I don't know if that's damaging to the foam.
• At this point the seat bottom is held to the pan only by two gray plastic clips. The manual says to cut these, but you can also squeeze them with needle-nose pliers from the bottom and they will pop out of the seat pan.

You're done (except for reassembly).

What I did at this point is glue Velcro onto the areas where the foam had been glued to the seat pan (don't bother trying the sticky-back Velcro, it won't stick to the foam for long), figuring that it's a good thing not to have the foam sliding even minutely around against the pan. I did NOT reinstall the gray clips, since to uninstall them requires removing the seat which defeats the whole purpose of the project.

I leave the rear seat back upholstery unattached, although you can follow the related service bulletin by drilling four holes in the wide plastic clip and inserting four of the $2 removable rivets mentioned in the SB.

On advantage of leaving it unnattached is that if you have the Comptech or similar 6-point restraint system you can route the anti-sub belt through the resulting opening, which gives the anti-sub strap a much straighter shot at your...uhhh..... body. Otherwise it has to go around the seat bolsters.

The front upholstery tongue you can just tuck up into the seat bottom upholstery, or if you're a perfectionist use another four of the $2 removable rivets from the seat-back SB. However, this just makes it a little more tedious to remove the seat bottom on race morning.

To reinstall the stock seat bottom simply slide it well back into the seat pan and reach around from the back to clip it's plastic clip onto the rear edge of the seat pan. The whole idea is to do this with the seat in the car at which time you will not be able to see any of this, so you may want to practice a bit before reinstalling the seat itself.

Seat Reinstallation:

• Put it back in the car, tilted toward the center.
• Reconnect harness, and fasten harness into its white retaining clip.
• Apply Loctite to the seatbelt bolt and install, torquing to the specified figure.
• Snap in seat belt bolt cover plug.
• Position the seat down on its four mounting points. You may want to apply some anti-seize to the four mounting bolts; I had one gall on the way out, and had to chase the threads in the captured nut. Replacing that nut would not be a pretty sight.
• Install two front bolts finger tight (don't torque yet until rear bolts are started).
• Slide seat forward
• Install two rear bolts and torque to correct figure.
• Snap in bolt cover plugs
• Slide seat rearward.
• Torque two front bolts to correct figure.

The main way to come to grief in this project is to drag the seat frame over the door threshold pieces and scratch them up, or perhaps the console, steering wheel, etc.. So therefore, if you are careful and protect those pieces you're at no particular risk.

The 16" x 18' x 1" "Backsaver Energy Absorbing Comfort Pad" is available from Pegasus Racing at 800-688-6946 for $56.59 and is highly  recommended by me as a track-use substitute for the seat bottom. It's a ~1" thick pad that drops right into the aluminum seat pan. I've driven for 100+ miles and been perfectly comfortable. It's a "drop-in" fix.