My quest for more headroom - custom moulded seat cushion

[Geraint]

Now then.

I’ve owned my NSX for a couple of months now and just haven’t been able to get comfortable in it.

I’m quite a big fella (6’4” and about 16st), not ‘all legs’ and so headroom has been a real issue for me. It seemed OK on the test drive but I suppose I was excited about the car and busy trying to assess its condition, so it didn’t really hit me as a problem.

However on the long-ish drive home, and then on another couple of long trips in it (3 hours or so) I found that my head was very close to the roof, and I was tensing my shoulders to pull my head downwards away from the roof. Not good.

I could adjust the seat to make it a bit better, but this resulted in bizarre positions with bent/splayed legs, weird body angles and extended arms. Not really ideal for enjoying the car.

I looked at various options, including the Dali seat cushion, a pair of Recaro PPs, the Downforce seats, the SOS rails etc, but they all seemed less than ideal and/or very expensive.

As part of my research, I tried the standard seat without the cushion, and found that it transformed the seating position for me. One friend suggested a moulded custom cushion (like they use in single seaters), another offered an old camping foam mat, and soon a plan was formed.

The plan was to create a moulded seat base to replace the OEM item using two-pack expanding foam, tidy it up and then get it trimmed in black leather to match the rest of the interior.

The moulding is done by mixing two liquids together, putting the mixture into a bin liner and then sitting on it while it moulds and then sets.

With the OEM cushion already removed, I taped around the edges to stop the mould finding its way into the crevices under the side bolsters:



Then protected the interior with polythene sheet, again taped to stop it moving around



Bin liner in place, to check it was big enough to contain the foam



Two-pack foam ready for mixing

[Geraint]

Mixing the foam using an old milk carton. Need to ensure thorough mixing but not a lot of time to mess about, as it starts reacting quite quickly...



Mixture placed in bin liner, ensure a thin layer was spread across the floor of the seat, then driver installed. I wore some winter cycling leggings to give a bit of padding without the seams/pockets etc that come with normal trousers, that might affect the shape of the mould.

The moulding process itself takes about 20 minutes, you feel the foam reacting, warming up and expanding, quite an odd feeling but not unpleasant. Need to sit still in driving position while it moulds and then sets.



Result of moulding process:



Removed from car:

[Geraint]

Re-positioned:



You can see from the above pic that the foam is very thin in some places, this is where there was a lot of pressure between the tops of my legs and the raised parts of the seat. I did some smaller secondary moulds, using the original foam, a bin liner and a smaller amount of mixture, then reinforced the thinner parts with some fibreglass as shown in the next pic



Then trimmed the moulded part down and tidied it up. The foam sets quite hard, it’s very much like that domestic foam filler you can buy in aerosol cans for filling holes in walls etc. I decided to give it a layer of softer foam from the camping mat I mentioned earlier, just cut roughly to size, affixed using spray glue, then trimmed to fit.

The result

[Geraint]

Comparison with the OEM seat cushion, showing the difference in height

[Geraint]

Then had it trimmed in leather at a local place, this took a while but the place was busy, I wasn’t in a rush and I wanted a nice job. The face is very nice leather, in my opinion nicer than the OEM stuff, and the sides are vinyl.






Fitted to the car:





I’m delighted with the results, it’s a nice custom job, something a bit different, keeps the interior mostly OEM and worked out cheaper than any of the other options I looked at.

Hope this is useful for anyone else in the same boat as I was.

I’ll be at Japfest, anyone who would like a closer look at it will be more than welcome

Contacts
Foam: Merlin Motorsport, Castle Combe www.merlinmotorsport.co.uk
Trimming: Krych Trimming, Bristol www.krychtrimming.co.uk

[Nick Graves]

Nice job!

Let us know how ergonomic it is on a longer journey.

I know it's missing the obvious, but I find the idea of someone being too tall for a -T intrinsically funny. I had a friend of similar height who could only properly drive his FIAT nuova 500 with the sunroof open.

[Geraint]

Thanks

Yeah I see your point about headroom in a targa - having tried a S2k I think I'd have to leave the top down all the time

The problem is that my head isn't under the targa panel, it's under the hoop, so removing the panel doesn't help

[Ewan]

Some lanky bugger trying out my -T for size ...

[nobby]

good job, hope it works out for you on those longer journeys

[SILVER BULLET]

Brilliant solution to your problem Geraint and looks very professional , not something that's troubled me being 5'-6".

Cheers,

Ian