Back in April of 2017, I wrote an article that had to do with adding lumbar support to the seats, and it touched on lunchbox660’s idea of unfastening the support mesh on the seat bottom, to lower the seat height a little more for extra-tall passengers/drivers.
Because of the seat heater panel and the configuration of the weight sensor for the passenger air-bag switch, another 124 Spider forum reader, carpasio, posed the question today, wondering how to raise the passenger seat height, so that his 5′ wife could experience normal viewing out the windows, without having to use a seat cushion, which he stated, worked against both of the mentioned items.
Just to reiterate, the seats in the ND Miata and our 124 Spiders, have no springs and foam like previous generation Miata (NA, NB, and NC) seats did, so all of the comfort and support in both the seat bottom and seat back is attributed to the combination of the outer covering and the tight mesh panels fastened along both sides of the frame underneath that covering. Likewise, they have no means for adjusting height, other than sliding forward on the inclined track, which probably only results in the rear portion of the seat gaining no more than an 1″ of height, if that.
In addition to extending his pedals, David Paul resolved this issue as a driver back in 2016, by raising the rear of his seat rails some 2½” (getting rid of the incline, as shown in the second and third photos below), by using longer hardened bolts (metric, 10 x 1.25, 70 mm long, zinc-plated Class 10.9 steel, 2 per seat) with a stack of fender washers between the floor and seat rails. He originally used nuts (appears to be about 1½” worth), rather than fender washers when the photos ⇓ were taken, but realized that the washers:
- are much easier (no need to thread the bolt through them all)
- provide a little more stability
- allow more flexibility in the amount of incremental height change
- are much easier again, if readjusting height
He further stated:
This effectively allowed me to move the seat all the way back as far as it will
go, without having the seat dropping in height, also allowing less pressure on the back of the thighs that the seat can cause.
This is a semi-permanent change that, although easily reversible, once the passenger seat has been raised, 6’+ tall passengers may not “fit” in the car, especially when the convertible top is closed (likewise, if the driver’s seat has been raised).
MGSF has an additional tip for those with the Miata RF, that probably isn’t applicable to the GT hardtop, but I’m addending it to the article anyways:
On the RF, raising the rear of the seat rails more than about 1½” (I did all the work with the top retracted) caused contact between the top of the seat back and the closed hardtop. If using stacked washers for spacers I suggest wrapping the washers in tape so they can be installed as a unit and won’t slide around during placement.