How to add 1" of headroom to your Miata - for free!

The basic trick is to cut an inch out of the seat-bottom foam - cheaper and less painful than having a vertebra removed, it makes the Miata cockpit alot friendlier to drivers over 6' tall.

First thing you have to do is remove the seat. The enthusiast's manual isn't terribly helpful on this point, except to point out that you more or less must use a 6 point socket, not a 12 to get the 14mm bolts out. They say something about the head being tapered, I think the problem is just that the bolts were torqued in at the factory to something like 90ft-lbs. Whatever the reason, if you do go ahead and use a 12 point socket, you'll likely round off the bolt heads, and still not get them out (BTDT).

When you get the seat out, you'll see why it's impossible to make a seat frame that sits lower than the stock seats - the bottom is actually set in-between the adjustment rails and actually scrapes the carpet. The only way to get a lower seating position is to remove some foam. It has been suggested on Miata.net that the seat might be bolted directly to the floor without the rails to get a lower position, but I think this would simply result in eliminating the suspension effect of the thin metal seat frame, gaining only about a half an inch in exchange for a spine-jarring ride.

If you're going to do this job, you'll need a pair of needle nose pliers and the patience to work with these hog rings. They're made of fairly stout wire, require a bit of twisting to get off, and I think I had to remove about 12 of them to get to the foam for cutting. Perfectionists should practice attitude adjustment before approaching the hog rings, you can get them back on securely with the pliers, but only 2 or 3 of the 12 will look like they did before you took them off.

I only removed the hog rings from 3 sides of the seat-bottom, then I was able to pull the seatcover back from the foam sufficiently to get at it for cutting.

I used a 9" fillet knife to cut into the seat foam, basically I was shooting to slope down about 1" across the length of the knife, the cutting was fairly easy after doing a "puncture" start. This left me with a few more inches of cut to make at the back of the seat - it was awkward to get the knife in there, so I reached in with my hand and pushed the foam apart with my fingers. This may not work if your seats haven't been baked in the Florida heat for 8 years, in which case, you should be able to get a knife in there. I did get too much foam on one side, but it was no trouble at all to cut a chunk from the removed piece and place it back in the seat frame.

So, how does it ride? Well, I can see out underneath my rollbar much better now, and it is a bit easier to see traffic lights under the windshield header too... nothing drastic, just like I was maybe 5'11" instead of 6'1". Comfort wise, it feels like I've put a 1" cushion under the front part of the seat - I do squish the seat a bit more than I used to when the clutch pedal is depressed, but otherwise it's comfy. I haven't gone on an extended trip yet, but for a 45 minute ride including lots of bumpy road, the missing foam wasn't missed.

Update October 10, 2000:
Well, the foam has been out for what seems like a year now - and the only thing strange about it is when I sit in the passenger seat, which still has the stock foam, I wonder where all the headroom went. Long trips are no problem, and in an autocross situation, the extra side bolster is a great thing.




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