Grassroots Motorsports

Register Log in to GRM
- Community

Birthdays
Recently on the Classic Motorsports forums

Subscribe get a full year for only $23.95 Sample Free Test Drive—no strings attached

Login to post Forums » Grassroots Motorsports » Miata seat modification

Dec. 29, 2010 10:10 p.m. Lugnut HalfDork

Ok, standard disclaimer here - this is just a thought exercise and if it is unsafe or just plain stupid just tell me nicely.

I know that a dedicated, one-piece racing seat is the ideal choice for safety. More and more track day organizers are saying no more harnesses around the seat backs. They seem to be accepting of passing through a passthrough, such as with this RX7 seat:

Or the Swift GT seat:

The Miata, on the other hand has no opening in the seatback. Is it possible to modify the seat by opening a hole in the seatback for belts? Perhaps welding in a guide bar going across the seatback if there is nothing suitable already there? Basically, is it feasible to modify the Miata seatback to resemble that RX7 seatback so that shoulder harness could pass through?
Dec. 29, 2010 10:23 p.m. peter New Reader

I dunno what size you are, but at 6', the cutouts for shoulder belts in my Miata seats would have to be basically in the headrest. I don't think you could get the required horizontal separation for the shoulder belts there, even if it were acceptable to cut the seat.

Frankly, this is safety gear we're talking about. Not somewhere I'd like to get caught skimping. There's a correct way to use a harness, and this is not it.

I lucked into a set of race buckets that were in good condition, but past their certification date. Since racers can't use them, they were cheap. That's a safety/price tradeoff I'm willing to make.
Dec. 30, 2010 7:40 a.m. DeadSkunk HalfDork

The Miata seat back has the frame encapsulated in the foam, so cutting away the foam and welding the frame might result in a fire. You might try finding a set of the 1995 (I think) M editon seats with the seperate headrest.
Dec. 30, 2010 8:53 a.m. mw HalfDork

I think it would be easier and end up with a nicer outcome if you modified other seats to fit in the miata rather than modify the miata seats. But in reality, I would just find a cheap race seat and bolt it in for track days.
Dec. 30, 2010 12:26 p.m. mtn SuperDork

Might want to talk to Willy(numbers) on this board. He is in Racine and probably has a Miata seat that could be used as a donor to try it out on.

I think that I'd just be on the lookout for a cheap racing seat though.
Dec. 30, 2010 4:52 p.m. Woody SuperDork

'95 M edition seats:
Dec. 30, 2010 4:57 p.m. Woody SuperDork

Or, look here:

http://grassrootsmotorsports.com/forum/200x-classifieds/free-na-miata-seat-dayton-...
Dec. 30, 2010 4:59 p.m. Keith SuperDork

The NA seats (other than that 95M) have a cavity for headrest speakers. I've seen at least one car where those were turned into pass-throughs for harnesses. Never tried it myself, but it can be done without messing with the frame.
Dec. 30, 2010 5:25 p.m. mrhappy Reader

MX-3 seats?
Dec. 30, 2010 9:08 p.m. fastmiata Reader

95 M seats are too flat in the butt to work
Dec. 31, 2010 8:19 a.m. skrzastek Reader

peter wrote:

Frankly, this is safety gear we're talking about. Not somewhere I'd like to get caught skimping. There's a correct way to use a harness, and this is not it.

Using a factory seat is unacceptable with a harness and dangerous. Don't use just a portion of safety equipment, use all or go back to the oem belts. In a hard impact the oem seats will buckle leaving your body to absorb the impact instead of the safety equipment. It's only your life you are trying to protect
Dec. 31, 2010 12:10 p.m. Woody SuperDork

fastmiata wrote:

95 M seats are too flat in the butt to work
Dec. 31, 2010 3:13 p.m. modernbeat HalfDork

fastmiata wrote:

95 M seats are too flat in the butt to work

They use the exact same bottom as all the other 90-97 Miata seats.

You'll need to log in to post.