I'm getting ready to do a seat base foamectomy on a Miata seat. I'd done the seat back pad removal before, but this is my first attempt at lowering the base. I've found a bunch of threads, but no decent photos.
Is the plan basically to just cut off the bump that sits down into the indentation of the pan?
I've also heard that there is metal reinforcement in some areas of the foam. Is that accurate?
These are 95M seats, so I want to get it right.
I found that if I just cut off the bump my butt sat in the hole and made my knees stick up. It also caused my wife's lower back to contact the metal bar at the base of the seat back. I put the bump back and haven't messed with it since. If I did it again I would just cut an inch or so off of the entire seat bottom center. The only metal I remember in the foam was a rod on each side aiming front to back in the grooves to give the fabric something to clamp down to. The low back hitting the bar could probably be remedied by the lumbar lump some people make out of a towel or some other item after removing the back pad.
MrJoshua wrote: If I did it again I would just cut an inch or so off of the entire seat bottom center.
Do you mean that you would make two cuts, taking an inch out of the middle and leaving the original top and bottom sections in place?
I know so many people do that ectomy. and there are a lot of people that swear lowering the cg is worth it. but every car that ever comes in here that this has been done to, is just so out right un comfortable to me. (yes Im a big boy) and the seats always look like baggy cloths on a person that has lost a ton of weight. Is there any where around you that you can put your hands on a crappy miata seat to try ahead of time before boogering up your M? We toss crappy ones all the time, if you were close I would let you have one (I HATE shipping seats ;) )
I've been told that the bottom foam is the same for the M seat. Any interest in shipping just a piece of foam?
Woody, where this guy took an angled section out of the back half of the top of the seat base as shown in these pics:
I would just take an horizontal slice off of the base between the bolsters so the entire center is an inch or so lower. The pics should give you an idea of what you are going to encounter and what you think would work best.
BTW-the linked page is the first person I have seen do it that way. Back when I did mine it sounded like most people either cut out the bump on the bottom or carved out the top.
They don't have to look saggy, it all depends on how much foam you remove. Personally, I do it in multiple stages and sit in the seat between each one. You can always put some of the foam back in if you go too far, but it's easier to start off conservatively. I end up with a seat that fits me perfectly, although nobody's complained about how we did Elvis' seats. Note the sculpting to the back as well. It turned these fairly flat stock seats into ones with much more lateral support. I do tend to take the foam out of the bottom of the seat base and not the top, but rarely do I pull the whole "bump" off the bottom.
If you are wide in the lats or gut you will feel the frame in the seat back when you remove the base foam and have already removed the back pad. Slouch in your seat first and drive around a bit to see whether the frame bothers you.
It kind of makes sense to me to leave the top and bottom surfaces alone and just section the middle, or even pie cut the middle, taking little or none from the front and more from the rear.
Just a warning, I have a comically small steering wheel and removing the bump almost made my knees hit the wheel.
Woody, If you do this, could you take a LOT of pictures? I see myself getting a miata in the near future (this might be a pipedream, but I really hope not), and will need to be doing the same.
Willy, if I do win in this pipedream, I'll have to look into taking you up on your offer (30 mins from Racine)
It's not really that hard. Just do a bit at a time, then sit in the seat to see how it fits you. I often doodle on the seat with a Sharpie so I know where to cut.
When I did mine (cloth NA), I used an electric carving knife to take a wedge out like the one MrJoshua posted. To avoid the saggy seat bottom, I replaced the higher density foam I took out with some resilient lighter density stuffing. When I sit on it, I sink to the bottom of the lighter density stuff to where I carved out. When I get out of the car, the stuffing fills the seat back up. My passenger seat is untouched and you cannot tell I did anything to the drivers seat looking at them side-by-side.
I don't cut the bottom off, I carve the top part off to the shape I want taking small areas off at a time with testing in-between. Sorry I don't have any pictures. In the end you get a custom made seat that has a fit that you want. I find they are a lot less bouncy and the car rides better for it.
Basically I use an electric knife and cut the basic shape, then I use a modified electric knife blade (bent the way I want) and scrape it across like you are shredding it. It takes off small amounts at a time and shapes it fairly smooth. It makes a mess but this is the best way I've found to get the shape I want. It's a vast improvement over the stock seat.
In reply to mtn:
Normal Il? as in Bloomington Normal? bah your 2 hours at least ;) Stayed at the chalet 2 weeks ago when I went to St Louis to get a car, just needed Rest, a drink, a steak, and a private john. decided not to make it all the way home ;)
If you want to reshape the top surface, it can be done with a pneumatic body sander (a light one) and a 4" sanding disc.You can sand polyurethane foam to any contour you want with a little practice. That's how prototypes and repairs are done in the industry.
Warren
willy19592 wrote: In reply to mtn: Normal Il? as in Bloomington Normal? bah your 2 hours at least ;) Stayed at the chalet 2 weeks ago when I went to St Louis to get a car, just needed Rest, a drink, a steak, and a private john. decided not to make it all the way home ;)
Normal Il, as in Bloomington Normal, as in Illinois State University. Home is Libertyville.
DeadSkunk wrote: If you want to reshape the top surface, it can be done with a pneumatic body sander (a light one) and a 4" sanding disc.You can sand polyurethane foam to any contour you want with a little practice. That's how prototypes and repairs are done in the industry. Warren
Great suggestion! I don't have a pneumatic sander, but maybe I can (carefully) use my favorite tool: The angle grinder with a flapdisc.
My only concern with the grinder/sander would be that your mistakes are irreversible.
Woody, do it someplace where the dust won't matter. there'll be lots of it.
DeadSkunk wrote: Woody, do it someplace where the dust won't matter. there'll be lots of it.
Oooh....another good tip. Thanks.
Anybody have pictures of a finished seat?
How's this?
Thanks Woody!
Great photos. I'll have to save this thread for later!
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