Region: CFR
Car #: 81
Year : 1994 Posts: 86
Status: Offline
posted
I have run into a problem that I cannot see resolution for. Last weekend, I purchased the seat for my SM build along with the rest of the safety gear (helmet, etc). This weekend I wanted to get the seat in postion so that we could get the car to the cage builder after the holidays. But I realized today that I will not be able to drive this car with the hard top installed. I was having difficulty yesterday getting enough headroom (I couldnt put on the helmet in the car. So this afternoon I measured the interrior height of the car at 40 inches and had my wife to take a measurement of me sitting on the floor with the helmet on and I am 39 3/8 inches tall, so this leaves 5/8 of an inch for the seat under me and some head room. Can not see a way to make it work (if you have suggestions, I'm listening) . So having never seen a SM without a top, and understanding it to be a disadvantage it doesnt appear that my future is in SM. So what class could a miata without a hardtop be competitive? Then further are you aware of a website like this one for that class. Thanks for any and all advice & suggestions.
Region: OVR
Car #: 88
Year : 1991 Posts: 2401
Status: Offline
posted
Just curious, how tall are you? I'm 6'2" and fit OK. How are you mounting your seat. Some tall folks have removed the 'humps' from the floor and mount the seat directly on the floor.
[edit: I didn't see your other post when I wrote this. I don't know your size but I suppose it's possible to be too big for a Miata.]
Region: NWR / Oregon
Car #: 88
Year : 95 Posts: 2000
Status: Offline
posted
Greg, You'll probably need to tilt your seat back to get your head lower. When I had my cage built, the builder repositioned the rear bars that go from the main hoop back into the trunk so if necessary I could get my seat back as far as possible and tilted back to provide head clearance for really tall people if needed.
It's good to do the seat at the same time as the cage. You need to be able to reach the pedals, have room for your head, have room for your elbows and knees, and then there's the steering wheel. Each of those variables may complicate the other ones. I had my cage half installed with the seat on hand, test fit it before the final welding was done, then sat in the car and we decided how to move things and get it right.
I'm taking a short break from home repair and improvement projects but I'll try to dig up the thread where I have pics that show how my rear bars are positioned to allow the seat to be far back and tilted without hitting the seat later this evening.
-------------------- Keith Novak (Will work for tires)
Region: SF
Car #: 68
Year : 91 Posts: 186
Status: Offline
posted
Aluminum seats are only around 1/2 inch thick on the bottom. Remove the humps in back, leave the front cross and mount directly to the floor, you should fit. Topless Miata run EP but it's expensive and car counts are much lower.
Region: CFR
Car #: 81
Year : 1994 Posts: 86
Status: Offline
posted
Thanks for the responses, I have the front and rear humps removed from the car, the seat is flat on the floor, at this point my helmet is rubbing the roof. I am 6'3" so I am not at a height that others have not been able to make this work, but appears that my torso is longer than average. I really want to make this work, we have done most of the work to prep the car for competition, so there are substantial dollars invested. I will play with tilting the seat back, just as an aside, how much head room is acceptable?
Region: mid south
Car #: 2
Year : 1999 Posts: 4275
Status: Offline
posted
Greg the problem is seat is too upright. I too and 6'3 and fit fine. The front of my seat is elevated about 3.5 inches to get enough recline in order to have engough head room. Lots of shops in CFR that can help you if needed Jim
Region: CFR
Car #: 81
Year : 1994 Posts: 86
Status: Offline
posted
Thanks, I think my panic attack is over (or almost over). Paul, I am in Plant City. I have started to recline the seat, and things are getting much better, not where it needs to be just yet but closer. For the record the seat is a Sparco Pro ADV. I have removed the back bolts from the side mounts and let the back of the seat rest on the floor of the car and have the front bolts in the highest position. I still need some more room. So I think we will need to have custom mounts fabricated. I wil mock some up myself to see what we will need. Is there any point at which you have too much layback to the seat? What is considered a "safe or reasonable" amount of clearance above your helmet?
(I don't use this seat. I stuck it in to show how some seats don't fit a miata well and why.)
This one shows how the rear bars on my cage were set out a bit from center of where they typically go at the connection to the main hoop to give room for the seat.
Region: CFR
Car #: 81
Year : 1994 Posts: 86
Status: Offline
posted
Jim - Thanks for the tip, its out but wasnt too thick to begin with.
Keith thanks for the pictures and information.
I have found as I lean the seat back, the base moves forward which is fine, but where I thought I may need to extend the steering column to reach the wheel doesnt appear to be the case, as the incline increases the driving position feels better, almost like when I used to race sprint karts. Have flat bottom steering wheel so the knees appear to be ok. Just need mounts with more layback.
Region: CFR
Car #: 81
Year : 1994 Posts: 86
Status: Offline
posted
Paul,
Will do, I spoke to Mike about doing the cage this past summer. My progress on the car really got delayed over the past several months. I am intending to call him about doing the cage in January. Ultimately I am trying to get done in time for the drivers school at Daytona in April.
Region: WDCR
Car #: 04
Year : 1993 Posts: 519
Status: Offline
posted
I have the Sparco Pro ADV seat in my car. I am 6' tall and my son is 6'1". We both use the full cushion and have no clearance problem. I will try to take pics of the mounting tonight and post them but here is one of me in the seat.
-------------------- Lee Tilton 1993 Meowta #04 Brimtek Motorsports/ Team Four Racing Team Four Racing
Region: CFR
Car #: 81
Year : 1994 Posts: 86
Status: Offline
posted
Lee,
That would be very helpful. I stopped by Lowes at lunch today and purchased some thin plywood to mock up some side mounts with more layback than the set I have.
Region: WDCR
Car #: 04
Year : 1993 Posts: 519
Status: Offline
posted
Greg, here is the best picture I can get right now. The stock front seat mounting rail is still in place. The rear rail has been cut out. The mounting bracket is simply a piece of flat bar that has been welded to the front rail and the floor in the rear. There are two tabs that stick up for the bolts that go into steel threaded inserts in the seat. The front of the seat sits almost right on the front rail and the rear of the seat sits on the floor. If you have any questions about my poor description, just PM me.
-------------------- Lee Tilton 1993 Meowta #04 Brimtek Motorsports/ Team Four Racing Team Four Racing
Region: NWR / Oregon
Car #: 88
Year : 95 Posts: 2000
Status: Offline
posted
Since those mounts are steel, probably not a big deal but if I were to do it that way or especially if it were made out of aluminum, here's what I'd change...
I'd make the base of the tabs wider than at the top (more of a triangular tab than a rectangle). That gives a larger footprint to distribute the load where the tabs meet the rails. It also reduces the abrupt corners at the front and rear of each tab. Sharp corners greatly increase the stress in the area so the more gradual the transition, the less stress on the welds. Rule of thumb...radiused corners good. Sharp corners bad.
Not meant to be a criticism. Just my as a former designer and stress guy on sheet metal parts.
-------------------- Keith Novak (Will work for tires)
Region: WDCR
Car #: 04
Year : 1993 Posts: 519
Status: Offline
posted
quote:Originally posted by Keith in WA:
I'd make the base of the tabs wider than at the top (more of a triangular tab than a rectangle). That gives a larger footprint to distribute the load where the tabs meet the rails. It also reduces the abrupt corners at the front and rear of each tab. Sharp corners greatly increase the stress in the area so the more gradual the transition, the less stress on the welds. Rule of thumb...radiused corners good. Sharp corners bad.
Not meant to be a criticism. Just my as a former designer and stress guy on sheet metal parts.
Excellent points that I agree with. But since the seat was installed when I bought the car that's the way it will stay.
-------------------- Lee Tilton 1993 Meowta #04 Brimtek Motorsports/ Team Four Racing Team Four Racing
Region: NWR / Oregon
Car #: 88
Year : 95 Posts: 2000
Status: Offline
posted
I wouldn't either. Eyeballing it, it looks pretty stout. I'd guess 3/16 sheet. I'd trust that. It's stronger than the base mounted attachements on my all AL seat I'm pretty sure.
I don't actually get to design much anymore. I mostly critique other people's stuff these days so it's sort of fun to play the jr. engineer when I can.
-------------------- Keith Novak (Will work for tires)
Region: CFR
Car #: 81
Year : 1994 Posts: 86
Status: Offline
posted
I wanted to give an update on this post in case others may find this useful in the future. I have had an opportunity to work on leaning the seat back to gain some head room. But with the leaning of the seat it is causing other issues. To make this as useful as possible, I am 6'3", when seated I measure 27.5" to the top of my shoulders and 36.75" to the top of my head and have a 34" inseam. What I found was as the seat was reclined I did gain some headroom, but ended up with the front of the seat so high that I couldnt comfortably use my feet on the pedals (now I understand why the GCR allows pedal modifications). Further with the bottom cushion out of the seat, the seat is rather deep which kept my legs close togehter which contibuted to difficulting in using my feed on the pedals. Also as I leaned the seat back, I think I would have had the top of my helmet on the main hoop of the roll cage. For those with less torso height this would be a good choice for a seat. As for the seat itself, there is little if any layback in its contruction. I think if it had some layback, that it would work fine. I am still working with it some in hopes to make it work, but most likely will be looking for a seat with some amount of layback built into the seat. I will post some pictures when I get a chance, and if we find a way to make it work, I'll let you all know.
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. So having never seen a SM without a top, and understanding it to be a disadvantage it doesnt appear that my future is in SM. So what class could a miata without a hardtop be competitive? Then further are you aware of a website like this one for that class. Thanks for any and all advice & suggestions.
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as a former designer and stress guy on sheet metal parts.![[Smile]](smile.gif)
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