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Finally had tech tell me my helmet is way to close to like the whole car. And my co driver well he "fits" head lean and top out, not smart we know. Just figured id start a thread for anyone else curious on the matter. or for anyone else who has done it drop your pics and input. Ill be starting on this in a week or so so stay tuned
Hit up the Race car tech forum area and also the build and discussion threads for first gens. I know some have done this before, just don't remember where I read it.
I didn't have to cut into the floor to fit my seat and clear the roll cage. However this is a common modification in Miatas and JPM (https://www.jesseprathermotorsports.com/) has or installs a kit to do this. My seat is an aluminum Kirkey Road Race Intermediate so the seat bottom is thinner than some of the composite seats that are available.
Before you cut the floor look for ways to move the seat closer to the floor without cutting into the OE structure. This may mean that you have to take your seat off of a slider or lower it on the mounts that you are using now. In my car, I added rectangular structure to the tunnel, the rocker and seat sets inside this structure, much lower than the OE location. I also connected the structure side to side behind the seat and I did not modify the OE box section that is in front of the seat.
If you do change the floor pan, keep in mind that what ever you add needs to approximate the multiple plane structure that Mazda used. In other words, adding a completely flat replacement floor pan to lower you seat will not properly secure the seat bottom in a crash. This could allow the seat to move more than it should.
Saw this first hand when a driver backed an RX7 with a modified floor pan into a wall. The result was that the driver's head contacted the roll cage and sent him to the hospital with a brain bleed. So don't FAFO with this kind of a modification.
Hit up the Race car tech forum area and also the build and discussion threads for first gens. I know some have done this before, just don't remember where I read it.
i found a few posts but either due to age or just lack of input or not following through. Knowledge seams sparce. I was going to post this there but the race tech just doesn't get the views from most.
Originally Posted by mustanghammer
I didn't have to cut into the floor to fit my seat and clear the roll cage. However this is a common modification in Miatas and JPM (https://www.jesseprathermotorsports.com/) has or installs a kit to do this. My seat is an aluminum Kirkey Road Race Intermediate so the seat bottom is thinner than some of the composite seats that are available.
Before you cut the floor look for ways to move the seat closer to the floor without cutting into the OE structure. This may mean that you have to take your seat off of a slider or lower it on the mounts that you are using now. In my car, I added rectangular structure to the tunnel, the rocker and seat sets inside this structure, much lower than the OE location. I also connected the structure side to side behind the seat and I did not modify the OE box section that is in front of the seat.
If you do change the floor pan, keep in mind that what ever you add needs to approximate the multiple plane structure that Mazda used. In other words, adding a completely flat replacement floor pan to lower you seat will not properly secure the seat bottom in a crash. This could allow the seat to move more than it should.
Saw this first hand when a driver backed an RX7 with a modified floor pan into a wall. The result was that the driver's head contacted the roll cage and sent him to the hospital with a brain bleed. So don't FAFO with this kind of a modification.
My seat is located inside of this structure.
Fortunately or unfortunately i won a composite fia seat at a banquet. And i have tried multiple ways for it and even the stock seat to fit me just right and maintain distance. No sliders, a really low profile seat bracket. And just cant get the balance of comfortable driver position vs requirements.
Ive been looking on the web and almost every drop pan is miata related. But I will send out a email to jpm as his site has never came up.
Under research id agree with you on dont just do a flat peice of steel. I have planned a drop that re included the factory " frame rail" and flanged u chanel to reinforce the structure. With a design that wasn't a 90° vertical on any side, Instead opt for a 45° downward. Re include a horizontal u for the seat to mount on like oe in the front. And the same for the rear mount.
Ill fire up the pc and do some cad work with the idea. And post pictures. I probably have every post about your car bookmarked and use it all for reference on my car. Your input is very welcome and anyone else with the experience.
Even before drop pans came about in Miatas, we would drill out the rear seat mounts and mount the seat to the floor using the typical L shaped, generic seat mounts. Some would cut out the front seat mount sill and the smart ones would reinforce the floor with some angle or square tube to add back some strength.
Eventually, a drop pan was allowed and many of us did it for the added safety of getting your head away from the roll cage bars. I believe JPM uses the drop pan from East STreet Racing: https://www.eaststreetracing.com/col...oor-drop-panel
You can probably find install pics on mazdaracers.com
All that said about the approach in Miatas, I don't know how much of that is actually useful in a FB or SA given the goofy, not-flat shape of the floor pan. You might need to cut out all the stock seat mounts and make your own. Or cut the floor and make it flat (with or without a drop) and reinforce it.
I definitely recommend doing it for safety. I had a bad wreck once that resulted in a concusion that had me out of work for 9 months and had me fearing for my ability to return to a normal life for a while. Did the drop pan once I recovered.
Last edited by gracer7-rx7; Oct 13, 2025 at 04:56 PM.
That pan is the one ive been considering from the start of this idea in June. But cutting it up to fit doesn't sit right. " i have no idea if i would or not" just a guess. But after looking at alot of different pans im certain i can pull off the job. I mean what else to do with a full sheet of 18ga. Mabey a tad undersized but will be braced back.
I don't know what gauge metal East Street uses but it is definitely thicker than the stock sheet metal on the floor board. Beefy.
Advanced Autosports also has an option: https://www.advanced-autosports.com/...ata-floor-drop
Apparently, they use 16 gauge / 060. Rules seem to specify at least that thickness if I'm reading their product description correctly.
Definitely harder to do this on a first gen RX7 than a Miata. since the existing floor has so many transitions. The side-to-side cuts were made at the seam laps of the stiffeners...more materiel to support the pan and weld to. I made the first piece out of cardboard, the next piece out of lighter gauge sheet-metal that my brake could bend. I hand to send out the final version to a shop that had a commercial brake with proper 'fingers' to get it done right. As you can see, I kept but trimmed the rail vs. scabbing on channel stock like the Miata kits. I felt this would be stronger (but more work).
As I posted elsewhere, this is a fair amount of work. Cutting out the floor was the easy part. I was already cutting the tranny tunnel for the EMCO dogbox tranny so figured I would do this at the same time. I watched the Youtube videos for the Miata kits and thought it would be pretty easy. Found out that there was a bit more involved with our chassis. That said, it was totally worth it. I am very happy with the seat position and you can see daylight above my helmet in pictures on track. I would also recommend modifying your steering column(offset to right). After dropping and moving my seat, I felt it was quit necessary.
Finally got the garage cleaned up from all my other summer activities and got the car in. I knew the car was rusty but after pulling the carpet and sound det on the driver's side I find this.
i should have known really. Last year I did the rear arches and the famous inner wheel well rust repair.
So i did the same for the passenger side ie removed the sound det and its way worse. Rust is moving up towards the seat belt mount hole. While it may be small, now its a matter of preventing + the added benefit of lowering the seat.
Im glad I had it on the winter list. But i need some serious heat management from the exhaust.
I also see what everyone is talking about, with the uneven floor. It goes just about every direction but flat.
Looking your image, I see you do not have a roll cage or roll bar. I would check rules or ask around if this mod is permitted without some other chassis stiffening. Even if it is allowed, you may want to confer with someone who understands the type of loads generated from competition driving and whether a stock chassis like ours can handle that much material removal. If not a daily driver, maybe a good time to consider at least a roll bar.
I use DEI Floor and Tunnel Shield under the transmission tunnel to keep the heat out of the cabin. Works very well.
And id say its reasonably priced, thank you for the tip!
Originally Posted by kurtf
Looking your image, I see you do not have a roll cage or roll bar. I would check rules or ask around if this mod is permitted without some other chassis stiffening. Even if it is allowed, you may want to confer with someone who understands the type of loads generated from competition driving and whether a stock chassis like ours can handle that much material removal. If not a daily driver, maybe a good time to consider at least a roll bar.
I have been telling my self to not go into a full race car. Ive just been doing autocross, but this next season I want to get into hdpe at a semi local track. So that is going out of the window. Because I know as soon as I do I will want to work up from that into door to door racing.
I have been looking into a auto power bar along with the seat and drop to round out the conversion. I think I put a total of 1 mile on the street this year and that was just around my block a few times after some new parts.
Well had all day due to snow shutting down our job. So I hit up the steel yard and got a full sheet of 16ga. The pan is bent up and tacked into the car now just gotta finish welding and add my reinforcements. Im thinking instead of a u chanel rib, I have some 11ga 6 inch strap cut in half so a 3 inch strip welded to the pan to double as a reinforcement and a place to actually run my seat bolts through. Something about 16ga and 4 bolts doesn't seam rigid enough. Or just some 3x3 pads where the bolts go through?
For the Sparco seat rails that I used, I started with 3 bolts/rail then added one more each for a total of eight. Double 2" fender washers on the underside. Seat only has four bolts at the base from the factory so I considered that the weak link. All performed well in a head-on into a tire wall at Road America. Impact g-force recorded on my Flagtronic device was significant and enough that it req'd a trip to the medical unit.
If you are using competition harness, you should do yourself a favor and get a roll bar. Harness bars are mostly useless in a real impact. Obviously less risk on an auto-x course but if you start tracking that car regularly, should be strongly considered.
Finally got it in, we'll 90% i need to get the car up higher to run a few stich welds from the pan to the factory rail. And seam seal /paint the under side. Plopped in the seat and have what i would say a fist and a half of room from my helmet to the top of the door area.
And yeah I sent autopower a email about there u weld bar.
They have two options sunroof and non sunroof. I would imagine the non sunroof would hug the roof line a bit more. But will see what they say. I know it won't be as good as a bar/cage built in the car fitment wise. But while im doing all my other maintenance and changing a few other things I cant really take the car to have it done or let alone have someone come and do it.
Our tech guy said he would like to see at least a bar in the car because of the drop and moveing to a bucket. And advised to not use a standard seat belt. Gotta make him happy haha. Plus safety so im okay with that.
You may want to research the Auto power kit. I had one for a brief period in one of the cars. If I recall the main hoop bolted to the floor in front of the major stiffener cross frame member behind the seat. In your case, I believe you have removed material where it is designed to sit. As a weld in kit, you may be able to make it work by modifying to sit behind horizontal frame and on built up plate. Just an FYI before you order anything.
That was kinda my plan with it. Move it up on the cross member right there behind the seats. With the "u weld" only the cross tubes are tacked. So really I can move it up and then lower the harness bar to within where I need it. But thinking of it now. With how the car is shaped that 750 bucks might just be a usable main hoop. Ill ask them some more questions on that.
my only other option right now is its 1.750x .134 wall. But doesn't state if its ewr or dom. But at the price of 95 usd id bet its ewr. But they do list the measurements. Humm, mabey I will just have someone local bend a hoop and I'll just do the rest.
I would also consider Kirk Racing Products, they may have a weld in option. Might be worth a call.
The Competition Engineering cage is spec'd more for drag racing - hence the diameter and thickness of the tubing. A bolt in Autopower roll bar will also be made out of heavier material than is required.
Ideally, installing a main hoop that could be used as the basis for a full cage would save you time and money in the future. I believe the SCCA spec for a car like yours would call for a 1.5" x .095 wall DOM roll bar. My race car is blessed with a 1.75" x .125" DOM 4 point cage as it was originally built by some Mustang racers in Nebraska. The balance of the cage is built with 1.5" tubing but the weight of the over built parts are still there and so is the extra weight.
