On the latest episode of Tall Man, Small Car, our heroic adventurer—err, me—ventures further into the never-ending quest of squeezing my large frame into the NC2 Miata. This time, I actually shelled out a few bucks for a set of Jass Seat Lowering Brackets. So, break out the angle grinder and let’s get this party started. Just a heads-up—my 2010 NC2 MX-5 Miata comes with OEM height-adjustable seats. If you're working with an earlier NC1 model that lacks height adjustment, the process might be slightly different for you.
First off, let’s take a moment to appreciate how shockingly fast these brackets made their way across the pond. I placed my order directly through Jass Performance on 2/17/2025. They shipped the very next day on 2/18/2025, and by 2/20/2025, UPS had them on my doorstep in Colorado. Yes, you read that correctly: shipped from Bulgaria and in my hands just two days later. No extra fees for expedited shipping, no sponsorship deals—just a standard order placed on their website, and voilà, they arrived in record time. I’m not sure whether to be more impressed with Jass Performance or UPS, but either way, color me impressed.
The brackets arrived well-packaged, complete with a printed set of instructions. Given that Jass Performance is a Bulgarian company, I can forgive the fact that some of the phrasing had me scratching my head a bit. Let’s just say I had a sneaking suspicion that English wasn’t the first language of whoever wrote them. Fortunately, the installation process isn’t overly complex, so let’s break it down and maybe add a little clarity along the way:
Step 1: Disconnect the Car Battery
Pretty self-explanatory. You’re disconnecting an airbag, and airbags explode. Not a bad little safety measure. Could you skip this step? Probably. Should you? That’s between you and your risk tolerance.
Step 2: Remove the Seat
The seat is secured by four easily accessible bolts and a single electrical connector underneath. The wiring harness plug/connector has a black locking tab— press "upward" on the locking portion of it, then gently pull it back, and it will slide in a semi-circular arc, like opening a book, releasing the connector. Once released from the wiring block, the connector should pull straight out. Once that’s done, you’re ready to lift the seat out. Pro tip: lay a blanket over your plastic trim before pulling the seat out to prevent scratches—unlike me, who only thought of this after leaving a nice reminder on mine. Oops.
Step 3: The Optional but Suggested Step
The instructions recommend removing the seat rails from the seat to make the job easier. I, however, skipped this entirely. Why? Because I apparently have no fear of using an angle grinder inches away from my fancy OEM leather seat. Call it bravery, call it foolishness—either way, we’re rolling with it.
Step 4: Remove the Rear OEM Seat Brackets
These are attached to the seat rails with just two bolts and come off in seconds. Here’s a quick pic of the OEM seat bracket still in place:
The OEM seat rail brackets removed:
With the brackets removed, the outer (painted black) seat rail should look like this:
Step 5: Trimming the Outer Seat Rail – Fire Up the Angle Grinder!
Now for the fun part—where one of my all-time favorite tools makes an appearance. That’s right, folks, back by popular demand: the angle grinder!
Jass Performance recommends trimming the outer (painted black) seat rail about 1mm behind the stopper slots (those two oblong holes at the bottom of the rail). This step is crucial—without it, the new brackets will hit the outer seat rail and won’t fit properly.
Technically, you could do this with a metal hacksaw… but let’s be honest, I wasn’t about to spend my afternoon sweating over hand tools. Instead, I made quick work of it with my trusty angle grinder. Here’s a reference photo showing roughly how much of the outer rail needs to be trimmed:
And just to be thorough, here’s another photo showing how the outer rail should look after trimming:
Step 6: Trimming the Inner Seat Rail
Next up, we move to the inner seat rail, which is unpainted bare metal—or at least a silverish color. If you take a look inside the rail, you’ll spot a captive bolt plate, as shown here:
See that rectangular piece of metal inside the inner seat rail? That’s the captive bolt plate. To maintain full rearward seat travel, you’ll need to measure about 6 to 8mm behind it and trim the rail at that point.
Here’s a photo of my rough measurement, where I marked the inner seat rail approximately 6 to 8mm behind the captive bolt plate:
If you're like me, you skipped the optional Step 3 and decided to embrace the chaos by leaving the seat rails attached. But before you unleash the angle grinder, take a second to notice those wires running right behind the inner seat rail. Yeah, those control your airbag, seatbelt sensor, and—if equipped—your heated seats. Personally, I’m a big fan of all three. So, before you start cutting with reckless abandon, it’s probably a good idea to at least attempt to move them out of the way.
For reference, this is approximately how much Jass Performance recommends trimming off the inner seat rail to maintain full seat travel:
Before moving on, I hit both the inner and outer seat rails with a metal file to avoid the inevitable pain of stabbing myself with tiny metal shards later. I also applied a bit of paint to the trimmed areas to keep the rust worm at bay.
At this point, you could install the Jass seat brackets/adapters onto the rails, but I’d personally recommend holding off until you're done working inside the car. Why? Because we still need to do some trimming, and I used the new brackets as a template to figure out exactly how much cutting, scraping, and trimming was needed before bolting the seat back in.
Step 7: Cutting the Carpet and Scraping Off Some Sound Deadening
Now, let’s shift our focus back inside the car. The whole point of installing these brackets is to get the seat as low as possible. To squeeze out every last millimeter, we’ll need to trim the carpet, remove a bit of the carpet insulation, and scrape off some sound deadening from the floor/tub of the car.
I used the Jass brackets as a guide to determine how much carpet needed to be trimmed. Instead of removing the entire carpet, I simply cut an outline that allowed me to flip up a section and work underneath it.
Don’t mind the small yellow particles all over the carpet. Apparently, when you shave your seat (as I did in a previous post) with a surform tool, it's a really good idea to remove the seat from the car first. Otherwise, you’ll end up with a carpet full of stubborn yellow seat foam particles that, as I’ve learned, laugh in the face of my home vacuum’s suction power. Cue the childhood jingle in my head: The more you know!
Now, see that black material stuck to the metal floor of the car’s tub? That’s sound deadening, and we need to remove some of it to get the new Jass seat brackets to mount correctly.
If you don’t mind marring the painted floor, you could just grab a screwdriver or your scraping tool of choice and have at it. The instructions claim that this material is simply glued down and can be peeled up—but since it was a bit chilly in my garage, I took a more strategic approach. Armed with a heat gun and a plastic razor blade, I got to work.
Step 8: Installing the Jass Brackets onto the Seat Rails
Now that I no longer needed the Jass brackets for measuring against the carpet and rear mounting position, it was time to install them onto the OEM seat rails. This step is incredibly straightforward—just bolt them into the existing OEM outer seat rail holes and hand-tighten to no more than 20Nm of torque (roughly 14.75 ft-lbs).
One important note: when mounted to the rails the stiffening rib on each bracket should be on the inside of the rails.
Step 9: Installing the Seat Back in the Car
Now it’s time to bolt the seat back into the car. Since the seat sits lower than before, it’s a good idea to reconnect the seat wiring harness before securing everything down.
After a bit of trial and error, I found a small trick that made reinstalling the seat much easier: start by loosely threading in the two front bolts first (don’t tighten them yet), then slide the seat all the way forward to install the two rear bolts. Initially, I tried installing the rear bolts first but struggled to line up the front holes—so trust me, starting at the front makes life easier.
Once everything is bolted down, reconnect the battery, and take it for a spin!
So, How Much Room Did I Actually Gain?
Jass claims their height-adjustable seat brackets lower the rear of the seat by approximately 1.5 inches. Based on my before-and-after photos, that estimate seems spot on to me. Before:
After:
I’ve read on forums that lowering the rear of the seat can also increase legroom due to the additional rake. Did I notice more legroom? Not exactly. I’ve seen posts from people saying their seating position is now 3-4 clicks closer to the steering wheel and pedals. Maybe their experience was different, or they have a different body shape, but that wasn’t the case for me.
Headroom, on the other hand, improved drastically. Thanks to the combination of cutting the lower seat pan mounts (from a previous post) and the Jass brackets, headroom now feels eerily similar to my old Honda S2000 with the top up. In fact, with all the small interior modifications I’ve made, the seating position now feels very S2000-esque.
When the car was stock, standing at 6'2" (with more legs than torso), my hair would brush against the soft top. Cutting the lower seat pan mounts gave me an extra 10mm of headroom. Now, with the Jass Performance adapters, I have nearly two inches between the top of my head and the soft top. My line of sight is improved, and the NC now fits me like a glove.
I should mention that with the Jass brackets installed and the seat in its lowest position, the seat doesn’t slide forward or backward easily. I suspect this is because I previously lowered the seat pan by 10mm, causing it to press against the floor of the car. The solution? I raised the seat height slightly, slid the seat all the way back, and then re-lowered it. Problem solved.
How Much Rake Did Lowering the Rear of the Seat Add?
Rather than going by impressions alone, I grabbed my trusty angle finder and measured the rake angle of the seat. Both before and after measurements were taken with the seat in its lowest position. Stock the seat rake angle was roughly 19 degrees:
With the Jass brackets, the seat rake angle increased by roughly 5 degrees, bringing it to around 24 degrees:
With the added rake, the OEM seat now feels noticeably more bucket-like. One unexpected benefit is the improved thigh support, which was definitely appreciated.
If you feel the new seat rake is a bit too aggressive, there are a couple of ways you can adjust it to your liking:
You could add shims underneath the rear brackets, but keep in mind that this will cost you a bit of the headroom you just gained.
Alternatively, you can shave down the front portion of the OEM seat cushion, which would reduce the rake—though it might come at the cost of a bit of extra padding.
How Long Did This Install Take?
Overall, the install was relatively straightforward and took me just a bit over an hour—this includes taking my time and making sure I didn’t rush anything.
Any Other Notes?
Before I started modifying the seat, my OEM seat belt guide wasn’t exactly confidence-inspiring—it didn’t stay tensioned very well, to say the least. I believe Mazda revised the seat-mounted guide for the NC3, but my humble NC2 didn’t get that upgrade. Lowering the seat just made the seat belt retraction even more awkward—it pretty much needs to be fed back in by hand.
Fortunately, the fine folks at Carbon Miata offer a solution: a set of aftermarket guides that make it easier for the seat belt to track in and out. Needless to say, after driving the car around a bit, I immediately ordered a set.
Was This Mod Worth It?
Absolutely! No question, the extra usable space, combined with the improved thigh support and the relative ease of installation, make these brackets a no-brainer. A++, would order again!
I can now comfortably sit in my NC—not just “comfortable for a Miata,” but actually comfortable. I could easily see myself spending a good amount of time in this car without much to complain about. Maybe enough time to swing by Flyin' Miata Summer Camp in June, or even head out to the Miata Reunion in California.
Now that the NC fits me, it’s time to tackle that body roll... and the limp-wristed brakes... and of course, more power never hurts.
UPDATE: After spending some time driving with the Jass Performance seat lowering brackets, I decided to remove them after realizing they actually reduced legroom for me. I’ve detailed the full experience in this blog post.
While I wouldn't discourage anyone needing more headroom from ordering these brackets, for my specific build (more legs than torso), I ultimately decided to prioritize legroom over headroom.
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