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Grabbed some scales from a buddy to try and get the car corner balanced. I was also really curious to see what the weight of the car was. The last time I weighed it was over a year ago before I added the turbo kit, wing, rebuilt the engine, etc...
This was a "good enough" attempt. I used a string and level to make sure the scales were roughly level with each other and surprisingly they were spot on. I didn't have ramps, so I had to use a jack to lift the car onto the scales. Gave each corner a little shake, climbed in the driver seat and boom, 50.1% cross weights with no adjustments.
Now, this isn't perfect, considering there were a few things left in the car like my tool bag and the fire extinguisher I keep in the glovebox, but I'm going to say it's good enough for autocross. A nice sanity check, and now I know that the car with around a 1/3 tank of gas is at 2353 pounds. That means that if I wanted to, and could find a way to, I could take about 185 pounds out of the car and still be class legal.
I'm not planning to try to hit that, but I bet I could get pretty close with the following
Remove soft top and hard top
Remove AC
Remove PS
Replace battery with a lightweight unit
Change out steel intercooler and piping for aluminum
At that point the car would be much less enjoyable as a daily for me, so I don't see that happening. I could also try to lose ~185 pounds but that would put my personal weight around -20 pounds, so that's not much of an option either.
My point is you may need to level your scales better, or you've got something heavy in the RR corner that's not the battery. I usually see these light RR corners with stock batteries.
Nothing jumps to mind that would make the RR heavier than any of the other corners. I've got the APR wing on the trunk and a regular/heavy battery back there, but nothing crazy.
To be fair, I only checked how level the front to back was. If I run out of other projects I might try to get it setup more correctly. This was mostly a sanity check.
I have very rarely seen a RR corner heavier than the LR on a Miata.
What's the reason for that? Anything aside from the fact that the driver is sitting on the left side? Apologies in advance for the potentially stupid question haha.
That’s just how Miata’s corner weight, couldn’t tell you why. Yes, it most likely has to do with drive weight. I’d be curious to corner weight a RHD Miata, but I’ve only worked on one or two and neither were in my shop for a corner weight.
Tecnas can be adjusted lower than 4.75" / 121mm but they won't ride well. It's what we recommend to ride/handle as well as you are expecting and we intended. To go lower requires a bunch more spring rate and the damping of Xidas.
Even 120mm might bottom too frequently on some heavier builds like a turbo NB2 with A/C, hard top, roll bar, full interior and big driver.
Thanks for the info Emilio. That's what I figured based on the instructions but the confirmation is great to have. I think after driving around a bit they've settled in around 4.5-4.75" ride height now, and I'm not having any issues with bottoming out. My old setup made me pucker on any roads with a sharp dip. Overall really enjoying them and can't wait to see how they do at Autocross in a couple weekends.
Cool.
If you have Sport springs and your car is really light, you can push that lower ride height limit. Heavier and GT springs, ride heights need to be taller generally.
I'm on the sport springs. I actually just weighed the car last week and it was sitting at 2350 with 1/3 tank of gas an no driver. Not sure if that's "heavy", but if anything the car will be getting lighter it progresses.
There's no hard number or spreadsheet for this. Just depends on how bumpy the roads are and how fast you're driving. If it feels like it's bottoming and becoming unsettled then raise it up. Your car is about average weight for an NA/NB. We see a range from 2000 to 2600 lbs.
I actually got the wing from my roommate who already had it on the risers, so I can't compare the two. I can say that side mirror functionality is unaffected
In actuality, the wing usually blocks the majority of cars behind me when cruising. They're easy to see if their close up, but if they're further away they can get mostly blocked by the wing. A positive side effect, is that the wing often is right in the beam of their headlights and helps block them at night. I'm pretty confident that if it was lower you would be able to see cars behind you easier but it probably wouldn't block headlights as well, which is the main reason to get a wing anyway.
Overall, rear visibility is adequate, but not excellent.
Do you know where the wing height is currently with the risers? On my NA, I had an 11" tall wing and rear visibility was completely unaffected. My second wing was 8" off the trunk and perfectly obscured any vehicle driving behind me lol. I had it on my list to make/buy a set of risers to get it higher but never got around to it. I'm 6'0 and had my seat mounted 1/2" off the ground for reference.
I've actually never measured it. It's the APR GTC-200 as far as I know, with their riser kit. Pretty close to being in line with the roof, but below it by a few inches
Ahh, going back through other photos, I see it now. So 12.5" height. I would've guessed that to not interfere with visibility, depending on driver height. Interesting..
Part of the reason I want to put a BIG **** on the NC is so I don't have to deal with a blind spot in my rearview mirror again haha.
Thanks. I’m leaning towards the 2.5” risers. I’ve seen some 5” ones from another company. But at that height, I might as well use a wing with a 2D element
3D wings should not be used with risers. That puts it up into the more laminar flow so you are intrinsically going to stall part of the foil. The whole point of a 3D is to use the ground effect off downward flow over the trunk in the center and catch the upwards flow coming off the side of the car on the ends.
The amount and location of that twist should be optimized for the actual airflow paths over the back of the car. The GTC200 and other 3D's are generic shapes and not necessarily optimized for any one car.
That's why we switched to high mounted 2D wings 12 years ago on Crusher, to reduce drag for a given foil surface area by eliminating the stalled sections. That seems to have started a trend and why high mount 2D wings are now basically standard for track Miatas.
09-06-2024, 10:13 PM
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