What’s the maxed out D Street setup for 2nd gen cars?
 

I’ve got a 2025 GR86 with the brembo package on order and want to immediately gear it up for D Street. I’m moving from an ND2 Miata in C Street and am wondering if the formula as far as mods is basically the same.

I plan to get the Karcepts front sway bar.

On my Miata I had swapped to Koni Yellows but am wondering if the Sachs dampers that come with the Brembo package are good on their own.

My biggest current question is around wheels and tires. What’s the ideal setup for D Street? Can somebody recommend exact wheels and tires that are known to fit and be the best for D Street?

One heads up is that the Brembos require wheels that clear the caliper. Many popular options are off the table like the RPF1, in the size you need at least. Fun fact, but the 8" one fits, but the 7.5" and even 9" doesn't clear due to the spoke design. It's not even just about width. The main issue is just finding any 5x100 that clears... and meets the 7.5" width rule. I saw someone recently in DS with Brembos with the PF01 and they looked good. IMO, there aren't a ton of good looking wheels that meet the requirements.

225's fit and will clear no problem. All competitive cars run 245/45/17 (yes, the 45's, not the 40's.. the extra gearing helps and the 2.4L isnt' hindered much from it like the 2.0 was). The problem then becomes clearance in the front to the strut with a pinched wheel setup. I believe everyone's running extended studs in the front to fit spacers in addition to the wheels to get the clearance needed for 245's. Rears are fine as is, no studs needed. When I was in DS with a first gen, I just abandoned the entire thing and did 225's on the stock wheels to learn, then went to STX/DST.

Competitive people in our region run "Gucci" shocks, aka, purpose build MCS shocks that get pricey. I think in the $3k range. Again, all depends how competitive you want to get and how much that extra tenth(s) are for you. I ran the performance pack Sachs dampers and they worked well. Koni Yellows weren't even worth it to me. The 2nd gen suspension is better and closer to Konis. Personally, I'd focus on the other items first, then go to Koni Yellows if you're that competitive.

Extra pro-tip, people are cutting the bumpstops and/or getting new ones, which is apparently legal somewhere in the rules. This helps at autocross using the full suspension travel, but still keeping enough bumpstop there to prevent the shock/strut from bottoming out. These cars ride close to the bumpstops as is.

Swaybar you have figured out - just remember it's nicknamed "Clunkcepts" for a reason.

Overall, it should be close to an ND CS setup. If CST is in the future down the line, I'd opt for the PF01's with 225's and call it a day. If you're sticking in DS, go the extended stud and 245 route.

Don't forget your catback for fun too.

Awesome, thanks for all the good info! Basically just what I was looking for.

I saw that TireRack says the PF01 should fit so I was planning on going with those in some 17x7.5... PF01 was my go-to ND wheel that cleared Brembos as well so I guess it's a good one for the Brembos.

That's interesting about Clunkcepts haha... I ran the ND bar from them for 3 years and had no clunks at all... maybe the design is different for the 86.

So, you're saying I could go with the PF01s and 245/45 17's and just mount the rears as-is without any clearance issues, and then for the front I'd need to get some 7mm spacers and the longer lug bolts, right? I probably lean towards that route as I tend to try to stay in the street classes because I feel like the ST classes become an arms race to get all the possible mods and my wallet can only take so much! Any idea what bolts and spacers people are using?

I'll probably roll with the Sachs to start and just see how they are. I felt kind of bad immediately swapping out the Bilsteins for Konis on the ND... but maybe the Sachs are closer to the Konis than the Bilsteins were.

Come to think of it, I think it is 7mm. That's why the extended lugs are needed. Don't quote me on the 7mm size though - double check somewhere else. The rears fit just fine as is... tons of room back there and the shock/strut doesn't have a perch that interferes with the wheel/tire.

Same feeling on the ST class arms race. However, my first gen wasn't competitive in DS with the 2nd gen. I bought it right in 2019, months before the 2nd gen was announced. The SCCA the left it in the same class too.... :bonk:
I've done mine 'cheap'. Used coilovers and rear control arms. Wheels were on Black Friday special. I put off doing the header and tune so far so I still have excuses lol.

1. 235/45/17 or 245/45/17 RE71RS, if stock offset, I think you need some spacer for the 245. The more common setup is stock offset (48mm) RPF1 and 7mm spacers. As mentioned, you'll need longer wheel studs to run a spacer that thick.
2. Upper OEM crash bolts from the dealer (like $12), these get your camber to roughly -1.1° to -1.2° per side. Subaru - 901000394, Toyota - SU00302818
3. Larger front sway bar - Perrin 19mm or Karcepts 0.804" bar, everything else is too big/stiff.
4. Koni Yellows - these add an additional 0.5° to 0.6° camber, usually end up around -1.7° per side.
5. Koni front centering washers (free, need to email Koni - info@koni-na.com)
6. Stiffer bumpstops, RE-Suspension COT Series, 22mm internal diameter, trimmed to stock length or shorter. Med-White all the way around is a common setup right now.
7. Optional: axle back or catback exhaust
8. Optional: drop-in air filter
9. MCS double adjustable rear dampers - roughly $3k from Karcepts.
10. Overfill the oil 0.5-1.0 quart. Running at a full on the dipstick is not recommended for any motorsports activities.

*I believe that the 17x7.5 48mm RPF1 clears Brembo setups with a 7mm spacer, it will not clear without at least a ~5mm spacer.

Reasons for bigger/wider tires are for heat maintenance and higher top speed.

IMO, rear spacers are unnecessary.

I run everything listed besides MCS rear dampers. The MCS are extremely valuable if your site is bumpy.

I would recommend changing your transmission and rear differential fluid before ~10k miles. The OEM fluid is beat up after break-in. I run 30 or 40 weight oil, as it's commonly warm or hot at my events.

Thanks for the info! The PF01s are 45 offset, do you think those will still be okay to use with 245s and 7mm spacers or do I really need the 48 offset wheels?

Also, so it's okay to use the same wheels on the back without the spacers? Sounds strange to me since I picture the front wheels sticking out more than the back but maybe it's not a big deal for 7mm.

Where do you get the proper longer wheel studs? If I have those on the front does that then require me to leave the spacers on when I swap the OEM wheels back on for daily driving? I'm picturing the lug nuts not tightening enough if the studs are longer but the spacers aren't in place.

For the crash bolts, is there any kind of "how-to" on those? I've seen them mentioned several places but am not familiar with them.

I believe you need to be within +/-7mm for street class, unless something recently changed. Meaning you'd need the +48, then use the spacers. +45 and spacers puts you over the limit.

Yes, on the rears being stock offset and front being a different offset. No issues there. Just autocross things. Yes, I agree it's weird and preferably wouldn't want it like that on my own car because OCD things.

People run the ARP studs, usually the long versions vs the regular length versions. The regular length ones are what I have and are actually longer than stock, but not by much. Close ended lug nuts don't work then, so people run the open ended lug nuts, usually the longer 'tuner' style ones.

The crash bolts are weird and my alignment guy, who does autocross cars, was confused by them at first when I put them on my first gen before the second gen came out. Basically it's just a thinner bolt. You put it in and crank over the hub, then tighten it down. That's it. No eccentric lobe or anything like those aftermarket ones that get more like -2 degrees. You'll get about -1 degree.

Interesting... so is there some weird positive/negative thing going on here. Like if I add the 7mm spacers to the 45 offset wheels does it make them 38 offset, not 52 offset? And then 38 is 10mm different from stock 48 and thus not legal?

My simple thinking was that 45 + 7 = 52 and 52 is only a difference of 4 mm from stock... but it sounds like maybe the spacer is actually reducing the offset number, not increasing it? Is there someplace that lists the stock wheel specs for the 2nd gen? I keep seeing different numbers.

So you are able to run the "regular" length ARP studs with your spacers and the lug nuts still seat properly? Would I just leave the spacers on when I put the stock wheels back on the front, or do people remove the spacers and then have studs sticking way out from the wheels?

So I guess now what I really need is somebody with a 2nd gen car to confirm that the 17x7.5 RPFs with 245 tires will clear the Brembos with 7mm spacers added. Tire Rack says they won't, but they aren't considering the spacers.

It goes the other way. If you have a +45 wheel and add a 7mm spacer, you're removing offset, thus making it a 38mm. The problem here with autocross rules is you can move offset either way by only 7mm total by whatever means you use from stock. Stock is +48, so with a 7mm spacer, you have to use a stock offset +48. Using a +45 wheel and 7mm spacers is moving the offset a total of 10mm, thus against the rules.

Yes, I'd run the 3mm spacers that I ran all the time, even with stock wheels. The max spacer you really want to run is about 5mm on the regular/stock length studs. I stick to 3mm to be space and to give the Brembos from breathing room. Without that, the caliper is like 2mm from the wheel spoke. You could definitely run the 7mm spacer and extended studs with the stock wheels with no issues.

So I wonder, could I get the PF01s, that are known to clear the Brembos, and since they are +45 (already the equivalent of a 3mm spacer), could I then add a 4mm spacer and have the same result of a 7mm spacer as far as the 245 tires not rubbing, and then also still be within the 7mm DS rules? That might be the better way to go if it would work.

Ken Roller said they fit. I trust him.

Yes, this would likely work... and honestly is a better option because then you could avoid actually having to do the extended studs if you wanted to avoid that. You could run closed lug nuts too as an option. The ARP regular sized studs are an easier install than the extended ones because you can just fit the regular length ones in from the rear. The long, extended ones require taking a bunch of other things apart because there's not enough clearance.

Heads up thought that the stock studs on these cars are like butter. I treated mine as perfect as I could and two of mine stripped out after having the wheels/tires off maybe 6-7 times in my ownership. I have a 2004 WRX that literally has the original studs, so it wasn't me. Happens to everyone it seems. Get at least the ARP "regular" length studs and don't worry about it again. Plus, you should have plenty lug engagement for a 4mm spacer then.

Enkei PF01 17x7.5 +45 are confirmed to clear the Brembos. So if it's a +45 and 7.5", if you added a 4mm spacer to stick within the rules and everyone else's 7mm and 7.5" wheels fit with a 245, I don't see any reason why it wouldn't work.

So just so I have this straight... the spacers are reducing the offset number, so in the case of the stock 48 offset our goal is to reduce it to a 41 offset one way or another in order to fit the 245 tires on. Whether that's by putting in a 7mm spacer to stock offset wheels, or by just finding a wheel that is a 41 offset by default, it's the same either way, right? Just gotta get that offset number down to 41.

And you're saying the stock length studs can handle an additional 4mm reduction via the spacer, but not 7mm? Any idea what the part number is for the studs... and while we're at it where to get spacers?