Help needed for Street legal Track Car on a budget
 

Hi,
I have been tracking my car for more than two years with several hundred miles on her. I drive in Texas (MSR Houston, Cresson, COTA, EagleCanyon, San Marcos)

My objective is to prioritize track time and improve my driving skills. My main expenses are track fee/brakes/tires. In order to do that (with my limited budget) I have been modifying the car for reliability and performance, barely no cosmetic mods.
I do all my work myself but alignment.

Car is in very good condition (27K miles), using for weekends and track events (no Autox). I love it and love it more after tracking it.

I started tracking in OEM configuration, latter modifying it base on above criteria.

Finally this is what I have.

Engine: NA, OFT Tuned E85, Oil Cooler, Baffle Pan Blue Moon, Decatted, Verus Hood Vents.
Brakes: Front Willwood with racing pads, Rear OEM with Windmax W5. Motul 660 and brake lines.
Wheels: OEM 7 inches with 225/45/17 Federals RR or Falken 615. Tried 245/40/10 on OEM wheels with no better/no worse results.
Suspension: Bilstein B6, Eibach Springs (F 3.6 kg/R 4.9K) and sway bar. Front Camber -3.1 and Rear -2 (fix Pedders and crash bolts). Several (bushings mainly whiteline)
Interior: No mods (only 4 point harness with Hans Device)
Weight reduction: Antigravity YTX12-16 Lithium Battery (OEM died)
Aero: No big aero now or foreseeable future.
Drivability: Street Legal Track Car (do not have trailer)

A year ago, we bought with some friends a Miata NA 94 spec, for endurance racing. We did two races with Champs Car and one with Lemons this year. Surprisingly we won at Harris Hill with Champs Car…because is endurance.

Here is the my confusion,

Miata is a race prep car, old one but well sorted it out. I love the feeling and is helping me to improve a lot my driving. When I track my Scion, it feels very soft, I started not to enjoying it ,not feeling comfortable, and confuse trying to drive it like I do with the Miata.
My times with the SCION are worsening or not improving, time laps with Miata are improving.

So I wandering how much firmer need to be the suspension without having a solid rock car. I need to bring some of the joy of the Miata (without losing AC, stereo and drivability on weekends)

If go with Yellow Spring (F 4.5k, R4.5K) or Sports SPEC-R (F 4.4k, R 5.3K) with my current shocks (B6). Am I going to feel a big improvement against Eibach (F 3.6 kg/R 4.9K)?
Do I need to go Coil Overs with 6K springs (like Tein CGC spec or Racecom Superstreet-1) or do I need to go over 6K spring rates, like Racecomp Tarmac 2 (7.1K F&R)

I need some light here.

Thanks

Picture at MSR Houston Dec '20

The usual spring rate on track-oriented coilovers is 10k/10k, I would not bother with anything less than that. What are your best lap times at each of the tracks?

Based off what you are saying, coilovers does seem like the next logical step. If your goal is to maintain any sort of street comfort, I would not recommend 10k/10k as above. Even on bumpy tracks (at least like we have in CA) they can be overkill for some folks.

I have had similar goals as yours, and the two coilovers mentioned have many positive reviews in these forums. I'll throw my hat in the ring for the Tein CSG Spec. I was looking for something to give me better roll control as my skills were growing. They are a 6k spring setup, so stiffer than stock. But the crucial thing that makes them great on track, while also maintaining comfort, is how the damping is tuned to match. CSG feels smooth on normal pavement, but tightens up on bigger undulations and turn in, basically ensuring good tire contact. Adjusting the damping let's you soften it up decently for daily driving.

Basically, what you get from CSG and RCE is the R&D to make sure the springs and dampers are a well matched setup that can walk that line between street/track. I personally wouldn't try to do that R&D myself.

You already have good shocks in the car. And youre not running big tires. My vote is RCE Yellow springs and done. My thinking is that the "street" oriented eibach springs being much stiffer in the rear is making the car too loose to be stable and predictable. Hence your wavering lap times. Yellows are cheap, its the simplest improvement to get the car in the right direction.

***and Eibach rear swaybar? Yea, that really seems like it would be a tail-happy car.

First... Figure out how to get back to what you know you can do in this car. Driver mod is driver mod, and you haven't figured out the leap between cars yet. You can though, and that'll be the key to better times... Otherwise you'll be underperforming after any new mods.



I've run From SRC on their 10/12k setup and they passed the knit test... That is, will my wife happily road trip with me; that means she knits while I drive.
Step up to quality coilovers with proper valving for the spring rate and it'll be reasonable as a daily. The could you mentioned would be reasonable entry level options. Unsure if either can be rebuilt, but that's a future problem.
That said, it may be other improvements to consider. Alignment, wider wheel (8" for 225 will present a better contact patch). Are the brakes actually balanced right as setup?

And even if your 4 point is ASM ditch it or go 5/6 point. I've been in a car where ASM works but I've also seen it ruined without realizing over time tightening the belt down.

I'd probably jump for the rce tarmac springs 5k/5k over the yellows at 4.5k/4.5k. They should be better suited to 200tw rubber.

Lets face it, our cars are big and heavy and in particular NOSE-heavy relative to an NA Miata. Still, I *massively* enjoy driving mine to/at/from the track. i have a similar setup to yours as it is my daily-driver. Bilstein B8s, Swift Spec-R springs (4.5F/5.3R), Eibach 25mm front (soft position) and 19mm rear (set to stiff) anti-roll bars. I have a bit more front camber via Raceseng plates and being 30mm lowered on the Swift springs, I'm at -3.7F -2.7R camber.

Honestly I'm not tempted to change anything to make mine more trackworthy, despite the fact that I'm in close competition with a track-dedicated NA Miata in my time trials class (T50 with COMSCC).

I've never driven on the Falkens or Federals, maybe they're fine, but tires will play a big part in feel and fun. I'm running 245/40-17 Nankang CR-1s and 235/45-17 Yok A052s this year. VERY different feeling tires, but both fun in their own ways. CR-1s seem to enjoy being driven HARD and will grind their way to the apex if you overcook it a bit on entry, whereas the A052s are more delicate and require more precision.

One thing you might consider is going to 225s on 8" or 8.5" wheels, or 235s or 245s on 9" wheels. The front of these cars is very grip-challenged due to Pony-car-esque 55/45 weight distribution. I have a 5 lb. battery (-25 lb.), catless header (-10 lb?), and 2-piece rotors (-12 lb.), near-empty washer fluid reservoir (-6 lb) and still only 53.5/46.5 with me in it and a full tank. DOH!

But ultimately nothing you do is going to make it feel like a much smaller, lighter-weight, shorter-wheelbase, better-balanced NA Miata track car...

MSR CCW 1.50.3
COTA 2.43.26 (room to improve)
EagleCannyon 2.17.x (room to improve)

Thnaks for your feedback

Thanks Versatis,
I agree with you, make no sense to R&D yourself. My choises are limited to what you mentioned.

Do you know if you can change spring rates in CSC and RCE if you decide to go stiffer latter in life?

Thanks Versatis,
I agree with you, make no sense to R&D yourself. My choises are limited to what you mentioned.

Do you know if you can change spring rates in CSC and RCE if you decide to go stiffer latter in life?

Hi Westen86, you nailed my problems.
Happy tail is what i am fighting. I thought that was my driving style, not to be patiente enought on the gas pedal.

At same point I tried to go back to OEM Rear sway bar, but that track day was affected badly by my tire choise (Kumho 720 delamation isues), so it was dificult for mw to profit in the test.

How are your sways set now?

Thanks ZDan,
I see your pointwith the comparisson against Miata.

Just for budget constrain I am not moving to wider wheels, I have 2 set of OEMs, second set got at very low price. So I can play with tires, having one set for track and second for DD or rainy track days.

Do you think that Swift Spec-R springs (4.5F/5.3R) will work with Bilstein B6s?

F soft
R soft