Planning to race in HS next year, what mods to make

[George Patches]

So I've had a Bilstein PSS10 nearly since I bought my 2 in October 2013 and I'm ready for a change. I race in STF right now, but I want to move down to HS for next year. I have 3 questions on how to setup the car.

1. Koni makes shocks for the 2 in their STR line. These are non-adjustable units, are they worth investing in over my basically new stock pieces?
2. I'm allowed one sway bar change, should I go for the front or rear? What will yield maximum grip?
3. What is the lightest 15x6 wheel I can get my hands on?

 

[Zach@DDMWorks]

I say if you want to do HS run koni yellows so you have more dampening and the adjustability. Also you will need a rear bar. Ours would work great.

For the wheels I don't know what woudl be lightest, but the stock wheels are a good start. Also can't you change some of the dimension from the stock size? I can't remember anymore what the rules are for HS.

 

[eyeballs]

I think ssr makes (or made) a 15x6. Maybe volk too? Some of the OE miata wheels are fairly light as well. Another option for dampers is the CS set. Very cheap, super easy to adjust, and have been great for me (though I haven't been doing much auto-x lately, especially in the 2). I suspect that the konis may perform better for auto-x, based on their history and the fact that they ONLY make suspension parts. Good luck with the transformation. Don't forget to take out your camber bolts.

 

[okvol]

Wheels: stock width, +/- 1 inch diameter change allowed. 205/50x15 tires come in some good compounds for 200 ratings, and the clear just fine.
Get a good stiffener for the rear. It will make the front bite much better.
I got the CorkSport adjustable shocks - those are HS legal and make the slaloms much flatter on full stiffness.

A good driver in a FIST with good tires can beat me any day with more HP, but I've only run into one of those. These little beasts are good at HS.

 

[George Patches]

Thanks for the tip on CS dampers, I had forgotten that those were available. I would be interested in Koni Yellows, but they don't make them for the fronts of the 2, only the rear. How is the adjustability of the CS dampers? Do the rears need to be unbolted to adjust them? Cause I might lean towards the non-adjustable Koni STR.T dampers in that case.

Thanks for the tip on the Volk wheels, they do indeed make a 15x6 that is light, but I didn't know 15s could cost that much. So I think stock wheels will be it for next year. I already have a set of really sticky Kumho V720 tires in 205/50R15 that I'm running on a 15x7 rims now.

Has anyone used the Mazdaspeed adjustable rear sway?

 

[eyeballs]

Like I said, super easy adjustment. The adjuster is a thick knurled disc accessible by reaching behind and over the rear tire. With my racing beat springs (near stock ride height) I just stick my arm back there with the car on the ground. Lower cars would need to jack up the rear a little to reach the adjuster. And the fronts are in the normal spot over the tophats. I'm on my second set (one took a bad hit, and they are not available separately) and have noticed varying consistency in the "feel" of the adjustment knob from one unit to another. That's really the only imperfection I've noticed. They are sturdy too, my right rear took a huge hit (shattered the wheel, tweaked the axle) and the damper still felt and looked fine but started making a clunking sound.

 

[aaron.slawicz]

The mazdaspeed rear bar isn't legal in HS. The Fiesta ST is in HS? That's not cool, my Fiance just got one and it's fast.

 

[jasyatz]

So I've had a Bilstein PSS10 nearly since I bought my 2 in October 2013 and I'm ready for a change. I race in STF right now, but I want to move down to HS for next year. I have 3 questions on how to setup the car.

1. Koni makes shocks for the 2 in their STR line. These are non-adjustable units, are they worth investing in over my basically new stock pieces?
2. I'm allowed one sway bar change, should I go for the front or rear? What will yield maximum grip?
3. What is the lightest 15x6 wheel I can get my hands on?

George,

Can I ask why the down grade? HS and STF are almost a wash in PAX and less than a half second in raw on most local to you courses. The car is much safer to drive in STF. if the car is too "bouncy or harsh" for you on the street, it's the valving in the shocks not the spring rate. Have you tried trimming the rear bump stops? You'll never bottom out the rear shocks, so you can cut them in half.. Toss the marshmallow portion.

The wheel you are looking for is on the RRAX forum now for sale.. It was the SSR made specifically for the front of MR2/MR Spyder NB Miatas. . Big bucks but legal offset and width and only 8.9lbs. Tirerack has a few sets of alternates which don't offer much weight penalty but are much more affordable.

Konis do fit the Mazda, but you have to trick the springs into fitting. The car will sit higher because of the crazy gas pressure in them. The CS struts work extremely well with the stock spring rates but the car is still very top heavy (high CG) and you can easily get on 2 wheels with it during hard corner entry and tight digs. Especially on the Rolly-Polly FedEx lot. I had the CS struts on my car for exactly one event. Bicycle it, removed them and bought the Bilsteins. It's a great package you already have. It makes for a solid regional car. The 2 stands zero chance in HS against the Fiesta. It can't even keep up with the MINI.

Not to discourage you, but I'd hate to see pictures of your car upside down. Here's a pic of Ashley's car in HS. She's just about on 2 wheels and is running the rock hard ZIIs. Perfect weather, flat pavement. Any imperfection in the pavement on corner exit or if she was on the Stones or Rival S could have easily got this car up. The rear suspension in the LR is totally compressed, flat on the stops, no where to go but full cannon shot unload. The LF is matted also. A rear bar exacerbates this condition immensely.

Our car in stock form "barely" makes the SCCA cutoff for CG figures.

Look, I've been doing this a couple decades now. I'm a Safety Steward, instructor and Administrator for our local club. I've had mine up, it's not fun. Seriously. It makes you question why you do this at all.

And Ashley, if you have any objections to stealing the photo, let me know, I'll take it down and all the reference to you in the thread.

Posted for the greater good.

 

[George Patches]

George,

Can I ask why the down grade? HS and STF are almost a wash in PAX and less than a half second in raw on most local to you courses. The car is much safer to drive in STF. if the car is too "bouncy or harsh" for you on the street, it's the valving in the shocks not the spring rate. Have you tried trimming the rear bump stops? You'll never bottom out the rear shocks, so you can cut them in half.. Toss the marshmallow portion.

The entire reason for the change is the harsh street ride as the car is primarily my daily. Also, in my local region I don't really seem to be able to hang with the rest of my class. I'm not sure what it needs, maybe more spring the front, maybe the Kuhmo V720s in 205 are letting me down, maybe I just suck (I did pretty well at the MSCW autox at Bowie though). I don't know. The car is obnoxiously firm, on I-66 I can feel the road surface as a vibration through the steering wheel, and that's with the soft stock Yokohamas. And the stiffness of the front end is nothing compared to the rear.

To answer your question about the bump stops, I shoehorned the front bump stops into the rear. I didn't want to cut the rear ones in case I wanted to change back to stock at some point.

I'm not expecting to win HS, just have fun. If the tipping hazard really is this great, I might just bow out of the sport entirely. I need to change this, I have a bad back and neck. I just can't live with it day to day anymore. I'm also considering a CX-3.

 

[eyeballs]

Sounds to me like you really need a dedicated a-x vehicle. Unless you can daily a miata, then get an ND!

 

[Traum]

if the car is too "bouncy or harsh" for you on the street, it's the valving in the shocks not the spring rate.

I can't stress how important this point is. Unless you have installed some crazy stiff springs, or is running on ultra low (tire sidewall) aspect ratio, the most likely culprit is your shock valving.

Is the PSS10 not adjustable on shock valving? (I thought it was, but I honestly didn't check.) If you haven't done so yet, set them to full soft and see whether they are comfortable enough for you.

 

[George Patches]

Sounds to me like you really need a dedicated a-x vehicle. Unless you can daily a miata, then get an ND!

I agree, I'm always on the look out for a good NA, but haven't gotten luck yet.

I can't stress how important this point is. Unless you have installed some crazy stiff springs, or is running on ultra low (tire sidewall) aspect ratio, the most likely culprit is your shock valving.

Is the PSS10 not adjustable on shock valving? (I thought it was, but I honestly didn't check.) If you haven't done so yet, set them to full soft and see whether they are comfortable enough for you.

The PSS10 is non-adjustable.

 

[eyeballs]

Don't rule out the NBs! I love my '99. Picked it up for well under $3k.

 

[George Patches]

Don't rule out the NBs! I love my '99. Picked it up for well under $3k.

I would actually prefer a NB. I definitely can't daily a miata of any kind though. My torso is too tall and I hit my head on the roof unless I sit in a weird way my neck doesn't like. That's why I have a 2 in the first place, I traded in a much loved NC because I just couldn't drive it everyday anymore.

Sent from my Nexus 6 using Tapatalk

 

[Ciotti]

You'll love an NB man, they feel SO much lighter and smaller than NC's, plus you can make em look like this

 

[eyeballs]

Wow, are those all brand new cones or is everyone in your region REALLY good? Sweet looking NB though. NB1's FTW!

 

[George Patches]

You'll love an NB man, they feel SO much lighter and smaller than NC's, plus you can make em look like this

Your car does look pretty awesome. I do like they NB idea because then I can use the really awesome Konig Dial-In wheels I have on my 2 right now. I'll probably put it off for a little while though because I have a 85 Caprice I'm converting into a muscle car that I want to throw some money at first.

OK, so back to my 2. Lets forget racing in HS and reframe the question as I want to make a really fun daily driver. I want to use stock springs because while I like the lowered look, I'd rather have the suspension travel and correct front control arm geometry. I'm now on the fence about whether I want to just use the stock dampers or go for Koni STR.T dampers. I know I'd like ride comfort of the stock dampers, but I'd probably also like the sportier response of the Konis.

Last thing I'm considering for AX is stock springs, but front and rear sway bars. Would that solve the tipping problem?

 

[Traum]

IMO, the problem with sway bars is, they are supposed to be the final suspension tuning tool you use to fine tune the dynamic behaviour of your car. We're supposed to use springs and shocks to do the coarse grain tuning to get the handling almost right first, and then we adjust things with sway bars and shock dampening.

With the car being driven at anything less than 7/10, sway bars should make a cheap and effective bandaid solution in controlling body roll. But things get interesting the closer you approach the 10/10 limits. The problem is, as far as body roll control is concerned, sway bars acts like extra spring rates, and it will help you resist body roll on the shock's compression stroke. However, all that energy from the body roll resistance still needs to be released and controlled when the suspension rebounds. This is where you might run into trouble because if your shocks are only tuned to match your springs' spring rate, the added spring rates from any upgraded roll bars could easily overwhelm the suspension rebound stroke.

When I was young and naive, this was exactly what happened to me in my Miata. As my first (and cheap) mod, I only upgraded the sway bars and kept everything else stock. Body roll improved dramatically on the street and the car felt great. But as soon as I took it to autox, the increase spring rates from the roll bars overwhelmed the suspension rebound stroke. In a slalom / linked turn situation, there is too much energy being released when I try to transition the car from the first turn into the second. The rear end kind of snaps, and it was very easy to spin the car on anything after the 1st turn.

So nowadays, I don't really recommend sway bars as the only body roll control tool. There is a reason we want do start with springs and dampers first.

 

[George Patches]

I was more thinking front and rear bars with Konis. I agree that beefy bars and stock dampers sound like a bad plan. Though I'm totally fine accepting that this would be a bad plan and just giving up.

 

[flatlander937]

George if you come down to VA Beach some time you're welcome to see how my car feels with 550/450 springs and only a rear bar. I like it a LOT. I am planning on getting some 300# springs to ride nicer on the street, the only place I dislike it is the whoops and expansion joints in the Hampton Roads area. I had zero issues in Dayton Ohio.


You're welcome to co-drive as well at an event. Next is September 6th.