itskrees

iTrader: (1)

Hey everyone,

I just acquired a set of Tein SS coilovers that has 8k/7k springs on it to use on our budget track Miata build.

I'm sure we can all agree that those spring rates aren't ideal as it makes the car prone to oversteer (which some like, but I'm talking for the purposes of seeking neutral balance), and we plan on purchasing either a 9k or 6k spring to place the front or rear respectively. Tires are 15x7 Kosei K1's wrapped in 195/55/15 Star Specs.

With that said, I do know that oversteer/understeer characteristics can also be induced or corrected through sway bars as well as ride height (which subsequently affects camber settings). Until we change out one of the springs, which of the following do you guys think will do the best job compensating for the current rates in the meantime?

This is under the assumption that once we do have our ideal rates, we'll be shooting for the 949 race miata specifications:

4.25F/4.5R measured at the pinch welds, 1/4 inch of rake.
-3 degrees F camber, +4.7 caster, 0 toe
-2.6 degrees R camber, 0 or 1/8 toe-in

Until then, we intend on doing one or the combination of the following to neutralize the oversteer:

1) Lowering the rear to increase rear grip (-2.8 to -3 degrees rear)
2) Running less front camber (-2.8 to -2.6 degrees front)
3) Removing rear swaybar
4) RB Tubular front bar with 949 endlinks

All input is appreciated, thanks in advance!

Savington

iTrader: (31)

3 and 4 until you can get 9k/6k springs. Then undo 3.

itskrees

iTrader: (1)

Thanks Sav for the response.

For education purposes, let's say hypothetically I don't have an aftermarket front bar and don't have the option to purchase one. Why would playing around with ride height/camber setting not be a good option to correct oversteer/understeer vs using swaybars?

Savington

iTrader: (31)

Because playing around with ride height and camber isn't going to correct the major imbalance issues you have. If you're going to run on stock sways, I would want 10 or 11k springs in front to start, and then I'd correct the balance from there. With 8/6 and stock sways, that's going to be a drift machine.

wannafbody

iTrader: (1)

Get some cheap ebay coil springs

itskrees

iTrader: (1)

Sav, from your experience what would be more neutral for track use?

1. Stock front sway and rear sway, 10k/6k

Or

2. RB tubular front sway and stock rear sway, 9k/6k

Car 1: 15x8 on 205 star specs
Car 2: 15x7 on 195 star specs

itskrees

iTrader: (1)

Alignment specs are 949 race specs/height.

Car 1 has it like that already.
Car 2 has Tein SS so hopefully I can get those specs too but not sure if I can or if its ideal since height is adjusted through preload and not through the shockbody.

wannafbody

iTrader: (1)

RB front bar and stock or MSM 14mm rear bar.

Savington

iTrader: (31)

Car 2

itskrees

iTrader: (1)

Thanks again guys.

Here is an updated list of specs for the two cars:

Car 1:
15x8 wheels with 205/50/15 star specs
RB Tubular Front Sway, OEM rear sway
9k/6k with 949 Race Alignment

Car 2:
15x7 wheels with 195/55/15 star specs
OEM front and rear sway
9k/6k with 949 Race Alignment

Do both setups look good for neutral handling? Would you keep the OEM rear sway on Car 2 or take it off?

Savington

iTrader: (31)

Think about it yourself for a second. You have two cars with the same suspension and alignment, but one has a stock sway bar and one has a huge aftermarket tubular bar. Do you think they're both going to handle properly?

Car 1 will handle like a Miata should. Car 2 will suffer from vague turn-in and general oversteer. Disconnecting the rear bar on car 2 will help, but it will not alleviate the problem.